UK: Biomass energy’s dubious ‘green’ credentials

The UK relies heavily on forest biomass to boost its renewable energy production, but ‘renewable’ doesn’t necessarily mean ‘green’.

On the surface, chopping down trees, turning the wood into pellets and shipping them from the USA to the UK to be burned as fuel doesn’t sound like a great idea. But both the UK and the EU are betting big on so-called ‘forest biomass’ energy. What’s more, both consider it to be a carbon-neutral energy source, meaning that any CO2 emitted is balanced by CO2 captured and stored.

However, many climate experts disagree. ‘Back in 2008, when the European Union developed the first round of its renewable-energy directive, forest biomass was deemed a carbon-neutral method of energy generation, leading governments to rapidly subsidise technologies behind it,’ explains Sami Yassa, senior climate scientist at the USA-based Natural Resources Defence Centre. ‘But they made a mistake. They based their argument on erroneous claims.’

In simple terms, the argument for forest biomass being carbon neutral comes from the notion that ‘forests grow back’. Any emissions resulting from the burning of wood, so the argument goes, will be absorbed by new trees. Under this logic, wood is still considered a ‘zero-emissions fuel’ by climate regulatory bodies, even though burning it can produce more CO2 at the smokestack than burning coal.

Many climate experts say the carbon-neutral claim is flawed, partly because new tree growth doesn’t adequately make up for the emissions produced, and partly because of emissions produced within the supply chain – most steps of which produce CO2. First, trees must be clear-cut. Often, wood pellets for biomass are offshoots from trees cut for other industries, but even so, they often come from old forests, which absorb much more carbon than newly planted trees. If natural forests are converted into fast-growing plantations for biomass, it leads to a large release of carbon at the time of conversion, as well as a lower stock of carbon when trees are harvested. Next, timber must be dried and turned into pellets – an energy-intensive process. Then the pellets must be transported, often from the US southwest to the UK. And finally, any woody debris left on clear-cut sites releases carbon into the atmosphere as it decays.

The UK is the world’s largest importer of wood pellets made through this process and biomass is an important part of the country’s renewable energy targets. However, a recent report by the policy institute Chatham House argues that this is flawed. The report states that taking into account all emissions, including those across the supply chain, US-sourced wood pellets burned in the UK in 2019 were responsible for 13–16 million tonnes of CO2. Almost none of these emissions were included in the UK’s national greenhouse gas inventory; if they were, it would have added between 22 and 27 per cent to the emissions from total UK electricity generation, or 2.8–3.6 per cent of total UK greenhouse gas emissions – equivalent to the annual emissions from six million to seven million passenger vehicles.

Last year, Drax – the UK’s largest biopower company – received more than £800 million in government subsidies and tax breaks to support the conversion of its coal-powered plant to biomass. The company operates the largest power station in the UK and now fuels two-thirds of its output with biomass, 60 per cent of which arrives as processed pellets from hardwood forests in the US southwest. The company is now seeking subsidies from the UK government to scale up a type of biomass energy in which carbon emissions are captured at the smokestack. Known as ‘bioenergy with carbon capture and storage’, its proponents say that this enables the process to go one step further and become ‘carbon negative’. But many scientists deem this to be another erroneous claim. In its current iteration, carbon capture and storage technology doesn’t fully capture carbon emissions, and there’s still the issue of supply-chain emissions.

Earlier in 2021, 500 scientists sent a letter to world leaders warning that logging forests for bioenergy would undermine the fight against climate change. Yassa’s conclusion is resolute: ‘It’s time for policymakers in the UK and the EU to squarely address the emissions from this technology, because right now, they are not being counted.’