Life Cycle Assessment of Organic Waste: Application and Relevance to New Zealand

Simon Love

PRESENTATION OUTLINE

1. Introduction to LCA

2. LCA and Organic Waste

3. Scion’s ‘Waste 2 Gold’ Project

Part One: Brief introduction to LCA

Introduction to LCA

Life Cycle Assessment (LCA) is an analytical tool for the systematic and quantitative evaluation of the environmental impacts of a product or service system through all stages of its life.

ISO STANDARDS

• ISO 14040 – ‘Principles and framework’- Terms used- Phases of an LCA - Methodological framework- Need for critical reviews

• ISO 14044 – ‘Requirements and guidelines’- More detailed guidelines for each step- More specific requirements- Guidelines for critical reviews- Examples of application

Introduction to LCA

Life Cycle Assessment Framework

Interpretation

Impactassessment

Inventory analysis

Direct applications:• Product

development and

improvement• Strategic planning• Public policy

making• Marketing• Benchmarking• Ecolabels and

product

declarations

Goal and scope definition

Impact Categories in LCA

Input-related Categories1.Abiotic resources (e.g. minerals,

fossil fuels)

2.Biotic resources (e.g. fish, logs)

3.Land

Output-related categories4. Global warming

5. Depletion of stratospheric ozone

6. Human toxicological impacts

7. Ecotoxicological impacts

8. Photo-oxidant formation

9. Acidification

10.Eutrophication (incl. BOD and heat)

11. Odour

12.Noise

13.Radiation

14.Casualties

Impact categories according to SETAC-EUROPE working group on LCA

Two types of LCA

Attributional:

- Attributing impact to current activities

- i.e. ‘Footprint of process abc’

- Used for comparison and benchmarking

Consequential:

- Consequences of future activities

- i.e. What if we change a to z…?

- Higher uncertainty- Decision support

Notables in the Life Cycle Assessment scene

Specialist Organisations

Crown Research Institutes

Legislative and Government bodies

UniversitiesConsultants

Part Two: LCA and Organic Waste

Challenges and Opportunities of Organic Waste

Challenges:

- Large volumes - Methane gas from

decomposition- Odour- Leachate- Metals

Opportunities:

- Energy Source- Conversion to useful

products- Carbon-based- N & P - based- Land application

- Large volume reduction

New Zealand Waste figures

• Total waste to landfill, year to June 2010:~2.5 million tonnes1

• Organic waste at 23%:~570,000 tonnes1

1. http://www.mfe.govt.nz/issues/waste/

Options for Organic Waste

• A large proportion of organic waste in

New Zealand goes to landfill

• Other options:- Compost- Anaerobic digestion- Gasification- Pyrolysis- Incineration- Land application (biosolids)

LCA Studies

• Can quantify important environmental impacts such as:

- Global warming (methane production)- Energy (methane for heat/electricity, energy balance

of incineration/drying/gasification)- Eutrophication (leachate to rivers/streams)

• May not be as useful for impacts such as:

- Accumulation of heavy metals (land application)- Odour

Can be combined with:

• Economic (LCC):- Cost of processing- Useful byproducts- Energy production

• Social factors- Not traditionally in LCA- Emerging field- Necessary to account for human factors!

Part Three: Scion’s ‘Waste to Gold’ Project

Wet Oxidation Technology

• Feedstock: Biosolids from wastewater treatment

• High pressure and temperature in oxidising environment

• Outputs: Useful liquid products or energy, small amount of solids

• Over 90% solids reduction

Waste to Gold

BiomassDeconstruction

High CarbonSolid Wastes

Energy Recovery

Biodegradable Intermediates

Bioconversion Liquid biofuels

Biopolymers

Bioenergy

Economic and Other Potential Benefits

• Reduction in solid waste to landfill, resulting in increased landfill life

• Reduction of emissions from solid waste decomposition

• Can produce a range of useful outputs (organic intermediates or energy)

RDC Case Study

• Rotorua District Council were interested in wet oxidation of biosolids

• LCA was employed for environmental comparison of current and future options

Options Compared

• Current average NZ Landfill

• Landfill without methane capture

• Wet Oxidation (‘Waste 2 Gold’) variants

• Anaerobic Digestion variants

• Land Application

System Boundary Diagram

Wet Air Oxidation and/or Anaerobic Digestion

Wet Air Oxidation and/or Anaerobic Digestion

PreparationPreparation

EnergyEnergy

Landfilling

Sludge DisposalSludge Disposal

Other InputsOther Inputs

Output MixOutput Mix

Energy Generation from biogas outputs

Energy Generation from biogas outputs

Useful ProductsUseful

Products

Production of alternative products

Production of alternative products

System Expansion Conventional energy

generationConventional energy

generation

WaterWater

Use of energy & other productsUse of energy & other products

Infr

ast

ruct

ure

Bu

ildin

gs

Results

•W2G showed much promise in:- Global warming potential- Eutrophication potential- Solids Reduction

• But had high energy and ozone depletion potentials- Sensitivity analysis shows that results are very

sensitive to oxygen use and solids content, so much potential for improvement

Other Technologies

• Anaerobic digestion- Good energy production- Reasonable solids reduction

• Landfill- Landfill gas capture makes large difference- Still potential for eutrophication and acidification

• Land application- Low energy alternative- Potential for heavy metals build-up- Application and transport could be a challenge- Public perception

RDC Case Study

• Pilot scale plant currently being built

• MfE Waste Management Fund : $1m

Conclusions & Future Work

Conclusions• LCA can help to decide on the suitability of future

organic waste disposal options in NZ

• Can provide quantitative and qualitative results in many impact categories

• LCA assisted in putting case forward to gain WMF Funding for the Rotorua trial

Future Work

• New Zealand-specific data collection and impact categories

• Life Cycle Costing and Social LCA

• Assessment of other new technologies