Biomass for heat and power in the UK
Biomass can be used in the production of heat and electricity, as one alternative to fossil fuels. Its use is expected to increase significantly in the coming years in order to meet renewable energy targets.
Our vision for bioenergy
We want bioenergy to be an environmentally sustainable element of the UK's low-carbon energy mix, making a limited but important contribution to reducing emissions and mitigating climate change.
This can be achieved through prioritising the most carbon-effective and sustainable means of bioenergy production and use, in a way which limits damage to and preferably benefits biodiversity.
However, the UK has experienced a major rush to use biomass in large-scale electricity-only power stations in coal. The scale of proposed power plant development dwarfs the planned use of domestic fuel resource.
The UK’s heat sector urgently needs decarbonisation solutions and heat-only or combined heat and power plant are the most efficient ways which a limited sustainable biomass resource could be used.
Instead, many of these large electricity-only plants are relying on imported wood pellets and chips, in particular from North America, which in many cases could be contributing to climate change.
Furthermore, new plants are often being sited in locations where it is either not possible or not economic to capture the substantial quantities of heat produced, significantly reducing their efficiency and therefore their ability to deliver greenhouse gas emissions reductions. More details on this can be found in our report Bioenergy – a burning issue.
This approach to the use of biomass for energy will potentially have very negative impacts on both the climate and wildlife.
The challenges we need to overcome
We want bioenergy to make a contribution to reducing emissions and mitigating climate change. However, there are major challenges that need to be overcome.
When wood and other biomass is burnt in a power station, it releases carbon dioxide, just like fossil fuels. Many assume bioenergy is low or even zero carbon, because they think that the regrowth of vegetation can very quickly compensate for any emissions.
Yet studies (see 'The upfront carbon debt of bioenergy') show that trees take decades or even centuries to reabsorb the initial carbon lost to the atmosphere and therefore repay the 'carbon debt' from their combustion.
What’s more, the trees would have continued to suck carbon out of the atmosphere if they had remained standing, but once felled they can’t do this so that carbon stays in the atmosphere. Combined with soil disturbance and indirect land use change, government-produced science has shown that some types of biomass used for electricity can be significantly worse for climate change than the fossil fuels they replace.
This results in biomass sometimes being more harmful to the climate than the fossil fuel it replaces.
Flawed international accounting rules
International guidance requires emissions from bioenergy to be accounted for in the land use, land-use change and forestry (LULUCF) sector.
This means the carbon released is recorded when and where wood is harvested, not when it is combusted for energy. It is therefore counted as zero carbon in the energy sector as the emissions have theoretically already been accounted for.
However, gaps in the accounting rules negotiated under the United Nations Framework Convention on Climate Change (UNFCCC) allow a significant proportion of emissions from forestry and agriculture to go unaccounted. What's more, developing countries, and countries which have not signed the Kyoto Protocol, like the US, will not account for these emissions at all.
This means millions of tonnes of carbon emissions arising from burning biomass imported from these countries are being entirely unaccounted for.
Bioenergy and biofuels can still contribute to climate change mitigation, but only if we use technologies and feedstocks that genuinely deliver timely emissions reductions. Honest emissions accounting is the crucial first step.
How fuelling biomass plants affects wildlife
Wood demand to fuel UK biomass plants will be fulfilled either through logging existing forests or establishing plantations on new land. Both can potentially lead to serious harm to wildlife and ecosystems.
Logging of old growth or seminatural forests for biomass can be very damaging to wildlife as vital habitat is destroyed. Equally, over-extraction from managed forests by, for example, removing dead wood and extracting stumps, can also have significant impacts on biodiversity, hydrology and soils.
The planting of woody energy crops like miscanthus in the UK could harm wildlife if not planted sensitively. If done at a significant scale it can result in a monoculture landscape which can be harmful to wildlife, particularly if natural habitats are replaced in order for it to be grown.
Data shows that imports of wood into the UK from the US and Canada are expected to increase significantly. British Columbia has seen increased extraction of woody biomass which would previously have been left behind after traditional logging practices in response to demand for wood for bioenergy.
When left in the forest, this woody biomass provides habitat and shelter for birds, such as woodpeckers and owls, and mammals.
It supports a wide diversity of smaller organisms from insects to fungi, as well as micro-organisms which support the nutrient cycle.
Finally, it protects the soil from erosion into streams and serves as a source of nutrients and moisture for the growth of new trees. Removal of dead wood therefore has significant detrimental impacts on this ecosystem.
In the southeast US, there has been a significant increase in the use of newly harvested wood for wood pellets (that are exported to the UK to be burned for energy). The southeast US has recently been declared the world’s 36th biodiversity hotspot. These forests provide an important home to rare and threatened wildlife, as well as storing vast amounts of carbon and protecting communities from the effects of climate change, like flooding.
How can we make this work?
We believe bioenergy can play a meaningful and environmentally sustainable role in the UK's low-carbon energy mix, making a genuine contribution to mitigating climate change.
However, this requires prioritising the most carbon-effective and sustainable means of bioenergy production and use, preferably in a way which also benefits wildlife.
As such, we believe subsidies should be removed from imports of virgin wood in favour of supporting an industry based on wastes and domestic woodfuel production.
Comprehensive, robust, legally binding and well implemented sustainability standards will also play an important role.
There is a substantial bioenergy resource available from waste wood, food, municipal, garden and plant wastes. Agricultural products, such as straw and livestock manure for anaerobic digestion can also play an important role.
Bringing domestic unmanaged woodlands back into management for woodfuel, could further reduce our dependency on imported feedstocks and increase wildlife in woodlands at the same time.
This could reverse the decline of many woodland species, such as woodland bird populations which have declined 32 per cent since 1970 and woodland butterflies which have declined 74 per cent since 1990 as a result of under-management of woodlands.
Thanks to government funding, the RSPB has successfully trialled the use of materials from wetland habitats on its nature reserves, helping wildlife and demonstrating a low-emissions fuel can be generated at the same time.