Organic-Waste LCA Case Studies11th December 2014Daniel Sandars, daniel.sandars@cranfield.ac.ukIHREF, School of Applied Sciences

Evaluating Sustainability:Waste managementcase studies in LCA

Waste in Europe

Population 500 million

Municipal solid waste 3 billion tonnes (10-25% organic)

Sewage sludge 9 million dry tonnes

Livestock population 136 million livestock units

136 million dry tonnes slurry/manure

Organic waste disposal?

EU waste priorities

1. Waste Prevention

2. Recycling and Reuse

3. Improved Final Disposal & Monitoring

globalwarming

ozone depletion

N2O, CH4

acidification

drainageNutrient

OverloadMetals NO3

-

BOD, PO43+

deposition

ammonia

pathogens

Best environmental options?

The System

The Functional Unit

Natural resource

consumption

Inputs to

farming

Synthetic inputs

to farming

Losses to the

environment

Production System

Environment

Nutrients

recycledThe slurry and solid manure

handling chain

Animal

1 tonne lean pig meat

Fertilisers

Feed

Bedding

Waste

to landCroppingLand

Waste

management

Emissions

to water

Emissions

to airLand

degradation

Consumable

resources

Energy

The System

The Functional Unit

Natural resource

consumption

Inputs to

farming

Synthetic inputs

to farming

Losses to the

environment

Production System

Environment

Nutrients

recycledThe slurry and solid manure

handling chain

Animal

1 tonne lean pig meat

Fertilisers

Feed

Bedding

Waste

to landCroppingLand

Waste

management

Emissions

to water

Emissions

to airLand

degradation

Consumable

resources

Energy

Slurry tankers

Standard

splash-plate

spreader

Over-the-fence

broadcast spreader

Low trajectory

splash-plate

spreader

Trailing

pipe/shoe

Sub-soil shallow

injection spreader

Slurry stores

Carbon long time scales

Reference system

• Start with a typical system as a reference

– Pigs on slatted floor

– Uncovered storage

– Splash plate spreading on arable

• Functional Unit(s)

– 1 tonne of pigmeat

– 1 dry tonne organic waste? 100,000 population

equivalent? 1 ha?

Weighting Factors

Impact Unit UK 1998

Global Warming Potential 100yr, kg CO2 Equ 7.48E+11

Eutrophication, kg PO4 Equ 4.60E+7

Acidification, kg SO2 Equ 3.89E+9

Photo Chemical Oxide Formation, kg Ethyl Equ 2.11E+9

Source: Department of the Environment Transport and Regions (1988)

Results

Weighted Environmnetal Impacts

-5.00E-09

0.00E+00

5.00E-09

1.00E-08

1.50E-08

2.00E-08

2.50E-08

3.00E-08

GWP 100

Smog

Eutrophication

Acidification

Splash Plate (30%)Trailing Pipe (30%)Injector (30%)Trailing Pipe (50%)Injector (50%)

Uncertainty

• What does slurry injection can result in up

to 85% ammonia abatement mean in

practice, most of the time? Why say it?

• Heterogeneity (variability)

• Climatic and environmental uncertainty

• Measurement error and incomplete

knowledge

Uncertainty

• What does a claim of up to 85% reduction in

ammonia emissions mean?

• Uncertainty can be due to measurement

difficulties or chance conditions

• The LCA requires well rounded management

averages. It is the uncertainty of this mean rather

than the population that we use.

• To be worthwhile, the benefits of a technique need

to be due to more than random chance.

10% coefficient of variation of ammonia emissions

Farm scale AD

Farm scale AD

Holsworthy Centralised Anaerobic Digester

Holsworthy CAD

• 12,100 t CO2 eqv reduction of global warming (100

years)

• 48 t NO3 eqv eutrophication reduction

• 310 t SO2 eqv acidification increase

• 59 t PO4 eqv habitat nutrification increase

Unfortunately the later two are the more sensitive

impacts where agriculture’s contribution is

proportionally greater

Controlling the N

-0.020

-0.015

-0.010

-0.005

0.000

0.005

0.010

0.015

0.020

0% 10% 20% 30% 40% 50% 60% 70% 80% 90%

Abatement of digestate NH3 landspreading losses

t/kt

Weste

rn

Eu

ro

pean

Im

pacts

Global Warming Normal

Acidification Normal

Eutrophication Normal

Fig. 6.6 LCA predictions of the overall effects abating ammonia losses from land spreading of

digestate on Global Warming, Acidification and Eutrophication, each normalised with respect to

current Western European environmental emissions inventory (Anon, 2005)

• 1. Reduce the volume of sewage sludge

produced

• 2. Improve sewage sludge treatment

• 3. Develop a high quality sewage sludge based

fertiliser product

• 4. Improve the energy efficiency of waste water

treatment

• Three median…representative systems are defined

• A On-site sludge treatment c. 5k person

equivalents

• B Small scale centralised with 50% of sludge

imported c. 75 k person equivalents

• C Large scale centralised with 50% of sludge

imported c. 200 k person equivalents

• When multiplied/scaled up these will be

representative of approximately 80% of the European

Union (Geographical scope)

Conclusions