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Appendix 7.1

Additional Information

WIDNES 3MG BIOMASS COMBINED HEAT POWER (CHP) PLANT

WIDNES, HALTON

BURMEISTER AND WAIN

SCANDINAVIAN CONTRACTOR A/S (BWSC)

TECHNICAL APPENDIX 7.1 AIR QUALITY

October 2012

Our Ref: RPS 6-7 Lovers Walk Brighton East Sussex BN1 6AH Tel: Contact Fax: Contact Email: Email

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QUALITY MANAGEMENT

Angela Spinks Prepared by:

Jon Pullen Authorised by:

October 2012 Date:

Project Number/Document Reference:

JAP6849

COPYRIGHT © RPS

The material presented in this report is confidential. This report has been prepared for the exclusive use of Burmeister and Wain Scandinavian Contractors A/S (BWSC) and shall not be distributed or made available to any other company or person without the knowledge and written consent of Burmeister and Wain Scandinavian Contractors A/S (BWSC) or RPS.

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CONTENTS

1 BACKGROUND ...................................................................................................................................... 2 2 STACK HEIGHT DETERMINATION ...................................................................................................... 5 REFERENCES ................................................................................................................................................ 11

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1 BACKGROUND

1.1 A detailed air quality assessment of the potential impacts of emissions generated during the construction and operation of the proposed biomass CHP facility at Stobart Park/3MG, Mersey Multi-Modal Gateway, Widnes, has been undertaken as part of the Environmental Impact Assessment (EIA) process. The results have been compared against relevant UK and EU air quality objective and limit values, as well as relevant Environmental Agency (EA) Environmental Assessment Levels (EALs).

1.2 Chapter 7 of the Environmental Statement (ES) describes the results of the air quality assessment carried out in support of the EIA. This document contains further technical information relevant to that assessment.

Key Atmospheric Emissions

1.3 The principal source of operational emissions to atmosphere from the Proposal will be gases exhausted from the stack after abatement in the flue gas treatment system. Other potential sources of emissions include dust and emissions from traffic accessing the site. A brief description of the key pollutants and their behaviour in the atmosphere is provided in the following sections.

Oxides of Nitrogen

1.4 Oxides of nitrogen (NOx) is the collective term used to describe a mixture of nitric oxide (NO) and nitrogen dioxide (NO2). These are formed as a result of high temperature combustion of atmospheric and fuel nitrogen. The main sources of NOx in the UK are road traffic and power generation.

1.5 During the process of combustion, atmospheric and fuel nitrogen are partially oxidised via a series of complex reactions to NOx. The process is dependant on the temperature, pressure, oxygen concentration and residence time of the combustion gases in the combustion zone. Most NOx exhausting from a combustion process is in the form of NO, which is a colourless and tasteless gas. NO is readily oxidised to NO2, a more harmful form of NOx, by chemical reactions with ozone and other chemicals in the atmosphere, at high concentrations, and is therefore both a primary and secondary [1] pollutant. NO2 is a yellowish-orange to reddish-brown gas and is a strong oxidant.

[1] Primary pollutants are directly emitted into the atmosphere from a source. Secondary pollutants are not emitted as such, but are formed within the atmosphere itself. They tend to accumulate over long timescales and transport distance and are normally addressed in emissions inventories at a national scale. Conversions ratios of NOx to NO2 provided by the Environment Agency used within this air quality assessment takes into account both primary and secondary NO2.

Particulates

1.6 Particulate matter (PM) is a complex mixture of organic and inorganic solid substances suspended in the atmosphere. Primary sources are numerous and include road transport, domestic coal burning, industrial processes, power stations and trans-boundary pollution. Secondary particulates, in the form of aerosols, attrition of natural materials and sea spray, are significant contributors to the overall atmospheric loading of particulates. In urban areas, road traffic is generally the greatest source of particulate matter, although localised effects are also associated with construction and demolition activity.

Sulphur Dioxide

1.7 Sulphur dioxide (SO2) from anthropogenic sources is almost all due to combustion of fossil fuels, which contain sulphur. SO2 is a major contributor to acid deposition. Natural sources of SO2, such as volcanoes, phytoplankton and soil and vegetation decay processes are now heavily outweighed by man-made sources.

Carbon Monoxide

1.8 Carbon monoxide (CO) is a colourless, odourless gas produced by the incomplete combustion of carbon-based fuels and by biological and industrial processes. The major source of carbon monoxide is traffic, particularly in urban areas. CO is produced under conditions of inefficient combustion and is relatively inert over the timescales relevant for its dispersion.

Hydrogen Chloride

1.9 There is some natural contribution to atmospheric hydrogen chloride (HCl) from, for example, volcanoes, but anthropogenic emissions predominate, with the major sources being reactions of other acids with sea salt particles, coal combustion and waste incineration. The decline in coal use and the installation of flue gas desulphurisation at remaining coal-fired power stations (HCl is typically captured preferentially to SO2 by Flue Gas Desulphurisation (FGD) absorbents) has resulted in a decline in HCl emissions of up to 55% since 1970. In the UK, HCl is a minor pollutant emission.

Heavy Metals

1.10 The general public and the environment can be exposed to compounds containing metallic elements, which occur naturally or are released from domestic or industrial processes. Emissions of metals in the UK arise from a variety of sources, including in particular, fuel and power, metal production and processing and mineral production and the chemical industry. Minor sources include waste incineration and road transport [1] [2].

1.11 The intake of metals via inhalation is very small in comparison with the intake via food. The natural range of many metals in soils is very wide.

Hydrocarbons

1.12 Anthropogenic emissions estimates usually focus on non-methane hydrocarbons (NMHCs) because the methane concentration in the atmosphere has historically been regarded as a stable natural background, although emissions from intensive animal and rice production are now increasingly important. The major UK emissions of NMHCs are solvent use and road transport

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(both fuel evaporation and exhaust emissions), with combustion of coal in inefficient domestic, commercial and industrial facilities following. Individual hydrocarbons of interest in a local air quality context include benzene and 1,3-butadiene, however NMHCs can also undergo many transformations in the atmosphere, most of which are photo-chemical reactions with ozone or hydroxyl radicals, to form other organic species.

Polycyclic Aromatic Hydrocarbons

1.13 Polycyclic aromatic hydrocarbons (PAHs) are a group of semi-volatile organic compounds that are formed by incomplete combustion of carbon-containing fuel. Some PAHs have been identified as carcinogenic, mutagenic or teratogenic. As there are numerous compounds classified as PAHs, the potential effect of PAHs is commonly assessed against an indicator compound in the group, benzo(a)pyrene (B(a)P).

Dioxins and Furans

1.14 Dioxins and furans are a group of chemicals which can be formed in very small quantities when organic chemicals are burnt in the presence of chlorine. Municipal solid waste was in the past a significant source of these chemicals, but following reductions in emissions from waste incineration now accounts for only 1% of emissions to the air, shared approximately equally between incineration and emissions from burning landfill gas. Domestic sources such as cooking and burning coal for heating are the UK’s single largest source of dioxins, accounting for about 18% of emissions. Transport accounts for about 3% and electricity generation about 4% of the UK total [3]. A number of other sources contribute to emissions of dioxins to a similar or greater extent: accidental vehicle fires; fireworks and bonfires; small-scale waste burning (for example on building sites); incineration of other wastes; and the iron and steel industry.

Polychlorinated Biphenyls

1.15 Polychlorinated Biphenyls (PCBs) are a class of organic compounds with 1 to 10 chlorine atoms. Low quantities of PCBs are found in most municipal waste streams. Wastes with elevated proportions of PCBs generally only arise from specific PCB collection and destruction programmes.

Persistent Organic Pollutants

1.16 The AEA UK Emissions of Air Pollutants 1970 to 2006 [4] summarises the 2006 UK emissions of Persistent Organic Pollutants (POPs) as follows: 1,209 tonnes PAHs (USEPA 16), 197 g I-TEQ PCDD/Fs (grams of ‘toxic equivalent’ of dioxins & furans) and 1.00 tonne PCBs. Emissions from all three of these pollutant groups have decreased significantly since 1990. Emissions in 2006 equate to decreases of 84%, 83% and 85% on the 1990 emissions, for PAHs, PCDD/Fs and PCBs respectively.

Carbon Dioxide

1.17 Carbon dioxide (CO2) is formed by combustion of fuels and emissions are dependant on the carbon content of the fuel. CO2 does not give rise to local health effects at ambient concentrations, but it is a significant contributor to the global warming effect. This process allows incoming radiation to pass through the Earth’s atmosphere but prevents much of the outgoing radiation from escaping to outer space.

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2 STACK HEIGHT DETERMINATION

Approach to Determination

2.18 Even with all appropriate pollution abatement measures in place, there is still the need to discharge the exhaust gases of pollution sources through an elevated stack to allow dispersion and dilution of the residual pollutants. The stack needs to be of sufficient height to ensure that residual pollutant concentrations are acceptable by the time they reach ground level. The stack also needs to be high enough to ensure that this is not within the aerodynamic influence of nearby buildings, or else wake effects can quickly bring the undiluted plume down to the ground.

2.19 A stack height determination ensures that ground level concentrations of the released pollutants remain within acceptable limits and is a formal requirement under the Environmental Permitting Regulations (EPR) 2007 [5].

Methodology

2.20 A stack height determination has been undertaken to establish the height at which there is minimal environmental benefit associated with the cost of further increasing the stack. This is consistent with the approach set out in the Environment Agency’s (EA’s) Horizontal Guidance Note EPR H1 [6] which requires the identification of “an option that gives acceptable environmental performance but balances costs and benefits of implementing it.”

2.21 The emissions data used in the stack height determination are summarised in the Air Quality Chapter. Simulations have been run using ADMS 4.2 to determine what stack height is required to overcome local building wake effects.

2.22 The stack height determination considers ground level concentrations over all averaging periods relevant to the air quality assessment, together with the full range of all likely meteorological conditions through the use of five years of hourly sequential meteorological data from a representative measuring station (Liverpool Speke).

2.23 The model was run assuming stack heights of 35 m to 65 m at 2 m incremental spacing. Results were obtained for all relevant averaging periods to this assessment.

2.24 The dispersion modelling for the purposes of stack height determination assumed a domain of 20 km by 20 km centred on the proposed development and a grid spacing of 200 m. Results are reported for the location where the highest concentration is predicted. This is considered a robust and conservative approach.

2.25 The simulations used an emission rate of unity (1 g.s-1): this is because for the stack height determination we are interested in the relative change in ground-level concentrations with stack height; the absolute concentrations have been considered as part of the detailed air quality assessment that follows. The ground-level concentrations were plotted against the different stack heights so that the point could be identified on the resulting curve where the predicted ground-level concentration showed a significant drop-off with increasing height. This is taken to illustrate the height at which the stack has taken the plume out of the aerodynamic influence of the building.

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2.26 Figure A7.1 shows the curves resulting from the maximum predicted ground-level contributions for all relevant averaging periods and stack heights considered in the dispersion modelling of an emission rate of unity (1 g.s-1).

2.27 The curves illustrate that for stack heights above 59 m, there are only marginal decreases in ground level concentrations with further increases in stack height. This indicates that a stack of 59 m would be high enough to ensure that the plume is taken out of the aerodynamic influence of nearby buildings, minimising ground level pollutant concentrations.

2.28 The above stack height of 59 m was also used to check that the absolute ground-level concentrations of the residual emissions would be within acceptable limits, as this is a formal requirement for new developments under the Environmental Permitting Regulations (EPR) 2010.

2.29 The results reported in Table 3.1 and Table 3.2 below is based on the actual emission rates for each pollutant and it shows that the resulting total Predicted Environmental Concentration (PEC) at sensitive receptors are well below the relevant EAL for all pollutants.

2.30 This stack height of 59 m would be subject to agreement with the EA when EPR permitting for the development is progressed.

Table 3.1: Process Contributions (µg.m-3) at Sensitive Receptors

Receptors Pollutant Averaging Period EQS

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 PM10 24 hour (90.41th percentile)

50

0.04 0.03 0.02 0.01 0.04 0.05 0.15 0.21 0.09 0.06 0.08 0.06 0.04 0.09 0.13 0.04 0.04 0.04 0.03 0.03 0.03 0.02 0.03 0.02 0.02 0.02 0.02

PM10 Annual

40

0.02 0.01 0.01 0.00 0.01 0.01 0.04 0.07 0.03 0.02 0.02 0.02 0.01 0.03 0.04 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

PM2.5 Annual

25

0.02 0.01 0.01 0.00 0.01 0.01 0.04 0.07 0.03 0.02 0.02 0.02 0.01 0.03 0.04 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

HCl 1 hour (maximum)

750

0.74 0.54 0.40 0.30 0.71 0.70 0.60 0.75 0.77 0.64 0.61 0.52 0.51 0.83 0.68 0.64 0.64 0.50 0.46 0.35 0.45 0.56 0.51 0.49 0.36 0.32 0.34

HF 1 hour (maximum)

16

0.07 0.05 0.04 0.03 0.07 0.07 0.06 0.07 0.08 0.06 0.06 0.05 0.05 0.08 0.07 0.06 0.06 0.05 0.05 0.03 0.05 0.06 0.05 0.05 0.04 0.03 0.03

HF Annual

160

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

SO2 15 minute (99.90th percentile)

266

3.57 2.17 1.69 1.28 1.93 2.52 2.97 4.11 2.85 2.12 2.46 2.15 2.04 3.32 3.20 2.15 2.15 2.13 1.86 1.63 1.89 1.72 1.77 1.66 1.41 1.50 1.57

SO2 1 hour (99.73th percentile)

350

2.93 1.64 0.96 0.68 1.46 2.04 2.48 3.45 2.25 1.63 1.96 1.53 1.31 2.70 2.70 1.48 1.42 1.12 1.10 0.98 1.11 1.14 1.08 1.02 0.88 0.93 0.97

SO2 24 hour (99.18th percentile)

125

1.47 0.79 0.29 0.22 0.60 0.98 1.35 2.10 1.05 0.76 0.78 0.55 0.42 1.33 1.31 0.65 0.43 0.39 0.29 0.22 0.26 0.32 0.36 0.35 0.29 0.23 0.26

SO2 Annual

50

0.08 0.05 0.03 0.02 0.05 0.07 0.22 0.35 0.15 0.10 0.12 0.09 0.07 0.13 0.20 0.06 0.07 0.06 0.05 0.04 0.04 0.04 0.04 0.03 0.03 0.03 0.03

NO2 1 hour (99.79th percentile)

200

4.35 2.32 1.45 1.00 2.06 2.88 3.53 4.84 3.18 2.31 2.77 2.21 1.91 3.86 3.86 2.11 2.03 1.71 1.60 1.39 1.60 1.63 1.54 1.51 1.27 1.33 1.40

NO2 Annual

40

0.23 0.14 0.08 0.04 0.14 0.20 0.61 0.98 0.43 0.29 0.35 0.26 0.20 0.36 0.57 0.17 0.18 0.17 0.13 0.12 0.12 0.10 0.12 0.09 0.07 0.07 0.08

CO 8 hour (maximum daily running)

10000

2.54 1.35 1.45 0.62 1.40 1.86 2.33 3.16 1.82 1.31 1.67 1.31 0.96 2.87 2.48 1.42 1.46 1.93 0.89 1.03 0.91 1.33 1.16 1.21 1.38 0.89 0.96

Cd Annual

0.005

8.34E-05

4.87E-05

2.77E-05

1.52E-05

5.05E-05

7.02E-05

2.19E-04

3.49E-04

1.55E-04

1.03E-04

1.24E-04

9.26E-05

7.08E-05

1.28E-04

2.02E-04

6.23E-05

6.58E-05

6.17E-05

4.75E-05

4.19E-05

4.37E-05

3.55E-05

4.33E-05

3.28E-05

2.68E-05

2.52E-05

2.72E-05

Tl 1 hour (maximum)

30

3.69E-03

2.68E-03

2.00E-03

1.51E-03

3.55E-03

3.51E-03

2.99E-03

3.75E-03

3.86E-03

3.18E-03

3.05E-03

2.60E-03

2.56E-03

4.13E-03

3.38E-03

3.20E-03

3.22E-03

2.48E-03

2.31E-03

1.73E-03

2.25E-03

2.79E-03

2.54E-03

2.43E-03

1.79E-03

1.59E-03

1.72E-03

Tl Annual

1

8.34E-05

4.87E-05

2.77E-05

1.52E-05

5.05E-05

7.02E-05

2.19E-04

3.49E-04

1.55E-04

1.03E-04

1.24E-04

9.26E-05

7.08E-05

1.28E-04

2.02E-04

6.23E-05

6.58E-05

6.17E-05

4.75E-05

4.19E-05

4.37E-05

3.55E-05

4.33E-05

3.28E-05

2.68E-05

2.52E-05

2.72E-05

Hg 1 hour (maximum)

7.5

3.69E-03

2.68E-03

2.00E-03

1.51E-03

3.55E-03

3.51E-03

2.99E-03

3.75E-03

3.86E-03

3.18E-03

3.05E-03

2.60E-03

2.56E-03

4.13E-03

3.38E-03

3.20E-03

3.22E-03

2.48E-03

2.31E-03

1.73E-03

2.25E-03

2.79E-03

2.54E-03

2.43E-03

1.79E-03

1.59E-03

1.72E-03

Hg Annual

0.25

8.34E-05

4.87E-05

2.77E-05

1.52E-05

5.05E-05

7.02E-05

2.19E-04

3.49E-04

1.55E-04

1.03E-04

1.24E-04

9.26E-05

7.08E-05

1.28E-04

2.02E-04

6.23E-05

6.58E-05

6.17E-05

4.75E-05

4.19E-05

4.37E-05

3.55E-05

4.33E-05

3.28E-05

2.68E-05

2.52E-05

2.72E-05

Sb 1 hour (maximum)

150

3.69E-02

2.68E-02

2.00E-02

1.51E-02

3.55E-02

3.51E-02

2.99E-02

3.75E-02

3.86E-02

3.18E-02

3.05E-02

2.60E-02

2.56E-02

4.13E-02

3.38E-02

3.20E-02

3.22E-02

2.48E-02

2.31E-02

1.73E-02

2.25E-02

2.79E-02

2.54E-02

2.43E-02

1.79E-02

1.59E-02

1.72E-02

Sb Annual

5

8.34E-04

4.87E-04

2.77E-04

1.52E-04

5.05E-04

7.02E-04

2.19E-03

3.49E-03

1.55E-03

1.03E-03

1.24E-03

9.26E-04

7.08E-04

1.28E-03

2.02E-03

6.23E-04

6.58E-04

6.17E-04

4.75E-04

4.19E-04

4.37E-04

3.55E-04

4.33E-04

3.28E-04

2.68E-04

2.52E-04

2.72E-04

As Annual

0.003

8.34E-04

4.87E-04

2.77E-04

1.52E-04

5.05E-04

7.02E-04

2.19E-03

3.49E-03

1.55E-03

1.03E-03

1.24E-03

9.26E-04

7.08E-04

1.28E-03

2.02E-03

6.23E-04

6.58E-04

6.17E-04

4.75E-04

4.19E-04

4.37E-04

3.55E-04

4.33E-04

3.28E-04

2.68E-04

2.52E-04

2.72E-04

Cr 1 hour (maximum)

150

3.69E-02

2.68E-02

2.00E-02

1.51E-02

3.55E-02

3.51E-02

2.99E-02

3.75E-02

3.86E-02

3.18E-02

3.05E-02

2.60E-02

2.56E-02

4.13E-02

3.38E-02

3.20E-02

3.22E-02

2.48E-02

2.31E-02

1.73E-02

2.25E-02

2.79E-02

2.54E-02

2.43E-02

1.79E-02

1.59E-02

1.72E-02

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Cr Annual

5

8.34E-04

4.87E-04

2.77E-04

1.52E-04

5.05E-04

7.02E-04

2.19E-03

3.49E-03

1.55E-03

1.03E-03

1.24E-03

9.26E-04

7.08E-04

1.28E-03

2.02E-03

6.23E-04

6.58E-04

6.17E-04

4.75E-04

4.19E-04

4.37E-04

3.55E-04

4.33E-04

3.28E-04

2.68E-04

2.52E-04

2.72E-04

Cr (VI) Annual

0.0002

1.67E-04

9.74E-05

5.55E-05

3.04E-05

1.01E-04

1.40E-04

4.39E-04

6.99E-04

3.10E-04

2.06E-04

2.48E-04

1.85E-04

1.42E-04

2.56E-04

4.04E-04

1.25E-04

1.32E-04

1.23E-04

9.51E-05

8.38E-05

8.73E-05

7.10E-05

8.65E-05

6.56E-05

5.36E-05

5.05E-05

5.43E-05

Co (m) 1 hour (maximum)

6

3.69E-02

2.68E-02

2.00E-02

1.51E-02

3.55E-02

3.51E-02

2.99E-02

3.75E-02

3.86E-02

3.18E-02

3.05E-02

2.60E-02

2.56E-02

4.13E-02

3.38E-02

3.20E-02

3.22E-02

2.48E-02

2.31E-02

1.73E-02

2.25E-02

2.79E-02

2.54E-02

2.43E-02

1.79E-02

1.59E-02

1.72E-02

Co (m) Annual

0.2

8.34E-04

4.87E-04

2.77E-04

1.52E-04

5.05E-04

7.02E-04

2.19E-03

3.49E-03

1.55E-03

1.03E-03

1.24E-03

9.26E-04

7.08E-04

1.28E-03

2.02E-03

6.23E-04

6.58E-04

6.17E-04

4.75E-04

4.19E-04

4.37E-04

3.55E-04

4.33E-04

3.28E-04

2.68E-04

2.52E-04

2.72E-04

Cu 1 hour (maximum)

200

3.69E-02

2.68E-02

2.00E-02

1.51E-02

3.55E-02

3.51E-02

2.99E-02

3.75E-02

3.86E-02

3.18E-02

3.05E-02

2.60E-02

2.56E-02

4.13E-02

3.38E-02

3.20E-02

3.22E-02

2.48E-02

2.31E-02

1.73E-02

2.25E-02

2.79E-02

2.54E-02

2.43E-02

1.79E-02

1.59E-02

1.72E-02

Cu Annual

10

8.34E-04

4.87E-04

2.77E-04

1.52E-04

5.05E-04

7.02E-04

2.19E-03

3.49E-03

1.55E-03

1.03E-03

1.24E-03

9.26E-04

7.08E-04

1.28E-03

2.02E-03

6.23E-04

6.58E-04

6.17E-04

4.75E-04

4.19E-04

4.37E-04

3.55E-04

4.33E-04

3.28E-04

2.68E-04

2.52E-04

2.72E-04

Pb Annual

0.25

8.34E-04

4.87E-04

2.77E-04

1.52E-04

5.05E-04

7.02E-04

2.19E-03

3.49E-03

1.55E-03

1.03E-03

1.24E-03

9.26E-04

7.08E-04

1.28E-03

2.02E-03

6.23E-04

6.58E-04

6.17E-04

4.75E-04

4.19E-04

4.37E-04

3.55E-04

4.33E-04

3.28E-04

2.68E-04

2.52E-04

2.72E-04

Mn 1 hour (maximum)

1500

3.69E-02

2.68E-02

2.00E-02

1.51E-02

3.55E-02

3.51E-02

2.99E-02

3.75E-02

3.86E-02

3.18E-02

3.05E-02

2.60E-02

2.56E-02

4.13E-02

3.38E-02

3.20E-02

3.22E-02

2.48E-02

2.31E-02

1.73E-02

2.25E-02

2.79E-02

2.54E-02

2.43E-02

1.79E-02

1.59E-02

1.72E-02

Mn Annual

150

8.34E-04

4.87E-04

2.77E-04

1.52E-04

5.05E-04

7.02E-04

2.19E-03

3.49E-03

1.55E-03

1.03E-03

1.24E-03

9.26E-04

7.08E-04

1.28E-03

2.02E-03

6.23E-04

6.58E-04

6.17E-04

4.75E-04

4.19E-04

4.37E-04

3.55E-04

4.33E-04

3.28E-04

2.68E-04

2.52E-04

2.72E-04

Ni Annual

0.02

8.34E-04

4.87E-04

2.77E-04

1.52E-04

5.05E-04

7.02E-04

2.19E-03

3.49E-03

1.55E-03

1.03E-03

1.24E-03

9.26E-04

7.08E-04

1.28E-03

2.02E-03

6.23E-04

6.58E-04

6.17E-04

4.75E-04

4.19E-04

4.37E-04

3.55E-04

4.33E-04

3.28E-04

2.68E-04

2.52E-04

2.72E-04

V 24 hour (maximum)

1

1.71E-02

1.03E-02

3.57E-03

2.60E-03

8.50E-03

1.25E-02

1.68E-02

2.64E-02

1.19E-02

8.71E-03

9.49E-03

7.24E-03

4.97E-03

1.58E-02

1.36E-02

7.53E-03

5.76E-03

6.15E-03

3.80E-03

3.10E-03

3.51E-03

4.33E-03

4.99E-03

5.61E-03

3.20E-03

3.32E-03

3.55E-03

V Annual

5

8.34E-04

4.87E-04

2.77E-04

1.52E-04

5.05E-04

7.02E-04

2.19E-03

3.49E-03

1.55E-03

1.03E-03

1.24E-03

9.26E-04

7.08E-04

1.28E-03

2.02E-03

6.23E-04

6.58E-04

6.17E-04

4.75E-04

4.19E-04

4.37E-04

3.55E-04

4.33E-04

3.28E-04

2.68E-04

2.52E-04

2.72E-04

Dioxins and furans

Annual

1.67E-10

9.74E-11

5.55E-11

3.04E-11

1.01E-10

1.40E-10

4.39E-10

6.99E-10

3.10E-10

2.06E-10

2.48E-10

1.85E-10

1.42E-10

2.56E-10

4.04E-10

1.25E-10

1.32E-10

1.23E-10

9.51E-11

8.38E-11

8.73E-11

7.10E-11

8.65E-11

6.56E-11

5.36E-11

5.05E-11

5.43E-11

Ammonia

1 hour (maximum)

2500

7.37E-01

5.36E-01

4.00E-01

3.02E-01

7.10E-01

7.02E-01

5.98E-01

7.49E-01

7.72E-01

6.36E-01

6.09E-01

5.20E-01

5.12E-01

8.27E-01

6.75E-01

6.40E-01

6.44E-01

4.97E-01

4.62E-01

3.47E-01

4.50E-01

5.59E-01

5.08E-01

4.85E-01

3.58E-01

3.18E-01

3.43E-01

Ammonia

Annual

180

1.67E-02

9.74E-03

5.55E-03

3.04E-03

1.01E-02

1.40E-02

4.39E-02

6.99E-02

3.10E-02

2.06E-02

2.48E-02

1.85E-02

1.42E-02

2.56E-02

4.04E-02

1.25E-02

1.32E-02

1.23E-02

9.51E-03

8.38E-03

8.73E-03

7.10E-03

8.65E-03

6.56E-03

5.36E-03

5.05E-03

5.43E-03

B[a]P Annual 0.00025

1.67E-06

9.74E-07

5.55E-07

3.04E-07

1.01E-06

1.40E-06

4.39E-06

6.99E-06

3.10E-06

2.06E-06

2.48E-06

1.85E-06

1.42E-06

2.56E-06

4.04E-06

1.25E-06

1.32E-06

1.23E-06

9.51E-07

8.38E-07

8.73E-07

7.10E-07

8.65E-07

6.56E-07

5.36E-07

5.05E-07

5.43E-07

PCB

1 hour (maximum)

6

3.69E-04

2.68E-04

2.00E-04

1.51E-04

3.55E-04

3.51E-04

2.99E-04

3.75E-04

3.86E-04

3.18E-04

3.05E-04

2.60E-04

2.56E-04

4.13E-04

3.38E-04

3.20E-04

3.22E-04

2.48E-04

2.31E-04

1.73E-04

2.25E-04

2.79E-04

2.54E-04

2.43E-04

1.79E-04

1.59E-04

1.72E-04

PCB Annual 0.20

8.34E-06

4.87E-06

2.77E-06

1.52E-06

5.05E-06

7.02E-06

2.19E-05

3.49E-05

1.55E-05

1.03E-05

1.24E-05

9.26E-06

7.08E-06

1.28E-05

2.02E-05

6.23E-06

6.58E-06

6.17E-06

4.75E-06

4.19E-06

4.37E-06

3.55E-06

4.33E-06

3.28E-06

2.68E-06

2.52E-06

2.72E-06

TOC Annual 5

1.67E-02

9.74E-03

5.55E-03

3.04E-03

1.01E-02

1.40E-02

4.39E-02

6.99E-02

3.10E-02

2.06E-02

2.48E-02

1.85E-02

1.42E-02

2.56E-02

4.04E-02

1.25E-02

1.32E-02

1.23E-02

9.51E-03

8.38E-03

8.73E-03

7.10E-03

8.65E-03

6.56E-03

5.36E-03

5.05E-03

5.43E-03

8 rpsgroup.com

Table 3.2: Predicted Environmental Concentrations (µg.m-3) at Sensitive Receptors

9 rpsgroup.com

10 rpsgroup.com

Receptors Pollutant Averaging Period EQS

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

PM10 24 hour (90.41th percentile) 50 24.24 24.23 24.22 24.21 24.24 24.25 24.35 24.41 24.29 24.26 24.28 24.26 24.24 24.29 24.33 24.24 24.24 24.24 24.23 24.23 24.23 24.22 24.23 24.22 24.22 24.22 24.22

PM10 Annual 40 24.22 24.21 24.21 24.20 24.21 24.21 24.24 24.27 24.23 24.22 24.22 24.22 24.21 24.23 24.24 24.21 24.21 24.21 24.21 24.21 24.21 24.21 24.21 24.21 24.21 24.21 24.21

PM2.5 Annual 25 12.82 12.81 12.81 12.80 12.81 12.81 12.84 12.87 12.83 12.82 12.82 12.82 12.81 12.83 12.84 12.81 12.81 12.81 12.81 12.81 12.81 12.81 12.81 12.81 12.81 12.81 12.81

HCl 1 hour (maximum) 750 1.46 1.26 1.12 1.02 1.43 1.42 1.32 1.47 1.49 1.36 1.33 1.24 1.23 1.55 1.40 1.36 1.36 1.22 1.18 1.07 1.17 1.28 1.23 1.21 1.08 1.04 1.06

HF 1 hour (maximum) 16 4.99 4.97 4.96 4.95 4.99 4.99 4.98 4.99 5.00 4.98 4.98 4.97 4.97 5.00 4.99 4.98 4.98 4.97 4.97 4.95 4.97 4.98 4.97 4.97 4.96 4.95 4.95

HF Annual 160 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.47 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.46 2.46

SO2 15 minute (99.90th

percentile) 266 15.97 14.57 14.09 13.68 14.33 14.92 15.37 16.51 15.25 14.52 14.86 14.55 14.44 15.72 15.60 14.55 14.55 14.53 14.26 14.03 14.29 14.12 14.17 14.06 13.81 13.90 13.97

SO2 1 hour (99.73th percentile) 350 15.33 14.04 13.36 13.08 13.86 14.44 14.88 15.85 14.65 14.03 14.36 13.93 13.71 15.10 15.10 13.88 13.82 13.52 13.50 13.38 13.51 13.54 13.48 13.42 13.28 13.33 13.37

SO2 24 hour (99.18th percentile) 125 7.67 6.99 6.49 6.42 6.80 7.18 7.55 8.30 7.25 6.96 6.98 6.75 6.62 7.53 7.51 6.85 6.63 6.59 6.49 6.42 6.46 6.52 6.56 6.55 6.49 6.43 6.46

SO2 Annual 50 6.28 6.25 6.23 6.22 6.25 6.27 6.42 6.55 6.35 6.30 6.32 6.29 6.27 6.33 6.40 6.26 6.27 6.26 6.25 6.24 6.24 6.24 6.24 6.23 6.23 6.23 6.23

NO2 1 hour (99.79th percentile) 200 66.35 64.32 63.45 63.00 64.06 64.88 65.53 66.84 65.18 64.31 64.77 64.21 63.91 65.86 65.86 64.11 64.03 63.71 63.60 63.39 63.60 63.63 63.54 63.51 63.27 63.33 63.40

NO2 Annual 40 31.23 31.14 31.08 31.04 31.14 31.20 31.61 31.98 31.43 31.29 31.35 31.26 31.20 31.36 31.57 31.17 31.18 31.17 31.13 31.12 31.12 31.10 31.12 31.09 31.07 31.07 31.08

CO 8 hour (maximum daily running) 10000 253.54 252.35 252.45 251.62 252.40 252.86 253.33 254.16 252.82 252.31 252.67 252.31 251.96 253.87 253.48 252.42 252.46 252.93 251.89 252.03 251.91 252.33 252.16 252.21 252.38 251.89 251.96

Cd Annual 0.005 2.83E-04 2.49E-

04 2.28E-

04 2.15E-

04 2.50E-

04 2.70E-

04 4.19E-

04 5.49E-

04 3.55E-

04 3.03E-

04 3.24E-

04 2.93E-

04 2.71E-

04 3.28E-

04 4.02E-

04 2.62E-

04 2.66E-

04 2.62E-

04 2.48E-

04 2.42E-

04 2.44E-

04 2.36E-04 2.43E-

04 2.33E-04 2.27E-04 2.25E-

04 2.27E-04

Tl 1 hour (maximum) 200 4.09E-03 3.08E-

03 2.40E-

03 1.91E-

03 3.95E-

03 3.91E-

03 3.39E-

03 4.15E-

03 4.26E-

03 3.58E-

03 3.45E-

03 3.00E-

03 2.96E-

03 4.53E-

03 3.78E-

03 3.60E-

03 3.62E-

03 2.88E-

03 2.71E-

03 2.13E-03

2.65E-03 3.19E-03

2.94E-03 2.83E-03 2.19E-03

1.99E-03

2.12E-03

Tl Annual 40 2.83E-04 2.49E-

04 2.28E-

04 2.15E-

04 2.50E-

04 2.70E-

04 4.19E-

04 5.49E-

04 3.55E-

04 3.03E-

04 3.24E-

04 2.93E-

04 2.71E-

04 3.28E-

04 4.02E-

04 2.62E-

04 2.66E-

04 2.62E-

04 2.48E-

04 2.42E-

04 2.44E-

04 2.36E-04 2.43E-

04 2.33E-04 2.27E-04 2.25E-

04 2.27E-04

Hg 1 hour (maximum) 7.5 9.29E-03 8.28E-

03 7.60E-

03 7.11E-

03 9.15E-

03 9.11E-

03 8.59E-

03 9.35E-

03 9.46E-

03 8.78E-

03 8.65E-

03 8.20E-

03 8.16E-

03 9.73E-

03 8.98E-

03 8.80E-

03 8.82E-

03 8.08E-

03 7.91E-

03 7.33E-

03 7.85E-

03 8.39E-03 8.14E-

03 8.03E-03 7.39E-03 7.19E-

03 7.32E-03

Hg Annual 0.25 2.88E-03 2.85E-

03 2.83E-

03 2.82E-

03 2.85E-

03 2.87E-

03 3.02E-

03 3.15E-

03 2.95E-

03 2.90E-

03 2.92E-

03 2.89E-

03 2.87E-

03 2.93E-

03 3.00E-

03 2.86E-

03 2.87E-

03 2.86E-

03 2.85E-

03 2.84E-

03 2.84E-

03 2.84E-03 2.84E-

03 2.83E-03 2.83E-03 2.83E-

03 2.83E-03

Sb 1 hour (maximum) 150 3.83E-02 2.83E-

02 2.15E-

02 1.66E-

02 3.70E-

02 3.66E-

02 3.14E-

02 3.89E-

02 4.01E-

02 3.33E-

02 3.19E-

02 2.75E-

02 2.71E-

02 4.28E-

02 3.52E-

02 3.35E-

02 3.37E-

02 2.63E-

02 2.46E-

02 1.88E-

02 2.40E-

02 2.94E-02 2.69E-

02 2.57E-02 1.94E-02 1.74E-

02 1.87E-02

Sb Annual 5 1.57E-03 1.23E-

03 1.02E-

03 8.92E-

04 1.24E-

03 1.44E-

03 2.93E-

03 4.23E-

03 2.29E-

03 1.77E-

03 1.98E-

03 1.67E-

03 1.45E-

03 2.02E-

03 2.76E-

03 1.36E-

03 1.40E-

03 1.36E-

03 1.22E-

03 1.16E-

03 1.18E-

03 1.10E-03 1.17E-

03 1.07E-03 1.01E-03 9.92E-

04 1.01E-03

As Annual 0.003 1.73E-03 1.39E-

03 1.18E-

03 1.05E-

03 1.40E-

03 1.60E-

03 3.09E-

03 4.39E-

03 2.45E-

03 1.93E-

03 2.14E-

03 1.83E-

03 1.61E-

03 2.18E-

03 2.92E-

03 1.52E-

03 1.56E-

03 1.52E-

03 1.38E-

03 1.32E-

03 1.34E-

03 1.26E-03 1.33E-

03 1.23E-03 1.17E-03 1.15E-

03 1.17E-03

Cr 1 hour (maximum) 150 4.81E-02 3.80E-

02 3.12E-

02 2.63E-

02 4.67E-

02 4.63E-

02 4.11E-

02 4.87E-

02 4.98E-

02 4.30E-

02 4.17E-

02 3.72E-

02 3.68E-

02 5.25E-

02 4.50E-

02 4.32E-

02 4.34E-

02 3.60E-

02 3.43E-

02 2.85E-

02 3.37E-

02 3.91E-02 3.66E-

02 3.55E-02 2.91E-02 2.71E-

02 2.84E-02

Cr Annual 5 6.43E-03 6.09E-

03 5.88E-

03 5.75E-

03 6.10E-

03 6.30E-

03 7.79E-

03 9.09E-

03 7.15E-

03 6.63E-

03 6.84E-

03 6.53E-

03 6.31E-

03 6.88E-

03 7.62E-

03 6.22E-

03 6.26E-

03 6.22E-

03 6.08E-

03 6.02E-

03 6.04E-

03 5.96E-03 6.03E-

03 5.93E-03 5.87E-03 5.85E-

03 5.87E-03

Cr (VI) Annual 0.0002 1.29E-03 1.22E-

03 1.18E-

03 1.15E-

03 1.22E-

03 1.26E-

03 1.56E-

03 1.82E-

03 1.43E-

03 1.33E-

03 1.37E-

03 1.31E-

03 1.26E-

03 1.38E-

03 1.52E-

03 1.24E-

03 1.25E-

03 1.24E-

03 1.22E-

03 1.20E-

03 1.21E-

03 1.19E-03 1.21E-

03 1.19E-03 1.17E-03 1.17E-

03 1.17E-03

Co (m) 1 hour (maximum) 6 3.74E-02 2.73E-

02 2.05E-

02 1.56E-

02 3.60E-

02 3.56E-

02 3.04E-

02 3.80E-

02 3.91E-

02 3.23E-

02 3.10E-

02 2.65E-

02 2.61E-

02 4.18E-

02 3.43E-

02 3.25E-

02 3.27E-

02 2.53E-

02 2.36E-

02 1.78E-

02 2.30E-

02 2.84E-02 2.59E-

02 2.48E-02 1.84E-02 1.64E-

02 1.77E-02

Co (m) Annual 0.2 1.08E-03 7.37E-

04 5.27E-

04 4.02E-

04 7.55E-

04 9.52E-

04 2.44E-

03 3.74E-

03 1.80E-

03 1.28E-

03 1.49E-

03 1.18E-

03 9.58E-

04 1.53E-

03 2.27E-

03 8.73E-

04 9.08E-

04 8.67E-

04 7.25E-

04 6.69E-

04 6.87E-

04 6.05E-04 6.83E-

04 5.78E-04 5.18E-04 5.02E-

04 5.22E-04

Cu 1 hour (maximum) 60 1.14E-01 1.04E-

01 9.68E-

02 9.19E-

02 1.12E-

01 1.12E-

01 1.07E-

01 1.14E-

01 1.15E-

01 1.09E-

01 1.07E-

01 1.03E-

01 1.02E-

01 1.18E-

01 1.11E-

01 1.09E-

01 1.09E-

01 1.02E-

01 9.99E-

02 9.41E-

02 9.93E-

02 1.05E-01 1.02E-

01 1.01E-01 9.47E-02 9.27E-

02 9.40E-02

Cu Annual 2 3.92E-02 3.89E-

02 3.87E-

02 3.86E-

02 3.89E-

02 3.91E-

02 4.06E-

02 4.19E-

02 3.99E-

02 3.94E-

02 3.96E-

02 3.93E-

02 3.91E-

02 3.97E-

02 4.04E-

02 3.90E-

02 3.91E-

02 3.90E-

02 3.89E-

02 3.88E-

02 3.88E-

02 3.88E-02 3.88E-

02 3.87E-02 3.87E-02 3.87E-

02 3.87E-02

Pb Annual 0.25 1.06E-02 1.03E-

02 1.01E-

02 9.95E-

03 1.03E-

02 1.05E-

02 1.20E-

02 1.33E-

02 1.13E-

02 1.08E-

02 1.10E-

02 1.07E-

02 1.05E-

02 1.11E-

02 1.18E-

02 1.04E-

02 1.05E-

02 1.04E-

02 1.03E-

02 1.02E-

02 1.02E-

02 1.02E-02 1.02E-

02 1.01E-02 1.01E-02 1.01E-

02 1.01E-02

Mn 1 hour (maximum) 1500 5.59E-02 4.58E-

02 3.90E-

02 3.41E-

02 5.45E-

02 5.41E-

02 4.89E-

02 5.65E-

02 5.76E-

02 5.08E-

02 4.95E-

02 4.50E-

02 4.46E-

02 6.03E-

02 5.28E-

02 5.10E-

02 5.12E-

02 4.38E-

02 4.21E-

02 3.63E-

02 4.15E-

02 4.69E-02 4.44E-

02 4.33E-02 3.69E-02 3.49E-

02 3.62E-02

Mn Annual 1 1.03E-02 9.99E-

03 9.78E-

03 9.65E-

03 1.00E-

02 1.02E-

02 1.17E-

02 1.30E-

02 1.10E-

02 1.05E-

02 1.07E-

02 1.04E-

02 1.02E-

02 1.08E-

02 1.15E-

02 1.01E-

02 1.02E-

02 1.01E-

02 9.98E-

03 9.92E-

03 9.94E-

03 9.86E-03 9.93E-

03 9.83E-03 9.77E-03 9.75E-

03 9.77E-03

Ni Annual 0.02 3.93E-03 3.59E-

03 3.38E-

03 3.25E-

03 3.60E-

03 3.80E-

03 5.29E-

03 6.59E-

03 4.65E-

03 4.13E-

03 4.34E-

03 4.03E-

03 3.81E-

03 4.38E-

03 5.12E-

03 3.72E-

03 3.76E-

03 3.72E-

03 3.58E-

03 3.52E-

03 3.54E-

03 3.46E-03 3.53E-

03 3.43E-03 3.37E-03 3.35E-

03 3.37E-03

V 24 hour (maximum) 1 2.11E-02 1.43E-

02 7.57E-

03 6.60E-

03 1.25E-

02 1.65E-

02 2.08E-

02 3.04E-

02 1.59E-

02 1.27E-

02 1.35E-

02 1.12E-

02 8.97E-

03 1.98E-

02 1.76E-

02 1.15E-

02 9.76E-

03 1.02E-

02 7.80E-

03 7.10E-

03 7.51E-

03 8.33E-03 8.99E-

03 9.61E-03 7.20E-03 7.32E-

03 7.55E-03

V Annual 5 2.83E-03 2.49E-

03 2.28E-

03 2.15E-

03 2.50E-

03 2.70E-

03 4.19E-

03 5.49E-

03 3.55E-

03 3.03E-

03 3.24E-

03 2.93E-

03 2.71E-

03 3.28E-

03 4.02E-

03 2.62E-

03 2.66E-

03 2.62E-

03 2.48E-

03 2.42E-

03 2.44E-

03 2.36E-03 2.43E-

03 2.33E-03 2.27E-03 2.25E-

03 2.27E-03

Dioxins & Furans Annual -

4.9E-08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-

08 4.9E-08 4.9E-08 4.9E-

08 4.9E-08 4.9E-08 4.9E-08 4.9E-08 Ammonia 1 hour (maximum) 2500 6.10 5.90 5.76 5.66 6.07 6.06 5.96 6.11 6.13 6.00 5.97 5.88 5.87 6.19 6.04 6.00 6.00 5.86 5.82 5.71 5.81 5.92 5.87 5.85 5.72 5.68 5.70 Ammonia Annual 180 2.70 2.69 2.69 2.68 2.69 2.69 2.72 2.75 2.71 2.70 2.70 2.70 2.69 2.71 2.72 2.69 2.69 2.69 2.69 2.69 2.69 2.69 2.69 2.69 2.69 2.69 2.69

B[a]P Annual 0.00025 3.20E-03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.21E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-

03 3.20E-03 3.20E-

03 3.20E-03 3.20E-03 3.20E-

03 3.20E-03

PCB 1 hour (maximum) 6 2.71E-03 2.61E-

03 2.54E-

03 2.49E-

03 2.70E-

03 2.69E-

03 2.64E-

03 2.71E-

03 2.73E-

03 2.66E-

03 2.64E-

03 2.60E-

03 2.60E-

03 2.75E-

03 2.68E-

03 2.66E-

03 2.66E-

03 2.59E-

03 2.57E-

03 2.51E-

03 2.57E-

03 2.62E-03 2.59E-

03 2.58E-03 2.52E-03 2.50E-

03 2.51E-03

1.17E-03 PCB Annual 0.20 1.18E-03 1.17E-

03 1.17E-

03 1.17E-

03 1.18E-

03 1.18E-

03 1.19E-

03 1.20E-

03 1.19E-

03 1.18E-

03 1.18E-

03 1.18E-

03 1.18E-

03 1.18E-

03 1.19E-

03 1.18E-

03 1.18E-

03 1.18E-

03 1.17E-

03 1.17E-

03 1.17E-

03 1.17E-03 1.17E-

03 1.17E-03 1.17E-03 1.17E-

03

TOC Annual 5 8.17E-01 8.10E-

01 8.06E-

01 8.03E-

01 8.10E-

01 8.14E-

01 8.44E-

01 8.70E-

01 8.31E-

01 8.21E-

01 8.25E-

01 8.19E-

01 8.14E-

01 8.26E-

01 8.40E-

01 8.12E-

01 8.13E-

01 8.12E-

01 8.10E-

01 8.08E-

01 8.09E-

01 8.07E-01 8.09E-

01 8.07E-01 8.05E-01 8.05E-

01 8.05E-01

11 rpsgroup.com

REFERENCES

1 NPL, 2010, Report to Defra: Annual Report for 2009 on the UK Heavy Metals Monitoring Network.

2 Defra, 2008, Consultation on guidelines for metals and metalloids in ambient air for the protection of human health.

3 Defra, 2004, Review of Environmental and Health Effects of Waste Management: Municipal Solid Waste and Similar Wastes - Extended Summary.

4 AEA UK Emissions Inventory Team, 2008, UK Emissions of Air Pollutants 1970 to 2006.

5 OPSI, 2007, The Environmental Permitting (England and Wales) Regulations 2007.

6 Environment Agency, 2010, Environmental Permitting Regulations (EPR) – H1 Environmental Risk Assessment, Annex K.

Appendix 7.2

Carbon Assessment

Carbon Footprint Report – Widnes 3MG Solid Biomass CHP Plant

JAS7040 RPS Planning & Development Ltd 21

st September 2012 | Rev. 3 Brighton Office

Quality Management

Revision History

Rev Date Status Reason for revision Additional comments

0 18/07/12 Draft - -

1 19/07/12 Draft Internal review comments -

2 31/08/12 Draft Update CHP scenario -

3 21/09/12 Final Increase normalised volumetric

stack flow -

DISCLAIMER

RPS has used reasonable skill and care in completing this work and preparing this report, within the terms of its brief and contract

and taking account of the resources devoted to it by agreement with the client. We disclaim any responsibility to the client and

others in respect of any matters outside the stated scope. This report is confidential to the client and we accept no responsibility to

third parties to whom this report, or any part thereof, is made known. The opinions and interpretations presented in this report

represent our reasonable technical interpretation of the data made available to us. RPS accepts no responsibility for data provided

by other bodies and no legal liability arising from the use by other persons of data or opinions contained in this report.

Except for the provision of professional services on a fee basis, RPS does not have a commercial arrangement with any other

person or company involved in the interests that are the subject of this report.

COPYRIGHT © RPS

The material presented in this report is confidential. This report has been prepared for the exclusive use of Burmeister and Wain

Scandinavian Contractor A/S (BWSC) and shall not be distributed or made available to any other company or person without the

knowledge and written consent of Burmeister and Wain Scandinavian Contractor A/S (BWSC) or RPS.


JAS7040 i RPS Planning & Development Ltd 21


Executive Summary

S.1 A greenhouse gas (GHG) emissions assessment has been carried out for the proposed Widnes

3MG solid biomass CHP plant (combined heat and power) plant, which would combust a mixture

of recycled wood and virgin biomass fuel to generate around 20 MW (net) of electricity and up to

3.5 MW of heat that would be exported to local customers such as Stobart warehousing,

increasing the facility’s useful energy generation and combined efficiency.

S.2 Emissions associated with the fuel production/supply chain and road or rail transport have been

estimated. Together with emissions avoided through electricity and heat export (displacing

emissions associated with conventional energy generation) and through diversion of waste wood

from landfill disposal (where it would decay to produce landfill gas, with a high global warming

potential), these form part of an annual emissions balance for the proposed facility that has been

estimated for each year of its expected operational lifetime.

S.3 All virgin biomass would be from sustainably-grown sources meeting the requirements of the

Renewable Energy Directive (RED), and would thus engender net neutral emissions from its

biogenic carbon fraction released during combustion. Recycled wood that would be combusted in

the solid biomass CHP plant would be an end-of-life material. Its biogenic carbon fraction,

released during combustion, would therefore likewise have a net neutral atmospheric impact

attributable to the facility, as it was drawn down from the atmosphere and temporarily stored

during the wood’s useful lifetime. Bottom ash from the solid biomass CHP plant would be

transported to a processing facility for subsequent re-use as a construction material.

S.4 The location of the solid biomass CHP plant at the multi-modal gateway would allow both rail and

road delivery of fuel for combustion. The assessment has considered as 'scenario 1' a mixture of

transport modes, with rail used for 20% of the total fuel by weight. A ‘worst-case’ transport

'scenario 2' of 100 % road delivery has also been assessed, and shown not to cause any

significant change to the facility’s GHG benefits.

S.5 The results indicate that the solid biomass CHP plant could achieve emissions savings of over

one point one million tonnes of carbon dioxide equivalent (CO2e) over its assumed operational

lifetime of 20 years (1.15 mtCO2e). This is equivalent to the present-day annual emissions of

around 226,000 homes or 437,000 cars.




Contents

Executive Summary ....................................................................................................... i

1 Introduction ............................................................................................................. 1

Background ....................................................................................................................... 1

GHG emissions assessment ............................................................................................ 1

2 Approach and Assumptions .................................................................................. 3

Overview ............................................................................................................................ 3

Emissions Scope .............................................................................................................. 3

Baseline ............................................................................................................................. 4

Proposal ............................................................................................................................ 4

Attribution and allocation ............................................................................................... 17

3 Results ................................................................................................................... 18

Results summary ............................................................................................................ 18

Results discussion ......................................................................................................... 20

4 Conclusion ............................................................................................................ 21




Tables, Figures and Appendices

Tables

Table 2.1: Biomass fuel supply .................................................................................................................... 4

Table 2.2: Fuel supply chain emissions ....................................................................................................... 5

Table 2.3: Process emissions....................................................................................................................... 8

Table 2.4: Transport emissions .................................................................................................................. 11

Table 2.5: Baseline landfill emissions ........................................................................................................ 14

Table 2.6: Landfill emissions over 100-year timescale assigned to lifetime of solid biomass CHP plant .. 14

Table 2.7: Baseline emissions burden from grid electricity generation ...................................................... 16

Table 2.8: Baseline emissions burden from heat generation ..................................................................... 17

Table 3.1: GHG emissions balance results ................................................................................................ 18

Figures

Figure 3.1: Annual GHG emissions (tCO2e/annum)

Figure 3.2: Cumulative total GHG emissions (tCO2e)

Appendices

Appendix A – Results Breakdown By Year

Appendix B – Biogenic Emissions

Appendix C – Transport Emissions Alternative Scenarios


JAS7040 1 RPS Planning & Development Ltd 21


1 Introduction

Background

1.1 Burmeister & Wain Scandinavian Contractor A/S (BWSC) is planning to develop a renewable

biomass combined heat and power (CHP) plant, fuelled by a mixture of virgin and recycled wood.

The solid biomass CHP plant would generate around 20 MW (net) of electricity for export and,

subject to demand, could also provide up to 3.5 MW of exported heat to local customers.

1.2 Climate change is recognised as an important challenge, and mitigating its impacts through

reduction of greenhouse gas (GHG) emissions is a key focus of Government energy policy and

planning legislation.

1.3 All wood fuel would be sourced from within the UK, and all virgin wood would be from

sustainably-grown sources meeting the requirements of the Renewable Energy Directive (RED).

Due to the facility’s location within the Widnes multi-modal gateway, fuel delivery by road or rail

would be possible.

1.4 Operation of the proposed facility would give rise to GHG emissions due to fuel production,

transport and consumption of reagents, among other factors. However, it is anticipated to offer

significant net GHG emissions reductions when compared with the generation of electricity and

heat through fossil fuel combustion and conventional disposal of waste wood.

GHG emissions assessment

1.5 This GHG emissions assessment seeks to quantify the expected GHG emissions associated with

operation of the proposed development and to place them in comparison with emissions from

fossil fuel based energy generation and waste wood disposal, identifying any GHG reductions

achieved.

1.6 The assessment focuses upon the operational carbon footprint of the proposed facility, as the

operational phase would be the most significant source of emissions over the facility’s lifetime.

Although this assessment is therefore not a life-cycle analysis, ‘scope 3’ fuel supply chain

emissions are important to consider, as direct ‘scope 1’ emissions from the combustion of

biomass are considered to have a net neutral impact due to the renewable nature of the fuel.

Emissions scopes are explained in the following section. For the purposes of completeness and

comparison, lifecycle scope 3 emissions (wherever available) have been included in emissions

factors estimated for activities included throughout the assessment, unless otherwise specified.

1.7 At this stage of the planning process, not all details of the proposed development have been

finalised. For example, the location within the UK of fuel sources and the transport arrangements

will not be confirmed until fuel supplier contracts are agreed, and fuel sources could potentially

change over the lifetime of the facility. The assessment therefore considers a range of options

and incorporates operating assumptions based on concept design data and RPS’ experience of

similar facilities, where appropriate.




1.8 The solid biomass CHP plant is designed to generate both heat and electricity for export to

consumers. Export of heat is subject to securing local customers with suitable heat demand.

Although potential heat customers have been identified by BWSC, the degree of heat supply also

cannot be confirmed until heat contracts are entered into, and again may change over the

facility’s lifetime. However, BWSC is committed to CHP operation for the facility, which is

designed to export up to 3.5 MW of heat while still exporting 20 MW (net) of electricity.

Accordingly, the assessment has assumed 3.5 MW of heat export will be achieved to a range of

potential local heat customers identified by BWSC.




2 Approach and Assumptions

Overview

2.1 The following sections present the key data inputs and assumptions used in the assessment. The

GHG emissions balance compares the proposed facility with a business-as-usual baseline for

energy generation and waste wood disposal. Discussion of the approach is likewise structured

around defining the characteristics of the proposal and the baseline scenarios.

Emissions Scope

2.2 The scope of the assessment comprises direct and indirect emissions associated with the

operational phase of the proposed development over its expected 20 year lifetime. Construction

and decommissioning phase emissions are not included within the scope, as their significance is

expected to be minor compared to the operational phase, based upon lifecycle data for similar

facilities.

2.3 Within the field of carbon footprint assessment, the terms ‘scope 1, 2 and 3’ (coined in ‘The

Greenhouse Gas Protocol’1) have become widely used to denote specific subsets of direct and

indirect emissions. These terms may be defined as follows:

Scope 1 - Direct emissions from sources or sites controlled by the company or project

assessed. This covers, for example, direct GHG releases from combustion on the solid

biomass CHP plant site (although biogenic emissions from renewable biomass fuel are

treated separately – see detail in following sections) or emissions from transport by

vehicles owned or controlled by the project assessed.

Scope 2 – Indirect emissions associated with the generation of electricity consumed or

displaced by the company or project assessed (excluding transmission and distribution

losses).

Scope 3 – All other indirect emissions that arise as a consequence of the project or

company’s activities. These include supply chain emissions and other indirect effects.

2.4 As noted, scope 3 emissions have been included within the assessment where possible.

Similarly, in order to form the most comprehensive assessment, where available the emissions

factors used include the Kyoto basket2 of GHGs, converted to CO2-equivalent global warming

potential (GWP). This is denoted by CO2e units in emissions factors and calculation results.

1 The Greenhouse Gas Protocol – A Corporate Reporting and Accounting Standard, Revised Edition (WRI and WBCSD, 2004)

2 Methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride




Proposal

Boundary

2.5 The proposal assessment boundary comprises:

operation of the solid biomass CHP plant facility itself, including on-site fuel handling,

combustion, energy generation, and air pollution control processes;

fuel preparation;

delivery transport of the fuel, other operational inputs, and residues; and

process residue disposal and re-use.

2.6 It excludes employee-specific emissions (such as employee travel), other BWSC business

emissions not directly related to the facility, and construction / decommissioning phase

emissions.

Fuel supply

2.7 A number of options exist for the grade of wood chip and supply of biomass fuel for the proposed

facility, which may comprise both recycled and virgin wood. All wood fuel would be sourced from

within the UK, and all virgin wood would be from sustainably-grown sources meeting the

requirements of the RED.

2.8 For the purposes of this assessment, an indicative scenario of likely wood supply has been

developed, based upon a review of fuel types and sources conducted by BWSC. Table 2.1 shows

the annual fuel throughput assumed in this scenario. Throughput is scaled to the facility’s design

thermal input assuming a typical net calorific value (energy content, NCV) for the fuel and annual

operating availability, detailed in the process section.

Table 2.1: Biomass fuel supply

Fuel Tonnes/day Tonnes/annum (tpa) Proportion NCV (MJ/kg)

Recycled wood chips 399 134,000 91%

13.80

Virgin wood chips 39 13,000 9%

Totals 438 147,000 100 % -

2.9 GHG emissions are associated with the production of the fuel in chip form. These scope 3

emissions include those from machinery used in harvesting and transport within the production

chain, power used in chipping, and potentially heat for virgin biomass drying (although this is less

common for wood chips than wood pellets). Emissions may vary depending upon factors such as

the location, machinery and methods employed. These cannot be quantified in detail at this stage

of the project, as fuel suppliers have not yet been selected.




2.10 Because no distinction can be drawn between suppliers, a typical scope 3 emissions factor

(61.41 kgCO2/tonne fuel) for wood chips, provided by Defra3, has been used in the assessment in

order to capture the supply-chain GHG emissions. This in turn is based upon the dataset used for

the Government’s Standard Assessment Procedure for Energy Rating of Dwellings (SAP 2009).

The emissions factor does not include non-CO2 GHGs (which unlike CO2 would not have a net-

neutral impact), and as noted could vary significantly dependent upon the details of the fuel

supply chain. Emissions estimates from the biomass supply chain should therefore be regarded

as indicative possible GHG emissions from the operation of the proposed development, rather

than precisely calculated global warming impacts.

2.11 Wood chip production from recycled wood may involve less energy consumption compared to

virgin wood chips due to the obviated requirement for harvesting and drying of green wood; use

of the virgin wood chip emissions factor (which includes emissions from those activities) is

therefore a conservative assumption from the point of view of the development’s GHG emissions

benefits, likely to overestimate emissions.

2.12 It is also possible that some virgin wood will be delivered as logs for on-site chipping. As a

conservative assumption, the assessment includes the power requirement for chipping the full

13,000 tpa of virgin wood on-site within the parasitic load for the facility. Again, use of the virgin

wood chip production emissions factor for this fraction may lead to double-counting of the energy

required for chipping, and is therefore a conservative scenario in that it would overestimate

emissions for the facility.

Table 2.2: Fuel supply chain emissions

Fuel Amount (tpa) GHG emissions (tCO2e/annum)

Scope

Recycled wood chips 134,000 8,229

3 Virgin wood chips 13,000 798

Totals 147,000 9,027

Process

2.13 The proposed facility is designed to operate at a thermal input of 70 MW, with 92 % annual

uptime (equating to 8,059 hours of operation per year). At the expected fuel NCV (13.80 MJ/kg),

this yields the required 147,000 tpa of fuel input. Direct biogenic scope 1 emissions would arise

from the combustion of this biomass fuel.

2.14 Throughout the assessment, a distinction is drawn between short-cycle (or biogenic) carbon

sources and fossil (non-biogenic) carbon sources. The biogenic sources are part of the short-

term carbon cycle, which holds that such carbon was taken up recently by the biomass when it

grew. If such materials are grown sustainably, there is negligible or beneficial land use change

3 2012 Defra/DECC GHG conversion factors for company reporting




and an equilibrium is reached between carbon drawn down from the atmosphere and that

released to it.

2.15 Conversely, non-biogenic (fossil) sources are part of the long-term carbon cycle, based on

carbon which prior to release was stored underground for a long time (geological time period) and

hence is regarded as a net addition to the atmosphere when released in the present.

2.16 In line with Defra guidance for GHG reporting4, biogenic carbon emissions from combustion of

virgin biomass are therefore considered to have no net global warming impact, provided that the

biomass is grown in a sustainable manner that includes replacement of wood fuel crops

harvested and does not induce emissions indirectly through land-use change. This is the case for

virgin biomass that would be used as fuel for the solid biomass CHP plant, which would be from

sustainable sources and would meet the requirements of the RED. Recycled wood has acted as

a temporary carbon store while in use, and its biogenic carbon fraction released through end-of-

life disposal via energy recovery at the proposed facility will therefore also have a net-neutral

atmospheric impact attributable to the facility.

2.17 Biogenic emissions have nevertheless been estimated and reported separately from the net

emissions of the facility in Appendix B, as an information item.

2.18 Two further sources of GHG emissions due to biomass combustion are considered within the

assessment: combustion of auxiliary fuel; and GHGs released by the air pollution control (APC) /

flue gas treatment (FGT) system.

2.19 Due to the fact that the proposed development could utilise recycled wood as a fuel, it would

comply, as a condition of the environmental permit under which it would operate, with the

requirements of the EC Waste Incineration Directive (WID) 2000 as recast within the Industrial

Emissions Directive 2010. A temperature of >850 degrees Celsius must be achieved for at least

two seconds after the last injection of combustion air in the secondary combustion chamber,

requiring auxiliary fuel burners to establish and maintain this temperature during start-up and

shut-down of the facility. A standby boiler using auxiliary fuel would also operate during planned

outage of the main plant.

2.20 Light fuel oil would be used as the auxiliary fuel. BWSC estimates that the auxiliary fuel will be

required to deliver a 1 MW thermal output for approximately 336 hours each year, yielding an

annual fuel consumption of 36,353 l, based on an NCV of 44 MJ/l. The Defra emissions factor of

3.6028 kgCO2e/l for gas oil (assumed equivalent to light fuel oil) has been used.

2.21 The proposed facility would be fitted with a FGT system that includes the use of selective non-

catalytic reduction (SNCR) with urea as the reagent to control nitrogen oxide (NOx) emissions.

The EC IPPC BREF for waste incineration5 indicates that with urea-based SNCR, the typical

4 2012 Defra/DECC GHG conversion factors for company reporting methodology paper

5 2006 European Commission Integrated Pollution Prevention and Control Reference Document on the Best Available Techniques

for Waste Incineration




release rate of nitrous oxide (N2O) is 25-35 mg/Nm3 of stack flow. The mean of this range (30

mg/Nm3) is assumed, which at the anticipated normalised stack flow rate for the facility of

139,716 Nm3/hour would lead to N2O emissions of approximately 33.8 t/annum. A global warming

potential (GWP) factor of 298 has been used to convert N2O to CO2 equivalent6.

2.22 Finally, the combustion and APC processes would give rise to ash residue: bottom ash and FGT

residue containing fly ash. The former can be treated and re-used beneficially as an aggregate

substitute. The FGT residue/fly ash forms a smaller proportion of the total ash. Although there are

some emerging options for re-use of FGT residue, it may be regarded as a hazardous waste

requiring disposal to a hazardous waste landfill. This has been assumed as a conservative option

for the assessment (i.e. no further GHG savings from re-use).

2.23 BWSC estimates that 4,030 tpa of bottom ash (dry basis) and 2,240 tpa of FGT residue would

arise for treatment and re-use or disposal.

2.24 The FGT residue would be inert with regard to GHG emissions and its disposal is relevant to the

GHG emissions balance only in the transport to landfill required, discussed in the transport

section.

2.25 BWSC intends that the bottom ash will be sent for treatment and re-use. This is an established

industry, with a number of bottom ash treatment facilities operated by Ballast Phoenix, for

example, available in the UK. The bottom ash is stabilised by weathering, following which it can

be used to replace virgin aggregates, for example in the construction industry. The weathering

process includes a degree of carbonation, in which CO2 is absorbed from the atmosphere and

sequestered in stable form in the bottom ash product. In addition, the use of bottom ash to

replace virgin aggregates avoids the GHG emissions associated with their production.

2.26 An avoided emissions factor of 2.3 kgCO2e/t virgin aggregates replaced7 has been used.

Research into bottom ash carbonation is ongoing. A conservative estimate of 3 % CO2 uptake by

semi-dry weight has been used8 and a final bottom ash water content of 6.7 % by weight

assumed9.

6 2007 IPCC Fourth Assessment Report (FAR) 100-year time horizon factor

7 ERM (2006): Carbon Balances and Energy Impacts of the Management of UK Wastes. Defra R&D Project WRT 237

8 Estimate from data in Rendek, E., Ducom, G. and Germain, P. (2005): Carbon dioxide sequestration in municipal solid waste

incinerator bottom ash and pers. comm. Mr N. Nolan, Ballast Phoenix Environmental Manager, 22/06/12

9 Creswell, D (2007): Case Study: Municipal Waste Incinerator Ash in Manufactured Aggregate (BRE/SmartWaste, available at:

http://www.smartwaste.co.uk/filelibrary/Incineratorbottomash_ManufacturedAgg.pdf)




Table 2.3: Process emissions

Process item Amount Emissions (tCO2e/annum) Scope

Auxiliary fuel 36,563 litres 132 1 & 3

Nitrous oxide (N2O) 33.8 tonnes 10,066 1

Bottom ash 4,030 tonnes -123 3

Energy exported

2.27 The solid biomass CHP plant is designed to generate electricity at 31.4 % gross efficiency,

providing 22 MW of electricity from the 70 MW thermal input. The parasitic load (electricity

required internally for fans, pumps, FGT equipment, and virgin biomass chipping) would be 2.01

MW, leaving 19.99 MW (161,089 MWh per annum) of electricity for export to the grid or local

power consumers (net electrical generation efficiency: 28.6 %).

2.28 With expected annual uptime of 8,059 hours, the proposed facility would export approximately

161,089 MWh of electricity per annum. This would displace marginal sources of conventional

electricity generation, detailed in the baseline scenario section.

2.29 CHP operation will allow the proposed facility to achieve slightly greater combined net thermal

efficiency, exporting a greater total amount of energy (heat and electricity). BWSC has estimated

the potential continuous low-grade heat demand from local consumers that could be met by the

solid biomass CHP plant through a district heating network, for a total of 3.5 MW:

3x Stobart warehouses – 0.5 MW (4,030 MWh per annum);

Up to 1,300 homes – 2 MW (16,118 MWh per annum); and

Public buildings including council offices, secondary college, leisure centre, police

station, library, NHS centre and primary school – 1 MW (8,059 MWh per annum).

2.30 The total heat that would be exported by the facility estimated by BWSC is therefore 28,207 MWh

per annum. The combined net thermal efficiency in CHP operation would be 35.6 %, and the heat

exported would displace conventional heat generation at the customers identified; the avoided

emissions burden of this is discussed in the baseline section.

Transport

Modes and distances

2.31 The sources and transport modes for fuel delivery to the proposed development have not been

confirmed at this stage of the project. Example transport scenarios have been constructed that

allow indicative emissions for the different options available to be compared. Transport emissions

for operational inputs (including biomass fuel) and outputs (including ash residue) have been

assessed.




2.32 The scope 3 lifecycle emissions factors used for the biomass fuel consumption are believed to

include typical transport required as part of the harvesting and processing stages of the lifecycle.

This assessment separately estimates the transport associated with fuel delivery to the Widnes

3MG site, in order to ensure that the most significant sources of transport emissions are

adequately captured. It is possible therefore that a degree of double-counting in transport

emissions exists, forming a conservative scenario that would overestimate emissions associated

with the facility.

2.33 The proposed facility’s location at the multi-modal gateway site means that rail transport may be

possible for a fraction of the fuel delivered. Accordingly, this assessment has taken an 80:20 split

between road and rail biomass fuel delivery as the basis of transport 'scenario 1'. As a sensitivity

test, emissions if all biomass fuel were to be delivered by road have also been estimated. This is

discussed further in Appendix C, as 'scenario 2'.

2.34 The sources of recycled wood and virgin biomass fuel would be confirmed once supplier

contracts are entered into at a later stage of the project development. BWSC has estimated a

typical distance of 80.5 km (50 miles) for road delivery and 241.5 km (150 miles) for rail delivery.

It would be necessary to consolidate biomass fuel delivered by rail at an appropriately equipped

railhead for loading, which is unlikely to be co-located with the biomass source(s). BWSC has

further estimated a distance of 80.5 km (50 miles) for this transport stage, with an additional 0.5

km (0.3 miles) for transport from the Widnes rail unloading point to the solid biomass CHP plant.

2.35 The solid biomass CHP plant would require delivery of additional operational inputs, including

reagents used in the FGT system, lubricants and the auxiliary fuel, for example. In total these are

anticipated to amount to approximately 738 tpa (material breakdown detailed in the project

description ES chapter). It is anticipated that these inputs can be sourced from suppliers in the

local area (which is a centre of the chemicals manufacturing and suppliers industry), and a

transport distance of 25 km (16 miles) is assumed (sufficient to encompass delivery from

Liverpool, Warrington or Runcorn, for example).

2.36 The solid biomass CHP plant would generate approximately 8,754 tpa of bottom ash (on a wet

basis after ash quench and some evaporation) and 2,240 tpa of FGT residue. It is intended that

the former would be sent to a facility for treatment and re-use, while the latter would be disposed

of to hazardous landfill. The closest existing Ballast Phoenix treatment facility is located in

Birmingham, approximately 145 km away (90 miles), and this distance has been assumed for the

bottom ash transport. The closest known hazardous landfill is an Augean facility (Port Clarence),

near Middlesbrough, approximately 230 km (143 miles) from the solid biomass CHP plant site.

2.37 All process inputs other than biomass fuel and all residues would be transported by road. Energy

recovery from waste wood at the proposed facility would avoid transport required for its disposal

to landfill. This is discussed in the baseline section.




Emissions factors

2.38 All transport emissions factors are taken from the 2012 Defra guidelines for company reporting.

Rail transport has been assessed using a rail freight emissions factor of 0.03694 kgCO2e/tonne-

km. This factor was estimated by Defra using a top-down calculation in which, essentially, the

locomotive fuel or power consumption (with known emissions per unit) by the UK rail freight

sector for one year is divided by the distance and total mass of freight transported in that time,

based on data collected by the Office of Rail Regulation for 2008/9. The emissions factor

calculation is combined for both diesel and electric rail freight; however approximately 93-95 % of

rail freight in the UK is hauled by diesel locomotive10,11

, so the factor can be regarded as

representative of diesel-hauled rail freight as would be used for delivery of biomass fuel.

2.39 Road transport heavy goods vehicle (HGV) emissions have been estimated on the basis of

vehicle journeys required, using the Defra emissions factor for a >33t gross vehicle weight (GVW)

articulated HGV.

2.40 Linear interpolation has been used to scale the emissions factor given by Defra at 0 %, 50 % and

100 % loading to the specified payload, as consistent with ARTEMIS data and Defra’s guidance

on the use of the published vehicle-km factors for specific payloads. An expected payload of 28 t

for bulk biomass fuel delivery has been given by BWSC; this payload is also assumed for other

HGVs (ash residue and operational input transport). An empty return journey at 0 % load is

assumed for all road transport trips. Assuming all HGV journeys require an empty return journey

is a conservative scenario, as freight logistics could allow some empty journeys to be avoided,

reducing emissions. HGV emissions factors that have been used are 1.3120 kgCO2e/vehicle-km

for loaded vehicle and 0.8602 kgCO2e/vehicle-km for empty return journeys.

2.41 Table 2.4 summarises the estimated transport emissions associated with the proposal.

10 Department for Transport UK Transport and Climate Change Data (2009) – Factsheet 3: Railways

11 Office of Rail Regulation (2011): National Rail Trends Yearbook, cited in Defra (2012): Methodology Paper for Emissions Factors




Table 2.4: Transport emissions

Transport stage Amount (tpa) One-way

distance (km)

GHG emissions

(tCO2e/annum)

Wood chip fuel (road) 117,600 80 734

Wood chip fuel (rail) 29,400 241 262

Railhead fuel consolidation and unloading 29,400 81 185

Process inputs 738 25 1.4

Bottom ash 8,754 145 98

FGT residue 2,240 230 40

Avoided landfill 134,000 50 -520

Total 801

Avoided landfill

2.42 Energy recovery from waste wood at the proposed facility would avoid the wood's conventional

disposal to landfill. The avoided emissions burden is discussed in the baseline section.




Baseline

Boundary

2.43 The baseline assessment boundary comprises:

disposal of waste wood to landfill, including transport and landfill gas emissions;

generation of electricity using landfill gas engines;

conventional electricity generation for the national grid; and

conventional heat generation at potential heat customers of the solid biomass CHP plant.

2.44 It excludes any emissions burdens not directly avoided or displaced by the proposal.

Landfill

2.45 The 134,000 tpa recycled wood used as a fuel for the proposed facility would be diverted from

conventional waste disposal, typically landfill12

. GHG emissions associated with decomposition of

the wood under landfill conditions would therefore be avoided. As landfill gas is collected and can

be used for energy generation in landfill gas engines in a modern landfill, some power generation

(with concomitant displaced conventional generation) may also be avoided.

2.46 Landfill GHG emissions have been estimated using a bespoke version of the IPCC Tier-1 First-

Order Decay (FOD) modelling approach, with UK-specific factors used where available in line

with IPCC recommended best-practice (Tier-2)13

.

2.47 Based upon the IPCC default values for wood decay in wet temperate climatic zone well-

managed landfills, a degradable organic carbon (DOC) fraction of 0.43, dissimilable DOC (DDOC

or DOCf) fraction of 0.5, and 50 % proportion of methane in landfill gas (LFG, with the remainder

carbon dioxide) have been assumed. Assuming a decay half-life of 23.1 years and a methane

correction factor of 1, a methane generation exponent of 0.97 has been used.

2.48 A LFG capture rate of 75 % and remainder oxidisation fraction / fissure escape fraction of 50 %

have been assumed, based upon the suggestion of an appropriate factor for the UK by an expert

review group in consultation with Defra14

.

2.49 It is assumed for purposes of comparison with the solid biomass CHP plant that landfill gas

captured is used to generate electricity in landfill gas engines with a typical efficiency of 38 %,

12 Research carried out for Defra by AEA (An assessment of the environmental impact of management options for waste wood -

WR1209, 2011) indicates that the primary management routes for waste wood are panel board manufacture, landfill disposal and energy recovery, with the latter able to divert contaminated wood from landfill, which could not be accepted for panel board use.

13 2006 IPCC Guidance for National Greenhouse Gas Inventories, Volume 5: Waste – Tier 1 landfill calculation spreadsheet

14 2005Arnold, S. and Yang, Z. (Golder Associates) UK Landfill Methane Emissions – Evaluation and Appraisal of Waste Policies

and Projections to 2050




and that the NCV of methane captured is 50 kWh/kg15

. The emissions factor for displaced

conventional electricity generation is based upon the DECC projected marginal factor, which

starts at 0.3735 kgCO2/kWh for year one of the operational period under consideration (expected

to be 2015), decreasing to 0.0226 kgCO2/kWh for year 36 onwards16

. (Further discussion of this

factor is given in the conventional electricity generation section, below.)

2.50 A GWP factor of 25 has been used to convert CH4 to CO2 equivalent17

.

2.51 Due to the relatively slow decay of waste wood under landfill conditions, a significant amount of

biogenic carbon is sequestered in the landfill rather than released as CO2 or CH4 over the

operational period of the solid biomass CHP plant. This, combined with the capture of LFG and

conversion of a high proportion of the CH4 (with GWP of 25) back to CO2 (GWP of 1) through

both combustion and oxidation by soil microbes, leads to landfilling of waste wood being a

significant net sink for CO2e in that time frame.

2.52 The expected operational lifetime of the proposed facility is 20 years, which given the similarity to

the assumed landfill decay half-life of approximately 23 years, leads to the point at which ongoing

landfilling of wood moves from being a net annual sink to a net annual source of GHG emissions

occurring after the end of the solid biomass CHP plant’s operating lifetime.

2.53 Landfill emissions have therefore been projected for a 100 year time frame, and all emissions

occurring after the end of the operational life of the proposed facility have been allocated in an

equal spread across the operational lifetime years. This ensures that the emissions flux over a

timescale appropriate to wood decomposition is captured within the assessment, and that future

GHG emissions avoided by diverting wood from landfill are reflected within the emissions balance

for the solid biomass CHP plant’s expected operational lifetime.

2.54 Table 2.5presents the net GHG flux and accumulated total net GHG emissions from landfill for

selected years. Positive figures indicate a net increase in atmospheric GHG concentration. The

end of the solid biomass CHP plant’s operational lifetime is shaded. Table 2.6 shows the

emissions as assigned over the years of the solid biomass CHP plant’s operational lifetime. Full

results showing the net GHG flux for all years are given in Appendix A.

15 2012 Defra/DECC GHG conversion factors for company reporting

16 2011 DECC IAG Valuation of Energy Use and Green House Gases (GHG) Emissions for Appraisal and Evaluation

17 2007 IPCC Fourth Assessment Report (FAR) 100-year time horizon factor




Table 2.5: Baseline landfill emissions

Year* Net GHG flux (tCO2e/annum) Accumulated total (tCO2e)

1 -105,637 -105,637

5 -98,312 -509,596

10 -90,309 -976,666

15 -75,097 -1,387,556

20 -53,765 -1,700,693

25 59,918 -1,408,875

30 51,905 -1,134,470

35 45,231 -895,331

40 39,027 -687,944

45 33,591 -509,445

50 28,912 -355,809

55 24,885 -223,573

60 21,418 -109,757

65 18,435 -11,794

70 15,867 72,523

75 13,657 145,095

80 11,755 207,559

85 10,117 261,322

90 8,708 307,596

95 7,495 347,425

100 6,451 381,706

*Intervening years not shown (refer to Appendix A for full results). Years beyond 20 shown before allocation to the facility’s operating lifetime

Table 2.6: Landfill emissions over 100-year timescale assigned to lifetime of solid biomass CHP plant

Year* Net GHG flux (tCO2e/annum) Accumulated total (tCO2e)

1 -1,517 -1,517

5 5,808 11,004

10 13,811 64,533

15 29,023 174,243

20 50,355 381,706

*Intervening years not shown (refer to Appendix A for full results). Emissions from beyond year 20 (shown in Table 2.5) allocated in equal spread to the 20 years of the facility’s operating lifetime

Transport

2.55 The baseline landfill scenario includes transport of waste wood to the landfill. A distance of 50 km

(31 miles) is assumed. For comparative purposes it is assumed that a similar bulk HGV would be

used to deliver waste wood to landfill as would be used in deliveries to the proposed solid

biomass CHP plant. Further discussion of the HGV payload and emissions factor is given in the

Proposal – Transport section.




Conventional electricity generation

2.56 Renewable electricity generated at the solid biomass CHP plant can be compared to

conventional, mainly fossil-fuelled, generation for the national grid. Although electricity input to

the grid is generated from a range of sources, including nuclear and other renewables in addition

to gas-, oil- and coal-fired power stations, it is essential to consider as a baseline the marginal

source that would be displaced by the new renewable capacity provided by the solid biomass

CHP plant.

2.57 For cost and operational reasons, nuclear and coal-fired generation presently form the existing

grid generation baseload, with peaking capacity and new capacity constructed in the operational

lifetime of the solid biomass CHP plant likely to be gas-fired or renewable. The former is regarded

as marginal, rather than ongoing baseload and other incentivised renewable generation. DECC

publishes an emissions factor for marginal displaced grid generation of 0.3735 kgCO2/kWh from

the present year through to 2025, projecting a central scenario in which this gradually decreases

to 0.0226 kgCO2/kWh between 2025 and 205018

, thereafter remaining at that level. A full list of

marginal projected emissions factors is shown in Appendix A.

2.58 DECC’s projected marginal factor is significantly lower than the average carbon intensity of the

current mix of electricity generation technologies. Defra indicates that the five-year rolling

average to 2010 for all grid generation, as-generated (excluding transmission and distribution

losses) but including remaining scope 3 emissions, is 0.54702 kgCO2e/kWh19

. The most carbon-

intense mainstream electricity generation (coal-fired facilities) have considerably higher

emissions again20

. It is also noteworthy that the DECC projected scenario assumes rapid

decarbonisation of grid generation, with a 54 % reduction in the carbon intensity of marginal

generation and 72 % reduction in grid average generation between 2015 and 2034 (the solid

biomass CHP plant’s expected operational lifetime).

2.59 As Table 2.7 demonstrates, use of the DECC projected marginal factor forms a conservative

scenario for the baseline electricity generation emissions burden that would be avoided by the

solid biomass CHP plant.

18 2011 DECC IAG Valuation of Energy Use and Green House Gases (GHG) Emissions for Appraisal and Evaluation

19 2012 Defra / DECC GHG Conversion Factors for Company Reporting

20 Major coal-fired plant thermal efficiency in 2010 (gross CV): 36.1% (DUKES – DECC, 2011). Carbon intensity of coal used for

electricity generation (gross CV): 0.37988 kgCO2e/kWh (Defra, 2012). Coal-fired power plant emissions: 1.05230 kgCO2e/kWh (0.37988 * (1 / 0.361)).




Table 2.7: Baseline emissions burden from grid electricity generation

Emissions factor source

Operating year

A

Electricity exported by

solid biomass CHP plant (MWh) in

electricity-only mode

Marginal displaced emissions

factor (tCO2/MWh)

B

Emissions burden displaced by solid biomass

CHP plant (tCO2/annum)

Cumulative total displaced

emissions (tCO2)

DECC projected marginal

1 161,089 0.3735 60,167 60,167

5 161,089 0.3735 60,167 300,834

10 161,089 0.3735 60,167 601,667

15 161,089 0.2836 45,690 866,310

20 161,089 0.1713 27,595 1,040,474

Defra five-year rolling grid average

(2010) 161,089 0.5470 88,116 -

Coal-fired generation

(2010) 161,089 1.0523 169,514 -

Note A: Selected years shown. For full results, refer to Appendix A Note B: Displaced emissions factor rounded to four significant figures

Conventional heat generation

2.60 Heat supplied by the solid biomass CHP plant to potential local heat customers would displace

conventional on-site heat generation from coal-, gas-, oil-, wood-fired or electric-powered boilers

or space heaters. Information published by DECC in the Digest of UK Energy Statistics (DUKES)

regarding the domestic, industrial and public/service sector fuel consumption mix for heating

purposes in 201021

has been used to establish a weighted average emissions factor by sub-

sector, based on the fuel types and amounts used and the Defra GHG emissions factors for each

fuel and DECC IAG projected future average grid mix factor for electricity per unit of energy.

2.61 Heating energy consumption data for domestic and warehousing subsectors has been used for

the household and Stobart warehouse potential heat customers, respectively. An average of the

heating energy consumption data for the education, government, health and sport & leisure sub-

sectors has been used for the remaining potential heat customers. It is anticipated that the

public/service sector and domestic household potential heat customers would be supplied with

low-grade waste heat via a district heating network; Defra estimates that typical heat losses in

such a network amount to 5 %, and this loss factor has been applied to heat that would be

exported to these customers.

2.62 Table 2.8 summarises the exported heat and combined weighted emissions factor for selected

years (full results given in Appendix A).

21 2011 DECC Digest of United Kingdom Energy Statistics, data tables




Table 2.8: Baseline emissions burden from heat generation

Operating year

A

Heat exported by solid biomass CHP plant (MWh) in CHP

mode

Combined weighted displaced emissions factor (tCO2/MWh)

B

Emissions burden displaced by solid biomass CHP plant

(tCO2/annum)

Cumulative total displaced emissions

(tCO2)

1 28,207 0.2431 6,856 6,856

5 28,207 0.2342 6,606 33,573

10 28,207 0.2305 6,502 66,340

15 28,207 0.2253 6,354 98,389

20 28,207 0.2203 6,214 129,740

Note A: Selected years shown. For full results, refer to Appendix A Note B: Displaced emissions factor rounded to four significant figures

Attribution and allocation

2.63 Emissions and avoided emissions burdens within the defined proposal and baseline assessment

boundaries have been attributed entirely to the solid biomass CHP plant as an entity. This

includes scope 3 supply chain emissions and avoided emissions burdens, which have been

attributed fully to the solid biomass CHP plant with no discount factor applied in this assessment

to supply chain stages (i.e. maximum emissions attributed to facility itself).

2.64 As discussed in the Baseline – Landfill section, the relatively slow decay of wood in landfill leads

to GHG emissions in the baseline scenario that would occur well beyond the operational lifetime

of the solid biomass CHP plant. In order to reflect the avoided burden of these future emissions

within the emissions balance for the facility, they have been allocated in an equal spread to the

20 years of the solid biomass CHP plant’s operational lifetime.

2.65 Waste wood that would be combusted in the proposed facility is an end-of-life material. Any

emissions associated with its active lifespan (e.g. production and use) are therefore not

attributable to the solid biomass CHP plant. Its biogenic carbon fraction, released during

combustion, is taken to have a net neutral atmospheric impact, as it was drawn down from the

atmosphere and temporarily stored during the wood’s useful lifetime.




3 Results

Results summary

3.1 Table 3.1 summarises the estimated GHG emissions at intervals over the proposed facility’s operational lifetime. A full results table showing all years is given in

Appendix A.

Table 3.1: GHG emissions balance results

Year Biomass fuel (tpa)

Scope 3 biomass

emissions (tCO2e / annum)

Electricity exported (MWh / annum)

Displaced electricity emissions

factor (tCO2e/ MWh)

Displaced emissions

(tCO2e / annum)

Heat exported (MWh / annum)

Displaced heat

emissions factor

(tCO2e/ MWh)

Displaced emissions

(tCO2e / annum)

Transport emissions

(tCO2e / annum)

Process emissions

(tCO2e / annum)

Avoided landfill

emissions (tCO2e / annum)

Net emissions

(tCO2e / annum)

Cumulative total

emissions (tCO2e)

2015 1 147,000 9,027 161,089 0.3735 -60,167 28,207 0.2431 6,856 801 10,075 -1,517 -45,603 -45,603

2019 5 147,000 9,027 161,089 0.3735 -60,167 28,207 0.2342 6,606 801 10,075 5,808 -52,677 -245,893

2024 10 147,000 9,027 161,089 0.3735 -60,167 28,207 0.2305 6,502 801 10,075 13,811 -60,576 -533,505

2029 15 147,000 9,027 161,089 0.2836 -45,690 28,207 0.2253 6,354 801 10,075 29,023 -61,164 -840,388

2034 20 147,000 9,027 161,089 0.1713 -27,595 28,207 0.2203 6,214 801 10,075 50,355 -64,261 -1,153,849




3.2 Figure 3.1 and Figure 3.2 show the annual GHG emissions and cumulative total emissions over

the lifetime of the proposed facility.

Figure 3.1: Annual GHG emissions (tCO2e/annum)

Figure 3.2: Cumulative total GHG emissions (tCO2e)

-70,000

-60,000

-50,000

-40,000

-30,000

-20,000

-10,000

0

0 2 4 6 8 10 12 14 16 18 20

Em

issio

ns

savin

g o

ver

ba

seli

ne

(tC

O2e/a

nn

um

)

Operational year

-1,400,000

-1,200,000

-1,000,000

-800,000

-600,000

-400,000

-200,000

0

0 2 4 6 8 10 12 14 16 18 20

Em

issio

ns

savin

gs

ov

er

ba

seli

ne

(tC

O2e)

Operational year

Operating year




Results discussion

3.3 The proposed facility is estimated to achieve GHG emissions savings of 1.15 mtCO2e over its

assumed operational lifetime of 20 years, with the facility operating in CHP mode, exporting heat

to the full range of potential customers identified by BWSC and electricity to the grid.

3.4 The rate of increase of cumulative emissions savings decreases over time from year 11 of the

operational lifetime of the facility, due to the assumed displaced electricity emissions factor

decreasing from that point. The transition point is illustrated in Figure 3.1. However, this effect is

partially offset by the increasing rate of avoided landfill emissions over time as temporarily

sequestered carbon in landfilled waste wood decays.

3.5 ‘Process emissions’ (excluding the wood chip fuel supply chain and biogenic combustion

emissions) form the largest component of direct or indirect GHG releases to the atmosphere. This

is due to the FGT technology selected for the development, which gives rise to a small amount

(around 34 tpa) of nitrous oxide that nevertheless has a relatively large greenhouse gas impact

due to the high global warming potential of this gas.

3.6 Transport emissions are estimated to be a very minor proportion of the overall emissions

balance, amounting to 16,021 tCO2e over the 20 year operational lifetime of the facility, compared

to the 1,153,849 tCO2e total net emissions savings. As a further transport emissions sensitivity

test, a ‘worst-case’ scenario in which all transport is by road has been considered (detailed in

Appendix C, as 'scenario 2'). This results in a very minor 0.2 % change in the total emissions

savings in electricity mode. Transport is therefore not considered to be significant in GHG terms;

other considerations (cost, practicality and other environmental impacts) are likely to be of greater

importance in managing transport options.

Operating year




4 Conclusion

4.1 The proposed Burmeister & Wain Scandinavian Contractor A/S (BWSC) Widnes 3MG solid

biomass CHP plant would combust 147,000 tpa of recycled and virgin wood chips to generate

electricity and heat for export to the national grid and local customers. This assessment has

estimated the greenhouse gas (GHG) emissions balance of the facility’s operation, compared to a

baseline scenario of conventional energy generation and waste wood disposal.

4.2 BWSC is committed to CHP operation for the facility, which is designed to export up to 3.5 MW of

heat to a range of potential heat customers identified by BWSC, alongside 20 MW of electricity to

the national grid. CHP operation allows a greater amount of useful energy to recovered and

utilised, improving the facility’s combined efficiency compared to electricity generation alone.

4.3 The results of the assessment show that the facility would achieve emissions reductions,

compared to the baseline, of over one million tonnes of carbon dioxide equivalent (CO2e) during

its assumed operational lifetime of 20 years (1.15 mtCO2e). This is equivalent to the present-day

annual emissions of around 226,000 homes or 437,000 cars.

4.4 Process, supply chain and transport emissions are offset by a significant avoided GHG emissions

burden from future projected baseline conventional electricity and heat generation and methane

released by the decay of waste wood in landfill. This leads to a net emissions balance in which

the proposed facility achieves significant annual emissions reductions compared to the baseline

scenario in which it is not operational.

4.5 Transport emissions have been assessed and the sensitivity of the facility’s overall emissions to

distance and modal shift tested. Transport emissions have been shown not to be significant to the

overall emissions savings achieved by the facility, with the overall emissions savings achieved

through the facility’s operation changing by 0.2 % between scenario 1 (80:20 split between road

and rail for wood chip fuel delivery) and scenario 2 (100% road delivery for wood chip fuel).




Appendices




Appendix A – Results Breakdown By Year

Table A.1: Results summary for all years of the solid biomass CHP plant’s anticipated operating lifetime

Year

Energy generation Process and transport emissions

Avoided landfill emissions

(tCO2e/annum)

Totals

Electricity exported (MWh)

Displaced electricity

generation factor (tCO2/MWh)

Avoided emissions

(tCO2e/annum)

Heat exported (MWh)

Displaced heat factor (tCO2/MWh)

Avoided emissions (tCO2e/annum)

Scope 1 auxiliary fuel and N2O emissions

(tCO2e/annum)

Scope 3 biomass consumption

emissions (tCO2e/annum)

Scope 3 bottom ash carbonation

and re-use (tCO2e/annum)

Transport emissions

(tCO2e/annum)

Net emissions (tCO2e/annum)

Cumulative net emissions (tCO2e)

1 2015 161,089 0.3735 -60,167 28,207 0.2431 -6,856 10,198 9,027 -123 801 1,517 -45,603 -45,603

2 2016 161,089 0.3735 -60,167 28,207 0.2396 -6,758 10,198 9,027 -123 801 -398 -47,419 -93,022

3 2017 161,089 0.3735 -60,167 28,207 0.2384 -6,725 10,198 9,027 -123 801 -2,256 -49,244 -142,266

4 2018 161,089 0.3735 -60,167 28,207 0.2350 -6,627 10,198 9,027 -123 801 -4,059 -50,949 -193,215

5 2019 161,089 0.3735 -60,167 28,207 0.2342 -6,606 10,198 9,027 -123 801 -5,808 -52,677 -245,893

6 2020 161,089 0.3735 -60,167 28,207 0.2349 -6,627 10,198 9,027 -123 801 -7,506 -54,396 -300,289

7 2021 161,089 0.3735 -60,167 28,207 0.2335 -6,586 10,198 9,027 -123 801 -9,154 -56,003 -356,292

8 2022 161,089 0.3735 -60,167 28,207 0.2319 -6,540 10,198 9,027 -123 801 -10,753 -57,556 -413,849

9 2023 161,089 0.3735 -60,167 28,207 0.2309 -6,512 10,198 9,027 -123 801 -12,305 -59,080 -472,929

10 2024 161,089 0.3735 -60,167 28,207 0.2305 -6,502 10,198 9,027 -123 801 -13,811 -60,576 -533,505

11 2025 161,089 0.3735 -60,167 28,207 0.2292 -6,466 10,198 9,027 -123 801 -15,272 -62,001 -595,506

12 2026 161,089 0.3510 -56,548 28,207 0.2282 -6,438 10,198 9,027 -123 801 -18,396 -61,478 -656,984

13 2027 161,089 0.3286 -52,928 28,207 0.2272 -6,410 10,198 9,027 -123 801 -21,736 -61,171 -718,155

14 2028 161,089 0.3061 -49,309 28,207 0.2263 -6,382 10,198 9,027 -123 801 -25,282 -61,069 -779,224

15 2029 161,089 0.2836 -45,690 28,207 0.2253 -6,354 10,198 9,027 -123 801 -29,023 -61,164 -840,388

16 2030 161,089 0.2612 -42,071 28,207 0.2243 -6,326 10,198 9,027 -123 801 -32,951 -61,445 -901,833

17 2031 161,089 0.2387 -38,452 28,207 0.2233 -6,298 10,198 9,027 -123 801 -37,057 -61,904 -963,737

18 2032 161,089 0.2162 -34,833 28,207 0.2223 -6,270 10,198 9,027 -123 801 -41,332 -62,531 -1,026,269

19 2033 161,089 0.1938 -31,214 28,207 0.2213 -6,242 10,198 9,027 -123 801 -45,767 -63,320 -1,089,588

20 2034 161,089 0.1713 -27,595 28,207 0.2203 -6,214 10,198 9,027 -123 801 -50,355 -64,261 -1,153,849

Totals 3,221,780 - -1,040,474 564,130 - -129,740 203,958 180,545 -2,454 16,021 -381,706 -1,153,849 -




Table A2: Avoided landfill baseline emissions summary for 100 year projected timespan

Year Waste wood deposited (t/annum)

DOC sequestered

(t/annum)

Cumulative total DOC

sequestered (t/annum)

CO2 released (t/annum)

CH4 released (t/annum)

Electricity generated

(MWh/annum)

Displaced electricity generation

factor (tCO2e/MWh)

Avoided electricity generation emissions

(tCO2e/annum)

Net GHG flux (tCO2e/annum)

Cumulative total emissions

(tCO2e)

1 2015 134,000 28,810 28,810 0 0 0 0.3735 0 -105,637 -105,637

2 2016 134,000 27,959 56,769 2,927 71 7,982 0.3735 2,981 -103,722 -209,359

3 2017 134,000 27,132 83,901 5,767 140 15,729 0.3735 5,875 -101,864 -311,223

4 2018 134,000 26,330 110,231 8,524 207 23,247 0.3735 8,683 -100,061 -411,285

5 2019 134,000 25,552 135,783 11,199 271 30,542 0.3735 11,407 -98,312 -509,596

6 2020 134,000 24,797 160,580 13,795 334 37,622 0.3735 14,052 -96,614 -606,210

7 2021 134,000 24,064 184,644 16,314 395 44,492 0.3735 16,618 -94,966 -701,176

8 2022 134,000 23,353 207,997 18,759 455 51,160 0.3735 19,108 -93,367 -794,543

9 2023 134,000 22,663 230,660 21,131 512 57,630 0.3735 21,525 -91,815 -886,358

10 2024 134,000 21,993 252,653 23,434 568 63,910 0.3735 23,870 -90,309 -976,666

11 2025 134,000 21,343 273,996 25,668 622 70,003 0.3735 26,146 -88,848 -1,065,514

12 2026 134,000 20,712 294,708 27,836 675 75,917 0.3510 26,649 -85,724 -1,151,238

13 2027 134,000 20,100 314,808 29,940 726 81,656 0.3286 26,829 -82,384 -1,233,621

14 2028 134,000 19,506 334,314 31,982 775 87,225 0.3061 26,700 -78,838 -1,312,460

15 2029 134,000 18,930 353,244 33,964 823 92,630 0.2836 26,273 -75,097 -1,387,556

16 2030 134,000 18,370 371,614 35,887 870 97,874 0.2612 25,562 -71,169 -1,458,725

17 2031 134,000 17,827 389,441 37,754 915 102,964 0.2387 24,578 -67,063 -1,525,788

18 2032 134,000 17,300 406,741 39,565 959 107,904 0.2162 23,332 -62,788 -1,588,576

19 2033 134,000 16,789 423,530 41,322 1,002 112,697 0.1938 21,837 -58,353 -1,646,929

20 2034 134,000 16,293 439,823 43,028 1,043 117,349 0.1713 20,102 -53,765 -1,700,693

21 2035 0 -12,999 426,824 44,683 1,083 121,863 0.1488 18,137 56,605 -1,644,088

22 2036 0 -12,615 414,210 43,363 1,051 118,262 0.1264 14,944 57,589 -1,586,498

23 2037 0 -12,242 401,968 42,081 1,020 114,766 0.1039 11,924 58,466 -1,528,033

24 2038 0 -11,880 390,088 40,837 990 111,375 0.0814 9,070 59,240 -1,468,792

25 2039 0 -11,529 378,559 39,630 961 108,083 0.0590 6,373 59,918 -1,408,875

26 2040 0 -11,188 367,371 38,459 932 104,889 0.0365 3,828 57,939 -1,350,936

27 2041 0 -10,857 356,514 37,323 905 101,789 0.0351 3,574 56,368 -1,294,567

28 2042 0 -10,537 345,977 36,219 878 98,780 0.0337 3,331 54,840 -1,239,727

29 2043 0 -10,225 335,752 35,149 852 95,861 0.0323 3,099 53,352 -1,186,375

30 2044 0 -9,923 325,829 34,110 827 93,028 0.0309 2,878 51,905 -1,134,470

31 2045 0 -9,630 316,199 33,102 802 90,278 0.0296 2,668 50,496 -1,083,974

32 2046 0 -9,345 306,854 32,124 779 87,610 0.0282 2,467 49,126 -1,034,849

33 2047 0 -9,069 297,785 31,174 756 85,021 0.0268 2,276 47,792 -987,057

34 2048 0 -8,801 288,984 30,253 733 82,508 0.0254 2,094 46,494 -940,562

35 2049 0 -8,541 280,444 29,359 712 80,070 0.0240 1,921 45,231 -895,331

36 2050 0 -8,288 272,155 28,491 691 77,703 0.0226 1,756 44,003 -851,329

37 2051 0 -8,043 264,112 27,649 670 75,407 0.0226 1,704 42,702 -808,626

38 2052 0 -7,806 256,306 26,832 650 73,178 0.0226 1,654 41,440 -767,186

39 2053 0 -7,575 248,731 26,039 631 71,016 0.0226 1,605 40,215 -726,971

40 2054 0 -7,351 241,380 25,269 613 68,917 0.0226 1,558 39,027 -687,944

41 2055 0 -7,134 234,246 24,523 594 66,880 0.0226 1,511 37,873 -650,071

42 2056 0 -6,923 227,323 23,798 577 64,903 0.0226 1,467 36,754 -613,317

43 2057 0 -6,718 220,605 23,095 560 62,985 0.0226 1,423 35,668 -577,649

44 2058 0 -6,520 214,085 22,412 543 61,124 0.0226 1,381 34,614 -543,035

45 2059 0 -6,327 207,758 21,750 527 59,317 0.0226 1,341 33,591 -509,445

46 2060 0 -6,140 201,618 21,107 512 57,564 0.0226 1,301 32,598 -476,847

47 2061 0 -5,959 195,659 20,483 497 55,863 0.0226 1,262 31,634 -445,212

48 2062 0 -5,783 189,876 19,878 482 54,212 0.0226 1,225 30,700 -414,513

49 2063 0 -5,612 184,265 19,290 468 52,610 0.0226 1,189 29,792 -384,721

50 2064 0 -5,446 178,819 18,720 454 51,055 0.0226 1,154 28,912 -355,809

51 2065 0 -5,285 173,534 18,167 440 49,546 0.0226 1,120 28,057 -327,752

52 2066 0 -5,129 168,405 17,630 427 48,082 0.0226 1,087 27,228 -300,524

53 2067 0 -4,977 163,428 17,109 415 46,661 0.0226 1,055 26,423 -274,100

54 2068 0 -4,830 158,598 16,603 403 45,282 0.0226 1,023 25,642 -248,458

55 2069 0 -4,687 153,911 16,113 391 43,943 0.0226 993 24,885 -223,573

56 2070 0 -4,549 149,362 15,636 379 42,645 0.0226 964 24,149 -199,424

57 2071 0 -4,414 144,948 15,174 368 41,384 0.0226 935 23,435 -175,989

58 2072 0 -4,284 140,664 14,726 357 40,161 0.0226 908 22,743 -153,246

59 2073 0 -4,157 136,507 14,291 346 38,974 0.0226 881 22,071 -131,175

60 2074 0 -4,034 132,472 13,868 336 37,822 0.0226 855 21,418 -109,757




Year Waste wood deposited (t/annum)

DOC sequestered

(t/annum)

Cumulative total DOC

sequestered (t/annum)

CO2 released (t/annum)

CH4 released (t/annum)

Electricity generated

(MWh/annum)

Displaced electricity generation

factor (tCO2e/MWh)

Avoided electricity generation emissions

(tCO2e/annum)

Net GHG flux (tCO2e/annum)

Cumulative total emissions

(tCO2e)

61 2075 0 -3,915 128,557 13,458 326 36,704 0.0226 830 20,785 -88,972

62 2076 0 -3,799 124,758 13,061 317 35,620 0.0226 805 20,171 -68,801

63 2077 0 -3,687 121,070 12,675 307 34,567 0.0226 781 19,575 -49,226

64 2078 0 -3,578 117,492 12,300 298 33,545 0.0226 758 18,996 -30,229

65 2079 0 -3,472 114,020 11,936 289 32,554 0.0226 736 18,435 -11,794

66 2080 0 -3,370 110,650 11,584 281 31,592 0.0226 714 17,890 6,096

67 2081 0 -3,270 107,380 11,241 273 30,658 0.0226 693 17,361 23,457

68 2082 0 -3,174 104,206 10,909 264 29,752 0.0226 672 16,848 40,305

69 2083 0 -3,080 101,127 10,587 257 28,873 0.0226 653 16,350 56,656

70 2084 0 -2,989 98,138 10,274 249 28,019 0.0226 633 15,867 72,523

71 2085 0 -2,900 95,237 9,970 242 27,191 0.0226 615 15,398 87,921

72 2086 0 -2,815 92,423 9,675 235 26,388 0.0226 596 14,943 102,864

73 2087 0 -2,732 89,691 9,390 228 25,608 0.0226 579 14,501 117,365

74 2088 0 -2,651 87,040 9,112 221 24,851 0.0226 562 14,073 131,438

75 2089 0 -2,572 84,468 8,843 214 24,117 0.0226 545 13,657 145,095

76 2090 0 -2,496 81,972 8,581 208 23,404 0.0226 529 13,253 158,349

77 2091 0 -2,423 79,549 8,328 202 22,712 0.0226 513 12,862 171,210

78 2092 0 -2,351 77,198 8,082 196 22,041 0.0226 498 12,482 183,692

79 2093 0 -2,282 74,916 7,843 190 21,389 0.0226 483 12,113 195,804

80 2094 0 -2,214 72,702 7,611 185 20,757 0.0226 469 11,755 207,559

81 2095 0 -2,149 70,554 7,386 179 20,144 0.0226 455 11,407 218,966

82 2096 0 -2,085 68,468 7,168 174 19,549 0.0226 442 11,070 230,036

83 2097 0 -2,024 66,445 6,956 169 18,971 0.0226 429 10,743 240,779

84 2098 0 -1,964 64,481 6,750 164 18,410 0.0226 416 10,425 251,205

85 2099 0 -1,906 62,575 6,551 159 17,866 0.0226 404 10,117 261,322

86 2100 0 -1,849 60,726 6,357 154 17,338 0.0226 392 9,818 271,140

87 2101 0 -1,795 58,931 6,169 150 16,826 0.0226 380 9,528 280,668

88 2102 0 -1,742 57,190 5,987 145 16,328 0.0226 369 9,247 289,915

89 2103 0 -1,690 55,499 5,810 141 15,846 0.0226 358 8,973 298,888

90 2104 0 -1,640 53,859 5,638 137 15,377 0.0226 348 8,708 307,596

91 2105 0 -1,592 52,267 5,472 133 14,923 0.0226 337 8,451 316,047

92 2106 0 -1,545 50,723 5,310 129 14,482 0.0226 327 8,201 324,248

93 2107 0 -1,499 49,224 5,153 125 14,054 0.0226 318 7,959 332,206

94 2108 0 -1,455 47,769 5,001 121 13,639 0.0226 308 7,723 339,930

95 2109 0 -1,412 46,357 4,853 118 13,235 0.0226 299 7,495 347,425

96 2110 0 -1,370 44,987 4,710 114 12,844 0.0226 290 7,274 354,698

97 2111 0 -1,330 43,657 4,570 111 12,465 0.0226 282 7,059 361,757

98 2112 0 -1,290 42,367 4,435 108 12,096 0.0226 273 6,850 368,607

99 2113 0 -1,252 41,115 4,304 104 11,739 0.0226 265 6,648 375,255

100 2114 0 -1,215 39,900 4,177 101 11,392 0.0226 257 6,451 381,706

Totals 2,680,000 39,900 - 1,843,532 44,692 5,027,814 - 511,677 381,706 -




Appendix B – Biogenic Emissions

Table B.1: Annual biogenic CO2 emissions from wood chip combustion

Fuel Amount (tpa) Biogenic emissions

factor (kgCO2/t)A

Biogenic emissions (tCO2/annum)

Recycled wood chips 134,000 1,372 183,848

Virgin wood chips 13,000 1,372 17,836

Totals 147,000 - 201,684

Note A: Emissions factor rounded to four significant figures. From Defra 2012 GHG reporting factors

Table B.2: Biogenic CO2 emissions from landfill baseline

Operational year Annual net biogenic CO2 release

(tCO2/annum) Cumulative total net biogenic CO2

release (tCO2)

1 68,737 68,737

2 71,664 140,401

3 74,504 214,905

4 77,261 292,165

5 79,936 372,101

6 82,532 454,632

7 85,051 539,683

8 87,495 627,178

9 89,868 717,046

10 92,170 809,217

11 94,405 903,622

12 96,573 1,000,195

13 98,677 1,098,872

14 100,719 1,199,591

15 102,701 1,302,292

16 104,624 1,406,916

17 106,490 1,513,406

18 108,301 1,621,708

19 110,059 1,731,767

20 111,765 1,843,532

Emissions from beyond year 20 allocated in equal spread to the 20 years of the facility’s operating lifetime




Appendix C – Transport Emissions Alternative Scenarios

The solid biomass CHP plant’s location at the multi-modal gateway means that both road and rail

transport for wood chip fuel could be possible. Rail transport typically has lower GHG emissions per

tonne-km than road transport, but is most useful when transporting large bulk loads over long distances.

The logistics of rail freight handling, requirement for a suitable freight railhead with loading facilities, and

existence of only limited fixed rail freight routes, may render rail transport impractical and/or economically

unviable for transport over short distances, or where the freight to be moved is only available in small bulk

loads from disparate sources.

It is desirable, if supply is available, to source wood chip fuel for the solid biomass CHP plant from the

local area. The greater flexibility of road transport is more conducive to achieving this. Rail transport, as

noted, is likely to be of any benefit only where the fuel is sourced from farther afield. These considerations

have informed transport 'scenario 1' described in the report.

As a sensitivity test, the transport scenario has been re-calculated assuming that 100 % of the wood chip

fuel is delivered by road, with the same distances as in scenario 1 as a ‘worst case’ assumption

(estimated by BWSC, as specific fuel supplier locations are not known at this stage). This forms

'alternative scenario 2a'. BWSC would aim, however, to source all wood chip fuel from the local area in an

all-road fuel delivery scenario. A further transport scenario with this distance assumed has therefore also

been calculated ('alternative scenario 2b'). The results of scenario 1, used in the assessment, are

presented in Table C.1, with the alternative all-road scenario results given in Table C.2 and Table C.3.

Table C.1: Scenario 1 transport emissions

Transport stage Amount (tpa) One-way distance

(km) GHG emissions (tCO2e/annum)

Wood chip fuel (road) 117,600 80 734

Wood chip fuel (rail) 29,400 241 262

Railhead fuel consolidation and unloading 29,400 81 185


Bottom ash 8,754 145 98

Fly ash 2,240 230 40


Total 801




Table C.2: Alternative scenario 2a - all-road transport emissions

Transport stage Amount (tpa) One-way

distance (km) GHG emissions (tCO2e/annum)

Wood chip fuel (road - local) 117,600 80 734

Wood chip fuel (road – non-local) 29,400 241 551


Bottom ash 8,754 145 98

Fly ash 2,240 230 40


Total 905

Table C.3: Alternative scenario 2b - all-road local sourcing scenario transport emissions

Transport stage Amount (tpa) One-way distance

(km) GHG emissions (tCO2e/annum)

Wood chip fuel (road - local) 147,000 80 918


Bottom ash 8,754 145 98

Fly ash 2,240 230 40


Total 538

Although the stage of road transport to consolidate the wood chip at a railhead is no longer necessary in

alternative scenario 2a (reducing emissions by 185 tCO2e/annum), the longer distance road transport

adds 551 tCO2e/annum to the total, compared to 262 tCO2e/annum for rail transport over the same

distance in the central scenario. The total transport emissions in this alternative scenario are around 104

tCO2e/annum, or 13 %, greater per annum than scenario 1. In alternative scenario 2b, the avoidance of

long-distance transport for the wood chip fuel leads to the transport emissions total being 264

tCO2e/annum lesser compared to scenario 1, a 33 % decrease.

The results of the scenarios suggest that there is likely to be little significant benefit in rail transport for the

fuel supply, given the greater flexibility and practicality offered by road transport. It is important to note

that the transport emissions in all scenarios are insignificant to the overall GHG emissions benefits that

would be achieved by the solid biomass CHP plant. Total transport emissions over 20 years of operation

in the three scenarios are around 11 – 18 ktCO2e, compared to the 1,151 – 1,159 ktCO2e net savings

achieved by the facility. The percentage change in the total net emissions savings achieved by the facility,

from scenario 1 to the ‘worst-case’ transport scenario (scenario 2a), is 0.2 %. On this basis, the GHG

benefits of the proposal are not significantly sensitive to transport assumptions.

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