REPORT V1.2 GREAT SOUTHERN WASTE TECHNOLOGIES … · Great Southern Waste Technologies (GSWT) is...

REPORT V1.2

GREAT SOUTHERN WASTE TECHNOLOGIES (GSWT) 7 OCTOBER 2019 S1812

GSWT – Streamlined LCA of Waste-to-Energy Project

©2019 start2see Pty Ltd 2

Project Details

Project Title

GSWT – Streamlined GHG assessment of 100 ktpa MSW/C&I waste-to-energy project

Client Details

Great Southern Waste Technologies

19-25 Thomas Murrell Crescent Dandenong South, Vic 3175

Australia

Client Contacts start2see Project Manager

Stuart Gilbert, William Keating Rob Rouwette

Report version Author(s) Date

Report v1.2 Rob Rouwette 7 October 2019

Disclaimer

Where conclusions have been drawn based on information provided

to start2see by the recipient of this report, start2see has relied upon the accuracy of the information provided. Whilst every effort has

been made to ensure the completeness and accuracy of existing and projected data, results and conclusions, no liability is accepted by

start2see for losses due to information provided in this report.

If you would like to discuss any of the topics or have any questions please feel

free to contact start2see (Rob Rouwette) on mobile +61 403 834 470.

© start2see Pty Ltd Melbourne, Australia ACN: 143 127 315



Table of Contents

Executive summary ..................................................................... 4

1 Project Brief .......................................................................... 7 1.1 Objectives .............................................................................. 7

2 GSWT – proposed Dandenong South facility .............................. 8

3 Key scope elements .............................................................. 10 3.1 Scope .................................................................................. 10 3.2 Intended use of the study ....................................................... 10 3.3 Selected environmental indicators ............................................ 10 3.4 Product system description ..................................................... 11 3.5 Reference unit ...................................................................... 11 3.6 System boundaries ................................................................ 11

3.6.1 GSWT Waste-to-Energy ..................................................... 12 3.6.2 Business-as-usual ............................................................. 13

4 Life Cycle Inventory (LCI) data ............................................... 15 4.1 Data and data sources ........................................................... 15 4.2 Choices and assumptions ....................................................... 17

5 Life Cycle Assessment results ................................................. 20 5.1 GSWT waste-to-energy .......................................................... 20 5.2 Business-as-usual ................................................................. 21 5.3 Comparison of scenarios ........................................................ 22

6 Interpretation ....................................................................... 23 6.1 Hot-spot analysis .................................................................. 23 6.2 Sensitivity analyses ............................................................... 25

6.2.1 Transport of waste streams ................................................ 25 6.2.2 Exclusion of capital goods .................................................. 25 6.2.3 Use of filter dust and bottom ash......................................... 25 6.2.4 Electricity emissions intensity ............................................. 27 6.2.5 Future electricity grid ........................................................ 28

7 Conclusions .......................................................................... 32

8 Limitations ........................................................................... 33

References ................................................................................ 34

Appendix A. Renewable components of MSW ................................. 36

Appendix B. Useful applications of bottom ash ............................... 37



Executive summary Background Great Southern Waste Technologies (GSWT) is proposing a Waste-to-Energy

project at 70 Ordish Road, Dandenong South (Victoria). The new facility will take in 85% Municipal Solid Waste (MSW) and 15% Commercial and Industrial

(C&I) waste sources and process them into energy and potentially useful products (e.g. ashes and recovered scrap metals).

Scope start2see has applied a streamlined life cycle assessment (LCA) methodology

to determine the carbon footprint of GSWT’s proposed waste-to-energy facility and compare this to business-as-usual.

- The included life cycle stages cover transport of waste from its source to GSWT’s waste-to-energy plant and operation of GSWT’s facility, which produces energy, waste and useful products.

- The business-as-usual scenario assumes all MSW and C&I waste is taken to landfill.

To make a fair comparison, an alternative (virgin) production method for the useful products (from GSWT’s facility) needs to be included as well.

Methodology and scope

The LCA methodology is based on ISO 14040:2006 and ISO 14044:2006 standards. This streamlined LCA has been prepared by start2see and has not undergone an independent third-party review.

The carbon footprints have been determined using the Global Warming

Potentials from the IPCC’s Fourth Assessment Report (AR4). Life cycle inventory data

GSWT has supplied data regarding the quantities of waste, transport modes and distances, operation of its planned facility and the materials that will be

recovered. GSWT and start2see have estimated the parameters of a functionally equivalent business-as-usual scenario. Modelling data have been complemented with literature data.



Results - comparison The LCA results indicate that GSWT’s proposed 100 ktpa facility on Ordish Road leads to an annual reduction in greenhouse gas emissions of approximately

143,000 t CO2e compared to business-as-usual.

Carbon footprint comparison of GSWT’s waste-to-energy project vs.

business-as-usual

Conclusions

- The key to the savings is diverting 85,000 tonnes of MSW and 15,000 tonnes of C&I waste from landfill, thereby avoiding 137,000 t CO2e.

- GSWT’s waste-to-energy project generates approximately 59,800 t CO2e (excluding transport of waste). An equivalent amount of average

electricity produced in the National Electricity Market would currently result in emissions of 50,300 t CO2e. Therefore, the project itself leads to net emissions of 9,500 t CO2e per year.

- Useful products recovered by GSWT lead to further savings in emissions, as they can replace other (virgin) materials. A high-level estimate puts

the benefits at 15,300 t CO2e. Further benefits are possible if useful applications are found for bottom ash and if filter dust is used in higher value applications.

The above results are based on current design parameters and generic data.

Our default BAU scenario assumes that MSW and C&I waste goes to landfill.

0

50

100

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GSWT proposal Business-as-usual

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Key assumptions and limitations

Key assumptions within the LCA that influence the results are:

- It is assumed that all exported electricity substitutes electricity with the

prescribed average NEM grid emissions intensity (0.82 kg CO2e/kWh).

- The net calorific value of MSW and C&I waste is 10 GJ/t, which is

assessed to be made up of 39% biomass and 61% non-biomass materials by energy content; 66% biomass and 34% non-biomass materials by mass.

- The emissions of bottom ash in landfill have been calculated using a total organic carbon content of 1.4% w/w as a representation for

Degradable Organic Carbon.

- Diesel consumption at the plant has been estimated for one wheel-

loader, bobcat and forklift.

- Capital goods are excluded from the LCA. A sensitivity analysis shows that the exclusion of capital goods does not materially affect the results.

There might be further opportunities to optimise the plant that would lead to

further savings. This is outside the scope of the current analysis.



1 Project Brief Great Southern Waste Technologies (GSWT) is proposing to develop a waste-

to-energy project at 70 Ordish Road, Dandenong South. The project will use Municipal Solid Waste (MSW) and Commercial & Industrial (C&I) waste sources and process them into energy and useful products (e.g. ashes and recycled

metals).

This project is expected to result in significant environmental benefits, such as reduction in overall greenhouse gas (GHG) emissions, compared to business as usual (BAU). GHG emissions from the project are expected to be offset by

landfill avoidance, a lower dependence on conventional power from the grid and avoided virgin products. Quantifying these benefits can assist the project

proponents in its dialogues with stakeholders. To achieve this, GSWT has commissioned start2see to undertake a streamlined

environmental Life Cycle Assessment (LCA) and calculate the GHG benefits of the proposed project and provide GSWT with insights into the key drivers of

GHG emissions and benefits.

This report describes the LCA methodology, key data and results.

1.1 Objectives

The key objective of this high-level GHG LCA study is to compare two waste

disposal/treatment options: 1) Business as usual (BAU) –> MSW and C&I waste is sent to landfill.

2) GSWT waste-to-energy -> MSW and C&I waste is processed into energy

(electricity) and useful products.

a. Since GSWT’s process generates surplus energy, an equivalent

amount of electricity will have to be generated using conventional

sources under the BAU model.



2 GSWT – proposed Dandenong South facility GSWT plans to build and operate a (100,000 tonnes per annum) waste-to-energy facility at 70 Ordish Road, Dandenong South, approximately 30 km

southeast of Melbourne, Victoria.

Figure 1. Rendering of proposed GSWT waste-to-energy facility

The waste-to-energy plant consists of the following main systems (Figure 2): • Waste receipt and fuel preparation system

• Fuel bunker and transport system

• Thermal Conversion

o Gasification Chamber

o High Temperature Oxidation Chamber

• Heat Recovery Steam Generator (HRSG)

• Steam turbine and air-cooled condenser

• Flue-gas cleaning system

• Flue gas fan and flue gas stack

• Control and monitoring system



Figure 2. Schematic flow diagram for this facility



3 Key scope elements

3.1 Scope

start2see has applied a streamlined life cycle assessment (LCA) methodology

to determine the carbon footprint of GSWT’s proposed waste-to-energy facility and compare this to business-as-usual. The included life cycle stages cover transport of waste from its source to

GSWT’s waste-to-energy plant and the operation of the GSWT’s facility which produces energy and by-products.

The business-as-usual scenario assumes all MSW and C&I waste is taken to landfill. In order to make a fair comparison, an alternative (virgin) production method for the useful products (that would normally be lost in landfill) needs

to be included as well.

3.2 Intended use of the study

GSWT intends to use the outcome of the streamlined study to present the

estimated environmental impacts and benefits associated with diverting waste from landfill and operating the waste-to-energy plant at Dandenong South with

selected third parties (e.g. government policy makers).

3.3 Selected environmental indicators

This study considers the emission of greenhouse gases. The results of the LCA

are presented as the ‘carbon footprint’ of the scenarios, expressed in tonnes of carbon dioxide equivalents (t CO2e).

start2see has applied the Global Warming Potentials (GWP) taken from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report

(AR4) [IPCC 2007], using a 100-year time horizon. These factors are in line with current Australian Commonwealth Government reporting requirements under the National Greenhouse and Energy Reporting Act 2007 (NGER Act).

Note that there are other (environmental) indicators that might be of relevance

to specific stakeholders. These indicators, such as mineral and fossil fuel resource depletion, eutrophication, acidification, toxicity, etc. are outside the scope of this streamlined study.



3.4 Product system description

GSWT’s waste-to-energy facility will take MSW and C&I waste from local council areas (e.g. Dandenong, Hallam, Frankston). The MSW is made up of:

• biomass or biogenic materials (such as paper, cardboard, food waste,

organic waste, leather and natural fibre textile products)

• non-biomass combustible materials (such as plastics)

• non-combustible materials (such as glass and metals).

GSWT will retrieve ferrous and non-ferrous metal recyclables from the MSW

and C&I and use the remaining residue to feed their waste-to-energy plant.

3.5 Reference unit

All flows (waste, ancillary materials and fuels taken in; electricity, secondary

products and waste (ashes) leaving the site) have been estimated for one year of operation of the facility (as designed). The calculated greenhouse gas

emissions also represent a typical twelve-month period. The business-as-usual scenario considers the same quantity of MSW and C&I

(to landfill disposal) and electricity plus materials (that need to be produced using traditional processes).

3.6 System boundaries

The system boundaries describe which processes are included in and excluded from the LCA. In general, we have attempted to include all material and energy

flows that relate to either the BAU waste to landfill scenario or the alternative GSWT waste-to-energy scenario1. All major processes that change when the waste is diverted from landfill have been included. For example, this covers:

- Changes to transport movements

- Changes to waste processing

- Changes to the type and quantity of useful materials that are created.

GHG emissions attributable to the following items are omitted from the system

boundaries for both scenarios: - Infrastructure

- Capital goods

- Human labour and transport of employees.

1 Note: At this stage of the development, details in the design of GSWT’s project are still being determined.

Changes to the design or operation of the facility can have a significant impact on the results of this study

and these will have to be re-evaluated accordingly.



These exclusions are in line with common LCA practice. A sensitivity analysis is performed to analyse the impact of excluding/including GSWT’s waste-to-energy facility (buildings) (see section 6.2.2).

Figure 3. Flow diagram: GSWT Waste-to-Energy vs BAU

3.6.1 GSWT Waste-to-Energy

Figure 4 shows the system boundary for GSWT’s waste-to-energy scenario in more detail. In this LCA, the following life cycle stages are included:

- Collection of waste and transport to the Dandenong South plant

- Operation of GSWT’s facility

- Export of surplus electricity generated from the MSW/C&I waste

- Extraction of ferrous and non-ferrous metals (recyclables).



Figure 4. System boundary – GSWT waste-to-energy

* The benefits of potentially using bottom-ash as a secondary product have not (yet) been taken into account due to lack of data. This is a conservative approach. ** Some of the electricity and heat generated is consumed internally (parasitic power).

3.6.2 Business-as-usual

GSWT has provided information on the most likely business-as-usual scenario

that applies to the relevant waste stream. It is assumed that all MSW and C&I

waste is sent to a generic landfill. The following life cycle stages are included within the BAU system boundary

(see Figure 5, top): - Collection of MSW / C&I and transport to landfill site.

- Sequestration of carbon and emissions of methane (CH4) and carbon

dioxide (CO2) in landfill.



GSWT’s process recovers ferrous and non-ferrous recyclables from the waste stream, avoiding the need to manufacture a functionally equivalent amount of (virgin) products. These virgin products are accounted for within the BAU

system boundaries (see Figure 5, bottom). Furthermore, GSWT’s process generates electricity as well as bottom-ash and

filter dust (fly ash, lime, activated carbon). It is assumed that all electricity exported to the grid (i.e. after accounting for parasitic power) replaces grid electricity with the state average emissions factor. In the default analysis, filter

dust is assumed to replace sand (e.g. in road foundation), while bottom-ash is landfilled. This is a conservative approach. If these products can be used in

(higher) value applications in the future, it will increase the benefits associated with GSWT’s process.

Figure 5. System boundary – Business-as-usual (BAU)

* The benefits of potentially using bottom-ash as a secondary product have not (yet) been taken into account due to lack of data. This is a conservative approach



4 Life Cycle Inventory (LCI) data Data has been sourced from GSWT and a range of publicly available literature sources. The key data and assumptions are discussed in this section.

4.1 Data and data sources

start2see has used data obtained from GSWT and literature sources. The

following tables detail the key data and sources for the emission factors used in this study for modelling the carbon footprint for the two scenarios.

Table 1. Data, emission factors (EF) and sources for transport

Waste stream Transport modes GSWT BAU EF Source

MSW to GSWT facility Rigid trucks, 8 t load 20km 20km AusLCI 2018

C&I to GSWT facility Rigid trucks, 8 t load 20km 20km AusLCI 2018

Table 2. Data, emission factors (EF) and sources for waste disposal

Waste stream Disposal

option

Factor

(kg CO2e/t)

EF Source

MSW Landfill 1400 NGA 2018, table 44 (MSW)

C&I waste Landfill 1200 NGA 2018, table 44 (MSW)

Bottom-ash Landfill 105 Estimate; calculated by start2see 2 from NGA 2018, table 43

Filter dust# Landfill 601 Estimate; calculated by start2see 2 from NGA 2018, table 43

2 Calculated using the NGER determination method [NGER 2008] for solid waste disposal on

land (Part 5.2), Method 1 — emissions of methane released from landfills, as applied in [NGA 2018] for “Alternative waste treatment residues”.



Table 3. Data, emission factors (EF) and sources for MSW

Waste stream Energy

content

(GJ/t)

Factor

(kg CO2e

/GJ)

EF Source

Non-biomass municipal materials, if recycled and combusted to produce heat or electricity

10.5 88.9 NGA 2018, table 1

Biomass municipal and industrial materials, if recycled and combusted to produce heat or electricity

12.2 1.8 NGA 2018, table 1

MSW supplied to GSWT 10 54.9 Estimated by GSWT (39% biomass by energy)

C&I waste supplied to GSWT 10 54.9 Assumed to be similar to MSW (39% biomass by energy)

Table 4. Data, emission factors (EF) and sources for electricity

Waste stream Factor

(kg CO2e/kWh)

EF Source

Electricity (National

Electricity Market)

0.82 NGA 2018, table 6 (scope 2 only) 3

Electricity (Victoria) 1.16 NGA 2018, table 41 (Victoria; scope 2+3)

Table 5. Data, emission factors (EF) and sources for fuels

Waste stream Factor

(kg CO2e/GJ)

EF Source

Natural gas 55.4 NGA 2018, table 2 (Natural gas distributed in a pipeline) + table 38 (Victoria Metro)

Diesel 74.1 NGA 2018, table 4 + table 40 (Diesel oil)

Table 6. Data, emission factors (EF) and sources for ancillary materials

Waste stream Factor

(kg CO2e/t)

EF Source

Activated carbon 100 AusLCI 2018 (Charcoal)

Lime 1090 AusLCI 2018 (Lime, calcined)

3 Emissions factors for electricity grids to be used for calculating a carbon dioxide equivalent net abatement amount in accordance with a methodology determination under the Carbon Credits (Carbon Farming Initiative) Act 2011.



Table 7. Data, emission factors (EF) and sources for (avoided) virgin materials

Recovered

product

Avoided

material

Factor

(kg CO2e/t)

EF Source

Ferrous metal Steel 1700 Sustainability Victoria4

Non-Ferrous Aluminium 17000 Sustainability Victoria4

Filter dust# Sand 3.1 AusLCI 2018 (Sand)

Filter dust# Lime 1090 AusLCI 2018 (Lime, calcined)

# Filter dust is made up of fly ash, lime and activated carbon. GSWT might be able to sell it as

a secondary product, in which case benefits of replacing virgin materials have to be taken into account. If filter dust is sent to landfill instead, it will generate further emissions. In the LCA the default assumption is that the filter dust can replace sand in road construction. A sensitivity analysis looks at the consequences of using the filter dust to replace hydrated lime in asphalt production or sending the filter dust to landfill.

4.2 Choices and assumptions

The key choices and assumptions of this assessment are: - The quantity of MSW and C&I waste diverted from landfill is based on

current plant capacity modelling by GSWT.

- The energy content of MSW is presumed to be 10 GJ/t. [Personal

communication GSWT]

- The energy content of C&I waste is presumed to be 10 GJ/t. This is a

conservative estimate. [Personal communication GSWT]

- The percentage biomass in MSW is estimated to be 66% by mass / 39%

by energy content (based on Australian Greenhouse Office - Guideline

for Renewable Components in Waste).

- The percentage biomass in C&I is presumed to be 66% by mass / 39%

by energy content (assumed similar to MSW).

- The model differentiates between biogenic and non-biogenic stack

emissions from GSWT’s waste-to-energy plant. Biogenic emissions do

not count towards the total GHG emissions. (See comment on next page

regarding treatment of biogenic emissions.)

- The destination of waste under the BAU scenario is landfill. This is

currently the most reasonable assumption.

4 Accessed (8 June 2018) http://www.sustainability.vic.gov.au/Government/Victorian-Waste-data-portal/Lifecycle-assessment-of-kerbside-recyclables-in-Victoria/LCA-kerbside-recycling-calculator

http://www.sustainability.vic.gov.au/Government/Victorian-Waste-data-portal/Lifecycle-assessment-of-kerbside-recyclables-in-Victoria/LCA-kerbside-recycling-calculator





- The GSWT plant is expected to be largely self-sufficient from an energy

point of view. This is based on current modelling by GSWT.

o Around 1.5 MW of the electricity generated by GSWT is used for

parasitic loads [Energos 2017]; surplus electricity (7.8 MW) will

be exported to the grid. Although the electricity is exported to the

Victorian grid, the emissions factor used for calculating the carbon

dioxide equivalent net abatement amount is based on the

National Electricity Market (NEM) in accordance with [CFI 2017].

o Natural gas is projected to be used to start up the process after

interruptions, and to assist the process when required.

o Diesel fuel for the wheel loader, bobcat and forklift is supplied

from external sources.

- start2see has estimated which virgin products are being replaced by the

secondary materials generated by GSWT.

- Bottom ash is assumed to go to landfill. start2see has calculated the

emissions from bottom ash in landfill using the NGER determination

method [NGER 2008] for solid waste disposal on land, applying a Total

Organic Carbon content of 1.4% w/w as Degradable Organic Carbon.

- Transport distances / loads / modes have been provided by GSWT based

on current estimates of waste sources.

- The assessment excludes emissions embodied in the building, plant and

other capital goods. A sensitivity analysis shows that the emissions in

the building are immaterial over the lifetime of the plant.



Explained: Biogenic carbon

Due to the biogenic differences between fossil fuels and biomass, they are categorized differently in national inventories and most GHG accounts.

Emissions of CO2 from the combustion of biomass are reported for informational purposes, but not included in national totals. This is because

any net additions of CO2 to the atmosphere resulting from biomass combustion should be captured by analyzing land-use, land-use change activities and their associated effects on terrestrial biomass carbon stocks.

In other words, the “emissions” are counted when the trees are cut, not when they are burned. If, at the national level, biomass harvests exceed

growth and regeneration, the resultant depletion of national biomass stocks result in a net “emission” (flux to the atmosphere). When calculating emissions from the burning of biomass, the amount of CO2

emissions should reflect the amount of biomass used (i.e. if only biomass is burned, the emissions would be zero). Unlike CO2 emissions, the combustion

of biomass does in all cases result in net additions of CH4 and N2O to the atmosphere, and therefore emissions of these two greenhouse gases as a result of biomass combustion should be accounted for in emission

inventories under Scope 1. 5

The distinction between biogenic and fossil emissions is relevant for all types of processes (including combustion, landfill, composting, etc.), and thus applies to GSWT as well as the BAU scenario. The National Greenhouse

Accounts [NGA 2018] state in regard to “Emissions from waste disposal to landfill and wastewater treatment” [NGA 2018, section 4 and Appendix 4]:

Emissions of CO2 generated from waste management are considered to be from biomass sources and therefore do not need to be estimated. For

example, landfill gas comprises both methane and carbon dioxide but only the methane component should be considered. Methane (CH4) vented to the atmosphere is considered an emission as this

action would be adding to atmospheric CH4. The emissions are multiplied by 25 to calculate the carbon dioxide equivalent (CO2-e) emissions. Where

methane from waste biomass is recovered and flared or combusted for energy, the CO2 emitted is not counted as an emission but regarded as part of the natural carbon cycle.

Where waste material is diverted from landfill to recycling or to energy use, the reporting organisation will have less emissions attributed to its activities

because less waste is going to landfill.

5 http://www.ghgprotocol.org/calculation-tools/faq

http://www.ghgprotocol.org/calculation-tools/faq



5 Life Cycle Assessment results

This streamlined LCA compares (see section 5.3) GSWT’s proposed waste-to-energy project (section 5.1) with a business-as-usual scenario (section 5.2).

The results have been calculated using a basic, transparent Excel-based life

cycle model that captures raw data, emission factors and calculations.

5.1 GSWT waste-to-energy

Under the design parameters as modelled in this assessment, GSWT’s waste-to-energy project generates approximately 60,220 t CO2e per annum (see

Table 8 and Figure 6), which are partly offset by the electricity produced resulting in net emissions of around 9,900 t CO2e per annum.

Table 8. Annual carbon footprint of proposed GSWT 70 Ordish Road waste-to-energy project

Stage t CO2e Comments

Transport to facility 440 Waste, ancillary materials

Facility scope 1 emissions 55,560 Diesel, natural gas, fossil CO2

Ancillary materials 2,110 Lime, activated carbon

Facility waste (ash) 2,110 Bottom ash

Electricity exported to grid -50,320 NEM

Total net emissions from

GSWT

9,900

Figure 6. Carbon footprint of proposed GSWT’s project

440

55,560

2,110 2,110

-50,320-60,000

-40,000

-20,000

0

20,000

40,000

60,000

80,000

Transport tofacility

Facility scope 1emissions

Ancillarymaterials

Facility waste(ash)

Electricityexported to grid

GSWT Dandenong South WtE emissions (t CO2e)



5.2 Business-as-usual

In the business-as-usual scenario, the MSW and C&I waste that could have been recovered by GSWT is sent to landfill sites. The BAU scenario leads to

significantly higher greenhouse gas emissions, predominantly from decomposing waste in landfill and the virgin products that need to be manufactured (as a result of missed opportunities associated with the

recovered secondary products). Table 9 and Figure 7 show that total annual emissions of the BAU scenario are estimated at 152,730 t CO2e.

Table 9. Carbon footprint of BAU scenario

Stage t CO2e Comments

Transport emissions 420

MSW landfill disposal emissions 119,000 85% MSW (85,000 t)

C&I landfill disposal emissions 18,000 15% C&I (15,000 t)

Virgin products 15,310 Replacing secondary

products

Total emissions from BAU 152,730

Figure 7. Carbon footprint of BAU scenario

420

119,000

18,000 15,310

-

20,000

40,000

60,000

80,000

100,000

120,000

140,000

Transportemissions

MSW landfilldisposal emissions

C&I landfilldisposal emissions

Virgin products

BAU emissions (t CO2e)



5.3 Comparison of scenarios

As became evident from the previous sections, the emissions associated with GSWT’s proposed waste-to-energy project are significantly lower than the

emissions of the business-as-usual situation (see Figure 8).

Figure 8. Carbon footprint comparison of GSWT’s Dandenong South

waste-to-energy project vs. business-as-usual

start2see estimates that GSWT’s proposed waste-to-energy project will reduce greenhouse gas emissions by almost 143,000 t CO2e per year. The majority of

these savings are occurring in Victoria as avoided emissions from landfill sites.

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6 Interpretation

6.1 Hot-spot analysis

This hot-spot analysis shows the main contributors to the carbon footprint for each scenario. The following figures present a breakdown of the greenhouse

gas emissions for the proposed GSWT waste-to-energy plant and business-as-usual scenario respectively.

Figure 9. Hot-spot analysis, GSWT waste-to-energy

Figure 9 shows that waste combustion is the largest contributor to GSWT’s carbon footprint at 54.9 kt CO2e. In comparison, transport of waste and

ancillary materials to the facility, and (diesel and natural gas) energy use at the facility generate a relatively small volume of greenhouse gas emissions. The production of ancillary materials (mainly lime) contributes 2.1 kt CO2e.

Disposal of bottom ash in landfill is also expected to generate around 2.1 kt CO2e. Filter dust is considered a secondary material and therefore does not

create additional emissions. This assumption is tested in section 6.2.3.

420 10

54930

150 480 2110 2110

-50320-60,000

-40,000

-20,000

0

20,000

40,000

60,000

80,000

GSWT Dandenong South emissions (t CO2e)



The plant’s direct and indirect emissions (60.2 kt CO2e) are partly offset by the electricity that is exported to the grid (-50.3 kt CO2e), resulting in net emissions of 9.9 kt CO2e.

Figure 10. Hot-spot analysis, business-as-usual scenario

Figure 10 shows the GHG hot-spots in the BAU scenario:

- Disposal of MSW and C&I waste in landfill sites dominates the BAU carbon footprint.

- Transport of waste to landfill sites is dwarfed by the emissions from

decomposing MSW and C&I waste in landfill.

- GSWT expects to recover resources at its proposed Ordish Road site in

Dandenong South. These resources are expected to replace functional equivalents of virgin materials. The emissions associated with the production of the virgin materials (15,310 t CO2e) have been attributed

to the BAU scenario, making up around 10% of the BAU footprint.

o The recovery of 600 t aluminium scrap (non-ferrous) has twice

the greenhouse gas benefits of the recovery of 3,000 t steel scrap (ferrous).

360 60

119,000

18,000

5,10010,200

100

20,000

40,000

60,000

80,000

100,000

120,000

140,000

Transport ofMSW

Transport ofC&I

Landfilldisposal of

MSW

Landfilldisposal of

C&I

Ferrousmetals

Non-Ferrousmetals

Sand (filterdust)

BAU emissions (t CO2e)



o Using recovered filter dust to replace sand has a marginal benefit in avoided emissions from sand production. This scenario assumes that the carbon in filter dust does not decompose when

used as a construction material.

6.2 Sensitivity analyses

Sensitivity analyses have been performed to study the impact of key choices and assumptions within the LCA.

6.2.1 Transport of waste streams

Transport of waste to GSWT’s Dandenong South waste-to-energy plant is

expected to have no real effect on waste transport requirements compared to BAU. This is reflected in the model and the emissions associated with waste transport are 420 t CO2e for both scenarios.

Even if transporting MSW and C&I waste to GSWT’s waste-to-energy plant would have twice the impact of BAU transport to landfill sites, it would not

materially impact the comparison results of this LCA (<0.25% difference).

6.2.2 Exclusion of capital goods

Capital goods are excluded from the LCA. This sensitivity analysis estimates the effect of including the materials needed for GSWT’s building on the results.

Using a rough estimate of the quantity of concrete (13,800 m3) and steel

(1,200 tonnes) required to build a 13,800 m2 facility in Dandenong South, start2see estimates the emissions associated with the construction materials

are in the order of 8,830 t CO2e. The savings associated with the waste-to-energy plant (127,000 t CO2e per year) mean that the embodied emissions would be offset in less than one month of full operation. Therefore, the

exclusion of capital goods does not materially affect the results of the LCA.

6.2.3 Use of filter dust and bottom ash

In the default analysis, bottom ash is landfilled and filter dust (made up of fly ash, lime and activated carbon) is used as a low-value construction material

replacing sand. These are reasonably conservative assumptions.

In this sensitivity analysis we study a worst-case (all ash products sent to landfill) and best-case (all ash products are useful and substitute virgin

materials) scenario. Filter dust is expected to be able to replace sand, or perhaps act as a replacement of hydrated lime in asphalt or cement(clinker) in

concrete. If treated correctly, MSWI bottom ash can replace coarse aggregates in road construction or concrete (see Appendix B. Useful applications of bottom ash).



Figure 11 shows how using ash-products in low and high-value applications influences the range of emissions attributed to virgin products in the BAU scenario.6 In a worst-case for GSWT all ash products go to landfill. This would

increase landfill emissions and minimise the amount of substituted virgin products. This results in the lowest emissions for virgin products (Figure 11):

13,500 t CO2e. In the best-case scenario for GSWT, all ash products are utilised. This is depicted as the high-range emissions for virgin products: 20,900 t CO2e. The benefits of utilising ash products to their full potential is

equal to a reduction in greenhouse gas emissions of almost 7.5 kt CO2e compared to landfilling all ash products.

Figure 11. Sensitivity analysis: minimum/maximum value use of filter dust and bottom ash

The greenhouse gas benefits of using filter dust in useful applications are:

- Diverting 3,000 t of filter dust from landfill avoids 1,800 t CO2e

- Avoided production of virgin materials:

o Substituting 3,000 t of sand avoids 10 t CO2e; or alternatively

o Substituting 3,000 t of hydrated lime avoids 3,270 t CO2e.

6 The full impact of diverting bottom ash to landfill is included here (rather than adjusting the GSWT

scenario) to see the implications in one graph.

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The greenhouse gas benefits of using bottom ash in useful applications are:

- Diverting 20,000 t of bottom ash from landfill avoids 2,100 t CO2e

- Avoided production of virgin materials:

o Substituting 20,000 t of coarse aggregates avoids 220 t CO2e.

Note: We have assumed that useful application of ash products stabilises the embedded carbon. Changes to transport when substituting virgin products for ash products have not been assessed.

The assumption in the default analysis - regarding what happens to the ash

products - does not have a significant effect on the comparison between GSWT’s waste-to-energy proposal and BAU landfill. In a worst-case scenario,

the benefits of diverting MSW and C&I waste from landfill slightly decrease to 141 kt CO2e per annum.

6.2.4 Electricity emissions intensity

The default analysis uses a grid emissions intensity of 0.82 t CO2e/MWh, as

representative for scope 2 emissions in the National Electricity Market (NEM). The scope 2 emissions intensity in Victoria is significantly higher than the NEM

average (1.07 t CO2e/MWh), due to the significant use of brown coal for electricity generation. Owing to its location, the Dandenong South waste-to-energy plant is likely able to supply electricity to local users, thereby reducing

transmission losses. The scope 3 emissions factor for Victorian electricity is 0.10 t CO2e/MWh, bringing the full fuel cycle emissions factor to 1.16 t

CO2e/MWh7. [NGA 2018]

If the Victorian full fuel cycle emissions factor is used to estimate the benefits of exported electricity, it will significantly reduce the impacts associated with

GSWT’s plant. Figure 12 shows the benefit of exported energy increases by almost 21 kt CO2e. Under this valuation, the net impact of GSWT’s waste-to-

energy plant would become a net positive of around 11 kt CO2e per annum.

Although the comparison to BAU is not shown, the difference between GSWT and BAU also increases by 21 kt CO2e and would become 164 kt CO2e.

7 Totals do not add up due to rounding.



Figure 12. Sensitivity analysis: impact of grid emissions factor

6.2.5 Future electricity grid

The design life of the waste-to-energy plant is 25 years [Energos 2017]. This means that over the lifetime of the plant, there could be changes to various

factors that influence the LCA results.

The emissions intensity of the electricity grid is one such parameter that is

already decreasing due an increased penetration of renewable energy and more use of natural gas over coal-fired power generation. It is generally accepted that the trend of decarbonisation of the grid will continue, as most

Australian states have introduced renewable energy targets beyond the federal government’s (relatively weak) target (see Table 10).

Table 10. Current renewable energy targets by state

State within the NEM Renewable target Target date

NSW - -

ACT 100% 2020

VIC 40% 2025

QLD 50% 2030

SA 50% 2025

TAS 100% 2022

All states have a target of net zero emissions by 2050.

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Impact of grid factor on emissions (t CO2e)

Waste-to-energy emissions Electricity exported to grid TOTAL EMISSIONS GSWT



The two largest contributors to the NEM do not have a hard target (NSW) or are currently behind on their target (Victoria), which makes it difficult to predict exactly how the NEM will decarbonise. For this sensitivity analysis,

start2see has simplified the analysis and assumed that:

- the current emissions intensity will remain steady (0.82 t CO2e/MWh)

until the waste-to-energy plant comes online (2020)

- scenario A: the emissions intensity of the NEM in 2045 (at the end of the plant’s design life) will be half of the current intensity: 0.41 t

CO2e/MWh

- scenario B: the emissions intensity of the NEM in 2045 (at the end of

the plant’s design life) will be 15% of the current intensity 0.123 t CO2e/MWh. This scenario is based on a linear decarbonisation of the grid

resulting in net zero emissions by 2050.

- the NEM will see a linear decarbonisation from start of operation until the end of the design life (2045).

With the decarbonisation of the electricity grid over the design life of the plant, the direct emissions benefits are expected to diminish. Figure 13 and Figure

14 show that in these simplified sensitivity scenarios the average direct impacts could amount to 22.5 kt CO2e and 31.3 kt CO2e per year respectively. This means that if the grid intensity decarbonises significantly by 2045, the

waste-to-energy plant will see its own emissions balance increase accordingly.

Figure 13. Sensitivity analysis: future electricity grid, scenario A

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80,000

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Grid factor's effect on emissions (t CO2e) (scenario A: -50% by 2045)




Figure 14. Sensitivity analysis: future electricity grid, scenario B

Note that the direct emissions of the plant do not tell the whole picture of the waste-to-energy project compared to BAU. The main benefit, diversion of MSW

from landfill, is independent of the grid emissions intensity. Figure 15 and Figure 16 show how the direct benefits and overall benefits (compared to BAU) develop over time under the grid decarbonisation assumptions set out in this

sensitivity analysis.

Even though the direct emissions of the project more than double by 2045, in the most aggressive grid emissions intensity reduction scenario B, the overall

net benefits remain very strong at 100 kt CO2e/yr in 2045.8

Furthermore, this analysis only considers greenhouse gas impacts and does

not include other benefits the waste-to-energy project might provide, such as grid stability and reduction of required landfill space.

8 The emissions intensity of aluminium has not been altered in this simplified analysis, although the GHG

benefits of recycling aluminium would reduce with decarbonisation of the grid.

60,220 60,220

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80,000

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Grid factor's effect on emissions (t CO2e) (scenario B: -85% by 2045)




Figure 15. Sensitivity analysis: impact of future electricity grid, scenario A

Figure 16. Sensitivity analysis: impact of future electricity grid,

scenario B

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7 Conclusions

The key conclusions from this study are:

- The benefits of GSWT's proposed waste-to-energy project amount to

143,000 t CO2e per year.

o The key to these savings is diverting 85,000 tonnes of MSW and

15,000 tonnes of C&I waste from landfill, thereby avoiding 137,000 t CO2e.

o GSWT’s waste-to-energy project generates approximately 59,800 t CO2e (excluding transport of waste). An equivalent amount of average electricity produced in the National Electricity Market

would currently result in emissions of 50,300 t CO2e. Therefore, the project itself leads to net emissions of 9,500 t CO2e per year.

o Useful products recovered by GSWT lead to further savings in emissions, as they can replace other (virgin) materials. A high-level estimate puts the benefits at 15,300 t CO2e. Further benefits

are possible if useful applications are found for bottom ash and if filter dust is used in higher value applications.

The above results are based on current design parameters and generic data. The BAU scenario assumes that MSW and C&I waste goes to landfill.

Key assumptions within the LCA that are relevant to the results are:

- It is assumed that all exported electricity substitutes electricity with the prescribed average NEM grid emissions intensity (0.82 kg CO2e/kWh).

- The net calorific value of MSW and C&I waste is 10 GJ/t, which is assessed to be made up of 39% biomass and 61% non-biomass materials by energy content; 66% biomass and 34% non-biomass

materials by mass.

- The emissions of bottom ash in landfill have been calculated using a

total organic carbon content of 1.4% w/w as a representation for Degradable Organic Carbon.

- Diesel consumption at the plant has been estimated for one wheel-

loader, bobcat and forklift.

- Capital goods are excluded from the LCA. A sensitivity analysis shows

that the exclusion of capital goods does not materially affect the results.

There might be further opportunities to optimise the plant that would lead to further savings. This is outside the scope of the current analysis.



8 Limitations

This study presents a streamlined life cycle comparison of two waste disposal / waste treatment scenarios. The analysis is built around expected operation

of GSWT’s waste-to-energy plant at 70 Ordish Road in Dandenong South. Choices and assumptions are based on current knowledge of the processes;

any changes could have a material impact on the results of this study.

The streamlined LCA is not suited for project applications to the Australian

Government’s Emission Reduction Fund (ERF) [CFI 2017] or to generate Renewable Energy Certificates. These programs have specific guidelines that have not been fully considered in start2see’s analysis.

The principles of ISO 14040:2006 [ISO 2006a] and ISO 14044:2006 [ISO 2006b] have generally been applied in this study. However, any claim of

compliance can only be made after independent third-party review. This would require a more detailed study to be completed first.



References

AusLCI 2018 The Australian National Life Cycle Inventory Database (AusLCI) is an ongoing initiative delivered by the Australian

Life Cycle Assessment Society (ALCAS)

Retrieved from http://alcas.asn.au/AusLCI/

CER 2001 Clean Energy Regulator, Guideline for Determining the Renewable Components in Waste for Electricity

Generation, Prepared By Nolan ITU Pty Ltd in association with TBU Environmental Engineering Consultants, Ref: 3082-01, March 2001

CFI 2017 Commonwealth of Australia - Office of Parliamentary Counsel, Carbon Credits (Carbon Farming Initiative) Act

2011, No. 101, 2011, Compilation No. 16, 1 March 2017

Energos 2017 Energos, Description of an Energos gasification plant type 52 to produce energy from waste, EFW PLANT Type 52-6-

41, Revision A, 13 November 2017

ERF 2015 Australian Government, Emissions Reduction Fund, Carbon

Credits (Carbon Farming Initiative – Alternative Waste Treatment) Methodology Determination 2015

IPCC 2007 Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R.

Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van

Dorland: Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the

Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z.

Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2007

ISO 2006a ISO 14040:2006 Environmental management - Life cycle assessment - Principles and framework. Geneva,

Switzerland: International Organization for Standardization, 2006

ISO 2006b ISO 14044:2006, Environmental management - Life cycle

assessment - Requirements and guidelines. Geneva, Switzerland: International Organization for

Standardization, 2006

http://alcas.asn.au/AusLCI/



NGA 2018 Commonwealth of Australia - Department of the Environment and Energy, National Greenhouse Accounts factors, July 2018

NGER 2008 Commonwealth of Australia - Office of Legislative Drafting and Publishing, Attorney-General’s Department, National

Greenhouse and Energy Reporting (Measurement) Determination 2008, Canberra, 1 July 2012

V.d. Wegen 2013 Van der Wegen, Gert & Hofstra, Ulbert & Speerstra, John,

Upgraded MSWI Bottom Ash as Aggregate in Concrete, Waste and Biomass Valorization. 4. 10.1007/s12649-013-

9255-6, 2013

Retrieved from (accessed on 12 June 2018): https://www.researchgate.net/publication/257792748_Upgraded_MSWI_Bottom_Ash_as_Aggregate_in_Concrete

https://www.researchgate.net/publication/257792748_Upgraded_MSWI_Bottom_Ash_as_Aggregate_in_Concrete

https://www.researchgate.net/publication/257792748_Upgraded_MSWI_Bottom_Ash_as_Aggregate_in_Concrete



Appendix A. Renewable components of MSW



Appendix B. Useful applications of bottom ash Dutch research [V.d. Wegen 2013] into the suitability of “upgraded MSWI bottom ash” shows potential for replacing aggregates in concrete:

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