July 24, 2014

expert reaction to DECC biomass calculator

The Department of Energy & Climate Change (DECC) has launched a scientific calculator that investigates the impact on carbon emissions of biomass sourced from North America to produce electricity.

Dr Paul Adams, Post-Doctoral Researcher (Supergen – Bioenergy), University of Bath, said:

“It is a very positive step forward that the Government recognises the issues associated with carbon stocks, land use change, and modelling biomass supply chains using LCA (Life Cycle Analysis). The BEAC model provides lots of useful data on scenarios and counterfactual land uses which can be used by biomass suppliers, operators, researchers, and policy-makers to better understand the greenhouse gas implications of the biomass electricity generation.

“This is an important contribution to the evidence and knowledge base around the carbon impacts of bioenergy production. However the results do need to be properly understood by users of the model, and the transparency of modelling assumptions could be improved. A useful improvement would be to make the user guide more comprehensive and provide a map of key assumptions. Overall, the model shows that imported biomass from North America can provide a low carbon fuel which meets the GHG emission limits as defined by Biomass Sustainability Criteria. It also demonstrates the complexities of attempting to place a value on GHG emissions using consequential LCA. It will be interesting to see how this approach is applied to other biomass fuels and bioenergy production pathways.”

 
Mr Miles Seaman, a Member of the Institution of Chemical Engineers (IChemE), said:

“The report issued today contains some conclusions that are at odds with DECC’s previously-published 2050 Calculator, in terms of the overall contribution of biomass to CO2 emissions. Today’s report says “This work shows that in 2020 it may be possible to meet the UK’s demand for solid biomass for electricity using biomass feedstocks from North America that result in electricity with GHG intensities lower than 200 kg CO2e/MWh, when fully accounting for changes in land carbon stock changes. However, there are other bioenergy scenarios that could lead to high GHG intensities (e.g. greater than electricity from coal, when analysed over 40 or 100 years) but would be found to have GHG intensities less than 200 kg CO2e/MWh by the Renewable Energy Directive LCA methodology”, suggesting that biofuels will always emit more CO2 than they take up, whereas the old report from the 2050 Calculator had said “like all other fuels, when biofuels’ biomass are combusted, the model applies an emissions factor according to its physical state. However, unlike hydrocarbons, biofuels do not produce any CO2 when burned. UNFCCC accounting guidelines state that countries should treat biomass as an emissions neutral energy source. This is because carbon from the atmosphere is sequestered into the biomass while the feedstock is growing. To account for this, an equivalent negative quantity of emissions is included in the emission calculation. When biofuels are combined with CSS, the above treatments combine, resulting in a negative contribution to the overall CO2 emission calculation”, so it was previously and perhaps naively thought that in all circumstances trees take up as much CO2 than burning them would emit.

“For some time IChemE have promoted the use of Life Cycle Analysis (LCA) (which has been used in today’s report) to get a clearer more objective picture of the use of various options to achieve the very challenging emission reductions promised through the Climate Change Act.

“It is to be hoped that DECC will continue to utilise the approach taken here for all other energy vectors and incorporate this in the 2050 Calculator.”

Prof Roland Clift, Emeritus Professor of Environmental Technology, University of Surrey, said:

“This is a useful report looking at a diversity of supply options for wood fuel, reinforcing the conclusions of earlier studies. In particular, it highlights the fact that the environmental benefits (or otherwise) of using wood as a fuel depend on where and how it is produced. This in turn highlights the importance of assessing and guaranteeing the source and supply chain of the wood.”

Dr Bernie Bulkin, Formerly, Chair, Office of Renewable Energy, DECC, said:

“The DECC report on utilisation of biomass for generating UK electricity is the result of a long research project by Anna Stephenson. It’s a careful piece of work, that presents many different scenarios for how and where the biomass is grown, how it is transported to the UK, whether it is grown specially for this purpose or is waste, and so on. Some of these turn out to be very advantageous from the carbon savings perspective, and some are terrible. We have known this instinctively for a long time but this work confirms it. What it really shows is that if we do biomass electricity in the right way, it will make a great contribution to renewable energy in the UK, displacing coal and saving a lot of carbon emissions. Some people will undoubtedly pick up on the ‘bad’ scenarios and highlight them. This is a mistake. What we need to do now is put in place the systems and processes to make sure we achieve this in the best possible way.”

Declared interests

Dr Paul Adams: “I work as a post-doc researcher for the Supergen Bioenergy Hub and am a specialist LCA practitioner in GHG emissions from bioenergy systems.”

Prof Roland Clift was lead author of the Royal Commission on Environmental Pollution’s report on ‘Biomass as a Renewable Energy Source’, published in 2004.

Dr Bernie Bulkin is Director of Ludgate Investments Limited and Chairman of HMN Colmworth.