Systems analysis and its interpretation

Life cycle assessment (LCA):aims to evaluate the environmental burdens associated with a certain product or service in a cradle-to-grave perspective, from raw material extraction to waste management and final disposal.

Standardisation is made through the framework of ISO, the International Organization for Standardization

Source: Pernilla Tidåker

Raw material acquisition

Processes

Transport

Manufacture

Use

Waste management

Source: Pernilla Tidåker

Core orForegroundSystem

Extended or Backgroundsystem

Primary resources

OtherFunctionalOutput

EmissionsEmissions

Functionaloutput

Source: Pernilla Tidåker

We work with an “expanded system”

• In all scenarios the same amount of valued functions are produced, either by the waste system or by the compensatory system (external system)

Waste system Compensatory system

Product

Source: Jan-Olov Sundquist, IVL

Waste sources

Waste managementsystem

Emissions

Energy Fertiliser

Material

Energy

Energy Fertiliser

Costs

Compensatory system

Alternativeproductionof energy

AlternativeproductionofN-,P-fertiliser

System boundary

Alternativeenergy raw

material

Alternativefertiliser raw

material

Total system scenario 1-n

Source: Jan-Olov Sundquist, IVL

Conclusions, limitations and recommendations

Identification of significant issues

Evaluation by e.g. sensitivity and

consistency check

Goal and scope

definition

Inventory analysis

Impact assessment

Interpretation

Source: Pernilla Tidåker

• Resources - Energy and materials• Resources - Water• Resources - Land • Impacts on human health (toxicological and non-toxicological impacts, excluding and including work environment)• Global warming• Depletion of stratospheric ozone• Acidification• Eutrophication• Photo-oxidant formation• Eco-toxicological impacts• Habitat alterations and impacts on biological diversity

Impact categories to be considered in an LCA

Source: Pernilla Tidåker

Title

Data are collected…and aggregated

NOx

NH3

P

etc.

CO2

CH4

N2O

Eutrophication

Global warming

Index

Inventory Characterisation Weighting

Source: Pernilla Tidåker

Global Warming Potentials (GWP) as CO2 –equivalents for different trace gases and time-frames (IPCC, 2001) Trace gas GWP, 20 years GWP, 100 years GWP, 500 years Carbon dioxide, CO2 1 1 1 Methane, CH4 62 23 7 Nitrous oxide, N2O 275 296 156

Source: Pernilla Tidåker

Weighting factors for acidification for two scenarios, min and max (Lindfors et al., 1995). Substance Min [mol H+/g] Max [mol H+/g] SO2 0.031 0.031 HCl 0.027 0.027 NOx 0 0.022 NH3 0 0.059

Source: Pernilla Tidåker

Acidification

• 2 NH3+4 O2 2 NO3- + 2 H2O + 2H+

• 2 NO2+½ O2 + H2O 2 NO3- + 2H+

• 2 SO2+½ O2 + H2O 2 SO42- + 2H+

• NH3 and NOx are not acidifying if they are taken up

by plants instead of being oxidized to NO3- or if the

NO3- is taken up, because when taken up by the

root it is exchanged for OH-.

Source: Pernilla Tidåker

Weighting factors for eutrophication

Substance Maximum (g O2 per g) Minimum (g O2 per g) N to air 20 NOx to air 6 NH3 to air 19.8 3.8 N to water 20 NO3 to water 4,4 NH4 to water 18.6 3.6 P to water 140 140 PO4

3- 46 46 COD 1 1

Source: Pernilla Tidåker

Remember…

It is a great difference between potential and actual environmental impacts.

Source: Pernilla Tidåker

Which environmental effect is most important?

• Global vs local

• Long-term vs short-term

• Normalization: Compare the system under study to total national emissions

Source: Cecilia Sundberg

Normalized emissions from biowaste

Normalised emissions (% of total emissions)

Landfill Incin. 1 Incin. 2 Anaerobic digestion

GWP 0,99% 0,45% 0,35% 0,11% NH3 to air 0,05% 0,03% 0,03% 0,67% SO2 0,17% 2,48% 1,82% 1,15% SO2* 0,08% 0,11% 0,11% 0,83% NOx ca 0,1% ca 0,1% ca 0,1% ca 0,1% N to water 0,33% 0,01% 0,01% 0,55% P to water 0,10% 0,77% 0,77% 0,19% *complementary system excluded

Source: Cecilia Sundberg

ORWARE, LCA and waste management

• Waste occurs in most production systems – waste management included in most LCAs (but for food LCAs, it is often only included for the packaging)

Waste management models, applicable to various wastes a useful tool in LCA

ORWARE: mass flow model, including LCA assessment methodology

Source: Cecilia Sundberg

Functional unit, valued products

Core system incineration

Waste

Heat

Power

Functional unit

Core system Landfill

Waste

Heat

Power

Heat production

Power production

Complementary or alternative production

Functional unit

Which is the complementary production system?Source: Cecilia Sundberg

Complementary systems

• Marginal production: – If I would not produce heat from waste – how would

that heat be produced?– If I produce more heat from waste – what other heat

will not be produced?

• Short term marginal : changes within existing infrastructure/production capacity

• Long term marginal : changes in supply or demand will drive investment

• The goal and scope of your study guides the choice of complementary systems

Source: Cecilia Sundberg

Carbon budgeting

• Biogenic carbon is considered neutral, no GWP

• Most common assumption in LCA

• This can be justified – and it can be questioned!

Source: Cecilia Sundberg