wrgcsrreport.co.uk

Our carbon impacts

WRG manages waste produced by its customers by means of recycling, landfill with landfill gas management, and incineration with energy recovery. We report on the climate change impacts of all these activities, both positive and negative, including any carried out WRG’s behalf, which are a direct result of our operations. The diagram below shows the boundary of our carbon assessment:

Figure 2 - WRG 2008 carbon assessment

Our methodology follows the greenhouse gas (GHG) protocol and uses published emissions factors where possible. We have included our significant direct emissions and indirect emissions due to electricity consumption. We have not included other indirect emissions, such as from the transportation of waste to us by third parties. Where our renewable energy generation and recycling activities result in carbon savings, due to the avoidance of emissions, these are reported separately. This year, we commissioned an independent review of our carbon assessment methodology. We are also consulting our stakeholders on what information they would like to see reported and are committed to continually improving the quality and relevance of our carbon reporting.

Negative and positive impacts

Negative global warming impacts are produced when fossil carbon is extracted from long-term storage and burnt, releasing carbon dioxide into the atmosphere. WRG believes that positive global warming impacts also accrue if biogenic carbon*, from the short-term carbon cycle is placed into long-term storage. This process occurs naturally when carbonaceous material is stored in sediments, e.g. on the seabed. It also occurs when carbon compounds, such as the lignin component of wood, are retained in landfills, where they do not degrade in the anaerobic conditions. Landfills are where our largest negative global warming impacts occur -- from fugitive methane emissions -- but they are also where the positive impacts of energy generation from collected landfill gas and biogenic carbon storage, as described above, take place. Although a consensus on the methodology has not yet been achieved, we have tried to estimate this carbon storage using a conservative approach.

Other sources of emissions included in the carbon balance are indirect emissions from purchased electricity and direct emissions from burning fuel in vehicles, mobile and static plant. WRG’s 2008 carbon impacts are summarised in the table below. Whilst we have included figures for 2006 and 2007 for comparison, improvements in data collection mean that year-to-year figures are not directly comparable.

* Material derived from biomass of non-fossil origins. E.g. plants, animal or micro-organisms, including wood products.

Landfill degradation

Biodegradation of waste in landfills occurs under anaerobic conditions, i.e. in the absence of air. This degradation gives rise to two main products: methane and carbon dioxide. Even when recycling has been carried out efficiently, there are likely to be degradable materials, such as used tissues and kitchen paper, that will continue to be landfilled. The carbon dioxide produced from degrading waste (e.g. food waste, garden waste and wood products, such as paper) in landfills is short-cycle biogenic carbon dioxide and is not counted in the net emissions figure below.

The methane, by contrast, is at least 21-times more potent as a greenhouse gas than carbon dioxide, and would not have been produced were it not for the anaerobic conditions in landfill sites. Products made of fossil carbon, such as plastics, do not degrade in landfills and may be thought of as being put back into long-term storage. This storage of fossil carbon is not included in the carbon assessment, but it is estimated to be as much as 310,000 tonnes of CO2 equivalent.

Landfill gas management

Most of the methane produced in the landfill is collected, burnt and converted to carbon dioxide, thus reducing its global warming impact. As this originates from biogenic carbon, it similarly is not counted in the net emissions figure. Where this methane is burnt to generate electricity, it produces a renewable form of energy, displacing electricity produced from fossil fuels, with a further benefit in carbon terms. Fugitive methane gas, which is not collected, has a potent global warming impact, as described above. WRG reported emissions from 69 landfills to the regulators in 2008 and also collected gas from a further 17 closed sites. These figures are included in the table below.

Energy from Waste 

WRG also operates Energy from Waste (EfW) plants to thermally treat waste and recover the energy content. In this process, the entire carbon content of the waste is converted to carbon dioxide -- no methane is produced, but neither is there any carbon storage. The carbon dioxide produced from the biogenic fraction of the waste, e.g. paper, is not counted in the net total, whilst that produced from burning fossil carbon, e.g. plastics, is included. WRG operate two EfW plants. At Eastcroft in Nottingham, all the energy is exported as heat for use in a district heating scheme. At Allington in Kent, it is intended that electricity will be exported to the grid, but technical issues have prevented this in 2008.

Recycling

WRG also recycles various fractions of the waste stream, e.g. glass, paper and plastics. Figures for plastic recycling are new this year, due to improved data collection. There is a carbon benefit associated with this, since it is generally less carbon-intensive to make new products from recycled materials, rather than from virgin raw materials, and it also diverts these materials from landfill. Green waste is also composted, releasing some biogenic carbon dioxide, but no methane.

The carbon impacts of WRG’s activities are summarised in the table below. Please note that figures for CO2 from fuel use and electricity use and CO2 savings due to recycling in 2007 and 2006 have been recalculated using the same factors used in this year’s report, to obtain the best possible comparison. However, since data collection has improved over the period, exact comparisons are not possible.

Emissions - figures represent tonnes of CO2 equivalent

Benefits

¹ WRG estimate based on WRAP, Dr Julian Parfitt, Analysis for Waste Not, Want Not 2002.
² Defra/ERM 2006 Impact from energy from waste and recycling on UK Greenhouse gas emissions.
³ Defra Greenhouse gas reporting guidelines 2008.
⁴ Waste and Resources Assessment Tool for the Environment (WRATE) model of materials to landfill and recycling.