The government’s expected to publish a biomass strategy in the next few weeks. Delayed since its planned publication in late 2022, it is likely to have evolved after revelations about Drax’s unsustainable supply chains were exposed by the BBC’s Panorama programme.
This strategy is desperately needed. Many sectors already use organic materials – also known as biomass – like wood, straw and organic wastes in different forms, as a source of heat or power, as a building material or as an ingredient for making chemicals. Many sectors need to replace fossil fuels, and most expect to increase the use of biomass as a result.
Some sectors, like aviation, shipping, power and chemicals, could each, by themselves, swallow up most of the sustainable supplies of biomass. But they can’t all rely on unlimited access to this scarce resource.
There isn’t infinite biomass for net zero
Material Economics thinks existing European forests and waste biomass supplies could squeeze out an additional 15 per cent on top of current supplies, at most. It notes that increasing global pressures on land use will make importing greater quantities of sustainable biomass difficult.
An expanded need for biomass also competes directly with other land uses. Even if consumption of meat and dairy falls significantly to free up more land (and progress on this front is slow), greater demand for nature restoration and carbon storage in future will also require more space.
Swapping fossil fuels for biomass doesn’t necessarily solve the climate problem. On the one hand, carbon stored in biomass is not the same as that locked up in in fossil fuels, as it originated from the atmosphere and is, therefore, part of the fast carbon cycle. But cutting down forests where carbon has built up slowly over centuries, or degrading soils and therefore releasing more emissions, both result in an increase in atmospheric carbon. In some cases, it takes decades for this to be absorbed and built up again in natural environments.
All of this means we have to be careful when deciding how and where biomass is produced, how it can best be used to replace fossil fuels, and what incentives will ensure those routes are taken. We must also be aware of unacceptable uses of biomass where other more benign options to decarbonise should be pursued instead.
Not all biomass is equal
There are multiple ways to produce biomass resources. For instance, timber and sawn wood could be harvested from plantations, mixed woodlands or old growth forests, with very different carbon and biodiversity impacts from each. It’s unlikely that logging old growth forests will ever be considered sustainable. But timber and sawn wood are needed for long lived uses such as in buildings and furniture, which are considered the most sustainable means of locking up carbon for a long time.
Managing and harvesting wood from forests also produces residues, which can be turned into pellets for paper and pulp manufacturing, or used to generate energy, such as at the Drax power station, or in domestic, commercial or industrial heating. Residues include smaller branches, bark, thinnings, tree tops, diseased wood or sawdust. Not all of this should be extracted, some needs to be left in the forest to maintain soil health.
Biomass can also come from agricultural waste, including straw and corn husks, though again these also have an important role to play in maintaining soil health, so the quantity available for other uses is limited. Livestock manure and tallow from livestock carcasses are other sources. Biomass can also come from other organic wastes, like sewage sludge, used cooking oil and municipal wastes. These waste sources tend to be used for producing biofuels or feedstocks for chemical production.
Dedicated energy crops, such as miscanthus, wheat, corn and sugarcane, are often used to make biofuels for road transport, and they are increasingly being considered for aviation fuel. These are the most notable direct competitors to other land uses. Many argue they shouldn’t be promoted at all.
Cultivated algae and seaweed are also discussed as a potential source, without the associated demands on land. But those supplies are small, costs are high and their wider environmental impacts are less well known.
Best uses should be carefully assessed
The government needs to set out clear rules and appropriate enforcement, outlining how the different uses of these organic resources should be balanced and prioritised. Several organisations and individuals are looking at the safeguards needed to ensure sustainable biomass production, including the Climate Change Committee, consultants 3Keel and academics at the Supergen Bioenergy Hub. The government should consider several criteria in its strategic assessment.
Top of this list is thinking about the potential to abate emissions, ie how much carbon (or other greenhouse gas) can be saved using any type of biomass. The assessment should cover the full lifecycle emissions of the whole biomass supply chain, compared to the fossil fuel it replaces, and the time it takes for biomass to regrow and recapture carbon, known as the ‘carbon payback period’.
The government also needs to ask whether the wider supply chains for each type of biomass are truly sustainable, with zero or minimal impacts on nature, biodiversity, food production or other constraints taken into account. It should look at the scale of demand, and how this can be reduced, particularly if it might involve increased use of artificial fertiliser.
In the strategy, it must consider if there are other technologies that can provide the same source of carbon or energy, now or in the future, with lower costs or less impacts. And ask whether each biomass use could be combined with carbon capture and storage to facilitate net removal of carbon from the atmosphere. Again, the carbon payback period may affect this.
Finally, in considering the wider impacts and alternatives, the government should always question whether, even though it might be the cheapest route, using biomass to bring down emissions is the most sensible option for a sector. In this respect, the cost comparisons should account for all the externalities, including damage to nature and landscapes, and the impact on other sectors if they aren’t then able to use biomass as a result.
Green Alliance will be doing more work on this later this year, as well as looking at the allocation of other scarce resources necessary for the net zero transition, such as considering which are the best suited to help decarbonise different sectors.
To discuss this work please contact lhardy@green-alliance.org.uk
