Defra’s ex WRATE-ed guide

Incineration might be worse than landfill. Although not an unfamiliar conclusion for us at Eunomia – we suggested as much in a report written for Friends of the Earth eight years ago – it’s rather more surprising to hear Defra echoing it in a recent publication. Hitherto the department seems to have regarded the environmental benefits as incontrovertible.

Even more surprising, given Defra’s change of stance, is the Green Investment Bank’s (GIB) decision to invest £51 million in the proposed energy from waste (EfW) facility at King’s Lynn, Norfolk, apparently in the belief that this is a “green waste facility”. With serious amounts of public money still at stake, it’s never been more important to consider whether we’ve reached the point where most UK incineration plant will start to perform worse than landfill.

So why is Defra’s view changing? Perhaps it is because the facts are becoming clearer. In a previous article I highlighted the flaws in the influential WRATE analysis typically undertaken during the local authority planning process. WRATE has tended to understate the climate change impacts of waste incineration. The sensitivity of the analysis to the factors I discussed has now been highlighted in two studies the department recently published.

In the revised Guide to the Debate on Energy from Waste – updated just a year after its initial publication – Defra now concludes that there “are potential balance points beyond which energy from waste could perform worse than landfill in carbon terms”, if the incineration plant generates only electricity. The report implies there will be a net climate change benefit over the lifetime of a facility built today but that this will not be the case in the future, although it doesn’t indicate when this shift will occur. This leads Defra to promote the use of Combined Heat and Power (CHP) production to derive more benefit from the heat incinerators generate.

Defra supports its argument with a carbon based modelling study published alongside the Guide: interestingly, this does not use WRATE. In addition, since my earlier article, the Environment Agency has confirmed it has (without a competition) handed ownership of WRATE over to Golder Associates. WRATE appears to be increasingly side-lined.

Gas trick banned?

My previous article also explained how the Intergovernmental Panel on Climate Change (IPCC) was expected to significantly increase its estimate of the global warming potential (GWP) of methane. Although the revision had not been formally agreed, the anticipated increase had been raised as evidence in several recent public inquiries by advisors acting on behalf of applicants seeking to develop incineration facilities. Landfill releases methane, so if the damage caused by methane is higher than WRATE calculates, it gives incineration an advantage.

Eunomia has developed a waste model to look at the impact of changes to Landfill Directive targets, and in recent months colleagues have been in contact with the European Commission’s DG Clima on the topic. It has emerged that it is unlikely that any revision to the GWP of methane will be incorporated into European climate change policy until at least 2020, because the Phase 2 agreements of the Kyoto protocol recently incorporated into EU legislation have been based on the GWP assumptions from 2006. Defra says the GWP of 34 has not yet been widely adopted so the value is not used in the central case in its study. Now that it is clear that policy will be largely based on the 2006 assumptions, perhaps we will hear a little less about the GWP of methane in future planning enquiries.

I also highlighted the discrepancy between the default data used in WRATE for the ‘marginal source’ of electricity generation, and current government guidance. This is important because the electricity produced by an incinerator will have a much bigger climate change benefit if it replaces energy from a carbon intensive mix of generation that includes coal power, compared with a mix dominated by gas, nuclear and renewables.

Recent public inquiries I’ve studied or taken part in – including that for the King’s Lynn incinerator – confirm that the WRATE default values for energy mix are still widely used, inflating the apparent benefits of EfW. There, consultants ERM questioned the relevance of the government marginal source guidance – which is aimed at central government – to local authority assessments of residual waste treatment options. Now Defra has used the same guidance in its carbon modelling study, which ERM has peer reviewed, confirming that the guidance is valid in this type of assessment.

Buried assumptions

It seems strange to say it, but landfill can have certain climate change advantages. WRATE fails to account for the storage of biogenic carbon in landfill, although the European Commission’s ILCD handbook indicates that credits for the temporary storage of biogenic carbon should be included “where the goal of the study clearly warrants it”. The inclusion of this storage effect reduces the climate change impact of landfill by around 46%, suggesting this issue should not simply be ignored. Although Defra only considers this impact in sensitivity analysis, it confirms the results to be very sensitive to the approach used here.

Is CHP a hard SEL? Rotherhithe’s SELCHP Incinerator is a rare example of a transition from CHP-ready to CHP in use. Photo by Stephen Craven, via Wikimedia Commons

A further important assumption not considered in my earlier article is the proportion of landfill gas captured. When Eunomia produced a study aiming to improve the model used to estimate methane emissions from landfill for the UK’s annual submission to the United Nations Framework Convention on Climate Change, Defra rejected our recommendation to decrease the 75% landfill capture rate. Now, however, it finally appears to be back tracking on this: the carbon modelling study states the “default” value to be 75%, although the “central” value used in their scenario modelling is 60% capture.

WRATE analysis results are also sensitive to assumptions on residual waste composition. Defra confirms this in its carbon modelling study, although without linking composition with recycling performance. Its central case uses a UK national composition from 2011 when recycling was at 41%. The residual waste composition will change as materials are removed for recycling, and it is therefore highly dependent on local conditions. For example, as local authorities introduce separate food waste collection services, the relative performance of incineration worsens in comparison to landfill. Equally, as authorities introduce mixed plastics collections, the relative performance of landfill worsens in comparison to incineration. However, since you can only achieve high recycling rates (more than 65%) with good food waste capture, the general trend is for a worsening performance of incineration with an increase in recycling performance.

Losing their balance

Defra’s analysis of balance points suggests there is a net climate change benefit at present, but that there will come a point of balance at some point in the future – although it doesn’t given an indication of when that might be. My analysis suggests we’ve already reached that point for the typical UK incineration plant commissioned today.

If biogenic carbon storage is accounted for, using the national waste composition based on 41% recycling, government guidance on assumptions for electricity generation and a GWP of 25 for methane, even if we assume Defra’s central landfill gas capture rate of 60%, there will be no net climate change benefit over the lifetime of the plant for an incineration facility commencing operation next year if that facility generates only electricity. We would see a climate change benefit from incinerating waste if the GWP of methane is increased to 34, but this is eroded at higher rates of recycling, particularly if the capture of landfill gas improves in the future as Defra anticipates.

Only if the plant is able to utilise a significant amount of heat does incineration perform noticeably better than landfill over its lifetime. This is an important finding: the waste hierarchy would normally dictate that energy recovery through incineration should be preferred to disposal through landfill; however, the waste regulations also allow departure from this “so as to achieve the best overall environmental outcome where this is justified by life-cycle thinking”, including carbon modelling.

Defra’s new guide calls for a focus “on development of energy outputs beyond electricity, both for new plants and ensuring existing plants that are ‘CHP ready’ become ‘CHP in use’”. This may be read by some as opening up opportunities to develop a new generation of truly efficient EfW facilities. However, the example of London’s SELCHP demonstrates just how difficult it is to achieve the transition to ‘CHP in use’: their perseverance in the development of their heat network is admirable, but plans have only lately been finalised more than a decade after it first started to generate electricity. The disruption involved in connecting a densely populated urban district up to a central source of heat risks adding to the opposition new incinerators routinely attract.

Whilst it is far from the end of the road for EfW in the UK, the extent of the challenge of implementing large-scale CHP means that Defra’s Guide steers developers down a new and much more twisty path than hitherto. It’s a shame that no-one seems to have told the GIB to put the brakes on.