The main assumptions are listed and it is described how the climate change is considered within WRATE. (1000 t CO 2 -eq/year)

Transcription

1 MEMO Job Gloucester WRATE/Climate Change Customer Urbaser S.A. Memo no. GL Date 2012/02/27 To Carlos Garcia/Andrew Russell (axis) From Jens Moller Copy to Nick Evans, Javier Peiro, James Sturman, Geert Stryg, Andrew Woolcock 1. Aim This memo presents the WRATE results with regard to climate change. Date 2012/02/27 The main assumptions are listed and it is described how the climate change is considered within WRATE. 2. Results The WRATE model gives the following results. Scenario Climate change (1000 t CO 2 -eq/year) Ramboll Hannemanns Allé 53 DK-2300 Copenhagen S Denmark T F Baseline scenario (landfill) Glouchestershire project Savings from implementing the project RGL e fprepared by Jens Moller Checked by Paul Konig Approaved by Paul Konig 3. WRATE introduction WRATE (Waste and Resources Assessment Tool for the Environment) has been used to calculate the environmental impact of the project in terms of climate change. WRATE has been developed by the Environmental Agency for the purpose of providing a life cycle tool to assess, as accurately as possible, the environmental costs and benefits of integrated waste management systems for municipal solid waste (MSW). WRATE is generally credited as the primary UK calculation tool for life cycle impacts of waste handling systems. The model calculates the environment effects of the project within different six impact categories. 1/9 Rambøll Gruppen A/S DK reg.no

2 - Global warming [kg CO 2 eq.] Man-made global warming is caused by emissions of greenhouse gases (GHGs) that cause heat radiation to be reflected and retained in the atmosphere rather than being lost into space. - Abiotic resource depletion [kg antimony eq.] - There are finite resources that will eventually be used up at current rates of consumption. - Human toxicity [kg 1,4-dichlotobenzene eq.] Persistent toxic substances can slowly accumulate in living organisms (e.g. when exposed through the lungs, skin, from food, etc.), increasing the risk that toxic concentrations will be reached. - Freshwater aquatic ecotoxicity [kg 1,4-dichlotobenzene eq.] Toxic effects on ecosystems. - Acidification [kg SO 2 eq.] Emissions to air, water and land of acidifying compounds can contribute to the destruction of plants and acidify the soil. - Eutrophication [kg PO eq.] Emission of nitrogenous compounds, especially ammonia (NH 3 ) and nitrogen oxides (NO x ) and phosphates, can stimulate increased growth due to a fertilisation effect, leading to altered species in nutrient-poor ecosystems. The model includes impact throughout the entire project period including: Construction phase Operational phase Decommission phase. The main environmental impact is from the Operational phase. The actual impact from the Construction phase is listed in appendix Climate change The Operational phase can be divided into a number of waste handling steps. The main climate impacts for each of these processes are stated below. - Transportation o CO 2 emission from consumption of diesel. - Transfer stations o CO 2 emission from electricity usage and consumption of diesel. - EfW facility o CO 2 savings from power production (which will substitute other fuel usage) o CO 2 emission from the embedded fossil carbon in waste (biogenic carbon is considered climate neutral) o CO 2 emission from production of spent chemicals for flue gas treatment. o CO 2 emission from fossil fuel during start-up/shutdown. - Material recovery o CO 2 savings from metal recovery (as energy to produce virgin materials is saved). o CO 2 emission from electricity/energy usage of material recovery plants. - Landfill (relatively short period of bypass during maintenance) o CO 2 emission from energy to handle waste o Methane emission from degradation of the organic waste. 2/9

3 5. Main input assumptions 5.1 Waste flow The waste flow for the period selected as representative assessment year - is listed in table 1 below. Table 1 Waste flow Waste stream ( ) Annual tonnage Collected waste WCA waste 118,486 HRC waste 16,512 Third party waste 58,325 Total - collected waste 193,323 Waste to landfill Shutdown 1,435 WCA (rejected) 391 HRC (rejected) 1,205 Third party waste (rejected) 292 Total landfill 3,323 Waste treated by EfW WCA waste 116,836 HRC waste 15,131 Third party waste 58,033 Total treated by EfW 190, Waste composition The waste composition is based on studies from The waste composition is shown in table 2. The lower calorific values of the three waste streams are listed in table 3. Key physical/chemical parameters of the waste are shown in table 4. 3/9

4 Table 2 Composition of waste Waste fraction WCA Waste (%) HRC waste (%) Third party waste (%) Paper and card Plastic film Dense plastic Textiles Absorbent hygiene products Wood Combustibles Non-combustibles Glass Organics Ferrous metal Non-ferrous metal Fine material WEE Specific hazardous household waste Processed material Non municipal soild waste Table 3 Lower calorific value of the waste Parameter Net calorific value (MJ/kg) Annual tonnes (t/yr) WCA ,836 HRC ,131 Third party waste ,033 Average ,000 Table 4 - Key parameters of the waste Parameter WCA Waste HRC waste Third party Average waste Moisture content (%) Ash content (%) Carbon - biogenic (%) Carbon - fossil (%) Operational data The EfW plant is modelled by a user-defined bespoke process in order to model the plant operation as accurately as possible. The bespoke process is modelled with guaranteed figures, which is a conservative approach. The guarantees are shown in table 5. 4/9

5 Table 5 Guaranteed operational data Parameter Guaranteed value Net power efficiency in lower net calorific value 22.78% Fe recovery 80% Non-Fe recovery 40% Lime, activated carbon and ammonia water consumption (kg/h) Confidential but similar to other plants. Around 70% of the bottom ash is recycled and around 10% is sent to landfill. The remaining 20% consists of evaporated water and the removed metals. The used net efficiency of 22.78% - which is used in WRATE - corresponds to a gross power production of 17.4 MW. Calculations are shown in table 6 below. Table 6 Energy efficiency Parameter Guaranteed value Annual tonnage (t/year) 190,000 Annual availability (h/year) 8,000 Lower calorific value (GJ/t) 9.65 Net efficiency (%) Mechanical throughput Net power to grid 14.5 Parasitic load 2.9 Gross power production /9

6 6. Main WRATE model assumption 6.1 Electricity mix The electricity mix is based on the marginal fuel mix in UK 2020, please refer table 7. The UK2020 mix is a standard value within WRATE. The philosophy of the marginal electricity mix is to estimate which energy sources that will be substituted (normally the most expensive energy source to produce) when the EfW facility starts to export a constant base-load to the grid. Table 7 Marginal fuel mix (UK2020) Energy source Marginal fuel mix Generating efficiencies (%) Coal 33.8% 35.7% Gas 4.2% 34.9% Gas CCGT 62.0% 47.6% 6.2 Databases The environmental impacts are chemicals and substituting virgin material is based on Ecoinvent Data, which is considered the world leading supplier of such data Conclusion WRATE is a credited and widely used tool to calculate the lifetime impacts (including climate change) of the project. The impacts (including climate change) are dependent on assumptions, such as waste composition, marginal energy mix and the guaranteed operational parameters of the plant. It is therefore more relevant to discuss and agree on above assumptions instead of focussing on the actual calculations. 6/9

7 Appendix 1 WRATE model schematic An overview of the WRATE model for the Gloucestershire Residual Waste Pproject is given in figure 1, including the material flow between the facilities. Figure 2 shows the baseline case where all waste is disposed at landfill. Figure 1 Overview of WRATE scenario for Gloucestershire Residual Waste Project GCC Planning/Permit application GCC EfW ( t/yr to EfW, 3323 t/year direct to landfill) 0.20% Reject to landfill 0.62% SITA (Non-hazardous) 0.15% 0.74% 0.20% Reject to landfill WCA (Kerbside Residual) 61.29% WCA 0.62% 61.09% 0.15% Reject to landfill 0.74% 0.37% Bypass during maintenance Alunimium to recycling 0.37% Aluminium (Baynard Road GL2 5DF) 8.54% 7.92% 98.28% 1.75% 1.75% HRC HRC Waste transfer (Smiths) Urbaser GCC EfW Javelin Park 16.31% 30.02% Ferrous to recycling Ferrous (Baynard Road GL2 5DF) Third party waste 30.17% Third party waste 2.26% 2.63% IBA to recycling 16.31% OTHER Other Recycling (non-specified) 2.26% IBA to landfill Non-hazardous (Grundong) 2.63% APC to landfill Hazardous landfill (Augean PE8 6XX) Date Software Version Database Version /9

8 Figure 2 Overview of WRATE baseline-scenario (Landfill) GCC Planning/Permit application GCC Baseline ( tonnes per year to landfill) 61.29% WCA (Kerbside Residual) WCA waste to Landfill 61.29% 8.54% 8.54% HRC HRC waste to landfill 30.17% Landfill 30.17% Third party waste Third party waste to landfill Date Software Version Database Version /9

9 Appendix 2 Impact of construction phase The WRATE model calculates the climate change impact of the construction phase of 1319 tonnes CO 2 eq per year when evenly divided over a 20 year project period although in reality the plant would continue to operate for longer than a 20 year period. The calculation is based on the estimated quantity of construction material used for the Chineham plant. These values are standard values within WRATE. The Chineham plant has a capacity of 95,000 tonnes per year and the values are scaled 1:1 to reflect that the Glouchestershire plant has higher capacity. This is a conservative approach as e.g. a plant with twice the capacity does not require twice the material input in the construction phase. The input values for Chineham plant are listed below. Material Value Cement 15.5 Concrete Bricks 551 Hardcore 2300 Copper Insulation material 89 Refractory (Al, Si) 9.1 Refractory (metals) 25 Refractory (SiC) 8.75 Tar Brass 2.75 Steel (virgin) Cast iron 87.5 Aluminium Paint 24.5 Polyethylene (HDPE) /9