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Energy 70 (2014) 401e410

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Energy

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Life cycle assessment of rice straw-based power generation inMalaysia

S.M. Shafie a,b,*, H.H. Masjuki a, T.M.I. Mahlia c,d

aDepartment of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysiab School of Technology Management and Logistics, College of Business, Universiti Utara Malaysia, 06010 Sintok, MalaysiacDepartment of Mechanical Engineering, Universiti Tenaga Nasional, 43000 Kajang, Selangor, MalaysiadDepartment of Mechanical Engineering, Syiah Kuala University, Banda Aceh 23111, Indonesia

a r t i c l e i n f o

Article history:Received 2 June 2012Received in revised form3 April 2014Accepted 5 April 2014Available online 5 May 2014

Keywords:LCA (life cycle assessment)Rice strawPower generationMalaysia

* Corresponding author. School of Technology Manaof Business, Universiti Utara Malaysia, 06010 Sintok, Mþ60 174994562; fax: þ60 49287070.

E-mail address: shafini@uum.edu.my (S.M. Shafie)

http://dx.doi.org/10.1016/j.energy.2014.04.0140360-5442/� 2014 Elsevier Ltd. All rights reserved.

a b s t r a c t

This paper presents an application of LCA (Life Cycle Assessment) with a view to analyzing the envi-ronment aspects of rice straw-based power generation in Malaysia. It also compares rice straw-basedpower generation with that of coal and natural gas. GHG (Greenhouse gas) emission savings werecalculated. It finds that rice straw power generation can save GHG (greenhouse gas) emissions of about1.79 kg CO2-eq/kWh compared to coal-based and 1.05 kg CO2-eq/kWh with natural gas based powergeneration. While the development of rice straw-based power generation in Malaysia is still in its earlystage, these paddy residues offer a large potential to generate electricity because of their availability. Ricestraw power plants not only could solve the problem of removing rice straw from fields without openburning, but also could reduce GHG emissions that contribute to climate change, acidification, andeutrophication, among other environmental problems.

� 2014 Elsevier Ltd. All rights reserved.

1. Introduction

Malaysia energy industries largely depend on fossil fuel re-sources in the electricity generation sector. From 1990 until 2004,total CO2 emission increased by 221% inMalaysia, and it expected toincrease up to 328 million ton CO2-eq in 2020 [1] whereas fossil-fuel consumption contributed more than half of the total in-crements in CO2 emission [2].

As a tropical country, Malaysia has an abundance of biomass re-sources that could be utilized for reducing fossil fuel consumption.The commitment of government to the development of RE(Renewable energy) is by introducing the Five Fuel DiversificationPolicy in 1999 by addition of RE as the fifth source of fuel inMalaysia[3]. Currently, the government ofMalaysia encourages the utilizationof biomass resources to attain the energy independence through itsNational Green Technology Policy [4]. In 2010, Malaysia introducedthe National Renewable Energy Policy. Even though, the develop-ment of RE in Malaysia is still in the early stage, it estimated that by

gement and Logistics, Collegealaysia. Tel.: þ60 49287038/

.

utilizing only 5% of renewable energy in the energy mix could savethe country RM5Billion over a period of 5 years [5]. One potentialgreen application uses paddy residue to generate electricity. Thepotential of electricity generation frompaddy residue is 5652.4 GWhthat is 5.4% from total electricity demand inMalaysia. Unfortunately,development of paddy residue for electricity generation remains lowin Malaysia. Rice husk-based power generation only amounted to1.38 MW in 2009 [6]. While, rice straw consumption as fuel inbiomass energy plants is still unavailable not only in Malaysia but inSoutheast Asia [7]. Utilization of rice straw for generating electricityremains in the discussion phase in Malaysia with plans on thedrawing board for 12MWcapacity of electricity using rice straw as afuel [8]. The use of rice straw as a fuel requires a knowledge of itsheating value [9]. There are a lot of studies regarding the model ofpredicting the ultimate and proximate analysis. Table 1 listed thestudies related to rice straw heating value model.

Even though the moisture content of straw is usually more than60% on wet basis, Malaysian dry weather can quickly dry down thestraw to its equilibrium moisture content of about 10e12% [6].

Worldwide development of straw utilization for energy con-version has been studied for more than 10 years; research hasexamined adapting straw technology from a small scale (<200 kW)to a large scale (>100 MW) and looked at ways to improve thecombustion efficiency and reduce the pollutant emissions [18].

Nomenclature

A activity levelARS rice straw availability (tonne)AF availability factorBFC burning fraction of carbonCT carbon content of diesel for transportationCARS rice straw catchment area (km2)DC diesel oil consumption (L/ha)EBRS avoided GHG emission from burning rice straw in the

fieldsECOAL avoided GHG emission from displaced coal power

productionEP emission pollutant (CH4 or N2O)ERS GHG emission from rice straw-based power generationEPOWER; CO2

power plant emission of CO2

ECRSC energy consumption for rice straw collection (MJ/ha)EORS electricity output power from rice straw (MW)EUD energy unit of diesel oil (MJ/L)ET; CO2

transportation emission of CO2

EFP, S emission factor (CH4 or N2O)FVT volume of diesel combusted for transportationFF farmland factorFOT fraction oxidized of diesel for transportationHCT heat content of diesel for transportationHHVRS rice straw high heating value, MJ/kgLHVRS rice straw low heating value, MJ/kgMWC molecular weight of carbonMWCO2

molecular weight of CO2

Ŋ overall efficiency of the plantsC collection efficiencyPC carbon content in rice strawPRR rough rice production (k tonne/ha)RGHG GHG emission reductionRSavai, yr annual availability of rice straw, tonne/yearQRS quantity of rice straw (k tonne/ha)SGR Straw-to-Grain RatioT plant operating hoursYRS straw yield (tonne/km2)

S.M. Shafie et al. / Energy 70 (2014) 401e410402

In recent years, approximately 130 straw power plants havebeen established in Denmark, whereas the construction of thesepower plants is even high when we take into account the otherEuropean countries. The UN has enlisted the power generationbased on straw as a fundamental element when it especially comesto combating environmental setbacks [19].

In 2011 the production of rice straw in Malaysian fields was1,933,889.3 tonnes [20]. Unfortunately, the burning of rice strawremains the current cultural practice of disposal in Malaysia [21].One major problem of open-field straw burning is atmosphericpollution because about 1521.53 kg CO2-eq is produced from theopen burning of one tonne of crop residue. This burning causesreduced air quality and human respiratory ailments [22]. Besidesthe potential to reduce problems associated with air quality, thereis another advantage that is a move from fossil feedstock to ricestraw for power production would result in a reduction of GHG(greenhouse gas) emissions [23].

One significant way to assess these concerns is through LCA (LifeCycle Assessment) which is a process that evaluates the environ-ment impact for entire period of its life cycle [24].Some papers usethe life cycle to analyze the different indicators regarding rice strawbased power generation and therefore the literature of rice strawbased energy production has been listed in Table 2.

Table 1Listed the studies related to rice straw heating value model.

Calorific value (MJ/kg) LHV (MJ/kg)

10.2415.0314

HHV�212.2H (%W)�0.8 (O (%W) þ N (%34.8c þ 93.9h þ 10.5s þ 6.3n�10.8o�2.5(in %)14

14.97Crushed rice straw in China16.1smash rice straw in China

A few studies carried out to evaluate the life cycle of rice strawbased power generation for ethanol and electricity production. Themajority of biomass electricity life cycle assessments has beenprepared in a European context, where Asian countries onlycontribute 5% from the total studies [31]. However, there are sig-nificant differences of environmental performances among theexisting bio-fuel production system due to local condition man-agement practice [32]. For this study, it uses life cycle analysis ofenergy consumption and environment impact to the globalwarming potential of rice straw based power production inMalaysia. The environmental aspect of rice straw-based powergeneration is important to analyze because that aspect is a keyconsideration for technology investment. Information on environ-mental aspect should be disseminated to fully understand the di-rection of Malaysia future energy [33]. Rice straw-based powergeneration potential can be assessed with respect to both envi-ronmental and economic concerns based on the Malaysian situa-tion before a pilot study is conducted.

According to [34], application of the LCA method is helpful inanalyzing (and helpful in decreasing) environment effects. Thispaper presents an application of LCA in calculating the environ-ment impact and energy consumption of rice straw-based powergeneration in Malaysia. The emissions saving from rice straw

HHV (MJ/kg) References

[10][11][12]

14.71Experimental on California rice15e17 [13]

W)) [14]w [12]

[15]

[16]

17.8 in Denmark [17]

Table 2The literature of rice straw based power production.

Country Year Aim Paper

Thailand 2013 GHG analysis of bio-DME production [25]Sweden 2013 The performance of energy and

economic of rice straw based bio-refinery[26]

Thailand 2012 Impact of socio-economic variable forelectricity and ethanol production

[27]

Japan 2012 Techno-economic and environmentalevaluation of bio-ethanol production

[28]

China 2011 The energy study of bio-fuel industries [29]China 2010 Analysis of direct and indirect environmental impact [30]

S.M. Shafie et al. / Energy 70 (2014) 401e410 403

consumption compared to coal and natural gas electricity produc-tion are important parameters to see the potential of rice strawcombusted in the boiler. The environment impact of hauling dis-tance and plant efficiency discussed under sensitivity topic. Theresult of optimum and maximum distance allowed getting lowerenvironmental impact can help the decision of plant location in thefuture. The conclusion of the study would provide a direction forpolicy maker on biomass based power plant development inMalaysia and would be a feasible study for straw based, powerplant development for other countries. It also would provide thebenchmark to for continuing improvement of environmental per-formance from rice straw power production.

2. Overall approach

An LCA study is generally carried out by four phases (goal andscope definition, inventory analysis, impact assessment, interpre-tation) and is used to quantify major potential environmental im-pacts related to the aim of study. Generally LCA boundaries aboutthe rice straw electricity production is used comprehensiveboundary starting from rice straw production to electricitygeneration.

2.1. Goal and scope

This study performs a LCA of electricity generation from ricestraw alone and conventional fuel (coal and natural gas) inMalaysia.

Fig. 1. System boundaries for rice s

The aim of this study is to identify the environment impact ofrice straw consumption for power generation in Malaysia and tocompare it with conventional fuel electricity production. Accord-ingly, the more specific objectives of the study are to (a) calculatethe environment impact and energy consumption of rice strawbased electricity generation in Malaysia, (b) compare the environ-mental performance between rice straw and conventional fuel(natural gas and coal) for electricity generation and (c) analyze thesensitivity of the parameter that most effect the life cycleemissions.

The functional unit used in this study is 1 kWh of electricitygenerated by rice straw and by conventional fuel in power plant. Areference as 1 kWh is used due to common applied among LCAusers [35]. The result from rice straw alone is compared withconventional fuel reference system which produces the sameamount of electricity generation. Even though, the goal and scopeare identical with other studies, the outcome result may obtain indifferent ways due to different choices and approaches appliedduring the studied [36].

2.2. System boundaries

The system’s boundary contains the processes for paddy pro-duction, rice-straw collecting, rice straw transportation and elec-tricity generation. The environment impact involves in eachprocess is taken into account. If the boundary is set too narrowlysome important impacts might be undetected; conversely, if theboundary is set too broadly, impacts other than those of interestmight be included [37]. Most researchers have decided that theboundaries for bio energy LCA begin with the crop grown (input)and end with energy production [23,38e40]. In regard to thebiomass life cycle, biomass production is included in most bio-energy LCAs [31]. The system boundaries applied in this study isstarting from paddy production process and end up at biomassboiler process which is the same boundary setting or applied in thatpaper [32]. The steps involved in the process include: paddy pro-duction, rice straw collecting, rice straw transportation and powergeneration. Fig. 1 shows the schematic presentation of stepsinvolved in this study. For each step, the energy consumption andGHG (greenhouse gas) emission were calculated. Figs. 2 and 3 are

traw-based power generation.

Fig. 2. System boundaries for coal based power generation.

Fig. 3. System boundaries for natural gas based power generation.

S.M. Shafie et al. / Energy 70 (2014) 401e410404

the system boundaries for coal and natural gas based powergeneration.

2.3. Inventory analysis and impact assessment

In this phase, data are collected for each process involved tomeet the goal of defined study.

2.3.1. Collected dataThe study focused on the Northern region of Malaysia that en-

compasses the states of Perlis, Penang, Kedah and Perak and coversan area of 17,816 km2. Current agriculture activities in the Northernregion are cultivation of paddy with almost 42% out of 800,000 haagriculture land. About 61.2% of paddy productions in Malaysia isfrom Northern region areas [41]. Table 3 shows the availability ofrice straw for each state in 2011 [42].

The paddy production processes requires fertilizer, pesticides,mechanical field operation and irrigation. Data were drawn bothfrom Refs. [34,43e45] and from questionnaires sent to selectedfarmers in the northern region of Malaysia.

The rice straw collecting process uses the baler machine, tractorand stump cutting machine [46]. The baling method is usedbecause it is less expensive compared to others methods [17,47].The data to analyze was taken from Ref. [48] and an interviewsession with Manager MADA at the B11 area. Emissions for ricestraw collection were calculated based on the machine’s dieselcombustion.

Rice straw transportation consists of two processes which arefrom rice straw field to collection centre and from collection centreto power generation (refer Fig. 1). For estimating for both distanceto transport a unit of rice straw, it is assumed that the rice straw isdistributed uniformly in the whole catchment area. Equation (1)[49] used to estimate the rice straw catchment area.

CARS ¼ ARS=ðYRS � sC � AF� FFÞ (1)

It assumed that each district consist a rice straw collection

Table 3Availability of rice straw in Northern Region of Malaysia, 2011.

State Area (Ha) Paddy production (ton) Rice straw production (ton)

Perlis 52,075 232,674 174,505.5Kedah 215,930 878,430 658,822.5Penang 25,564 144,613 108,459.8Perak 82,150 323,445 242,583.8

centre and state has the rice straw power plant in the centre.Table 4 shows the parameter use for transportation process.

Paddy straw-based electricity generation is a new system thathas not yet reached its decommissioning age [30]; this means thatthe data sources are limited. Table 5 show the main process of lifecycle of rice straw power generation and their data sources. Forpower generation, the energy consumptions and emissions datawere taken from Ref. [51], and rice husk-based electricity genera-tion was taken from Ban Heng Bee Rice Mill, Pendang Kedah. Ac-cording to [23], rice straw-based power generation can beevaluated by referring to current conditions of feasible rice-huskpower plants operating in Malaysia. Today, almost all rice straw isburned in Malaysia [52], but the implementation of rice straw-based power generation could avoid the GHG emissions fromopen burning as well as that from fossil fuel-based power genera-tion that focuses on coal and natural gas. Equation (2) used tocalculate the GHG emission reduction [23]. GHG emission fromopen burning is calculated based on the Equation (4) from Ref. [12].

RGHG ¼ ðEBRS þ ECOALÞ � ðERSÞ (2)

The emission data for coal and natural gas based power gener-ation used the database from NREL [54] and Malaysia Departmentof Environment [55].

2.3.2. Analysis of rice straw lifecycleLife cycle analysis of electricity production from rice husks in-

volves two steps which are rice straw preparation and powergeneration. Energy consumptions and emissions of all processes forpaddy straw-based power generation were identified using mate-rial and energy balances (See Fig. 1).

2.3.2.1. Rice straw preparation. Rice straw preparation involves thepaddy farming process, collecting rice husks and transporting themto the power plant. Total energy consumption for the paddyfarming process is 12225.97 MJ/ha [45]. The amount of rice strawproduction was derived using the Equation (3) [12]. The value ofSGR is 0.75 [12].

Table 4Parameter use for transportation process.

State T1PP > CC (km) T2CC > POWER (km)

Kedah 15.29 55.49Penang 8.91 15.45Perak 23.24 81.78Perlis e 15.91

Table 7Environmental impact categories of CML baseline [35].

Environmentalimpactcategory

Relevant emissions Unit

Acidification Sulfur dioxide SO2 kg SO2 equivalentsNitrogen oxides NOxHydrochloric acid HCLHydrofluoric acid HFAmmonia NH3

Climate change Carbon dioxide CO2 kg CO2 equivalentsNitrous oxide N2OMethane CH4

Chlorofluorocarbon CFCs

Table 5Main process of life cycle of rice straw power generation and their data sources.

Process Subsystems Sources of data

1. Paddy production Fertilizers Measure data from Northern paddy farm areaLiterature data [56]

Irrigation Measure data from interview session (Senior Engineer, Irrigation and drainage service, MADA)Mechanical field operations Data from questionnaire to selected farmer in Northern region

Literature [45]Pesticides Data from Ref. [57]

Literature data [44]2. Rice straw collection Mechanical equipment Data from four case projects of rice straw in MADA area3. Rice straw transportation Transportation system Data from four case projects of rice straw in MADA area4. Power generation Rice straw bale combustion Data from wood waste combustion

Electricity generation

S.M. Shafie et al. / Energy 70 (2014) 401e410 405

QRS ¼ PRR � SGR (3)

Energy consumption for rice straw collection considers dieselconsumption in machinery [59]. Rice straw collection in Malaysiauses the baling technique because the method is simple and in-volves less cost. The average mass of a rice straw bale is 450 kg.Equation (4) used to calculate the energy consumption for ricestraw collection.

ECRSC ¼ EUD � DC (4)

Energy unit of diesel use was 47.8 MJ L�1. Data was taken fromMADA B11, Kedah who reported that 7L diesel was used per 1 ha ofpaddy fields, including all machinery needed in rice-straw collec-tion using the baling technique.

Transportation involve the process of rice straw from paddyproduction to collection centre (T1PP > CC) and collection centre topower plant (T2CC > POWER). The majority of vehicles used totransport material from Malaysian paddies have a capacity ofbetween 1 and 3 tonnes per load [60]. In this analysis theT1PP > CC link used a light truck (lorry) below 1.5 tonne capacitywith fitted 2 bales of rice straw per vehicle (lorry). Rice strawtransportation energy is calculated from energy unit of diesel(43.1 MJ L�1), fuel consumption (5.5 km L�1), average distance(100 km) and the amount of rice straw (4853.1 kg ha�1). Thetransportation of rice straw bale from collection centre to powerplant, T2CC > POWER consumed the truck with 400800 which had4 km L�1 [61]fuel consumption and able to carry 20 bales pertruck.

The CO2, CH4 and N2O emissions from transportation arecalculated based on Equations (5) and (6) [62].

ET;CO2¼

XFVT � HCT � CT � FOT �

�MWCO2

�MWC

�(5)

EP ¼ AS � EFP;S (6)

2.3.2.2. Power generation. Electricity output power from rice straw,EORS calculated based on Equation (7) [49]. HHVRS and LHVRS are16.28 MJ/kg and 15.34 MJ/kg based on collected after harvest [63].

Table 6Emission factor for rice straw fired boiler.

EmissionSpecies(kg/kWh)

N2O CH4 SOx NOx CO

Emissionfactor

2.01 � 10�5 3.25 � 10�5 3.87 � 10�5 7.58 � 10�4 9.28 � 10�4

EORS ¼ �RSavai;yr � s� LHVRS

��3:6� T (7)

The natural gas based generation offered net thermal efficiencyover 55% [64]. The emission of CO2 emission is 0.32 kg per kWh,calculated as Equation (8) [65].

EPOWER;CO2¼ PC*BFC*MWCO2

�MWC

�HHVRS (8)

Since Malaysia still not available the rice straw based powergeneration the emission factor for rice straw fired was assumed asdry wood combustion in the boiler, which taken from USEPAExternal Combustion Report [66]. Table 6 show the resultantemission factor for rice straw fired boiler.

2.3.3. Impact assessmentActually, there is hardly standard procedure set of environment

impact categories applied [67]. According to [31], the majority ofbio-energy LCAs studies applied the midpoint impact categorieswhich use the CML (Centrum voor Milieukunde Leiden) method. Inthis paper, for the life cycle impact assessment, the CML 2001method was used and the environmental impacts consideredinclude acidification, climate change, eutrophication, toxicity andsummer smog. In general, the different methodologies give similarcharacterization results for impact categories such as climatechange and acidification [35].Table 7 lists the environmentalimpact categories of CML baseline [35].

HydrochlorofluorocarbonHCFCs

Eutrophication Phosphate PO43� kg PO4

3� equivalentsNitrogen oxides NOxNitrogenNitrates NO3

Ammonia NH3

Toxicity Arsenic kg 1,4-dichlorobenzene (DB)Chromium equivalents VIBenzeneHexachlorobenzene

Table 8GHG emissions and energy consumption from rice straw preparation.

Rice straw preparation stages Energy consumption (MJ/kg rice straw) CO2 emission (g) Nitrous oxide emission (g) Methane emission (g) CO2-eq emission (g)

Paddy Production 2.52 �1690 295.02 1486.5 91.52Rice straw collection 0.11 3.89 0.0291 0.0048 3.92Transport 0.87 128.09 0.8969 0.0488 129.04

Table 9Emission from life cycle rice straw-fired alone for 1kWh electricity generated.

Emission CO2 CO CH4 N2O

Unit/kg 0.36 2.88 � 10�3 1.63 � 10�2 2.86 � 10�4

S.M. Shafie et al. / Energy 70 (2014) 401e410406

3. Results and discussion

3.1. Environment and energy assessment for rice straw preparation

GHG emissions and energy consumption is calculated for threestages of rice straw preparation; these stages are paddy farming,rice straw collecting and transportation to the power plant. Table 8shows the GHG emissions and energy consumption from rice-strawpreparation.

The highest energy consumption for rice straw preparation isfrom paddy production, which amounts to 72% of the total. This isidentical with wheat crop study in Canada [68], that consumed thehighest energy in farming stages due to nitrogen fertilizer. Con-sumption of fertilizer, pesticide and agriculture machinery usewere major contributors to the total energy consumption [69].Energy consumption of paddy production included both direct andindirect energy. These included fuel consumption and human load.The utilization of seed, pesticide, fertilizer and machinery was alsocategorized under indirect energy. Nevertheless, the paddy pro-duction process has a great advantage in relation to the globalwarming impact, due to absorption of carbon dioxide throughphotosynthesis [32].

Considering all the preparation stages of rice straw preparation,the highest contribution to GHG emissions was from transportationwith 57.48% of the CO2-eq emission. The overall contribution of ricestraw preparation to GHG emissions is 224.48 g CO2-eq/kg ricestraw or 261.3 g CO2-eq/kWh. This emission is lower compared tocucumber production in Iran which is contributed 526.7 g CO2 perkg cucumber [70]. The life cycle emission of corn stalk based bio-fuel production is obtained 16.15 g CO2 per kg corn with trans-portation distance 5.8 km [71]. Other difference in emissions is

Fig. 4. CO2-eq emission between base case (

likely due to difference between studies in farming location, type,allocation method, energy and emission coefficients [72].

3.2. Rice straw-based electricity generation

Emission of rice straw-based electricity generation begins withpaddy production and continues to power generation (Fig. 1).Table 9 indicates the emissions of life cycle rice straw fired alonegases for 1 kWh electricity generated. The obtained CO2-eq emis-sion is 0.845 kg CO2/kWh which is lower than wheat straw firedalone, 1.076 kg CO2-eq/kWh and Brassica carinata fired alone with1.086 kg CO2-eq/kWh [73]. CO2 emission results were obtainedfollowed a study done in 1999 [74]. About 42.6% GHGs emissionswere contributed from CO2 gas. Rice-straw electricity generationhad zero carbon emissions when CO2, BIOGENIC consumed 1.67 kg/kWh.

Fig. 4 shows the CO2-eq emissions between base case (58 km)and 250 km for each processes of 1 kWh rice straw-based powergeneration involved in the system boundaries. Transportationcontributes 6% to the total CO2-eq for the base case. Increase in thedistance of T1PP > CC and T2CC > POWER the contribution of trans-portation goes to 42%. The distance of rice straw bale transportationcontributed to the global warming (0.1875% per km) is much higherthan rice husk with 0.024% per km [75] due to vast condition of balerice straw. The rice straw bales are transported in 1.5 tonne lorries,consuming a large amount of space, with only 2 bales per lorry. Byusing a larger truck for transporting bales, GHG emissions couldreduce as the result of fewer trips taken. According to [76], payloadeffect the total emission of biomass based power generation.

Table 10 indicates the characterized results for 1 kWh of ricestraw-based electricity generated. The CO2 gases cause climatechange that contributes the highest impact to the environment asidentical to LCAwood based electricity generation analysis in Japan[77]. Most of the process emitted the highest of CO2 gases. Only asan exception, the paddy production emitted the CH4 and N2O gases.SO2, NOx and NH4 all contribute to acidification [24]. The highestcontribution to both impacts comes from rice straw transportation

58 KM) and 250 KM for each processes.

Table 10Characterized results for LCA of 1 kWh of electricity (CML 2001).

Acidification 6.78 � 10�3 kg SO2-EqClimate change 4.30 � 10�1 kg CO2-eqEutrophication 1.46 � 10�3 kg PO4-EqToxicity 1.41 � 10�3 kg 1,4-DCB-EqSummer smog 5.22 � 10�3 kg formed ozone

Table 11GHG emission potentials comparison for 1 kWh for entire life cycle assessment.

GHG emissions, kg

CO2 NOx CO NH4 N2O

Paddy Straw 0.36 1.15 � 10�2 2.88 � 10�3 1.60 � 10�2 2.86 � 10�4

Coal 1.21 3.98 � 10�3 2.13 � 10�4 1.64 � 10�3 2.02 � 10�8

Natural Gas 0.45 3.65 � 10�4 3.06 � 10�4 2.91 � 10�11 8.17 � 10�6Fig. 5. Global warming potential saving from rice straw based power generations andtotal CO2 emission from Malaysia electricity production.

S.M. Shafie et al. / Energy 70 (2014) 401e410 407

with 42.42% for acidification and 77.66% for climate change. Thesevalues are considered lower than value from coal-based powergeneration (0.3134 kg SO2-eq/kWh). All the impact results from ricewaste-based power generation are much lower compared to coal-based power generation [38,78e80].

3.3. Comparison with coal and natural gas based electricitygeneration

Rice straw-based power generation contributes 0.845 kg CO2-eqemission per 1 kWh of electricity generated. Open-burning ricestraw contributes 1.38 kg CO2-eq with an emission factor of 1460 g/kg [81] and coal-based electricity generating contributes 1.25 kgCO2-eq emission. Therefore, the GHG emission saving is 1.79 kg CO2e eq per kWh. GHG emissions from rice straw-based power gen-eration are less compared to contributions both from open burningand from coal-based electricity generation.

The data also [30] indicated that straw based electricity gener-ation has far fewer GHG emissions than coal. The pulverized coalpower plant obtained the GHG emissions about 1.3kgCO2-eq/kWhfrom the mining process to power production setting boundaries[82].

The GHG emission saving from natural gas power generation is1.05 kg CO2-eq per kWh. Table 11 shows the GHG emission po-tential comparison for 1 kWh for entire life cycle assessment.Table 12 indicates result comparisonwith others study in the strawbased power generation. The result seems not identical due tosystem boundaries setting and input data source. It identical toconclusion from Ref. [83], indicated that the result or finding of LCAstudies are difficult to compare due to research questions, methodand data set selection give a significant impact to the outcome.

The assumption and consideration of certain parameter de-pends on National level activities would generate different output.The size of straw bale transport also effected the total GHG

Table 12Result comparison with others study in the straw based power generation.

This study [27] [30] [73]

Country Malaysia Thailand China SpainBiomass fuel Rice straw Rice straw Wheat straw Wheat strawBale weight (kg) 450 15e18Collection centre distance

(km)58 (base) 25e32 20e42 100

Life cycle GHG reduction(g CO2-eq/kWh)

560 193 664 1076

emissions. Themost significant, are the biomass fired power stationefficiency and also the resource transport distance [73].

If all rice straw generated in the fields was utilized fully forpower generation, 1.93 Mt could be generated 1809.41 GWh in2011. GHG emissions saving from coal-based electricity generationwould be 1.03 Mton CO2-eq. Fig. 5 shows the graph of globalwarming potential saving from rice straw open burning and coalbased power generations and total Malaysia CO2 emission fromelectricity generation. Malaysia CO2 emission from electricity gen-eration sector shown an exponentially increase pattern for eachyear. The study by Ref. [84], indicate that the average annual growthrate of emission was 14.81% for CO2, 10.32% for SO2, 14.38% for NOx

and 21.52% for CO. According to [85], Malaysia is one of the world’sfastest growing countries in terms of carbon emissions. Before2008, total CO2 emission less than avoided of global warming po-tential. In 2010, the CO2 emissions reach 101.64 million tonne. In2011, the electricity generation sector contributed the highestsources of global warming and acidification with N2O emissionsand SO2 emission with 470292 tonnes (61%) and 86497 tonnes(46%) respectively [86]. However, the rice straw based powergeneration if applied can reduce the CO2 emission up to 1% of totalCO2 emission in Malaysia. This small percentage of reduction willbecome more attractive in the future, as Malaysia strives to reduceits carbon emission.

Table 13 listed the GWP (Global warming potential) saving inNorthern region of Malaysia based on rice straw availability. Thetotal potential installed capacity in Northern region was 132.4 MWwhich is 0.61% from total installed generation capacity in penin-sular Malaysia for 2011. Among of the state in the northern region,Kedah provided the highest GWP saving which is 55.7% with73.7 MW installed capacity.

3.4. Sensitivity analysis

The impact of different assumptions on the results can bemeasured by different parameters and the observation of subse-quent changes. In addition, with a view to identifying the impactsof change in power plant size, distance and plant efficiency,sensitivity analysis was aptly conducted.

Table 13Potential in Northern region of Malaysia based on rice straw availability.

State Potential capacity (MW) GWP saving (MtCO2-eq per year)

Kedah 73.7 0.405Penang 12.1 0.0673Perak 27.1 0.147Perlis 19.5 0.108

Fig. 6. Relationship between the plant efficiency and CO2-eq emission.Fig. 8. Specific GHG emissions with varies the distance.

S.M. Shafie et al. / Energy 70 (2014) 401e410408

Plant efficiency gives significant result to the overall GHGemissions as same as conclusion made by study from wheat straw[73]. Fig. 6 show the relationship between the plant efficiency andCO2-eq. Their linear relationship was CO2-eq perkWh ¼ �0.023s þ 1.061. Increase 0.5% plant efficiency, resulted thereduction about 2.3% of total GHG emissions. The plant efficiencycould be vary with 2e3% points depending on fuel moisture, boilerpressure drop and steam data [87].

Rice straw transportation may have significant implications foroptimizing the plant performance. Fig. 7 shows the graph of LCAGHG Emission for three different plant capacities (50 MW,100MW,150 MW) with varies the distance of T1 and T2. The capacities ofrice straw bale per lorry give significant impact to the total GHGemission for rice straw based power generation. Small capacitybelow 50 MW has a same pattern of GHG emission with distance.

The system boundary consists of two types of transportationlinks which are T1 (transportation of bale rice straw from paddyproduction to collection centre) and T2 (transportation of bale ricestraw of bale rice straw from collection centre to power plant). T2has slightly higher impact to GHG emissions compare to T1whenvaries the distance and plant size parameter. Fig. 8 shows thespecific GHG emissions with vary the distance. At shorter distance,T1 contributes more than T2 to the total GHG emission. After110 km, T2 emission became more dominant than T1. In this case,the minimum GHG emissions can be obtained by designing thedistance of collection centre to power plant (T2) not more than110 km. It shows the same pattern correction from the biomasshaulage study in Ireland [76]. Still, the suggestion from Refs. [88],nearly 78% of survey respondents believed that the plant site

Fig. 7. LCA GHG Emission for three different plant capacities (50 MW, 100 MW,150 MW) with varies the distance of T1 and T2.

should be turned up within a 20 km radius from the resourcepoints.

T1 has 0.97% increase for each 10 km increase, while T2 only0.13% increases with 10 km increase. It means, for long distance it isbetter to use the big size of lorry capacity that can save the GHGemissions. The plant capacity gives an impact to the total GHGemissions with 4832.65 ton CO2-eq per MW. The GHG Emissionschange in distance with varies the plant size is presented in Fig. 9.Varies the distance of T1 is more affected on CO2-eq emissionscompared to T2 with 10% more.

Fig. 10 shows the total GHG emissions varies with distance forrice straw based power generation and coal based power genera-tion. The maximum total distance should be below 235 km per tripfor GHG emission below coal based power generation.

4. Conclusion

The highest energy consumption for rice straw preparation isfrom paddy productionwhich is 72% of the total. Considering all thepreparation stages for rice straw preparation, the biggest contri-bution to GHG emissions is from transportationwith 57.48% of CO2-eq emission. Rice straw-based power generation contributes96.65% of CO2 gas to GHG emissions. Transportation process hassignificant implication to the total CO2-eq emission. T2CC > POWER

link slightly have higher impact of GHG emissions compare toT1PP > CC with varies the distance and plant size. The distance ofcollection centre to power plant less than 110 km to obtains min-imum GHG emissions. The maximum total distance should bebelow 235 km per trip for GHG emission below coal based power

Fig. 9. GHG Emissions change in distance with varies the plant size.

Fig. 10. Total GHG emissions vary with distance for rice straw based power generationand coal based power generation.

S.M. Shafie et al. / Energy 70 (2014) 401e410 409

generation. All impact assessments from rice straw are much lowercompared to coal and natural gas-based power generation.

The current management practice in Malaysia for disposing ofpaddy straw residue is open burning. Rice straw power generationcan save GHG emissions of about 1.79 kg CO2-eq/kWh compared tocoal and 1.05 kg CO2-eq/kWh with natural gas based power gen-eration. Thus, a rice-straw power plant not only removes the ricestraw from field without open burning, but also saves GHG emis-sions that can contribute to climate change, acidification, andeutrophication, among other environmental problems.

Issues regarding the government perspective on policy forencouraging the utilization of biomass-based residue and powerplant development should be analyzed in depth in the near future.Local criteria (plant size, location, and supply) also need furtherassessment for practical implementation.

References

[1] Shamsuddin AH. Development of renewable energy in Malaysia strategicinitiatives for carbon reduction in the power generation sector. Procedia Eng2012;49:384e91.

[2] Muis ZA, et al. Optimal planning of renewable energy-integrated electricitygeneration schemes with CO2 reduction target. Renew Energy 2010;35(11):2562e70.

[3] Mohamed AR, Lee KT. Energy for sustainable development in Malaysia: energypolicy and alternative energy. Energy Policy 2006;34(15):2388e97.

[4] National green technology policy [cited 2011 13 November]; Available from:http://www.greentechmalaysia.my/index.php/green-technology/green-technology-policy/national-green-techology-policy.html; 2011.

[5] Hashim H, Ho WS. Renewable energy policies and initiatives for a sustainableenergy future in Malaysia. Renew Sustain Energy Rev 2011;15:4780e7.

[6] Abdel-Mohdy FA, et al. Rice straw as a new resources for some beneficial uses.Carbohydr Polym 2009;75(1):44e51.

[7] Carlos RM, Khang DB. Characterization of biomass energy projects in South-east Asia. Biomass Bioenergy 2008;32(6):525e32.

[8] Paddy Straw programme [cited 2011 7 November]; Available from: http://www.mada.gov.my/web/guest/236; 2011.

[9] Vargas-Morenoa JM, et al. A review of the mathematical models for predictingthe heating value of biomass materials. Renew Sustain Energy Rev 2012;16:3065e83.

[10] Prasertsan S, Sajjakulnukit B. Biomass and biogas energy in Thailand: poten-tial, opportunity and barriers. Renew Energy 2006;31(5):599e610.

[11] Singh J, Panesar BS, Sharma SK. Energy potential through agricultural biomassusing geographical information systemda case study of Punjab. BiomassBioenergy 2008;32(4):301e7.

[12] Gadde B, Menke C, Wassmann R. Rice straw as a renewable energy source inIndia, Thailand, and the Philippines: overall potential and limitations for en-ergy contribution and greenhouse gas mitigation. Biomass Bioenergy2009;33(11):1532e46.

[13] Kargbo FR, Xing J, Zhang Y. Property analysis and pretreatment of rice strawfor energy use in grain drying: a review. Agric Biol J N Am 2010;1(3):195e200.

[14] Valerio V, V A., Nanna F, Barisano D. Chemical characterisation of biomassfeedstocks for the gasifier test. In: Task 5.3. Biomass selection and charac-terisation, Braccio G, Editor, Sezione Energia da Biomasse.

[15] Fu P, et al. Evaluation of the porous structure development of chars frompyrolysis of rice straw: effects of pyrolysis temperature and heating rate.J Anal Appl Pyrol 2012;98:177e83.

[16] Chou C-S, Lin S-H, LuW-C. Preparation and characterization of solid biomass fuelmade from rice straw and rice bran. Fuel Process Technol 2009;90(7e8):980e7.

[17] Kadam KL, Forrest LH, Jacobson WA. Rice straw as a lignocellulosic resource:collection, processing, transportation, and environmental aspects. BiomassBioenergy 2000;18:369e89.

[18] Suramaythangkoor T, Gheewala SH. Potential alternatives of heat and powertechnology application using rice straw. Appl Energy 2010;87:128e33.

[19] Wei-Hua Y, et al. CO2 emission reduction and energy recovery from strawcogeneration project. In: Bioinformatics and biomedical engineering; 2009.

[20] Malaysia economics statistics. Kuala Lumpur: Department of StatisticsMalaysia; 2009.

[21] Nori H, Halim RA, Ramlan MF. Effects of nitrogen fertilization managementpractice on the yield and straw nutritional quality of commercial rice vari-eties. Malays J Math Sci 2008;2(2):61e71.

[22] Xu Y, et al. Agronomic performance of late-season rice under different tillage,straw, and nitrogen management. Field Crops Res 2010;115(1):79e84.

[23] Suramaythangkoor T, Gheewala SH. Potential of practical implementation ofrice straw-based power generation in Thailand. Energy Policy 2008;36:3193e7.

[24] Kasmaprapruet S, et al. Life cycle assessment of milled rice production:Casestudy in Thailand. Eur J Sci Res 2009;30(2):195e203.

[25] Silalertruksa T, et al. Life cycle GHG analysis of rice straw bio-DME productionand application in Thailand. Appl Energy; 2013.

[26] Ekman A, et al. Possibilities for sustainable biorefineries based on agriculturalresidues e a case study of potential straw-based ethanol production inSweden. Appl Energy 2013;102:299e308.

[27] Delivand MK, et al. Environmental and socio-economic feasibility assessmentof rice straw conversion to power and ethanol in Thailand. J Clean Prod2012;37:29e41.

[28] Roy P, et al. A techno-economic and environmental evaluation of the life cycleof bioethanol produced from rice straw by RT-CaCCO process. Biomass Bio-energy 2012;37:188e95.

[29] Shie J-L, et al. Energy life cycle assessment of rice straw bio-energy derivedfrom potential gasification technologies. Bioresour Technol 2011;102:6735e41.

[30] Liu H, et al. Comprehensiveevaluationofeffectsofstraw-base-delectricitygeneration: a Chinese case. Energy Policy 2010;38:6153e60.

[31] Muench S, Guenther E. A systematic review of bioenergy life cycle assess-ments. Appl Energy 2013;112:257e73.

[32] Renó Maria Luiza Grillo, et al. A LCA (life cycle assessment) of the methanolproduction from sugarcane bagasse. Energy 2011;36:3716e26.

[33] Ali R, Daut I, Taib S. A review on existing and future energy sources forelectrical power generation in Malaysia. Renew Sustain Energy Rev 2012;16:4047e55.

[34] Chauhan MK, et al. Life cycle assessment of sugar industry:A review. RenewSustain Energy Rev 2011;15:3445e53.

[35] Corstena Mariëlle, et al. Environmental impact assessment of CCS chains elessons learned and limitations from LCA literature. Int J Greenh Gas Control2013;13:59e71.

[36] Turconi Roberto, Boldrin Alessio, Astrup Thomas. Life cycle assessment(LCA)ofelectricity generation technologies: overview, comparability and limitations.Renew Sustain Energy Rev 2013;28:555e65.

[37] Blengini GA, Busto M. The life cycle of rice: LCA of alternative agri-food chainmanagement systems in Vercelli (Italy). J Environ Manag 2009;90:1512e22.

[38] Ramjeawon T. Life cycle assessment of electricity generation from bagasse inMauritius. J Clean Prod 2008;16:1727e34.

[39] Nguyen TLT, Gheewala SH, Bonnet S. Life cycle cost analysis of fuel ethanolproduced from cassava in Thailand. Int J Life Cycle Assess 2008;13:564e73.

[40] Davis SC, Anderson-Teixeira KJ, Delucia EH. Life-cycle analysis and ecology ofbiofuels. Trends Plant Sci 2009;14(3):140e6.

[41] DOE. Paddy statistics of Malaysia 2011. Kuala Lumpur: Department of agri-culture; 2012. p. 141.

[42] MOA. Crops statistic report. Paddy statistic of Malaysia [cited 2013 May 25];Available from: http://www.doa.gov.my/c/document_library/get_file?uuid¼8b3bb7ed-4363-4471-b760-6f528e6273dc&groupId¼38371; 2013.

[43] Fertilizer use crop. Food and agriculture Organization of the United Nations;2007.

[44] Selected indicators of food agricultural development in Asian-Pasific region1996e2006. Bangkok: Food and agriculture Organization of the United Na-tions; 2007.

[45] Bockari-Gevoa SM, et al. Analysis of energy consumption in lowland rice-based cropping system of Malaysia. J Sci Technol 2005;27(4):819e26.

[46] MADA. Rice straw production project in MUDA area; 2011.[47] Kargbo FR, Xing J, Zhang Y. Pretreatment for energy use of rice straw: a re-

view. Afr J Agric Res 2009;4(13):1560e5.[48] MADA, editor. Laporan projek pengkomposan jerami padi menggunakan

cacing kerjasama JAS dan MADA; 2004. Kedah.[49] Delivand MK, Barz M, Gheewala SH. Logistics cost analysis of rice straw for

biomass power generation in Thailand. Energy 2011;36:1435e41.[51] Jittima-Prasra A. Comparative life cycle assessment of rice husk utilization in

Thailand. School of Global Studies, Social Science and Planning College; 2009.RMIT University.

[52] Ahmad F. Sustainable agriculture system in Malaysia, in regional workshop onintegrated plant nutrition system (IPNS); 2001. Bangkok, Thailand.

S.M. Shafie et al. / Energy 70 (2014) 401e410410

[54] NREL. In: NREL, editor. Life cycle inventory database. United States: NREL;2012.

[55] DOE. Air pollution index management system [cited 2012 5 July]; Availablefrom: http://www.doe.gov.my/; 2012.

[56] FOASTAT. Fertilizer use by crop. 5th edn. Food and Agriculture Organization ofthe United Nations; 2007.

[57] MADA. Lembaga Kemajuan Pertanian Muda [cited 2011 5 May]; Availablefrom: http://www.mada.gov.my/; 2012.

[59] Saga K, Imou K, Yokoyama S, Minowa T. Net energy analysis of ethanol pro-duction system from high-yield rice plant in Malaysia. Appl Energy2010;87(7):2164e8.

[60] Abdullah AM. A cost analysis of paddy transportation and distribution systemsin Muda Agricultural Development Authority Granary Area. In: Agriculture.Kuala Lumpur: University Putra Malaysia; 2006.

[61] Martensson L. In: V.T. Corporation, editor. Emissions from Volvo’s trucks(Standard diesel fuel); 2003.

[62] EPA. Direct emissions from mobile combustion sources, in climate leadersgreenhouse gas inventory protocol core module guidance. United States:Office of air and Radiation; 2008.

[63] Domalski ES, Jobe TL, Milne TA. Thermodynamic data for biomass conversionand waste incineration. US: National Bureau of standards Solar Energyresearch Institute; 1986.

[64] KeTTHA. Natural gas in power generation [cited 2013 26 June]; Available from:http://www.kettha.gov.my/en/content/natural-gas-power-generation; 2011.

[65] EPA. Direct emissions from stationary combustion sources, in climate leadersgreenhouse gas inventory protocol core module guidance. United States:United States environmental Protection Agency; 2008.

[66] EPA. Chapter 1: external combustion sources. In: AP 42 emission Factor.United States: US environmental Protection Agency; 2003.

[67] KalinciYildiz,HepbasliArif,Dincer I. Lifecycleassessmentofhydrogenproductionfrom biomass gasification systems. Int J Hydrogen Energy 2012;37:14026e39.

[68] Sultana A, Kumar A. Development of energy and emission parameters fordensified form of lignocellulosic biomass. Energy 2011;36:2716e32.

[69] Koga N, Tajima R. Assessing energy efficiencies and greenhouse gas emissionsunder bioethanol-oriented paddy rice production in northern Japan. J EnvironManag 2011;93(3):967e73.

[70] Pishgar-Komleh Seyyed Hassan, Omid Mahmoud, Heidari MD. On the study ofenergy use and GHG (greenhouse gas) emissions in greenhouse cucumberproduction in Yazd province. Energy 2013;59:63e71.

[71] Hu Jianjun, et al. Economic, environmental and social assessment of briquettefuel from agricultural residues in China e A study on flat die briquetting usingcorn stalk. Energy 2014;64:557e66.

[72] Miller P, Kumar A. Development of emission parameters and net energy ratiofor renewable diesel from Canola and Camelina. Energy 2013;58:426e37.

[73] Sebastián F, Royo J, Gómez M. Cofiring versus biomass-fired power plants:GHG (Greenhouse Gases) emissions savings comparison by means of LCA (LifeCycle Assessment) methodology. Energy 2011;36:2029e37.

[74] Norton B. Renewable electricity-what is the true cost? Power Eng J; 1999:6e12.[75] Chungsangunsit T, Gheewala SH, Patumsawad S. Emission assessment of rice

husk combustion for power production. Int J Civ Environ Eng 2010;2(4):185e99.

[76] Devlin Ger, Klvac Radomir, McDonnell K. Fuel efficiency and CO2 emissions ofbiomass based haulage in Ireland-A case study. Energy 2013;54:55e62.

[77] Tabata T, Okuda T. Life cycle assessment of woody biomass energy utilization:case study in Gifu Prefecture, Japan. Energy 2012;45:944e51.

[78] Prasana-A J, Grant T. Comparative life cycle assessment of uses of rice husk forenergy purposes. Int J Life Cycle Assess; 2011.

[79] Chungsangunsit T, Gheewala SH, Patumsawad S. Environmental profile ofpower generation from rice husk in Thailand. In: Sustainable Energy andEnvironment (SEE); 2004. pp. 739e42. Thailand.

[80] Hartmann D, Kaltschmitt M. Electricity generation from solid biomass via co-combustion with coal: energy and emission balances from a German casestudy. Biomass Bioenergy 1999;16(6):397e406.

[81] Gadde B, et al. Air pollutant emissions from rice straw open field burning inIndia, Thailand and the Philippines. Environ Pollut 2009;157(5):1554e8.

[82] Restrepo Á, et al. Exergetic and environmental analysis of a pulverized coalpower plant. Energy 2012;45:195e202.

[83] Soimakallio Sampo, Kiviluoma Juha, Saikku L. The complexity and challengesof determining GHG (greenhouse gas) emissions from grid electricity con-sumption and conservation in LCA (life cycle assessment) e a methodologicalreview. Energy 2011;36:6705e13.

[84] Shekarchian M, et al. A review on the pattern of electricity generation andemission in Malaysia from 1976 to 2008. Renew Sustain Energy Rev 2011;15:2629e42.

[85] ETP. Economic transformation programme a roadmap for Malaysia. KualaLumpur: Performance management & Delivery Unit (Pemandu); 2012.pp. 167e205.

[86] Rahman DZA, et al. Malaysia environment quality report 2011. Kuala Lumpur:Department of environment; 2011.

[87] Pihl E, et al. Highly efficient electricity generation from biomass by integrationand hybridization with combined cycle gas turbine (CCGT) plants for naturalgas. Energy 2010;35(10):4042e52.

[88] Umar MS, Jennings P, Urmee T. Sustainable electricity generation from oil palmbiomass wastes in Malaysia: an industry survey. Energy 2014;67:496e505.