It’s a question that causes a lot of confusion: why are carbon emissions from biomass electricity counted as zero in the electricity sector? Some people think this equals a ‘black hole’ in the carbon accounting of biomass, but that isn’t true. The emissions are always counted, but in a slightly different way to most electricity sources.

The UN's IPCC is the world's leading scientific body on climate change.

International carbon accounting

The international carbon accounting rules are decided by the world’s top independent climate science body, the UN’s Intergovernmental Panel on Climate Change (IPCC), which is made up of thousands of scientists, all focused on specific areas of climate policy. It regularly reviews and refines the ways in which greenhouse gas emissions are reported, to take account of changes in science and technology and to ensure it’s being done correctly. The last review was in 2019, when it confirmed the current arrangements.

The rules state that each country must report their carbon emissions, as set out in the Kyoto and Paris climate agreements. They do so by sector, so there are emissions numbers specific to the electricity sector, various parts of the transport sector, and so on. You can find the UK’s latest accounts here.

Of course, bioenergy used for power and heat sits across two sectors – forestry, agriculture and other land uses and energy.

Accounting for bioenergy

The fuel for bioenergy is accounted for in the ‘Agriculture, Forestry and Other Land Use’, or AFOLU, sector. Biomass from this sector plays a central role in absorbing carbon from the atmosphere, thereby helping to balance carbon levels. In the AFOLU sector’s accounts, carbon emissions are recorded whenever there are harvests. For example, if a tree is cut down, that’s counted as an ‘emission’ of carbon from the AFOLU sector. When a tree grows, capturing and storing carbon in the process, that growth is subtracted from the emissions of the sector. So, if deforestation occurs, this will be shown in the accounting as an increase in the emissions from the AFOLU sector. If a forest is experiencing net growth, then it will show as lower or possibly negative emissions in the AFOLU accounts.

In the electricity sector, most fuels are counted when they are used as fuel. This is because they don’t have a carbon impact until that point – a lump of coal is fairly inert until you burn it. So, when it’s burned, it is counted as an emission. But the fuel in bioenergy has already been accounted in the AFOLU sector, where it forms an active part of the carbon cycle.

In effect, the IPCC is saying that the forest and the power station form part of one carbon system. As the IPCC puts it, “This provides a complete picture of a country’s energy system and avoids double counting of emissions with those reported in the AFOLU sector.

Accurately reporting all emissions

It’s important to remember that carbon emissions from the supply chain – things like production, processing and transport – are recorded by the electricity sector and audited independently, so biomass isn’t seen as ‘zero carbon’. Methane and nitrous oxide emissions are also counted in the energy sector, as these are more a matter of power station operations and can’t easily be linked to biomass harvesting.

Because we count the CO2 emissions from bioenergy in the AFOLU sector, we don’t then count them again in the electricity sector (known as ‘stack emissions’ – a ‘stack’ is a power station’s chimney). Doing this would lead to double counting – the same carbon emissions counted twice. That would lead to inaccuracies in the carbon inventories, making it harder to understand what’s happening with global emissions. It might also falsely make bioenergy appear to have worse carbon emissions than it really does. Given that bioenergy is potentially one of the most abundant renewables in the world, it would be wrong and counter-productive to apply inaccurately stringent accounting conditions to it.

Some critics have argued that carbon emissions should not be counted in the AFOLU sector at all, but in the electricity sector, since that’s where the fuel is converted to energy. However, doing this would mean that we ignored what’s happening in the AFOLU sector. This is a vitally important sector, partly because it’s where a great deal of carbon absorption happens. Carbon is removed from the atmosphere by the oceans, forests, grasslands, peats and soils of the world. We therefore need to have a close eye on carbon emissions in this sector and can’t afford to ignore deforestation. Carbon emissions for bioenergy are therefore “counted in the forest”.

The IPCC approach to carbon accounting doesn’t remove the need for strict sustainability regulations, which the UK has had in place for over a decade, and also certification schemes such as the Sustainable Biomass Program. But it does ensure that the numbers are reported accurately.

The UK is the world-leader in sustainable bioenergy.

The UK is a world-leader in a decarbonisation story that many may not be aware of, but one that has helped to dramatically reduce emissions over the last decade and looks set to deliver a key part of the Net Zero solution. In a new edition of the Electric Insights report with Imperial College, we explored the example that the UK has set through its use of sustainable bioenergy and how the UK’s past, present and future might provide lessons for others.

The UK pioneered the use of large-scale biomass for electricity generation, and the report shows that the UK currently has the highest share of electricity production from biomass of any large country (countries with over 100 TWh/year electricity demand). This has meant that the UK has also had a large role in the development of the science-led sustainability criteria which govern the use of biomass, with the current UK system one of the world’s most rigorous. The results are shown in independent, official data from authorities such as the US Forest Service, showing that working forests supplying UK bioenergy feedstocks are continuing to see growth, backed-up by effective sustainability regulations.

The first stage of this ‘Coal-Biomass-BECCS’ (CBB) Pathway takes place in a high-fossil fuel power system (the UK’s past). Coal-to-biomass conversions have allowed some power stations to transition away from fossil fuels to renewables, maintaining thousands of jobs and investment in key infrastructure whilst securing emissions reductions of over 85% on a lifecycle basis. From 2012-2019, coal-to-biomass conversions reduced carbon emissions by 10 MtCO2 per year (the equivalent of taking 2.17 million cars off the road every year).

The second stage of the CBB Pathway is in a high-renewables system (increasingly the UK’s present). Sustainable biomass provides low-carbon, firm, dispatchable power, giving the similar reliable functionality of coal without the high emissions. The flexibility services of sustainable bioenergy, including inertia and grid balancing, help the overall system to integrate variable renewables like wind and solar, as well as lowering grid management costs, which are paid by energy consumers. These costs are expected to rise in coming years, so low-carbon energy sources that help to keep them down are especially welcome.

The third stage of the CBB Pathway is Bioenergy with Carbon Capture and Storage (BECCS), which offers one of the most credible routes to delivering negative emissions. The Climate Change Committee describes negative emissions as “a necessity, not an option” for Net Zero and sees a major role for BECCS in removing between 20 and 65 MtCO2e/yr. by 2050.

Not every country in the world will pursue this ‘CBB Pathway’, but the UK has shown how it can make a big contribution to decarbonisation: with a strong carbon price, implementation of the IPCC’s carbon accounting rules, strong sustainability criteria applied to the whole supply chain and investment in key technologies. The CBB Pathway is a stable, cost-effective route map for lasting and meaningful decarbonisation, supporting major emissions reductions in power systems as part of a range of energy options. The flexibility and stability that biomass brings as part of the transition away from coal allows for greater expansion of intermittent renewables such as wind and solar power. The use of biomass in a renewable energy mix not only supports decarbonisation now, but also opens the door for negative emissions, which will prove crucial if we are to have a chance of avoiding catastrophic global warming.

In response to a recent report from the think tank Ember, about the costs of delivering BECCS at scale, Dr Nina Skorupska, CEO of the REA said:

“The IPCC and the UK’s Climate Change Committee, which are the world’s and the UK’s leading climate science authorities agree that BECCS is a key tool in reaching Net Zero. It will help us to get there quicker and with less cost to energy bill payers.

A report by the energy consultancy Baringa estimated that BECCS at Drax will save the UK consumer £4.5billion over the next decade (and up to £5billion by 2050), compared to not using it to reach Net Zero.

“The costs of individual BECCS plants will be a matter for individual companies to assess and present to the government, and they have an incentive to drive down costs. Drax, themselves, have stated that it doesn't recognise the figures in Ember’s report, including the expected cost of building and running the plant, nor the scale of the BECCS operations that Ember projects.

“Sustainable biomass, which is at the heart of BECCS, has been crucial for moving the UK away from coal and in helping other renewable technologies to be deployed at scale. The working forests that supply UK biomass power generation have seen an increase in their tree cover whilst supplying thinnings and residues from forestry for use in UK renewable energy generation.

“As the Baringa report shows, BECCS has a key role in bringing down the cost of Net Zero and we would be unnecessarily raising costs if we went ahead without it.

“The UK is already facing a huge challenge in ramping up low-carbon generation in time to deliver its ambitious targets. BECCS will make this easier and more affordable.”


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