identification, assessment and selection of environmentally sound technologies · 2011-04-28 ·...

Project on

Converting Waste Agricultural Biomass to an Energy / Material Resource

Report V

Identification, Assessment and Selection of

Environmentally Sound Technologies

Prepared by

National Cleaner Production Center Sri Lanka

February 2010

CONTENT

1. INTRODUCTION 02

1.1 Background 02

1.2 Environmentally Sound Technologies 03

1.3 Environmental Assessment Tools 03

2. SAT METHODOLOGY 05

2.1 Rationale 05

2.2 Main Features 05

2.3 Development Process 07

2.4 Key Elements 08

2.5 Basic Steps in Implementation 09

3. CONVERTION OF WASTE TO RESOURCE: SITUATION ANALYSIS 14

3.1 Baseline Data Collection 14

3.2 Stakeholder Consultation 17

3.3 Mapping and Analysis 18

4. CONVERTION OF WASTE TO RESOURCE: STRATEGIC LEVEL

ASSESSMENT 21

4.1 Introduction 21

4.2 Overview of Applications and Technology Options 22

4.3 Description of Technologies 25

4.4 Short listing of Technologies 32

5. CONVERTION OF WASTE TO RESOURCE: OPERATIONAL LEVEL

ASSESSEMNT 33

5.1 Screening of Technologies 33

5.2 Scoping of Technologies 37

5.3 Detailed Assessment of Technologies 45

5.4 Selection of Technology Option for the Pilot Implementation Project 53

References 57

Appendices 59

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1. INTRODUCTION

1.1 Background

The project on “Converting Waste Agricultural Biomass to a Fuel / Resources” implemented

in the Moneragala District, Sri Lanka is initiated with the final objective of developing a pilot

project based on a selected resource-technology combination as a mean of managing waste.

The waste materials are considered as resources than rubbish and it is intended to explore the

most appropriate ways of converting these resources to value added products or materials,

thereby minimizing the social and environmental issues arisen due to present management

practices while generating additional income to the local community. Series of activities have

been developed for the successful conduct of the project, which are broadly categorized as:

� Activity 1: Formation and manage a project team,

� Activity 2: Characterize qualitatively and quantitatively the agro-residues available,

� Activity 3: Identify potential applications/users of agro-residues including market

potentials,

� Activity 4: Identify, assess and characterize environmentally sustainable technologies

(ESTs) related to conversion of agro-residues,

� Activity 5: Select a set of most viable resource-technology combinations and rank them

based on potential of implementation and social & environmental impacts,

� Activity 6: Develop a pilot project based on a selected resource-technology combination.

The details and results of the first two activities are presented in the first progress report [1].

The agricultural residues and other biomass wastes identified as potential resources include

paddy husk, paddy straw, sawdust, banana waste and market waste. In addition, a weed grass

known as Wild Guinea Grass (Scientific name: Panicam Maximum; Local name: Ginihirassa)

is found widely spread over almost all kinds of lands in the area. The properties of these

wastes and their present generation, utilization pattern and availability are identified. Further,

future generation potentials of these sources are predicted. The technologies available for

converting the agro-residues and other wastes are highlighted.

Now, in order to select and implement the most appropriate project(s) for converting waste

agricultural biomass to a fuel / material, it is essential to evaluation each resource-technology

combination under local context with a systematic approach such that all the important

aspects are included. In fact, conversion of agricultural residues and other waste materials for

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a fuel or other value added products or materials is not a new concept. Extensive volume of

literature on this topic could be found freely and there are many attempts to implement

different types of projects in Sri Lanka. However, it is evident that the majority of the

projects could not be implemented as planed and also unsuccessful in achieving the

objectives. Such failures could be attributed to the lack of systematic approach in developing

and implementing the project activities, as well as issues with the technology choices. In fact,

use of suitable technology assessment methodology and appropriate technologies is an

essential element of a project/programme. The present project thus considered the above

circumstances and incorporated an integrated and systematic approach in technology

selection. Prior to introduce the methodology selected in the present study, basic concepts

and tools related to technology evaluation methodologies are presented the following two

sections.

1.2 Environmentally Sound Technologies

The need for promotion of Environmentally Sound Technologies (ESTs) in the context of

sustainability was recognized in the early 1990s. In particular, at the United Nations

Conference on Environment and Development (UNCED) in 1992, the need to promote ESTs

was highlighted in Agenda 21. Chapter 34 of Agenda 21 defines ESTs as those technologies

that protect the environment, are less polluting, use all resources in a more sustainable

manner, recycle more of their waste and products and handle residual waste in a more

sustainable manner than the technologies for which they are substitutes. ESTs include a

variety of cleaner production process and pollution prevention technologies, as well as end-

of-pipe and monitoring technologies. Apart from just technologies, they can be considered as

total ‘systems’ that may include knowledge and skills transfer, operating procedures, goods,

services and equipment, and also organizational and managerial procedures [3]. Many

initiatives have been developed in relation to promotion of ESTs in developing countries and

countries with economies in transition.

1.3 Environmental Assessment Tools

In parallel to the promotion of ESTs, there was a need to evolve Technology Assessment

(TA) framework to assess and evaluate environmental technologies to facilitate identification

and selection of the ‘best possible technology option’. Accordingly, International

Environmental Technology Centre (IETC), UNEP initiated the development of a

methodology for Environmental Technology Assessment (EnTA). EnTA is defined as a

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systematic procedure whereby a proposed technology intervention is described and appraised

in terms of its potential influence on the environment, the implications for sustainable

development and the likely cultural and socio-economic consequences. Note that EnTA is not

meant to replace existing environmental assessment tools such as Environmental Impact

Assessment (EIA), Environmental Risk Assessment (ERA) and Life Cycle Assessment

(LCA), and a comparison between EnTA and these tools is presented in Table 1.1.

Table 1.1: Comparison of EnTA and Other Selected Environmental Assessment Tools Feature EnTA EIA ERA LCA

Purpose Assesses implications of a technology and guides choices of technology

Identifies and predicts the env. impacts of a project, policy or similar initiatives

Estimates risks to the environment and public health

Evaluates the impacts associated with a product/ process or activity over the entire lifecycle

Scope Implications for health, safety and well being, and for natural resources and ecosystems, costs of tech. Interventions & monetary benefits

Impacts on the natural resources, ecosystems, human health, safety and well being

Assessment of risks to the environment and human health

Implications for human health, safety and well being, and for natural resources and ecosystems

Initiator Proponent of technology, investor, stakeholders

Applicant for regulatory approval

Proponent of project/initiative, investor, stakeholders

Proponent of project/initiative, investor, stakeholders

Approach A systematic, comprehensive and qualitative comparison of the pressures on the environment and the resulting impacts

Requirements often prescribed by regulatory authority, including identification of impacts, mitigation & monitoring measures

Hazard identification, dose-response and exposure assessments, risk identification

Life cycle inventory of energy &material requirements and waste produced, impact analysis and improvement analysis

Timing Scoping tool at the pre-investment stage, before the development of the full/formal proposal

Prior to decision whether or not the initiative should proceed

At any time, as determined by the initiator

At any time, as determined by the initiator

Regulatory Status

None – often used to screen options before more detailed assessment

Often required under environmental protection legislation, especially for larger projects in environmentally sensitive areas

None - may be used to give support to conclusions of assessments required under law

None – typically used by producers or consumers to assess the environmental merit of the products or activity

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The scope of EnTA is outlined with a focus on identifying specific and broader

environmental impacts of technologies. EnTA is primarily qualitative and comparative and it

looks at broader processes over technology’s entire life cycle.

More recently, further improvements to the approach in technology assessment under the

concept of sustainability are introduced and the new methodology known as Sustainable

Assessment of Technology (SAT) is developed, which received commendation

internationally [2]. This methodology, as detailed in the next part of the report, is used to

accomplish the remaining activities of the project (i.e. Activity 3 to Activity 6).

2. SAT METHODOLOGY

2.1 Rationale

Technology plays an important role in development. In fact, the development of human

society is directly linked to development in technologies to cater for diverse and demanding

needs. However, with the physical development, mankind is also facing critical challenges,

especially associated with environmental issues. It is apparent that this situation is arisen due

to the consideration of only economic factors in selecting technologies, while dissociating

social and environment factors in the process. In fact this issue is found in the prevailing

systems for decision-making in general in many countries, where economic, social and

environmental factors are considered separately at the policy, planning and management

levels. This can influence the actions of all groups in society, including governments,

industry and individuals, and has important implications for the efficiency and sustainability

of development.

The general concept of Sustainable Development is defined in addressing the above issues

where full integration of economic, environmental and social factors is envisaged. As a vital

part in the development, choice of technology too should follow the same philosophy of

addressing the economic, environmental and social factors with due emphasis [3].

2.2 Main Features

The concept of SAT is fundamentally the integration of Sustainable Development in

Technology Assessment. Therefore the essential characteristic of SAT is the sustainability,

i.e. integration of three important aspects: environmental soundness, social/cultural

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acceptability and economic feasibility. This methodology is built on existing technology

assessment framework and could be adapted to local conditions, parameters and constraints.

It uses a progressive assessment procedure through tiers on screening, scoping and detailed

assessment allowing entry points for diverse stakeholders and optimizing information

requirements. Another important characteristic of SAT methodology is that it operates both

strategic and operational levels, addressing thereby choices to be made on a more robust

basis. It is also a quantitative procedure that allows more objective assessment, sensitivity

analyses and incorporation of scenarios. Further, SAT methodology comprises of Plan-Do-

Check-Assessment milestones that incorporate feedbacks and learning encouraging

continuous improvement.

The SAT methodology can be used by different stakeholders and at different levels of

decision making. At the policy / government level, SAT can be applied for strategic decision-

making. Once decisions at the strategic level are taken, SAT could be applied at the

operational level, primarily by the technical staff, designers, and consultants, to assess

alternate technology systems. SAT methodology can be used by communities and industrial

clusters, particularly for development of centralized systems. Similarly individual

hamlets/villages and enterprises can use the SAT methodology for comparing a number of

available options for a particular need. Further, target users of SAT could include

developmental as well as commercial financing institutions that often play a key role in

funding projects and programmes that make use of various technologies.

The SAT methodology can be applied in scenarios involving technology interventions in the

context of sustainable socio-economic development. These include, but not limited to,

� End of pipe or waste management technologies and recycling programmes,

� Environmental health related programmes,

� Provision of basic services/infrastructure such as roads, power, water etc.,

� Bio-diversity management,

� Remediation / land reclamation,

� Process technology modernization (at shop floors / in industrial clusters).

The development process and the main elements in the SAT methodology are discussed in

the section sections.

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2.3 Development Process

Prior to understand the key elements in the SAT methodology, it is useful to appreciate its

development process, which will facilitate one to distinguish the essential differences of SAT

with other existing methodologies and approaches.

It is apparent that the integration of the sustainable development concept fully addressing the

economic, environmental and social factors in a technology selection process is a very

challenging task. In fact, SAT methodology has been developed through an elaborate process

of research and expert consultations, as illustrated in Figure 2.1.

Figure 2.1: Development Process of SAT Methodology [3]

The development process was started with a comprehensive literature review to understand

past developments and to study the similar technology assessment approaches (especially

related to Environmentally Sound Technologies - ESTs and Environmental Technology

Assessment – EnTA, as briefed in Sections 1.2 and 1.3). In Stage 2, strengths and weaknesses

of the current methodologies and approaches were identified with areas for improvement. In

next stage, a draft SAT methodology was developed based on generic criteria and indicators.

STEP 2 Identify Strengths and Weaknesses

of Present Approaches

STEP 1 Literature Review

STEP 3 Propose New Methodology,

Criteria and Indicators

STEP 4 Peer Review and Consultations during the Review / Workshops

STEP 5 Finalization of New Methodology,

Criteria and Indicators

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Further, the generic set of criteria and indicators were customized for sector specific

applications covering number of important areas including solid waste management. The

generic methodology, criteria and indicators as well as sector-specific customization were

peer reviewed in Stage 4. Finally, the draft methodology, criteria and indicators as well as

evaluation were reviewed by experts to obtain the improved methodology. This elaborative

and structured process was able to come up with a methodology with stipulated features of

sustainability.

2.4 Key Elements

Number of key elements could be identified in the SAT methodology. These include the

following [3]:

� Assessment at strategic and operational levels

The SAT methodology incorporates assessments at both strategic level and operational level,

whereas other approaches in technology assessments concentrated primarily on operational

level. However, strategic considerations are important as these encourage a focus on situation

analyses, thus discussing broader issues such as institutional, financial, policy/planning

related aspects, rather than the technology alone.

� A tiered process including Screening, Scoping and Detail Assessments

The technology assessment is performed in a tiered process of screening, scoping and detail,

so that comprehensive information collection becomes essential only for short-listed

technology systems. The obviously non-feasible technical options are eliminated at the

screening stage, and then subjected to a second round of elimination through scoping process.

Scoping uses selected criteria that use more of qualitative or readily available quantitative

information for the evaluation. At the detailed assessment tier, the systems that pass through

scoping stage are subjected to a more rigorous evaluation using additional criteria. This tiered

process reflects progressiveness and optimized information requirement.

� Criteria and indicators

The most important element in the assessment process is the identification of appropriate

criteria and indicators. In the framework of sustainability, a set of generic criteria and

indicators are developed under the broad categories of technological, environmental, financial

and socio-cultural, giving due consideration to the risks and restrictions associated with the

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technology choices. Further, development of customized criteria and indicators applicable to

specific situations is required to ensure the rationality.

� Assessment of the technology with system approach

Any application of a technology represents a system and thus comprised of number of

individual technologies. Operational behaviour of a technology depends on the other

technologies taking part in the system and therefore individual optimization is not

appropriate. The SAT methodology recognizes the interdependencies within technology units

by putting an emphasis on the “system” rather than the individual technology.

� Framework for quantification and aggregation method

In order to facilitate decision making, the qualitative assessments based on selected criteria

and indicators are converted into quantitative figures through a quantification and

aggregation framework in the SAT methodology. The key elements in this approach are the

weights to be assigned to criteria and scores to be assigned to indicators. This process also

facilitates sensitivity studies and scenario building so that more flexible and dynamic results

could be obtained.

� Information, expertise and participation driven approach

The SAT methodology employs a number of tools and techniques, such as Information driven

benchmarking, Expert opinions and Participatory assessment by stakeholders, to facilitate the

assessment process. These tools are used in a mix and at different degrees depending on the

level of assessment – strategic or operational.

2.5 Basic Steps in Implementation

The SAT Methodology comprised of a number of basic steps that follow typical Plan-Do-

Check-Act cycle of continuous improvement. These steps are illustrated in Figure 2.2 and a

brief description of each key step is given in this section [3].

� Situational analysis

The purpose of technological intervention is usually to address a prevailing issue or problem.

Therefore the whole cycle essentially starts with the problem definition followed by a

situation analysis. The situation analyses will include baseline data collection, stakeholder

consultation, mapping and analyses as necessary. A situation analysis facilitates to identify

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the relevant issues as well as assess their affects and importance. Further, situation analysis

reveals the reasons behind successes and failures of earlier interventions and could help in

scenario building. Finally, situation analyses leads to setting of targets that should be

addressed by the proposed technology intervention.

Figure 2.2: Basic Structure of SAT Methodology [2]

� Strategic level assessment

At the strategic level assessment of SAT methodology, planners, decision-makers, etc. are

required to brainstorm and study various options at the policy and plan levels. The outcomes

of the strategic level assessment are very important on the following four accounts:

- The decision at the strategic level is the critical factor in the subsequent identification

of technology system options.

- Strategic decisions may help to develop customized criteria and indicators (possibly

with weights across criteria) from a generic list for the decisions to be taken at

operation level.

- Strategic level assessment facilitates short-listing and identification of suitable

technology systems for the situation at hand.

Preferred Technology Options

Implementation

Anticipating future scenarios

Detailed Engineering Design and Costing

Monitoring / Performance Evaluation

Issues to be Addressed / Problems to be solved

Situation Analysis

Define Targets

Strategic level Assessment

Operational level Assessment

Screening

Scoping

Detailed Assessment

Public Information / Consultation

Customized Criteria and Indicators by Considering

Environment, Social and Economic Aspects

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- The outcomes of the strategic level assessment can also provide some leads about the

possible future scenario building, which can influence the decision regarding the

technology choice.

In the strategic level assessment, the involvement of key stakeholders plays the main role,

followed by expert opinion. The technology information plays the least role in this level of

assessment.

� Operational level assessment

Once the strategic level options are finalized, the SAT moves on to a more operational level

assessment. Based on the problem definition, situation analysis and the outcomes of strategic

level assessment, a set of potential technology systems is identified, which are then subjected

to further rigorous three-tiered assessment (i.e. screening, scoping and detail). Depending

upon the specific situation and needs, the stakeholder group could adopt the set of generic

and/or sector specific criteria proposed at the strategic level without any changes. However,

in some situation-specific cases, it may be essential to revisit the generic set of criteria, and

modify or add some specific criteria. At this level, the assessment of available technology

systems is performed by engineers, technical staff etc. If the SAT methodology is to be

applied at a community or enterprise level, the earlier stage of strategic level may be skipped

and stakeholders can start with the operational level assessment. The levels of expert opinion

and technology information are the highest in the operational level assessment.

� Screening

At this stage, the short-listed system options first undergo screening using criteria in tier 1.

The tier 1 criteria yield only an objective Yes/No type answer and hence, those options that

do not qualify one or all the conditions, then get automatically eliminated.

� Scoping

At Tier 2, the short-listed system options from Tier 1 go through a comprehensive scoping

assessment. This assessment is more of qualitative in nature and usually the ratings of the

options are assigned as low, medium and high. The stakeholders are required to assess the

various technology system options against the generic and customized criteria and indicators

using an appropriate standard methodology, preferable simple weighted sum method. The

weighted sum method is a quantitative method for screening and ranking available

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technology options against multiple criteria. This method provides a means of quantifying

and emphasising the important criteria over the others. Firstly, the set of criteria is arranged

in order of priority and then weights for each criterion are assigned. Once the weights have

been assigned for each criteria, each available technology option is to be rated against each

criterion using a scale. Finally, the rating of each option for a particular criterion is multiplied

by the weight of the criterion. These values and calculations could be presented in a matrix

form (i.e. weighted sum matrix). An option's overall rating is the sum of the products of

rating times the weight of the criterion.

In the process of developing the weighted sum matrix, it can be seen that at times the

difference between the total scores for some options may be very marginal. Therefore, during

the group discussion, it is essential to try various iterations to check the sensitivity of the

matrix to such changes. Another limitation of weighted sum matrix is that at the end of the

process, users get an aggregated score for each technology option and it is not possible to see

as to which were the dominating criteria amongst all. To overcome such a situation, it is

recommended that the total scores for each of the technology options be represented by a star

diagram. Such a diagram can illustrate the influence of various factors in the final scores. In

some cases, for instance, the total score earned by a technology system may be the highest,

but this could be due to the contribution of non-priority criteria. This will require revisiting

the weights and scores to ensure that the total scores are in accordance with the priorities

defined by the stakeholder groups, and thus lead to a more rational and acceptable decision.

The final outcome of scoping assessment the selection of technology options with the best

overall ratings for the detailed assessment in tier 3. In this process a number of options with

lower overall ratings is eliminated.

� Detailed assessment

The selected list of technology options in the scoping assessment undergoes a detailed (Tier

3) technical and economic feasibility assessment. This level of assessment is rather situation-

specific and the suggested criteria at this stage demand a lot more detailed and quantitative

information to facilitate decision making. Using the information, the stakeholder group

should once again prepare a new weighted sum matrix or revise the existing one. It is

possible that the rating of the technology systems may change due to the new scoring based

on available information.

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� Anticipating future scenarios

If the current situation changes, the technology system choice made could be found to be

inadequate or inappropriate. Therefore, it is required to simulate certain future scenarios and

ensure that the outcome of the current exercise is robust enough and confirm that the

suggested technology system can stand the test of time. For new scenario, the weights as

well as scores could be different and this may alter the choices to be made.

� Decision-making on preferred technology options

Although some technology system may score the best in the current context, while simulating

different scenarios, the same option may not qualify as the best. Conversely, an option that

does not qualify due to lower scores in the current situation may probably top the list, with

appropriate technology transfer/adaptation or capacity building efforts or change in policies/

regulations. This is an important aspect to be considered before discarding the low-scoring

options. Hence a careful scrutiny of the options, going beyond the mere numbers, is required.

� Implementation / monitoring

Once the decision is made on the best technology system to be used as the intervention for

the problem, it would then form the basis for further steps such as detailed engineering

design, tendering, actual construction and commissioning. It is also important to continuously

monitor and evaluate the technology system during its operational phase to ensure that it is

meeting the desired objectives. As the conditions and environment under which the

technology intervention operates is dynamic and there would be increasing demand for better

technical and environmental performances due to more stringent regulations, provision for

continuous improvements should be incorporated in the system.

� Feedback loop

The SAT methodology also makes provision to use the experience gained through the

implementation of the present project for either duplication of the project into other locations

or for carrying out situational analysis of similar projects in future, and hence can help in

making better informed decisions. This could be realized by recording the outcomes of the

monitoring and evaluation and reporting them to the stakeholder groups, especially

government agencies, planners and other decision makers. In particular, the performance of

the technology under the real local conditions would be very useful information. Thus

feedback can help for future decisions at both strategic as well as operational level.

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3. CONVERTION OF WASTE TO RESOURCE: SITUATION ANALYSIS

3.1 Problem Definition

Lack of proper waste management practices could lead to severe social and environmental

problems. Further, dispose of such wastes could also be considered as a lost in useful

resources. Agricultural residues could be considered as one such waste category, especially in

the rural areas in the country. One of the most appropriate options for waste management is

to implement technological interventions to convert wastes to value added product such as

energy and/or material. Yet, at present there is a lack of such projects that are in successful

operation in Sri Lanka. Therefore identification of most appropriate technology option for a

specific situation / waste and implementation of a pilot project are required for the promotion

of the concept. As most of the aspects and issues related to waste management are site

specific, development and implementation of a pilot project by selecting a potential region /

site is required. The present study is developed to implement a pilot programme of utilizing

waste agricultural residues for useful application (energy / materials) in Moneragala District

in Sri Lanka.

3.2 Baseline Data Collection

The baseline data on types, generation and availability of agro-wastes were presented in the

first progress report, a summary of which is presented in this section [1]. The analysis was

restricted to the two district secretariat (DS) divisions Moneragala and Buttala in the district.

The waste materials considered include agricultural residues as well as other waste types

generated within the area that have significant generation potentials, as listed below:

- Paddy Straw

- Paddy Husk

- Sawdust

- Market Waste

- Banana Waste

- Wild Guinea Grass

In addition, though not considered for the present analysis, availability of coconut husks and

maize residues is also noticed. Present waste management practices (including present usage

and technologies) and related issues were also analysed. Table 3.1 presents the agricultural

residues and other waste materials identified in the selected area of study, including the

availability.

Table 3.1: Availability of Residues DS Division Source Residue Availability Remarks

Paddy Cultivation Paddy Straw(1) 10,041 t/yr 70% collection efficiency (15% - return to field as fertilizer and further 15%- losses)

Paddy Milling Processing

Paddy Husk 1,721 t/yr Considered as a potential source for the present study. 80% for the present project, 90% collection efficiency (20%-other uses, 10%-losses)

Sawmills Sawdust 162 t/yr Will not be considered for the present study, as the majority of the saw mills are in Buttala DS division, but the technology may be used. 90% collection efficiency, 10%-other uses

Public Markets Market waste 364 t/yr 6 tractor loads of market waste per wk, 80%- biodegradable organic waste in market waste.

Monaragala DS

Grassland Wild Guinea Grass(1)

5,673 t/yr Estimation is based on total yield of 18,909 t/yr at 20% moisture content and 30% collection efficiency (50% remains in the field, 20% for other uses) [4] (see Appendix A for more details of the estimation).

Paddy Cultivation Paddy Straw(1) 31,415 t/yr 70% collection efficiency (15% - return to field as fertilizer and further 15%- losses)

Paddy Milling Processing

Paddy Husk 970 t/yr 90% collection efficiency, 80% is allocated for the future potential expansions in the brick industry,

Sawmills Sawdust 648 t/yr Considered as a potential source for the present study, 90% collection efficiency, 10%-other uses

Public Markets Market waste 180 t/yr Potential is not quantified yet, but need is apparent. Banana Cultivation

Rejected Banana

4,500 t/yr Quantification is based on preliminary information, Generated in the processing industry, Not considered for the present study, but need for management of waste. 15 t per day, 300 working days.

Buttala DS

Grassland Wild Guinea Grass(1)

8,353 t/yr Estimation is based on total yield of 27,845 t/yr at 20% moisture content and 30% collection efficiency (50% remains in the field, 20% for other uses) [4] (see Appendix A for more details of the estimation).

Coconut Plantation Coconut husk - Potential is not quantified yet, but its significant is apparent. Other DS Divisions Maize Plantation cob & stalk - Potential is not quantified yet, but its significant is apparent.

Note (1): These residue types were not given high priority in the present project, but could be major resources in the future.

The percentage availability of the above wastes in each DS division is presented in Figure 3.1

(a) and (b). The estimation of the generation potential and availability of wild guinea grass is

not a simple task and another research group carried out a detailed study on this aspect, the

findings of which are briefed in Appendix A.

(a) Monaragala D.S. Division

(b) In Buttala DS division

Figure 3.1: Availability of wastes in percentages by weight

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Note that, in both DS divisions, paddy straw and wild guinea grass contribute to the majority

of the waste generation, which are field based residues/wastes. Both of these waste categories

were not given a high priority in the present study as there are uncertainties/difficulties in the

accessibility and collection, but could become high potential resources in future.

3.3 Stakeholder Consultation

A stakeholder consultation workshop was conducted to get the feedback on the data

collected, planned activities and also to identify the needs and potential applications. The

stakeholders participated in the workshop include

- Policy makers (local government, Chamber of commerce officials),

- Technology suppliers,

- Service providers,

- NGOs,

- Waste generators,

- Waste users (Present and Potential users) / Industrialists,

- Researchers.

After the inauguration session (during which the general objectives of the project and the

specific objectives of the workshop were briefed), progress of the project was presented to

the participants. The presentation comprised of information of generation and availability of

the waste categories, technology options available for the conversion of each waste to a value

added product / material, and also the present and potential applications. The presentation

was followed by a session for clarification and discussion. The aspects discussed during this

session could be categorized under the followings:

- Sustainable supply and availability of paddy husks,

- Real potential of paddy straw as a source in future,

- Future generation potential of sawdust,

- Technology options available for sawdust and market waste,

- Technology options available for applications such as drying of vegetable / food

products,

- Improved technology options available for present applications of paddy husk,

particularly brick making and tobacco processing.

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The final session was devoted to assess the prevailing stakeholder-based waste management

system in Moneragala district. Principles of the assessment of waste management system

could be identified as follows:

- Analyzing the availability, enforcement and impact of regulations and economic

tools;

- Assessing the institutional framework, resources and jurisdictions for current

institutions;

- Analyzing the efficiency and effectiveness of collection, treatment, usage and disposal

technologies and associated infrastructure;

- Analyzing the prevailing financial mechanisms including pricing, taxes, levies,

funding mechanisms etc.

- Understanding the role of different stakeholders at different levels of solid waste

management chain; and

- Identifying the gaps and opportunities.

In particular, feedback from the participants was obtained on prevailing technologies for

waste management in the areas of collection, transportation, pre-treatment, recycling/

recovery and disposal, under technical, economic, environmental and social aspects.

3.4 Mapping and Analysis

The findings of the above activities under the situational analysis could be used to identify

the issues associated with the present waste management systems and assess their

significance. Further, those findings would lead to setting of targets should be addressed by

appropriate technology interventions. Table 3.2 presents issues identified in the present study

together with the target set for each issue, under each waste stream.

Table 3.2: Issues and targets of the waste management system Waste Issues Target

Present policies resulting dumping of the total amount generated to the field resulting adverse effects on environment as well as yield of the crop itself, and loss of potential resource.

Use of relevant technology to convert waste to energy or material together with policy level interventions.

Increase in generation of waste in future Dissemination of technology for duplication or that capable of up-scaling

Paddy Straw

Lack of availability of appropriate Introduction of appropriate

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technologies / local expertise technology/technologies to suit local resources and expertise

Low bulk density resulting a decrease in the value as a raw material (e.g. “fuel value”)

Use of relevant technology (e.g. bailing, briquetting, pelletizing, pressing) to upgrade the value as a raw material

Table 3.2: Issues and targets of the waste management system (Cont...) Waste Issues Target

Inappropriate practices of dumping of excess amount resulting adverse environmental and health impacts and loss of potential resources

Use of relevant technology to convert waste to energy (process heat)

Improper practices of collection resulting adverse environmental and health impacts and loss of potential resources

Incorporation of appropriate design features for the present collection system following national regulatory standards

Use of conventional technologies for conversion to energy (brick making, drying) resulting low quality products, higher energy cost, waste of resource, and higher level of pollutions.

Introduction of improved technology and/or process modification to increase energy efficiency

Lack of availability of appropriate technologies / local expertise

Introduction of appropriate technology to suit local resources and expertise

Low bulk density resulting a decrease in “fuel value”

Use of relevant technology (e.g. briquetting) to upgrade the fuel value

High ash content leading to problem associated with dumping

Utilization of appropriate waste management system / identification of potential usages


Lack of land area for dumping Use of relevant technology to convert waste to energy

Paddy Husk

Public protest on open dumping / open burning

Introduction of appropriate technology/technologies to convert waste to energy addressing social issues

Inappropriate practices of dumping of waste resulting adverse environmental and health impacts and loss of potential resources

Use of relevant technology to convert waste to energy (process heat)


Introduction of appropriate technology (e.g. briquetting, pelletizing) to improve the fuel value

High moisture content resulting a decrease in “fuel value” and fast decomposition

Incorporation of appropriate pre-treatment process (i.e. drying) to improve the fuel value

Sawdust

Improper practices of collection resulting contamination of sand

Incorporation of appropriate design features for the present collection system

19




Public protest on open dumping Introduction of appropriate technology to convert waste to energy addressing social issues

Table 3.2: Issues and targets of the waste management system (Cont...) Waste Issues Target

Inappropriate practices of dumping of waste resulting adverse environmental and health impacts

Use of relevant technology to convert waste to energy (biogas generation for process heat)





Market Waste

Public protest on open dumping Introduction of appropriate technology/technologies to convert waste to energy addressing social issues

Extensive growth as a weed resulting adverse effects on agriculture / useful land

Use of relevant technology to convert waste to energy or material

Lack of availability of appropriate technologies / applications

Introduction of appropriate technology to suit local requirement / application

Difficulty in harvesting / cutting Incorporation of appropriate design features for the harvesting system


Introduction of appropriate technology (e.g bailing, briquetting, pelletizing) to improve the fuel value

Wild Guinea Grass

High moisture content resulting a decrease in “fuel value”

Incorporation of appropriate pre-treatment process (i.e. drying) to improve the fuel value

Inappropriate practices of dumping of waste resulting adverse environmental and health impacts

Use of relevant technology to convert waste to energy (biogas generation for electricity generation)




Banana Rejects

High moisture content resulting a decrease in “fuel value”

Introduction of a technology that is not sensitive to high moisture content (e.g. biogas generation)

Above analysis on issues and targets related to waste management in Moneragala district

clearly indicates the need for diverse spectrum of technology options, for example covering

20

technologies related conversion of waste to energy, fuels and materials, as well as

technologies related to simple physical conversions such as densification and drying.

Although there is limited number of such technologies in operation locally, extensive

developments and promotion of ESTs could be found in international level initiatives and

programmes. It also demands for adaptation of technologies to the local conditions.

4. CONVERTION OF WASTE TO RESOURCE: STRATEGIC LEVEL

ASSESSMENT

4.1 Introduction

As highlighted earlier, conversion of agricultural residues to energy, fuel or value added

material through appropriate technology intervention is not only a sustainable way of waste

management but also could be an economic activity that contributes to the development of

the local community. Usually direct usage waste materials including agricultural residues for

a useful application is not feasible due to some of their inherent properties including low

density, higher moisture level and physical characteristics. These features also affect

adversely the effort and cost for transportation, handling and storage. Therefore, prior to the

usage for end-use activities to some kind of beneficiation (i.e. conversion from its primary

form into a more convenient form) is needed to improve their relevant properties. These

beneficiation processes may involve a simple physical processing, densification, drying, or

upgrading to a variety of convenient chemicals or fuels.

ESTs relevant to the above requirements have been developed and practiced in different parts

of the world and information on those is available in many sources of literature. For example,

United Nations Environment Programme - UNEP (partnered with Development Academy of

the Philippines - DAP) has developed a compendium of biomass waste conversion

technologies (conversion to both energy and material) under the project titled “Using

Agricultural Biomass Waste for Energy and Material, Resource Conversion and GHG

Reduction” (the major outputs of which could be accessed online [5]). A section on biomass

conversion technologies was included in the first progress report of the present project [1].

Further literature sources ESTs were referred to gather more information related to the

specific technologies selected in the present study.

Other sources technology reviews referred in the above regard include a review of selected

biomass energy technologies covering gasification, combustion, carbonization and

21

densification [6], a global review on biomass densification with emphasis on developing

countries [7], a field document on technology and practices of biomass briquetting [8], an

information service on biogas technology covering biogas basics, application and product

development, costs and benefits, and biogas programme implementation [9], a report on

system approach to biogas technology [10], a review paper on biomass gasification in Sri

Lanka [11], an evaluation report on solid waste conversion technologies [12] and a review

report on technologies for energy use of rice straw [13]. Other literature sources on more

specific technology/plant were also referred and are indicated with the relevant text.

4.2 Overview of Applications and Technology Options

Based on the finding of the activities under situational analysis and the information on the

available ESTs, a list of applications and appropriate conversion process relevant to each

waste stream / residue was identified, as listed in Table 4.1. The remarks column is

introduced to present the overall observations of each application and conversion process,

which will facilitate to rank the technology options. Among the applications presented in the

table, thermal energy generation from agro-residues for process heating applications is

appeared to be more attractive than electricity generation options (both grid and off-grid).

Further, small scale applications are seemed to be at a higher priority compared with large

scale applications as the direct positive impact on the local community through fulfilling their

energy needs (especially for small scale local industry) is more.

Table 4.1: Overview of Technology Options Residue Application / (Process) Remarks

Value addition to the residue as a fuel/ (Briquetting)

- Increase in density and change in physical form diversify the applications and increase the fuel value (E.g.: Application – Tea Industry, Fuel value > 15 Rs/kg)

- Although the technology is not at the low- end, local manufacture / fabrication is possible

Value addition to the residue as a fuel/ (Charcoal making)

- Small scale / domestic level technology

Paddy Husk

Domestic cooking / (Direct combustion)

- At present, fuel wood is abundantly available in the area for cooking, and usage of this technology seems to be not viable.

- This is a small scale application and simple technology. ESTs are available at local as well as regional levels.

22

Process heat generation for vegetable and fruit drying / (Direct combustion – Indirect Heating)

- Available, but the technology is conventional - Very relevant to the local community and

could contribute to the development of local industry / agriculture.

- Local/regional level ESTs are available and complete local design/fabrication is possible.

Process heat generation for Brick making / (Direct combustion – Direct Heating)

- Available, but the technology is conventional. - There is a need as well as potential for the

introduction of an appropriate EST. Table 4.1: Overview of Technology Options (Cont...)

Process heat generation for tobacco curing / (Direct combustion – Indirect Heating)

- Available, but the technology is conventional. - Some technology interventions were attempted

but need further development. Grid electricity generation / (Direct combustion – Steam Turbine)

- As there is an increasing interests on large scale biomass based electricity generation, this could be a very viable solution in the future.

- This is a large scale operation and the technology should be acquired from a regional country

- May not be a viable option for the pilot plant to be developed under the present project.

Off-grid electricity generation / (Gasification – IC Engine)

- This technology, with fuel-wood as the source, is becoming popular under rural electrification programmes, and could be adapted for paddy husk too (at least co-firing with fuel wood).

- The initial cost is high and donor funding is required to implement.

- Although some part-manufacture is possible locally, technology needs to be imported.

Conversion to cement extender / (Carbonization)

- Presently the technology is not available locally.

- Should be coupled with an energy application to recover the thermal energy loss.

Paddy Husk

Fuel extraction – Ethanol / (Fermentation and Distillation with paddy straw)

- Immerging technology and at present not available locally.

- Relatively complex process, but the value addition is quite high.

- Probably viable in large scale and suitable for future.

Value addition as a fuel / (Baling)

- More applicable for large scale fields with mechanization of the process.

- Potential markets should be identified (e.g. thermal / electricity generation plants).

Cooking and Lighting / (Biogas Generation)

- Existing application practiced in domestic / small farm level, and the technology is available locally.

- Could be mixed with other waste types too.

Paddy Straw

Electricity Generation / (Gasification–IC Engine)

- Same remarks as in Paddy Husk

23

Conversion to material / (Paper pulping)

- Non-energy application with higher value addition

- Technology does exist but need more popularization / dissemination.

Fertilizer / (Composting) - Very relevant to the local community practicing agriculture

- Could be mixed with other waste types too. Fuel extraction – Ethanol (Fermentation and Distillation with or without husk)

- Same remarks as in Paddy Husk

Table 4.1: Overview of Technology Options (Cont...) Value addition to the residue as a fuel / (Briquetting / Pelletizing)

- Increase in density and change in physical form diversify the applications and increase the fuel value.

- Although the technology is not at the low-end, local manufacture / fabrication is possible.

Domestic cooking / (Direct combustion)

- At present, fuel wood is abundantly available in the area for cooking, and usage of this technology seems to be not viable.

- This is a small scale application and simple technology. Local as well as regional level ESTs are available.

Sawdust

Manufacture of particle boards/Medium fibre density board (Densification)

- Relatively complex process, but the value addition is quite high.

Cooking and lighting / (Biogas generation)

- Existing application practiced at community / municipality level, and the technology is available locally.

- Local manufacture / fabrication is possible. Off-grid electricity generation /(Biogas generation – IC Engine)

- This technology, with fuel-wood as the source, is becoming popular under rural electrification programmes, and could be adapted to biogas too.

- The initial cost is high and donor funding is required.

- Although some part-manufacture is possible locally, technology needs to be imported.

Market waste

Fertilizer / (Composting) - Very relevant to the local community practicing agriculture

- Could be mixed with other waste types too. Banana Rejects

Grid electricity generation (Biogas generation – IC Engine)

- High generation of waste could be managed by this technology / application

- As there is an increasing interest on large scale waste to energy (electricity) projects, this could be a very viable solution.

- May not be a viable option for the pilot plant to be developed under the present project due to its scale, but the industry may implement by their own resources if the appropriate technology is introduced.

24

Off-grid electricity generation (Biogas generation – IC Engine)

- Existing application practiced at community / municipality level, and the technology is available locally.

- Local manufacture / fabrication is possible. Value addition to the residue as a fuel / (Briquetting)

- Same remarks as in paddy husk.

Value addition to the residue as a fuel / (Baling)

- Same remarks as in paddy straw. - May not be viable of small scale operation.

Wild Guinea Grass

Conversion to material (Animal fodder)

- This is practiced at large scale industrial level and .possible to adapt to small scale.

4.3 Description of Technologies

It is evident, from the list of applications and related conversion processes presented in Table

4.1 above, that several varieties of technological options are needed to address the waste

management issues of the selected areas in the Moneragala district. Obviously,

implementation of all these technological interventions simultaneously is not only practicable

but also meaningless as the there would be varying degree of technical feasibilities, resource

requirements, outcomes and impacts, barriers, etc., among them. Especially, as the present

project works within limited resources and time frame, it is important to identify a set of

more appropriate technology options through a simple but fail-safe ranking process, prior to

conduct a detailed analysis to select the optimum option(s). In order to facilitate such ranking

process, in addition to the information provided in Table 4.1 above, more information on the

each technology in terms of the present status, capacity range, and other key technical

parameters is needed.

Table 4.2 presents descriptions of technology options available for each residue and

application. The information provided includes the type of equipment / devices, their capacity

ranges, present level of technology development, and also a remark column to provide

additional considerations, if any. The level of technology development is categorized under

three broad groups as Commercial level (C), Pilot Demonstration level (PD) and Research

level (R), which is the main criteria considered in the present study to eliminate or select a

given technology option. The technologies at research and pilot demonstration levels are

eliminated prior to conduct detailed analysis.

The capacity range for a given technology is denoted by different parameters, which are

basically the norms utilised by relevant industry. For example, these parameters include, in

the case of applications related to conversion to energy: rated energy output or energy input,

rate of material input, amount of product processed, etc., and in the case of conversion to fuel

25

or material: the rate of material processed, physical size, output rate, etc. Note that, in the

case of energy applications, the units kWth and kWe refer to the rate of thermal energy and

electrical energy, respectively in kilo watts.

Additional information including some performance indices are given under remarks column.

Table 4.2: Description of Technology Selection Residue Application Process /

Technology Equipment Capacity Range

R PD C Remarks

Value addition to the residue as a fuel for process heat generation in industry

Densification / Briquette making

Screw type briquetting machine

Typical Capacity Range: 100 – 250 kg/hr Selected Capacity: 200 kg/hr

X Briquette density = 0.8 – 1.2 t/m3, Energy Requirement = 150 – 225 kWh/t.

Value addition to the residue as a fuel for small scale heat generation

Carbonization / Charcoal making

Small scale charcoal kiln

Typical Capacity: Input - 6 kg/load; Output - 2 kg/load

X Low environment performances; Need hand operated extruder type briquetting machine for densification.

Direct combustion

Paddy husk cook stove

Heat Generated: 4.0 kWth Fuel input = 1.0 kg/load

X Overall efficiency - 20% Combustion efficiency - 80% Fuel input rate = 1.3 kg/hr

Gasification Paddy husk gas stove


X Overall efficiency - 15%; Combustion efficiency - 80%; Fuel input rate = 1.75 kg/hr

Domestic Cooking

Carbonization Charcoal making cook stove


X Overall efficiency - 10%; Charcoal output = 0.6 kg/load Fuel input rate = 1.8 kg/hr

Process Heat Generation for lime drying/smoking

Direct combustion / Direct heating

Paddy husk stove cum cabinet dryer

Product Input = 200 kg/batch Heat Generated: 5.0 kWth Fuel input = 72 kg/load

X Efficiency of Drying = 60%; Efficiency of Stove = 65%; Fuel input rate = 2 kg/hr

Paddy Husk

Process Heat Generation for vegetable / fruit drying

Direct combustion / Indirect heating

Paddy husk stove cum tray dryer

Product Input = 100 kg/batch Heat Generated: 8.0 kWth Fuel input = 54 kg/load

X Efficiency of Drying = 40%; Efficiency of Stove = 65%; Fuel input rate = 3 kg/hr

27

Table 4.2: Description of Technology (Cont...) Selection Residue Application Process / Technology Equipment Capacity Range R PD C

Remarks

Process heat generation for brick making


Improved brick kiln

Estimated capacity>100 kWth X Need further research to develop the technology

Process heat generation for tobacco curing


Tobacco barn

Selected capacity ~ 5.0 kWth X Need modifications to existing technology; Can be implemented in commercial basis

Grid electricity generation

Direct combustion & external combustion / Steam cycle

Boiler Steam turbine

> 500 kWe

X Overall Efficiency – 25%; May not be viable to implement under this project due to limitation in resources and time

Off-grid electricity generation

Gasification / Four Stroke Spark Ignition

Gasifier cum Internal combustion engine

< 30 kWe

X Overall Efficiency – 15%; Commercially proven technologies not available. Operational issues with gasifier

Conversion to cement extender

Carbonization Basket burner Input - 20 kg paddy husk Output – 4 kg ash /batch

X Considerable loss in energy unless a recovery system is used; Limited market locally

Paddy Husk

Fuel extraction (Ethanol)

Fermentation and Distillation (with or without husk)

Bio-refinery system

> 100 t/day of feed stoke > 30,000 l/day of ethanol (Commercial Systems)

X 1 t biomass mix yields about 300 l of ethanol and 150 kg of silica/sodium oxide.

28


Remarks

Value addition as a raw material for variety of applications

Baling / Densification Straw Baler

Wide range; Selected capacity: Field capacity - 0.25 ha/h Rate – 100 bales/hr

X Not very viable for small scale operations; Bale Size (d×w)- 80×45 cm Bale weight – 20 kg Need to create local market.

Straw boards manufacturing

Series of processes including baling, classifying, drying, blending, densification, sanding, etc

Series of equipment including press or extruder

Wide range; Selected capacity – 2 t/day of material input Output – 60 no. of panels of size 0.8m × 2.5m × 5 cm

X Density of straw panel – 0.7 t/m3.

Paper making Paper pulping Hand tools and utensils

Small scale X Low-end technology but high social impacts in rural areas.

Cooking/Lighting

Anaerobic digestion / Biogas Generation

Biogas digester– Continuous type

Typical capacity range: 2 to 100 kg/day of waste Tank volume 1 to 15 m3. Selected capacity: 40 kg/day of waste Tank volume 5 m3

X Biogas yield – 3.8 m3/day; Suitable for cooking and lighting for a family of 5 members.


Anaerobic digestion / Four Stroke Spark Ignition

Biogas Digester & Internal combustion engine

Typical capacity range: > 200 kg/day of waste Selected capacity: 500 kg/day of waste Plant capacity - 2.2 kWe

X Biogas yield – 47 m3/day, Could generate about 50 kWh/day, Energy conversion efficiency Digester – 13.5% Engine – 20%

Paddy Straw

Fertilizer

Composting

Only hand tools for the handling of waste

No specific capacity range X Low level technology. Other materials required.

29


Remarks

As animal fodder

Sizing / Mixing & Densification

Densified TMR Block Making Plant with TMR Mixer

Typical Capacity: 65 – 75 blocks per hr 12 – 15 kg/block Bale size:40×50×15 cm Rated power 15 kWe

X Densified Total Mixed Ration (DTMR) Block is made with straws, concentrates and minerals blends.

Paddy Straw


Fermentation and Distillation (with/ without husk)

Bio refinery system

> 100 t/day of feed stoke > 30,000 l/day of ethanol (Commercial Systems)

X 1 t biomass mix yields about 300 l of ethanol and 150 kg of silica/sodium oxide.




X Briquette density: 0.8–1.2 t/m3, Energy Requirement: 150 – 225 kWh/t.


Densification / Pelletizing

Pelletizing machine (Roller and Die Press)

Typical Capacity Range: 1 – 30 t/hr Selected Capacity: 1 t/hr

X Pellet size: 5 – 15 mm diameter, 30 mm length; Energy Requirement: 50 – 200 kWh/t Less reliable supply of waste Market response is uncertain

Domestic cooking

Direct combustion for cooking

Improved saw dust cook stove with multi-fuel capability


X Dissemination of this technology will enhance options for managing agro-waste, diversification of application

Saw Dust

Manufacture of Particle boards

Series of processes including size reduction, screening, drum chipping, resin blending, drying, mat formation, pressing, cooling, sanding, etc

Series of equipment including chipper and press

Typical Capacity Range: > 40 m3/day output

X Density of particle board – 0.45 t/m3.

30


Remarks

Saw Dust

Manufacture of Medium density fibre board(MDF)

Series of processes including size reduction, cooking, grinding, resin blending, drying, mat formation, hot pressing & curing, Sizing & sanding.

Series of equipment including chipper, boiler, grinder, blender, press.

Typical Capacity Range: 120 to 1000 m3/day output

X Density of MDF – 0.75 t/m3.

Cooking and lighting

Anaerobic digestion / Biogas Generation


Selected capacity: 500 kg/day of waste Tank volume 60 m3

X Biogas yield – 47 m3/day, Sufficient for cooking and lighting for 15 families. Energy conversion efficiency Digester – 13.5%

Off-grid Electricity Generation

Anaerobic digestion / Four Stroke Spark Ignition

Biogas Digester & Internal combustion engine

Selected capacity: 1 t/day of waste Plant capacity – 4 kWe

X Biogas yield – 95 m3/day, Could generate about 100 kWh/day, Energy conversion efficiency Digester – 13.5% Engine – 20% Less reliable supply of waste

Market waste

Fertilizer Composting Only hand tools for the handling of waste

No specific capacity range Selected capacity: 1 t/day of waste

X Low level technology. Need proper operations.

31

Table 4.2: Description of Technology (Cont...) Selection Residue Application Process /

Technology Equipment Capacity Range

R PD C Remarks

Off-grid Electricity Generation

Biogas generation for off grid electricity

Biogas Digester Internal combustion engine

Selected capacity: 1 t/day of waste input Plant capacity – 4 kWe Biogas yield – 95 m3/day

X Could generate about 125 kWh/day, Energy conversion efficiency Digester – 13.5% Engine – 20% Reliable supply of waste

Banana Rejects

Grid Electricity Generation

Biogas generation for grid electricity (net metering)


Selected capacity: 15 t/day of waste Plant capacity – 75 kWe Biogas yield – 1500 m3/day

X Could generate about 2MWh/day, High potential for energy generation. Finance by the company, technology transfer through the project.

Baling / Densification

Straw Baler

Wide range; Selected capacity: Field capacity - 0.4 ha/h Rate – 200 bales/hr

X





Densification / Pelletizing

Pelletizing machine (Roller and Die Press)

Typical Capacity Range: 1 – 30 t/hr Selected Capacity: 1 t/hr

X

Value addition as animal fodder


Densified TMR Block Making Plant

Typical Capacity: Refer that in paddy straw

X

Wild Guinea Grass


Fermentation and Distillation

Bio-refinery system

> 100 t/day of feed stoke > 30,000 l/day of ethanol

(Commercial Systems for other biomass residues)

X

There is potential to use this as a resource further research and development of technologies for collection, transportation, processing and conversion.

4.4 Short listing of Technologies

Based on the technical and other performance characterizations of the technology options

considered in the above section, especially referring to the technology status, short listing of

technologies is carried out. The result is presented in Table 4.3. Basically the technologies

that are commercialized (or possible to commercialize with minor modifications) were

selected.

Table 4.3: Shortlisted Technologies Residue Application Technology Equipment

Briquette making Screw type briquetting machine

Value addition to residue as a fuel

Charcoal making Small scale charcoal kiln Direct combustion Paddy husk cook stove Gasification Paddy husk gas stove

Domestic cooking

Carbonization Charcoal making cook stove Process heat generation for lime smoking



Process heat generation for fruit and vegetable drying



Process heat generation for tobacco curing


Tobacco barn


Direct combustion / Steam cycle


Paddy Husk


Carbonization Basket burner

Value addition as a raw material

Baling / Densification Straw Baler


Series of conversion processes


Paper making Paper pulping Hand tools and utensils Cooking/Lighting Anaerobic digestion /

Biogas Generation Biogas digester– Continuous type

Fertilizer

Composting


Paddy Straw

Value addition as animal fodder (total mixed ration - TMR)



Briquette making Briquetting machine Value addition to the residue as a fuel Pelletizing Pelletizing machine Domestic cooking Direct combustion for

cooking Improved saw dust cook stove with multi-fuel capability



Series of equipment including chipper and press

Saw dust



Series of equipment including chipper, boiler, grinder, blender, press.

33

Table 4.3: Shortlisted Technologies (Cont...) Residue Application Technology Equipment

Cooking and lighting Anaerobic digestion / Biogas generation


Market waste


Banana Rejects




Wild Guinea Grass




The shortlisted technologies listed above together with their performance characteristics

identified are the outcome of the strategic level assessment. Still the number of resource (i.e.

waste stream) and technology combinations is quite high for the implementation of waste

management programme within the selected areas in Moneragala district. The operational

level assessment, as detailed in the next section, is needed to identify most suitable and

effective technology option(s).

5. CONVERTION OF WASTE TO RESOURCE: OPERATIONAL LEVEL

ASSESSEMNT

5.1 Screening of Technologies

At this stage, the short-listed system options first undergo screening using criteria in Tier-1.

Tier-1 criteria yield only an objective Yes/No type answer and hence, those options that do

not qualify one or all the conditions, then get automatically eliminated. For the present study,

following seven tier-1 criteria were:

- No Policy Restrictions

- Alignment with MEAs and National Plans

- Positive/No impact on existing users of WAB

- Achievement of Project Objectives

- Economic Viability (Affordability)

- Good Environmental Performance

- Positive Social Impact (Employment/ Income generation)

Table 5.1 presents the status of each technology option with reference to each of the criteria.

Technologies satisfying all the above criteria are selected for the further analysis (i.e. scoping

assessment).

Table 5.1: Screening of Technologies Residue Application Technology Equipment

No

Pol

icy

Res

tric

tions

Alig

nmen

t with

ME

As

and

Nat

iona

l Pla

ns

Pos

itive

/No

impa

ct o

n ex

istin

g us

ers

of W

AB

Ach

ieve

men

t of

Pro

ject

Obj

ectiv

es

Eco

nom

ic V

iabi

lity

(Affo

rdab

ility

)

Goo

d E

nviro

nmen

tal

Per

form

ance

Pos

itive

Soc

ial I

mpa

ct

(Em

ploy

men

t/ In

com

e ge

nera

tion)

O

utco

me

Briquette making Briquetting machine Yes Yes Yes Yes Yes Yes Yes Selected Value addition to residue as a fuel Charcoal making Charcoal kiln Yes N/A Yes Yes Yes No Yes Not Selected

Direct combustion Paddy husk cook stove Yes Yes Yes Yes Yes Yes Yes Selected Domestic cooking Gasification Paddy husk gas stove Yes N/A Yes Yes Yes Yes Yes Selected Process heat for lime smoking



Yes N/A Yes Yes Yes Yes Yes Selected

Process heat for fruit and vegetable drying




Process heat for tobacco curing


Tobacco barn



Direct combustion / Steam cycle


Yes N/A No Yes

Yes Yes Yes Not selected

Paddy Husk1


Carbonization Basket burner Yes N/A Yes Yes

Yes Yes Yes Selected

1 Paddy husk generated in Buttala D.S. Division is used by brick kilns in the area. Therefore the paddy husk considered in the above matrix is for Monaragala D.S. Division only.

35

Table 5.1: Screening of Technologies (Cont...) Residue Application Technology Equipment

No

Pol

icy

Res

tric

tions

Alig

nmen

t with

ME

As

and

Nat

iona

l Pla

ns

Pos

itive

/No

impa

ct o

n ex

istin

g us

ers

of W

AB

Ach

ieve

men

t of

Pro

ject

Obj

ectiv

es

Eco

nom

ic V

iabi

lity

(Affo

rdab

ility

)

Goo

d E

nviro

nmen

tal

Per

form

ance

Pos

itive

Soc

ial I

mpa

ct

(Em

ploy

men

t/ In

com

e ge

nera

tion)

O

utco

me

Value addition as a raw material

Baling / Densification

Straw Baler No N/A Yes Yes No Yes Yes Not selected




No N/A Yes Yes Yes Yes Yes Not selected

Paper making Paper pulping Hand tools and utensils

No N/A Yes Yes Yes No Yes Not selected

Cooking/Lighting Anaerobic digestion / Biogas Generation



Fertilizer

Composting



Paddy Straw

Value addition as animal fodder (total mixed ration - TMR)




36

Table5.1: Screening of Technologies (Cont...) Residue Application Technology Equipment

No

Pol

icy

Res

tric

tions

Alig

nmen

t with

ME

As

and

Nat

iona

l Pla

ns

Pos

itive

/No

impa

ct o

n ex

istin

g us

ers

of W

AB

Ach

ieve

men

t of

Pro

ject

Obj

ectiv

es

Eco

nom

ic V

iabi

lity

(Affo

rdab

ility

)

Goo

d E

nviro

nmen

tal

Per

form

ance

Pos

itive

Soc

ial I

mpa

ct

(Em

ploy

men

t/ In

com

e ge

nera

tion)

O

utco

me

Briquette making Briquetting machine Yes N/A Yes Yes Yes Yes Yes Selected Value addition to residue as a fuel Pelletizing Pelletizing machine Yes N/A Yes Yes No Yes Yes Not selected Domestic cooking

Direct combustion for cooking

Improved saw dust cook stove



Series of conversions

Series of equipment including chipper/press


Saw dust



Series of equipment including chipper, boiler, press, etc.



Anaerobic digestion / Biogas generation


Yes N/A N/A Yes Yes Yes Yes Selected Market waste



Banana Rejects





Wild Guinea Grass




Yes2 N/A Yes Yes No Yes Yes Not selected

2 The removal of this grass from certain areas may be restricted.

5.2 Scoping of Technologies

Based on the results of the screening analysis, the resource - technology options selected for

tier 2 level assessment (scoping assessment) are presented in Table 5.2. Note that, as shown

in the table, each technology option is identified through a single letter code, which will be

used to represent the option in the subsequent analysis.

Table 5.2: Technologies Selected for Scoping Analysis Residue Application Technology Equipment


(A) Briquette making Briquetting machine

(B) Direct combustion Paddy husk cook stove Domestic cooking (C) Gasification Paddy husk gas stove

Process heat for lime smoking

(D) Direct combustion / Direct heating



(E) Direct combustion / Indirect heating


Process heat for tobacco curing

(F) Direct combustion / Indirect heating

Tobacco barn

Paddy Husk3


(G) Carbonization Basket burner


(H) Briquette making Briquetting machine

Domestic cooking (I) Direct combustion for cooking



(J) Pressing Series of equipment including chipper/press

Saw dust


(K) Pressing Series of equipment including chipper, boiler, press, etc.


(L) Biogas generation Biogas digester– Continuous type

Market waste

Fertilizer (M) Composting Only hand tools for the handling of waste

Banana Rejects 4


(N) Biogas generation Biogas digester– Continuous type and IC Engine

Short-listed system options from the Tier 1 then go through the comprehensive scoping

assessment (Tier 2) that is more of qualitative in nature. During this stage of SAT, the

stakeholders are required to assess the various technology system options against the generic

and customized criteria and indicators using an appropriate standard methodology. In the

3 Paddy husk generated in Buttala D.S. Division is used by brick kilns in the area. Therefore the paddy husk considered in the above matrix is for Monaragala D.S. Division only. 4 This is applicable in Buttala D.S. Division only as the plantation is in this area.

38

present study, a set of criteria under four different aspects, as (i) Technical, (ii) Financial, (iii)

Social and (iv) Environment, as presented in Table 5.3.

Table 5.3: Criteria Selected for Scoping Analysis Category Criterion Notation

Suitability to characteristics of waste stream TC1 Availability of adequate amount of waste TC2 Compliance with prevailing local environmental laws, regulations and standards TC3 Accessibility of technologies TC4 Availability of local expertise/capacity building requirement for design, operation and maintenance TC5 Level of use of local material and resources for fabrication and operation TC6 Availability of in country technical assistance during commissioning and operation TC7 Level of similar usages and performance records in Sri Lanka TC8 Adaptability - Ability to fit into local (project area) conditions TC9 Adaptability to future situations (scale-up/expansions) TC10

Technical

Ability to replicate TC11 Capital investment FC1 Operational and maintenance costs FC2 Payback period FC3 Value addition to WAB FC4 Investor attractiveness FC5 Availability of co-financing FC6

Financial

Co-benefits FC7 Job creation SC1 Acceptability to local culture SC2 Improvement of quality of life SC3 Occupational safety and health conditions SC4

Social

Improvement of local technical skills and knowledge base SC5 Additional support services/utilities (Water/Energy) EC1 Environmental emissions EC2 Noise, vibration and odour EC3 Space and infrastructure requirement EC4 Contribution to WAB management EC5

Environmental

Net carbon emissions EC6

Each criterion was given a weight in a 0 to 10 scale based on its importance. Each technology

was evaluated against each criterion using four different levels of importance as (i) None, (ii)

Low, (iii) Medium and (iv) High with scores 0, 1, 2, and 3, respectively. The results are

presented in a weighted sum matrix. The total score of each technology is calculated under

each of the four categories of criteria. The results are presented in Table 5.4.

Table 5.4: Weighted sum matrix Technology

A B C D E F G H I J K L M N

Criteria W

eig

ht

Max

. Wt.

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Technical Criteria

TC1 8 24 2 16 2 16 2 16 2 16 2 16 2 16 2 16 2 16 2 16 2 16 1 8 1 8 2 16 3 24 TC2 10 30 2 20 3 30 3 30 3 30 3 30 3 30 1 10 1 10 2 20 1 10 0 0 2 20 3 30 3 30 TC3 9 27 3 27 2 18 3 27 2 18 2 18 2 18 2 18 3 27 2 18 2 18 2 18 3 27 2 18 3 27 TC4 9 27 1 9 3 27 1 9 2 18 2 18 1 9 1 9 2 18 3 27 1 9 2 18 3 27 3 27 3 27 TC5 8 24 1 8 3 24 1 8 3 24 3 24 2 16 1 8 2 16 3 24 1 8 2 16 3 24 3 24 3 24 TC6 6 18 2 12 3 18 3 18 3 18 3 18 3 18 3 18 2 12 3 18 2 12 1 6 3 18 3 18 3 18 TC7 6 18 1 6 3 18 2 12 3 18 3 18 2 12 1 6 2 12 3 18 2 12 1 6 3 18 3 18 3 18 TC8 7 21 0 0 2 14 1 7 2 14 3 21 3 21 1 7 2 14 3 21 1 7 1 7 2 14 2 14 2 14 TC9 9 27 2 18 1 9 2 18 3 27 3 27 2 18 1 9 2 18 2 18 1 9 1 9 2 18 2 18 3 27 TC10 5 15 1 5 1 5 0 0 2 10 2 10 2 10 1 5 1 5 1 5 2 10 2 10 3 15 3 15 3 15 TC11 8 24 2 16 3 24 2 16 3 24 3 24 2 16 1 8 2 16 2 16 2 16 1 8 3 24 3 24 1 8

Total Score - TC 85 255 137 203 161 217 224 184 114 164 201 127 106 213 222 232

Financial Criteria FC1 9 27 1 9 3 27 2 18 2 18 2 18 2 18 2 18 1 9 3 27 2 18 1 9 2 18 3 27 2 18 FC2 9 27 1 9 3 27 2 18 2 18 2 18 2 18 2 18 1 9 3 27 2 18 1 9 2 18 2 18 3 27 FC3 5 15 1 5 3 15 1 5 2 10 2 10 2 10 2 10 1 5 3 15 2 10 1 5 1 5 2 10 3 15 FC4 7 21 3 21 1 7 2 14 2 14 2 14 2 14 2 14 3 21 1 7 3 21 3 21 3 21 2 14 3 21 FC5 6 18 1 6 0 0 1 6 2 12 2 12 2 12 1 6 1 6 0 0 1 6 0 0 1 6 1 6 2 12 FC6 6 18 1 6 0 0 1 6 2 12 2 12 1 6 1 6 1 6 0 0 1 6 0 0 2 12 2 12 1 6 FC7 5 15 0 0 0 0 0 0 0 0 0 0 0 0 1 5 0 0 0 0 0 0 0 0 2 10 0 0 2 10

Total Score - FC 47 141 56 76 67 84 84 78 77 56 76 79 44 90 87 109

40

Table 5.4: Weighted sum matrix (Cont...) Technology


Criteria W

eig

ht

Max

. Wt.

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Sco

re

Wt

Sco

re

Social Criteria SC1 8 24 2 16 0 0 1 8 3 24 3 24 1 8 1 8 2 16 0 0 2 16 2 16 1 8 2 16 1 8 SC2 7 21 1 7 1 7 1 7 2 14 2 14 2 14 1 7 2 14 1 7 1 7 2 14 2 14 2 14 3 21 SC3 6 18 2 12 1 6 2 12 2 12 2 12 2 12 1 6 2 12 1 6 2 12 1 6 3 18 3 18 1 6 SC4 6 18 1 6 1 6 2 12 2 12 2 12 2 12 1 6 1 6 1 6 1 6 1 6 2 12 1 6 3 18 SC5 6 18 1 6 0 0 1 6 2 12 2 12 1 6 2 12 1 6 0 0 2 12 2 12 2 12 2 12 2 12

Total Score - SC 33 99 7 47 3 19 7 45 11 74 11 74 8 52 6 39 8 54 3 19 8 53 8 54 10 64 10 66 10 65 Environment

Criteria

EC1 5 15 1 5 3 15 2 10 2 10 2 10 2 10 2 10 1 5 3 15 1 5 1 5 2 10 3 15 2 10 EC2 9 27 1 9 1 9 2 18 2 18 2 18 1 9 1 9 1 9 1 9 1 9 1 9 2 18 1 9 2 18 EC3 7 21 2 14 2 14 3 21 3 21 3 21 3 21 2 14 2 14 2 14 2 14 2 14 2 14 1 7 3 21 EC4 4 12 2 8 3 12 3 12 2 8 2 8 2 8 2 8 2 8 3 12 2 8 1 4 2 8 1 4 2 8 EC5 8 24 3 24 1 8 1 8 3 24 3 24 2 16 2 16 3 24 1 8 2 16 3 24 3 24 3 24 3 24 EC6 7 21 2 14 2 14 3 21 2 14 2 14 2 14 2 14 2 14 2 14 2 14 1 7 3 21 1 7 3 21

Total Score - EC 40 120 11 74 12 72 14 90 14 95 14 95 12 78 11 71 11 74 12 72 10 66 9 63 14 95 10 66 15 102

Note that there are altogether 29 criteria used in the above analysis (ten under technical,

seven under financial, five under social and six under environment). Typically in the scoping

analysis only few important numbers of criteria are selected for the scoping analysis and

more detailed list of criteria is used only after scoping assessment for the detailed assessment

of technology for their final ranking. However, in the present analysis, more detailed analysis

is carried out at the scoping level to as it is felt that most of the technologies selected are

important and difficult to differentiate through a simple assessment.

It is important to highlight at this juncture that, the weight assigned to each criteria is a

common value for all stakeholders and therefore different angle of opinions of these

stakeholders are captured in the data. One effective way of improving this situation is to

assign priority values for each category of criteria (i.e. technical, financial, social and

environment) and estimate the overall score as the weighted average of the four sub-total

scores. This is the methodology adopted in this study as the base case. However, sensitivity

analysis was carried out to analyse the effect of this approach in the final scores and rankings

of the technology options. However, establishment of priority values for the four different

aspects of the technologies basically involves conversion of qualitative judgement to a

quantitative value, which is obviously a very challenging task. A brief overview of the

methodology used in this aspect of the analysis is presented below.

Many methodologies, such as Guttman scale analysis, scale discrimination technique, rating

scales, semantic differential, multidimensional scaling, paired comparisons etc., are available

for the selection and construction of social scales and indices [14]. Among these approaches,

Analytical Hierarchy Process (AHP) has been widely used for conducting undertakings like

analysis of energy planning, distribution of resources planning, conflict resolution, selection

of projects, etc., and useful results have been obtained. Further, this method has been used for

similar type of studies for ranking of technologies [15], and therefore selected for the present

study.

AHP is a method of breaking down a complex, unstructured situation into its component

parts; arranging these parts, or variables, into a hierarchic order; assigning numerical values

to subjective judgements to determine which variables have the highest priority and should be

acted upon to influence the outcome of the situation. AHP involves different steps: (a)

statement of the problem/objective, (b) identification of the criteria that influence the

42

behaviour of the problem, (c) structuring a hierarchy of the criteria and alternatives. In AHP,

alternatives refer to the different solutions or choices available, for example the technologies

selected in this study. For the purpose of establishing priority values, AHP uses the pair-wise

comparison - that is to compare the elements in pair against a given criterion. The pair-wise

comparisons for the different criteria and alternatives are obtained through feedback of

different stakeholders (referred to as Actors) [16]. A summary of the AHP methodology is

presented in Appendix B.

The final overall score is calculated as the normalized weighted average of the four scores.

The weights (or priority values) for the four categories were derived from the feed-back from

stakeholders (or actors) by using pair-wise comparison technique defined in Analytical

Hierarchical Process (AHP). The priority values of seven different actors, based on their

responses, are presented in Figure 5.1. The overall priority values (the mean) are calculated

by equal weighted averaging of that of all the actors. The final priority values are given in

Table 5.5. Derivation of these results is presented in Appendix B.

Figure 5.1: Priority values of the four criteria

Table 5.5: Mean priority values of criteria derived from pair-wise comparison Category of Criteria Priority Values

Technical 0.266 Financial 0.105 Social 0.188 Environment 0.441

0.00

0.10

0.20

0.30

0.40

0.50

0.60

TC FC SC EC

Pri

ori

ty V

alu

e

Category of Criteria

Actor 1

Actor 2

Actor 3

Actor 4

Actor 5

Actor 6

Actor 7

Mean

43

Based on the priority values for the four criteria, weighted average score of each of the

technology could be calculated and the final overall results of the analysis are presented in

Table 5.6.

Table 5.6: Ranks of technological options based on pair-wise comparison of criteria Criterion

Technical (0.266)

Financial (0.105)

Social (0.188)

Environmental (0.441)

Weighted Average based on pair-wise comparison

Technology

Total % Total % Total % Total % Score % Rank A 137 53.7 56 39.7 47 47.5 74 61.7 54.63 11 B 203 79.6 76 53.9 19 19.2 72 60.0 56.93 9 C 161 63.1 67 47.5 45 45.5 90 75.0 63.44 7 D 217 85.1 84 59.6 74 74.7 95 79.2 77.97 3 E 224 87.8 84 59.6 74 74.7 95 79.2 78.71 2 F 184 72.2 78 55.3 52 52.5 78 65.0 63.59 6 G 114 44.7 77 54.6 39 39.4 71 59.2 51.05 13 H 164 64.3 56 39.7 54 54.5 74 61.7 58.83 8 I 201 78.8 76 53.9 19 19.2 72 60.0 56.72 10 J 127 49.8 79 56.0 53 53.5 66 55.0 53.42 12 K 106 41.6 44 31.2 54 54.5 63 52.5 47.81 14 L 213 83.5 90 63.8 64 64.6 95 79.2 76.05 4 M 222 87.1 87 61.7 66 66.7 66 55.0 66.54 5 N 232 91.0 109 77.3 65 65.7 102 85.0 82.17 1

The overall scores of the technologies are also presented graphically in Figure 5.2.

Figure 5.2: Overall percentage scores of different technology options

0

10

20

30

40

50

60

70

80

90

100


Sco

re (%

)

Technology

44

The technology options according to the ranks obtained through the above analysis are

presented in Table 5.7.

Table 5.7: Ranks of technological options Rank Technology Equipment Application Residue

1 Biogas generation - (N) Biogas digester– Continuous type and IC Engine


Banana Rejects

2 Direct combustion / Indirect heating - (E)



Paddy husk

3 Direct combustion / Direct heating - (D)


Process heat for lime smoking

Paddy husk

4 Biogas generation - (L) Biogas digester– Continuous type


Market waste

5 Composting - (M) Only hand tools for the handling of waste

Fertilizer Market waste

6 Direct combustion / Indirect heating - (F)

Tobacco barn Process heat for tobacco curing

Paddy Husk

7 Gasification - (C)

Paddy husk gas stove Domestic Cooking

Paddy husk

8 Briquette making – (H) Briquetting machine Value addition to residue as a fuel

Sawdust

9 Direct combustion – (B) Paddy husk cook stove

Domestic Cooking

Paddy husk

10 Direct combustion for cooking – (I)


Domestic cooking Saw dust

11 Briquette making – (A) Briquetting machine Value addition to residue as a fuel

Paddy husk

12 Pressing – (J) Series of equipment including chipper/press

Manufacture of particle boards

Sawdust

13 Carbonization – (G) Basket burner Conversion to cement extender

Paddy husk

14 Pressing – (K) Series of equipment including chipper, boiler, press, etc


Sawdust

The rank one technology represents electricity generation for off-grid application through

conversion of banana rejects to biogas. The second and third ranks go to similar applications

of dehydration of vegetable products (both direct and indirect heating).

45

5.3 Detailed Assessment of Technologies

• Scenario Analysis

As the technologies selected after tier 1 assessment were undergone a detailed evaluation

against 29 criteria in the scoping assessment, in this level of assessment some sensitivity

analyses are carried out to investigate the variations in ranking. Firstly, the effect of priorities

given in Table 5.5 for the four categories of criteria is analysed considering another situation

where each category is given equal priority value of 0.25. The results are presented in Table

5.8. It can be seen that the ranks of the ten technologies, including the first eight, remains the

same. In fact, the change is primarily due to the increase in ranking of J from 12th to 9th.

Table 5.8: Ranks of technological options based on equal weights for criteria Criterion

Technical Financial Social Environmental Average based on

Equal Weights Technology


During the discussions on the assigning the priority values, the effect of the concept of pair-

wise comparison (of AHP methodology) on the priority values against that of the

simultaneous comparison (where the priorities were assigned simultaneously with detailed

discussions among the participants and after arriving at common consensus) was explored.

The priority values obtained based on simultaneous comparison are given in Table 5.9.

Table 5.9: Priority values of criteria derived from simultaneous comparison Category of Criteria Priority Values

Technical 0.20 Financial 0.10 Social 0.35 Environment 0.35

46

Table 5.10: Ranks of technological options based on simultaneous comparison of criteria Criterion (Priority Weights)

Technical (0.20)

Financial (0.10)

Social (0.35)

Environmental (0.35)

Weighted Average based

on simultaneous comparison

Technology


The above results show that there is no change in the ranking of nine of the technologies

(including the top eight). Finally, another scenario is considered where total marks derived

from scores under all the 29 criteria, without grouping into the four categories, are taken to

rank the technologies. The resulting total marks and the ranks are presented in Table 5.11.

Table 5.11: Ranks of technological options based on total scores of all criteria Sub-Total Score of Criterion

Technology Technical Financial Social Environmental Total Score Rank

A 137 56 47 74 314 12 B 203 76 19 72 370 7 C 161 67 45 90 363 9 D 217 84 74 95 470 3 E 224 84 74 95 477 2 F 184 78 52 78 392 6 G 114 77 39 71 301 13 H 164 56 54 74 348 10 I 201 76 19 72 368 8 J 127 79 53 66 325 11 K 106 44 54 63 267 14 L 213 90 64 95 462 4 M 222 87 66 66 441 5 N 232 109 65 102 508 1

47

In this case too, the technologies with highest ranks remains at the same standing. There is no

change in the ranking of eight technologies (including the top six). Note that in this case, as

there are eleven criteria considered under the category of technical criterion –TC (against that

of seven in FC, five in SC and six in EC) , there is a considerable higher priority given for TC

in this analysis. In fact, based on the maximum total marks attainable in each category, the

priority values could be estimated as 0.41, 0.23, 0.16 and 0.20 form TC, FC, SC and EC,

respectively.

The results of all the scenario analysis shown above (in which there are considerable

variations in the priority values among different criteria) indicate the insensitivity of the top

ranking technologies to the relative priority values of the criteria. Therefore, it could be

concluded that the top ranking technologies basically have higher scores in all the categories.

Hence it is easier to arrive at a decision for the technology selection.

• Star Diagram for Detailed Assessment of Criteria

The results given in the tabular form through numerical values are usually not very effective

when one need to investigate more closely the reasons for relative ranking of different

technologies and also to identify the critical or important criteria that need more

considerations. One effective method is to employ a graphical representation of the results. In

this section, scores in each of the four categories of criteria for the first four top ranking

technologies are represented in star diagrams. These technologies are, in the order of ranking,

Biogas generation from banana rejects to generate off-grid electricity (N), Process heat

generation from paddy husk for indirect drying of fruit and vegetable (E), Process heat

generation from paddy husk for direct smoking of lime (D) and Biogas generation from

market waste for cooking and lighting applications (L), which basically represent two distinct

technology categories: conversion of waste to biogas and conversion of waste to heat through

direct combustion.

(a) Star Diagram for Environment Aspects

The category of environment criteria has the highest priority value and therefore considered

first in this analysis. There were six criteria considered under environment aspects and Figure

5.3 presents the scores of the top four ranking technologies in a star diagram. In this case,

there are not much different between the four technology options. Out of the maximum score

48

0

5

10

15

20

25

EC1

EC2

EC3

EC4

EC5

EC6

Rank 1

Rank 2

Rank 3

Rank 4

of 120 attainable under this category Rank 1 technology (N) scores 102 marks (i.e. 85%) and

all the other three have equal marks of 95 (i.e. 79%). Therefore all these four technology

interventions will have considerable positive impact on the environment.

Figure 5.3: Star diagram for environment aspects for the top four ranks technologies

(b) Star Diagram for Technical Aspects

The second highest priority is given for technical aspects. Under this, eleven criteria were

included in the analysis and the results are presented in Figure 5.4.

Figure 5.4: Star diagram for technical aspects for the top four ranks technologies

0

5

10

15

20

25

30

TC1

TC2

TC3

TC4

TC5

TC6TC7

TC8

TC9

TC10

TC11

Rank 1

Rank 2

Rank 3

Rank 4

49

It can be seen that all the four technologies have lover score under criterion TC10, which is

the ability to scale-up. Yet, except for Rank 1 technology, all other three technologies have

high potential for replication (i.e. TC11). As Rank 1 technology is based on a very specific

type or residue (banana rejects), the ability for future expansion as well as replication is low.

However, this technology has obtained higher scores against all the other technical criteria,

which contributed for its highest rank. As in the case of environmental aspects, all the four

technologies scored high marks under technical aspects, indicating the high technical

feasibility of the interventions. For example, out of the maximum score of 255, the scores of

the first four technologies are 232 (i.e. 91%), 224 (i.e. 88%), 217 (i.e. 85%) and 214 (i.e.

84%).

(c) Star Diagram for Social Aspects

The social aspects include five criteria as shown in Figure 5.5.

Figure 5.5: Star diagram for social aspects for the top four ranks technologies

In this case Rank 2 and Rank 3 technologies (being a very similar applications) have identical

shape in the star diagram with a total score of 74 out of 99 (i.e. 75%). Rank 1 and Rank 4

technologies have very similar total scores of 65 and 64, respectively. In general, all these

technologies have lower performances in terms of social aspects than environmental and

technical aspects. In particular, scores against SC5, which represents the improvement of

local technical skills and knowledge base, is quite low. Therefore, in order to improve the

0

5

10

15

20

25

SC1

SC2

SC3SC4

SC5Rank 1

Rank 2

Rank 3

Rank 4

50

performances against social criteria, some corrective interventions should be identified with

the implementation of these technical options.

(d) Star Diagram for Financial Aspects

This category has seven criteria and the scores of the four technologies are illustrated in

Figure 5.6. Except for the Rank 1 technology, all the technologies have poor performances

against the financial aspects, particularly when compared to environmental and technical

aspects. Even, Rank 1 technology has lower scores under criteria FC5, FC6 and FC7, which

represent Investor attractiveness, Availability of co-financing and Co-benefits, respectively.

Figure 5.6: Star diagram for financial aspects for the top four ranks technologies

(e) Composite Star Diagram for all Aspects

It is also useful to represent the scores obtained by the four technologies against all the 29

criteria in the same star diagram, as shown in Figure 5.7, so that overall picture of the

situation could be observed. The results primarily indicate weightiness towards technical

aspects in terms of their performances. The weakest area is the social aspects. Even the

environment aspects and some financial aspects show poor scores. In order to optimize the

benefits of these technological interventions, a more detail analysis is required firstly to

identify the root causes and secondly to develop remedial measures. Otherwise, it will not be

able to achieve the overall objective and expected outcome of the project.

0

5

10

15

20

25

30

FC1

FC2

FC3

FC4FC5

FC6

FC7

Rank 1

Rank 2

Rank 3

Rank 4

51

Figure 5.7: Star diagram of all criteria for the top four ranks technologies

(f) Star Diagram for comparison of two distinct technologies

Figure 5.8: Star diagram for two technologies using paddy husk

0

5

10

15

20

25

30

TC1TC2

TC3

TC4

TC5

TC6

TC7

TC8

TC9

TC10

TC11

FC1

FC2FC3

FC4FC5FC6

FC7

SC1

SC2

SC3

SC4

SC5

EC1

EC2

EC3

EC4

EC5EC6

Rank 1

Rank 2

Rank 3

Rank 4

0

5

10

15

20

25

30

TC1TC2

TC3

TC4

TC5

TC6

TC7

TC8

TC9

TC10

TC11

FC1

FC2FC3

FC4FC5FC6

FC7

SC1

SC2

SC3

SC4

SC5

EC1

EC2

EC3

EC4

EC5EC6

Rank 2

Rank 11

52

Another important application of the star diagram representation of the scores is to compare

two different technologies in terms of their performances against all the criteria. For example,

consider two technology options for the management of paddy husk: direct combustion for

process heat generation (Technology E having 2nd rank) and densification through briquetting

(Technology A having 11th rank). The scores are presented in Figure 5.8 above. It is evident

from the diagram that the direct combustion of paddy husk is better in almost all the criteria

that the briquetting, especially in the local context.

Meanwhile, performances of the same technology under different fuel categories could also

be analysed through star diagram. For example, consider briquetting technology option for

the management of paddy husk and sawdust. The corresponding options are denoted by

Technology A (having 11th rank) and Technology H (having 8th rank). Once again, the scores

are presented in the star diagram, as shown in Figure 5.9.

Figure 5.9: Star diagram for two residues (paddy husk and sawdust) using same

technology (briquetting)

The diagram indicates that the sawdust briquetting is a better option than paddy husk

briquetting as a waste management measure in the selected region, primarily due to its better

technical performances. Financial and environmental performances are identical, though

sawdust briquetting show slightly better social benefits.

0

5

10

15

20

25

30

TC1TC2

TC3

TC4

TC5

TC6

TC7

TC8

TC9

TC10

TC11

FC1

FC2FC3

FC4FC5FC6

FC7

SC1

SC2

SC3

SC4

SC5

EC1

EC2

EC3

EC4

EC5EC6

Rank 8

Rank 11

53

5.4 Selection of Technology Option for the Pilot Implementation Project

Selection of most appropriate and effective technology option or options could be done based

on the analysis carried out above. Another aspect that could influence the selection procedure

of the technology option is the future scenarios, for example with reference to the generation /

availability of waste, change in policies, etc. The scenario analysis carried out earlier

indicates that the order of raking didn’t change significantly, particularly the first eight

technology options. Therefore situations of the first few technology options are briefed in

here to select appropriate technology option(s) for the pilot implementation project.

• Rank 1 - Technology (N)

Residue/Waste: Banana rejects

Application: Off-grid Electricity Generation

Process / Technology: Anaerobic digestion of waste / Biogas generation

Equipment: Biogas digester (Continuous type) / Internal combustion engine

Capacity: 1 t/day of waste input; Plant capacity – 4 kWe

Biogas yield – 95 m3/day, Electricity generation - 125 kWh/day,

Performances: Energy conversion efficiency; Digester – 13.5%, Engine – 20%

Installation Cost: In the range of Rs 2.5 Million

This represents a technology with relatively high resource requirement, though the overall

benefits are the maximum. It is evident that the technology option will not be able to

implement under the present project due to limitation in finances and the available time

frame. However, it is recommended to develop a more detailed project proposal, such that the

company could implement with their own resources.

• Rank 2 - Technology (E)

Residue/Waste: Paddy husk

Application: Process Heat Generation for vegetable / fruit drying

Process / Technology: Direct combustion / Indirect heating

Equipment: Paddy husk stove coupled to tray dryer

Capacity: Product Input - 100 kg/batch, Drying time – 12 to 18 hr

Fuel input- 54 kg/load, Fuel input rate– 3 kg/hr; Stove capacity–8kWth

Performances: Energy conversion efficiency; Drying – 40%, Stove – 65%

54

Installation Cost: In the range of Rs. 400,000

This is a very viable technology option for the pilot implementation project. There is a high

potential for replication of this technology, not only within the selected region but also

throughout the country. Since the technology is a small scale one, the sustainable supply of

paddy husk is guaranteed. The technology could be applied to drying of wide variety of

products including other food products as well as non-food items. The technology suppliers

are also available and could be fabricated locally and therefore the technology transfer and

adaptation are possible. Therefore selection of this technology as the pilot implementation

project is highly recommended.

• Rank 3 - Technology (D)

Residue/Waste: Paddy husk

Application: Process Heat Generation for lime smoking

Process / Technology: Direct combustion / Direct heating

Equipment: Paddy husk stove coupled to tray dryer

Capacity: Product Input - 200 kg/batch, Drying time – 36 hr

Fuel input- 72 kg/load, Fuel input rate- 2 kg/hr, Stove capacity–5 kWth

Performances: Energy conversion efficiency; Drying – 60%, Stove – 65%


This is a very similar technology option as the previous one and has the same viability and

benefits. As the technology represents smoking of a food product, the application to other

products is limited. Yet, lime is one of the most common agricultural products grown in the

area, dissemination of the technology will have many benefits to the local community, while

achieving other objectives related to waste management. In this case too, the technology

suppliers are available and local fabrication is possible. Therefore selection of this technology

option for the pilot implementation project is recommended.

• Rank 4 - Technology (L)

Residue/Waste: Market waste

Application: Cooking and lighting

Process / Technology: Anaerobic digestion of waste / Biogas Generation

55

Equipment: Biogas digester (Continuous type)

Capacity: 500 kg/day of waste input; Tank volume - 60 m3

Biogas yield – 47 m3/day

Performances: Sufficient for cooking and lighting for 15 families


This technology intervention is one of the proven concepts for the management of market

waste, open dumping of which is becoming a growing problem in many part of the country,

especially in the urban sectors. The technology is available locally and the local authorities

are keen on implementing such waste management programme. Therefore, implementation of

this technology intervention is highly required as a solution to waste management activity,

though the previous two technology options are preferred over this one as the pilot

implementation project. As in the case of rank 1 technology, it is recommended to develop a

detailed project proposal to be submitted to the local authority for further actions.

• Other Technologies

The above four technologies represent use of three types of residues/waste: banana rejects,

paddy husk and market waste. Therefore, in selecting the other potential technology options

management of other residue types has to be given a due consideration. This will ensure the

maximum outcome of an overall waste management programme in the Moneragala district.

Therefore the technologies in the next ranks such as composting of market waste (M),

process heat generation from paddy husk for tobacco curing (F), and paddy husk gas stove for

domestic cooking (C), with ranks 5, 6 and 7, respectively will not be considered as potential

candidate technology options for the pilot implementation project. However, the importance

of these technology options in an overall waste management programme should be duly

recognized.

The next ranked (8th) technology is sawdust briquetting (H), which represents a residue and a

technology that are not covered in the earlier selections. Therefore, it is recommended to

analyse further the possibility of selecting this technology option, particularly to mitigate

adverse issues associated with lack of proper management practices of sawdust in

Moneragala district. The details of this technology option are given below:

56

Residue/Waste: Sawdust

Application: Briquette making for the process heat generation in industry

Process / Technology: Densification / Briquetting

Equipment: Screw type briquetting machine, including dryer and vibrating

screening machine

Capacity: 200 kg/hr of sawdust

Performances: Briquette density: 0.8–1.2 t/m3; Energy requirement: 200 kWh/t.

Installation Cost: In the range of Rs. 3.5 Million

Although the initial investment is quite high compared with the earlier technology options

considered, it has the highest value addition to the waste material. As there is a growing

market for biomass based energy generation in industry, the future market for biomass

briquettes is guaranteed. Therefore, although the limitations in financial resource may not

support the selection of this option for the pilot implementation, promotion of the technology

is highly recommended.

57

References

[1] Sugathapala, A.G.T. (2009). Converting Waste Agricultural Biomass to a Fuel/

Resources in Moneragala District, Sri Lanka - 1st Progress Report. Project funded by

UNEP and coordinated by NCPC, October 2009.

[2] Chandak, S.P. (2009). Sustainable Assessment of Technologies: Making the Right

Choices. International Environmental Technology Centre DTIE, UNEP. Presented at

the 1st Stakeholder Consultative Workshop / Training Programme of the Project on

Converting Waste Agricultural Biomass to Fuel/Resources in Moneragala District, Sri

Lanka funded byUNEP and coordinated by NCPC, 21st August 2009.

[3] DTIE-UNEP. EST Assessment Methodology and Implementation - Training Kit

prepared for the support of the project on Environmental Management of the Iraqi

Marshlands. Funded by International Environmental Technology Centre (IETC)

DTIE, UNEP.

[4] Seresinhe, T., Marapana, R.A.U.J. and Weerasinghe, W.M.C.B. (2009). Report

submitted to NCPC under the Project on Converting Waste Biomass into

Energy/Material Resource: Panicum Maximum – Wild Guinea Grass. Department of

Animal Science, Faculty of Agriculture, University of Ruhuna, Sri Lanka, December

2009.

[5] Converting Waste Agricultural Biomass into a Resource-Compendium of

Technologies. Compiled by United Nations Environmental Programme (UNEP)

(http://cshd.dap.edu.ph/unep_biomass).

[6] Bhattacharya, S.C. and Abdul Salam, P. (2006). A Review of Selected Biomass

Energy Technologies: Gasification, Combustion, Carbonization and Densification. A

Publication of Asian Regional Research Programme in Energy, Environment and

Climate (ARRPEEC). Energy Field of Study, AIT, Thailand.

[7] Bhattacharya, S.C. Biomass Energy and Densification: A Global Review with

Emphasis on Developing Countries. Energy Program, AIT, Thailand.

58

[8] Grover, P.D. and Mishra, S.K. Biomass Briquetting: Technology and Practices. Field

Document No.46. FAO Regional Wood Energy Development Programme in Asia,

Bangkok, Thailand, April 1996.

[9] ISAT-GTZ. Biogas Digest. Volume I: Biogas Basics; Volume II: Biogas - Application

and Product Development; Volume III: Biogas - Costs and Benefits and Biogas –

Programme Implementation, GTZ project Information and Advisory Service on

Appropriate Technology (ISAT).

[10] FAO. System Approach to Biogas Technology. FAO/TCP/NEP/4415-T. Consolidated

Management Services Nepal.

[11] Sugathapala, A.G.T. (2007). Biomass Gasification in Sri Lanka. Asia Pacific Tech

Monitor. Vol. 24, No. 4, Jul-Aug 2007, pp 42-50.

[12] DPW (2005). The Conversion Technology Evaluation Report, developed by the

Alternative Technology Advisory Subcommittee of Solid Waste Management

Committee/ Integrated Waste Management Task Force of the County of Los Angeles

Department of Public Works (DPW). August 2005.

[13] Gadde M., Menke C., Siemers W. and Pipatmanomai S. Technologies for Energy

Use of Rice Straw: A Review. Publication of the Joint Graduate School of Energy and

Environment, King Mongkut’s University of Technology, Bangkok, Thailand.

[14] Miller D.C. (1983). Handbook of research design and social measurement. Longman

Inc, New York.

[15] Sugathapala A.G.T. and Amarasinghe A.D.U.S. (2002). Ranking of Biomass Energy

Technologies and Barriers. Final Report Submitted to Asian Institute of Technology.

Asian Regional Research Programme in Energy Environment and Climate Change –

Phase II (ARPEEC-II).

[16] Saaty T.L. (1999). Decision making for leaders. RWS Publications, Pittsburgh.

59

APPENDIX A: ESTIMATION OF THE GENERATION POTENTIAL WILD GUINEA GRASS IN MONERAGALA DISTRICT

A1: Background

During the initial stage of the project, the availability of wild guinea grass (Scientific name:

Panicam Maximum, local name: Ginihirassa) was identified. Though not considered for

detailed assessment, it was concluded that this resource could have considerable potential in

the future. The extent of the land and the available quantity of guinea grass are difficult to

predict as the source is sparsely distributed all over the land. However, based on the

responses from the local farmers, a rough estimation for the generation potential is obtained

based on effective area of extent equivalent to 15% of paddy land and yield of 20 t/ha/yr. The

results were reported in the first progress report, and the values are 3018 t/yr in Moneragala

DS division and 9370 t/yr in Buttala DS division. However, a more detailed study on the

topic has been carried out by a team of researchers, the results of which are used in this report

to update the data [4]. Following section is included to outline the findings of that study. The

estimations were based on the available statistics and information collected from Veterinary

surgeons, Grama Niladharis, and personnel from district secretariats.

A2: Methodology

The extent of wild guinea grass land is estimated based on the following factors:

- Land use pattern in the selected DS division (say Ai in ha, where i represents the land

category),

- Effective fraction of the land covered with wild guinea grass in each land category

(say αi).

Then the extent of land of wild guinea grass in each land category is given by αiAi with a total

land area of ΣαiAi.

The estimation of the quantity of wild guinea grass (at a specified moisture content) is based

on the average yield per ha per year and its initial moisture content. The annual production

potential of wild guinea grass in each DS division is given by ΣyαiAi, where y is the yield in

t/ha/yr at the specified moisture content.

60

A3: Data

It is assumed that a significant extent of wild guinea grass is found in two land categories:

Grassland and Open forest. The land use pattern in each DS division provides the data

presented in Table A1 on the extent of land in each of these two categories.

Table A1: Extend of grassland and open forests Land Area (ha) DS Division

Grassland Open Forest Buttala 352.74 8193.3 Moneragala 90.36 6927.73

In order to estimate the effective area of wild guinea grass growth, it is assumed that the

fraction of the land covered with wild guinea grass in grassland and open forest are 0.25 and

0.30, respectively.

The annual generation potential is estimated with an average yield on 8 dry t/ha/yr or 10

t/ha/yr with 20% moisture content (MC) on wet basis for bath types of land. Note that the

water content of fresh wild guinea grass is estimated to be 70% on wet basis in this study.

Therefore, the above value corresponds to the yield of fresh grass of about 26.7 t/ha/yr.

A4: Results

The estimated the effective growth area of wild guinea grass in each DS division is presented

in Table A2. Further, the annual generation potential is also presented.

Table A2: Extend of grassland and open forests Extend of Wild Guinea Grass (ha) Generation Potential (t/yr) DS Division

Grassland Open Forest Total Dry Matter @ 20% MC Buttala 88.19 2458.00 2546.18 20369.4 25,461.8 Moneragala 22.59 2078.32 2100.91 16807.3 21,009.1

Note that the annual generation potential of wild guinea grass estimated above is that presents

in the field. The total amount will not be available for future applications due to the following

facts:

- Part of this amount should be kept in the field to maintain the natural habitat.

- As the amount is generated in the field, there will be a limitation in accessibility.

- Already the grass is used as animal fodder, and should be allocated to that in future

too.

61

APPENDIX B: PRIORITATION OF CRITERIA FOR RANKING OF TECHNOLOGIES

B1: Analytical Hierarchical Process (AHP)

• Hierarchy System

AHP requires that a hierarchy system be formulated with objective or goal, criteria for

ranking (or factors) and the different options or alternatives (i.e. the technologies in this

study). Information will be collected by interviewing actors/stakeholders. The different steps

involved in AHP are: (a) State the problem/objective; (b) Identify the criteria that influence

the behaviour of the problem; (c) Structure a hierarchy of the criteria and alternatives, as

shown in Figure A1.

Figure B1: General structure of hierarchy system

• Formulation of the Problem/Objective

Objective(s)

The objectives in the present study are to rank the alternatives (i.e. technology options) for

conversion of biomass waste materials to energy / resources.

LEVEL 1

Problem/Objective

Ranking of

Technologies

LEVEL 2

Actors

Actor 1

Actor 2

Actor 3

Actor 4

LEVEL 3

Criteria

Criteria 1

Criteria 2

LEVEL 4

Alternatives

Alternative 1

Alternative 3

Alternative 2

62

Actors/Stakeholders

There are various actors/stakeholders who have different perception about the importance of

the different technologies, such as Experts, Policy personnel, Users, Manufacturers,

Investors, NGOs.

• Criteria for Ranking of Barriers/BETs

In ranking of given alternatives, the criteria or attributes through which the technologies will

be ranked must first be developed. In the case of ranking of technologies, the following

categories of criteria were used:

- Technical (TC),

- Financial (FC),

- Social (SC) and

- Environment (EC).

• Alternatives

In AHP system, alternatives refer to the different solution or choices available. That is the

type of technology options, as listed below:

- Paddy husk briquetting (A)

- Paddy husk fired direct combustion for domestic cooking (B)

- Paddy husk fired gasification for domestic cooking (C)

- Paddy husk fired direct heating dryer for smoking of lime (D)

- Paddy husk fired indirect heating dryer for vegetable / fruit drying (E)

- Paddy husk fired indirect heating dryer for tobacco curing (F)

- Basket burner for conversion of paddy husk to cement extender (G)

- Sawdust briquetting (H)

- Sawdust fired direct combustion for domestic cooking (I)

- Manufacture of sawdust particle boards (J)

- Manufacture of sawdust medium density fibre boards (K)

- Biogas generation from market waste for cooking and lighting (L)

- Composting of market waste (M)

- Biogas generation from banana rejects for off-grid electricity generation (N)

Note that the technologies have been already evaluated using SAT methodology, as presented

in Section 5.2 and the objective of the use of AHP methodology is the assign priority values

63

for the four categories of criteria TC, FC, SC and EC. The following section presents the

AHP methodology adapted to the present study to assign priority values for the four criteria

based on the feedback of seven actors.

B2: Method and Analysis

• Pair-Wise Comparison - Weighting

This makes use of pair-wise comparison of criteria based their importance or preference. For

the purpose of comparison, AHP uses the pair-wise comparison scale shown in Table 1, with

values from 1 to 9 to rate the relative preference for two items.

Table B1: Pair-wise comparison scale for AHP preferences Numerical Ranking

Verbal Judgement of Ranking

Explanation

1 Equally important Both actors are of equal importance 3 Moderate importance One actor is slightly more important than the other 5 Essential or strong

importance One actor is strongly more important than the other

7 Very strong importance One actor is very strongly more important than the other9 Extreme importance One actor is extremely more important than the other

2,4,6,8 Intermediate values between two adjacent judgements

In-between two levels of importance wherein compromise is needed

Note that the reciprocals of the numerical ranking are used for inverse comparisons. For

example, Table B2 shows the basic structure of the matrix of the pair-wise comparison of

criteria together with the response of one of the actors (Actor 1).

Table B2: Pair-wise comparison of technologies – Response of Actor 1 Criteria TC FC SC EC

TC 5 1/4 1/4 FC 1/5 1/6 SC 1 EC

Note that the actor has to fill only the elements in upper triangle (i.e. un-shaded elements).

The diagonal elements of the above matrix should be unity. The other elements in the shaded

area are assigned as the reciprocal of value in the transpose element. In the present study the

actors assigned the value based on narrower scale than that presented in Table B2 proposed

by AHP methodology. Therefore, in order to use the numerical calculation procedure of

64

AHP, the response of actors were converted into the AHP scale of 1 to 9 and the results

presented in Table B2 (and the entire analysis) are the revised values.

• Establishment of Priorities

Based on the pair-wise comparison scale, the priorities of the different criteria could be set. In

the present study, the following sets of priorities are to be formed:

- The priorities of the actors in terms of the overall objective,

- The priorities of the criteria to the actors,

- The priorities of the each alternative technology in terms of the each criterion.

Note that, as stated earlier, the priorities of the each alternative technology in terms of the

each criterion have been already set through the SAT methodology. Further, it is assumed

that the actors are equally important to the overall objective of the present study and therefore

given equal weights (or priority).

STEP 1: Preparation of pair-wise matrix from the response

Based on the response of the Actor 2 presented in Table B2 above, the pair-wise comparison

matrix could be completed, as given in Table B3. The last row gives the column sum, which

is used in the next step to normalize the matrix.

Table B3: Pair-wise matrix – Actor 1 Criteria TC FC SC EC

TC 1 5 1/4 1/4 FC 1/5 1 1/5 1/6 SC 4 5 1 1 EC 4 6 1 1

Column Sum 9.20 17.00 2.45 2.42

STEP 2: Preparation of normalized pair-wise matrix

The normalized pair-wise matrix is prepared from the pair-wise matrix, by dividing the each

element by the sum of the elements in the corresponding column, which is given in the last

row of Table B3. The result is shown in Figure B4. The priorities of the different criteria

according the response of Actor 1 is then calculated as the average of the row elements, as

given in the last column of Table B4. Note that the total of the priority values becomes unity.

65

Table B4: Normalized pair-wise matrix – Actor 1 Criteria TC FC SC EC Row ΣΣΣΣ/n

TC 0.11 0.29 0.10 0.10 0.152 FC 0.02 0.06 0.08 0.07 0.058 SC 0.43 0.29 0.41 0.41 0.388 EC 0.43 0.35 0.41 0.41 0.402

STEP 3: Calculation of overall priorities based on response all actors

The two steps could be repeated for each actor and the overall priority values were calculated

based on equal weight for all actors. The results are presented in Table B5, in which the last

column represents the overall priority values of the four categories of criteria. According to

the results, the economic criterion has the highest priority followed by technical criterion and

social. The least priority value is assigned for environment criterion. These values are used in

Section 5.3 for the ranking of alternative technologies in the SAT methodology.

Table B5: Priorities of different actors and overall priority values Estimated Priority Values based on Responses of Actors Criteria

Actor 1 Actor 2 Actor 3 Actor 4 Actor 5 Actor 6 Actor 7 Overall

Priority Value TC 0.152 0.291 0.408 0.282 0.202 0.220 0.308 0.266 FC 0.058 0.264 0.119 0.123 0.052 0.056 0.064 0.105 SC 0.388 0.127 0.177 0.129 0.182 0.194 0.119 0.188 EC 0.402 0.319 0.297 0.466 0.564 0.530 0.508 0.441

Prior to the use of response of the actors, it is important to check its validity in terms of

consistency of the pair-wise comparison responses. In AHP methodology, this is facilitated

by defining a parameter referred to as inconsistency ratio (IR), which is a ratio or percentage

of time the actor is inconsistent in making judgement on a set of particular elements.

Originally it was recommended that an IR of 0.10 or less is required to consider the result as

valid. Literatures, however, indicate than an IR of up to 0.20 is acceptable.

The inconsistency ratio IR is given by the expression

where λmax is the maximum eigen value of the pair-wise comparison matrix, n is the size of

the matrix (i.e. n = 4 in the present case), and p is a parameter that depends on n. For n = 4, p

= 0.9.

,1

1IR max

−−

=n

n

p

λ

66

Calculation of IR is demonstrated below based on the response of Actor 1 presented in Figure

B3. Here, two additional columns are added to present eigen values of the pair-wise matrix.

The elements of principal eigen vector are the geometric average of the corresponding raw

elements of the pair-wise matrix. The normalized eigen vector is derived by dividing the

principal eigen vector by its column sum.

Table B6: Pair-wise matrix and eigen vectors – Actor 1 Criteria TC FC SC EC Principal

Eigen Vector Normalized

Eigen Vector TC 1.000 5.000 0.250 0.250 0.748 0.139 FC 0.200 1.000 0.200 0.167 0.286 0.053 SC 4.000 5.000 1.000 1.000 2.115 0.394 EC 4.000 6.000 1.000 1.000 2.213 0.413

Column Sum 9.200 17.000 2.450 2.417

The maximum eigen value λmax is calculated as the product of the column sum vector [9.200

17.000 2.450 2.417] with the normalized eigen vector [0.139 0.053 0.394 0.413]T, and the

result is 4.153. Therefore the inconsistency ratio IR for Actor 1 becomes

As IR < 0.2, the response of Actor 1 could be considered as consistent. Similarly IR values

for the other actors could be estimated and the result is summarized in Table B7.

Table B7: Inconsistency ratio Actor Inconsistency Ratio - IR

Actor 1 0.057 Actor 2 0.233 Actor 3 0.057 Actor 4 0.194 Actor 5 0.064 Actor 6 0.071 Actor 7 0.010

It can be seen that, except for Actor 2, the responses are consistent.

.057.014

4153.4

9.0

1IR1 =

−−=

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