A Changing Climate for Energy from Waste? Final Report for Friends of the Earth
This report lays down some challenges to conventional wisdom and some dearly held beliefs. It is a piece of work which, from the author’s perspective, has been many years in its gestation, and which has a number of important implications.
Fundamentally, it challenges what has become ‘conventional wisdom’: that energy from waste incineration is bound to ‘generate climate change benefits’. It does not, however, argue that such benefits may not be possible to derive. Rather, it highlights the fact that whether or not climate change benefits can be said to have been derived is dependent upon the assumptions used in the analysis and the performance of the relevant technologies, notably:
- the efficiency with which the incinerator generates energy (and in many UK-based studies, these have tended to be on the high side);
- the assumption concerning which energy source might be considered to be displaced by the incinerator (this will always be controversial);
- the efficiency with which these ‘displaced sources’ generate energy (these are tending to improve over time);
- whether or not one includes biogenic carbon in the analysis (most studies do not);
- the calorific value of the input waste; and
- what percentage of carbon (biogenic and non-biogenic, depending upon the view of the study) is in the waste combusted.
Notably, the study highlights the fact that typical UK incinerators, generating only electricity, are unlikely to be emitting a lower quantity of greenhouse gases, expressed in CO2 equivalents, per kWh electricity generated than the average gas-fired power station in the UK. Rather, since gas-fired power stations emit a smaller quantity of GHGs per kWh, the presumption that energy from waste is always ‘good for climate change’ appears to imply a range of assumptions which are not always stated (or, perhaps, understood by those who presume this to be the case).
This need not necessarily imply that energy from waste incineration is bad for climate change. It could, after all, be true that incinerating waste and generating energy from it is the best way of dealing with waste. This is the more-or-less unanimous outcome of the vast majority of studies which have looked at the matter from the perspective of life cycle assessment (LCA). However, we argue that the use of conventional LCA-based approaches, and most notably, the largely unquestioned assumption that ‘biogenic carbon can be ignored’ (or that only what is not liberated as CO2 after 100 years needs to be taken into consideration, which amounts to a similar assumption), is inappropriate for this type of analysis. Ignoring what happens to biogenic CO2 during a 100 year period can only be an acceptable way to proceed if all technologies behave in a similar way over this time period, and if society is not especially interested in the time profile of emissions. Neither would appear to be true.