Welcome to the Forest Biomass Basics FAQ, brought together by EPN’s Biomass Action Network. Whether you’re an activist, community member, researcher, or simply curious about biomass energy, you’ll find answers here to the most common questions about biomass and its impacts on forests and climate. If you have suggestions for additional questions, please contact us.
To find out more, please visit our Biomass Library for a deeper dive into the details.
In short, energy that is produced by burning things that have grown recently, usually plants.
There are lots of different terms:
More information: Environmental Paper Network Position Statement on Biomass Energy
It is often promoted as a solution to reducing global greenhouse emissions, but it isn’t.
Some people say that biomass energy is sustainable and carbon neutral, so it is seen as part of a solution to reducing global greenhouse gas emissions and tackling the climate crisis. In particular, large scale biomass energy is being encouraged by government subsidies or other incentives under the impression that its use can help tackle climate change. However, in almost all cases, it is not carbon neutral and it is rarely sustainable.
More information: Biomass energy: Clean or dirty?
No.
You might think that because biomass is produced by plants taking CO2 from the air and burning it merely releases the same CO2 back to the atmosphere, but that ignores how long it takes a plant to store up the carbon. Burning something immediately adds that CO2 to the atmosphere. It can take years for that same amount of CO2 to be locked into biomass by a plant. There is a “carbon debt” incurred when biomass is burnt. Biomass also emits more greenhouse gases per unit of energy than most fossil fuels. Cutting down long-lived plants such as trees and burning them means also that you are removing something which was taking in carbon from the air and storing it. You have removed a carbon sink and made it into a carbon source.
Added to that, when land is converted to plantations to grow trees or other plants for energy, it results in direct and indirect land use change which can cause significant carbon emissions (e.g. when agriculture or other activities are moved into forests or natural grasslands).
More information:
No.
The IPCC position is that national accounting should show CO2 emissions from bioenergy as happening in the land use sector where the biomass comes from, not in the energy sector where it is burned. They explain, “The IPCC approach of not including bioenergy emissions in the Energy Sector total should not be interpreted as a conclusion about the sustainability or carbon neutrality of bioenergy.”
The IPCC also calls on governments to report on the upfront CO2 emissions from burning biomass separately, and its guidelines show that those are almost always higher than CO2 emissions from fossil fuels.
It explains: “If bioenergy production is to generate a net reduction in emissions, it must do so by offsetting those emissions through increased net carbon uptake of biota and soils.”
More information: IPCC (2019) 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories Volume 2 Energy
Biomass crops are NOT carbon neutral.
If you clear land to grow energy crops, you would release carbon from the vegetation that was cleared to make way for the crops – carbon that would otherwise have remained locked in the vegetation.
To grow crops specifically for energy would need a huge area of land when there is already pressure on land for food crops.
Furthermore, attempts to persuade farmers to grow fast-growing crops such as miscanthus, switchgrass or poplar for energy have almost universally failed, due to high costs and and vulnerability to extreme weather. The only “successful” plantations of this type are fast-growing eucalyptus ones, especially in Brazil, commonly linked to land grabbing, destruction of natural ecosystems, human rights abuses, etc.
The IPCC Special Report on Land pointed out the potential serious adverse impacts of large scale biomass plantings for energy production, often associated with BECCS (Bioenergy with Carbon Capture and Storage), on food security, land degradation, and adaptation.
More information:
Biomass energy from forests is almost never carbon neutral.
Cutting down trees to burn for energy has been shown to produce more greenhouse gases in the short term than leaving a forest standing. And in the case of a forest “short term” can be more than 40 years – well beyond the time limits the IPCC recommends for serious action. Even over the long term, as a forest regrows, it may end up having released more GHGs than if it had been left standing as there will have been emissions from soil, stumps, roots and so forth in addition to what comes from burning the wood itself. if the forest is replaced wiht a quick-growing softwood plantation, for example, it will never hold the same amount of carbon as a mature hardwood forest would have.
A key point is that it is not simply the area of forest that is important, but the carbon density of that forest, whether it is a good trade off to lose that to atmosphere or keep it and add to it via ongoing sequestration – thus removing carbon from atmosphere. A primary forest will contain more carbon in a given area than will a secondary forest, which will generally contain more than a modified natural forest, and that more than a plantation. “Forest degradation” is thus a key issue additional to deforestation. Current policy settings don’t recognise these important differences, using only a simple “area of forest” approach, with no nuance relating to its condition.
More information: Bioenergy: A carbon accounting time bomb
Badly.
If you clear land to grow energy crops, you would release carbon from the vegetationIn the international climate convention, countries report on their carbon emissions from two different sources: land use and energy use. If you cut a forest down and burn it for energy, the carbon that would be released is counted as a land use emission. The way in which the amount of carbon released from land use change is calculated is very questionable. Then when the wood is burned, the carbon released is not counted as an energy use emission, because, in theory, it’s already been taken into account as a land use emission. That means that if a country has a biomass burning power plant, for example, it doesn’t include the carbon released from that power plant in its overall carbon emissions, because they have, in theory, already been included under land use.
When the biomass has been imported from another country, that producing country has responsibility for the emissions of combustion of the biomass for energy and not the country that actually burns the biomass, produces and uses the energy. If the country that grew the biomass is not party to the international agreement (such as the US, Canada, Russia in relation to the Kyoto Protocol), then nobody takes responsibility for the emissions. There is an emissions loophole in the carbon accounts.
More information: Bioenergy: A carbon accounting time bomb
No. Cutting down a tree and burning it is not carbon neutral, whatever type of forest it comes from.
Discussing “Sustainable Forest Management” is a distraction from the bigger issue: If you harvest a tree from a sustainable forest and burn it for energy, it doesn’t mean the energy is either sustainable or climate-neutral. The way biomass – a limited resource – is used rather than how forests are managed is the key issue here. In 2018, 800 scientists around the world signed a letter to the EU stating: “Even if forests are allowed to regrow, using wood deliberately harvested for burning will increase carbon in the atmosphere and warming for decades to centuries –as many studies have shown –even when wood replaces coal, oil or natural gas. The reasons are fundamental and occur regardless of whether forest management is “sustainable.”
More information:
No.
In most places where forests are increasing in area, they are recovering from previous deforestation, which is part of what has created the climate crisis in the first place… It’s a matter of how forests are best deployed to tackle climate change, to continue growing and drawing carbon out of the atmosphere or to log and burn them with substantial immediate emissions and no hope of even recovering the lost carbon in time scales relevant to tackling the climate problem.
In France, where forest cover has increased over the last 100 years, natural forests are under direct threat from the biomass energy plant at Gardanne in Provence.
In the USA, where southern swamp forests are being cut for biomass, claims of increasing forest cover ignore the conversion of natural forests to less carbon (and bioviersity) rich planations, and the degradation of carbon stores of existing forests via clearcut logging
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No. A mature forest is a carbon sink – it has locked up carbon in its trees and soil. Cutting it down releases a lot of that carbon back into the atmosphere.
Forests do not stop absorbing more carbon. It is true that older trees absorb less than mature ones, (and very young trees absorb less as well) – but that is only because they have already locked up a substantial amount of carbon that would be re-released into the atmosphere if you cut them down.
If the subsidy is for planting trees to burn, it will not reduce climate change.
Planting trees to burn them will not result in reforestation or in reducing greenhouse gases. What is needed for the climate is the restoration of standing forests.
A subsidy might also encourage replacing mature forests with plantations, which would be very bad for carbon levels in the atmosphere
More information:
No.
Even if it were, “going to waste” does not usually release as much carbon into the atmosphere as burning residues does. Added to that, genuine residues are those arising at sawmills as offcuts and sawdust generated during milling for sawn timber. So-called residues arising in the forest are a function of the decision to adopt intensive logging practices such as clearcutting.
Incentives for biomass production are encouraging more use of whole trees for biomass and changes in practice that mean that even more wood is burned rather than used in ways that locks the carbon in. Even in situations where it is genuinely only residues that are used, the carbon debt issue remains – burning adds carbon to the atmosphere today, when we are trying to reduce it. In particular, intensive harvesting of forest residues reduces the amount of carbon stored in forest soil.
Furthermore, there is no universally agreed definition of ‘residue’, and timber, pellet and energy companies frequently call the majority of trees in a forest ‘residues’, just because those trees are the wrong size or shape for sawmills. Frequently the definition of ‘residue’ in a forestry operatiom is derived from the monetary value per unit by weight or volume of the forest product taken. Thus a high value sawlog is defined as the primary product, although it is obtained in low volumes, whereas high volumes of biomass (often much greater than those of sawlogs) is defined as residue simply because it is worth less per tonne or cubic metre.
More information: Forest soil carbon is threatened by intensive biomass harvesting
True, but almost always only on a small scale for individual households.
It is true that in many countries, fuelwood is an important source of domestic energy. However, incentivising industrial use of such wood competes with domestic use and could encourage more intensive fuelwood harvesting, resulting in negative climate impacts. Use of wood and charcoal for cooking is important in some countries, but the adverse health impacts of the resulting particulate pollution are an issue that is gaining prominence, so that even for such uses we may see eventual change. Large scale district heating schemes in Europe converting to biomass are a problem.
More information: Forest soil carbon is threatened by intensive biomass harvesting
No.
We need to move Beyond Burning. In the short term, burning wood emits more carbon into the atmosphere, as it is less efficient. It takes between 44 and 104 years for the carbon to be reabsorbed by regrowing forest – assuming that the forest is allowed to regrow.
Added to that, to sustain the infrastructure of fossil fuel power generation addresses none of the fundamental structural changes that will have to take place to move to a low-carbon economy.
To prevent the worst impacts of climate change we need to stop burning fossil fuels and we need to stop degrading and destroying our natural ecosystems, including forests, too. We need to move to genuinely low-carbon renewables and reduce wasteful energy use.
More information: Does replacing coal with wood lower CO2 emissions? Dynamic lifecycle analysis of wood bioenergy
