Biomass power: when burning trees is 'net zero' emissions

Northeast of Drax, by Paul Glazzard

When wood burns, it releases carbon dioxide, unless it burns inside Drax’s power plants in the UK, apparently. The UK government considers the electricity Drax produces to be renewable and carbon-free and pays them subsidies accordingly. This is not just a legacy subsidy that will expire – the government is making plans to extend Drax’s subsidies after they end in 2027. How did it happen that we are letting forests burn to produce electricity in the UK and calling it a win for the climate?

Drax’s plant used to be a coal power station, but these were phased out by the UK government due to their high intensity of carbon emissions and Drax’s was refitted to become a “biomass” facility that burns wood as fuel instead. At that time, the subsidies might have made sense to support the phase out of coal, as wind and solar were expensive, but that still doesn’t explain why it was and still is acceptable to power our country with an enormous bonfire and slap a renewable, carbon-free sticker on it.

By Drax’s reckoning, though never take a company at face value when they are talking their book, its product is renewable, and the carbon dioxide emitted from its facilities doesn’t count.

When trees are cut down in their actively managed forests, they just plant new ones - in this sense, the fuel is “renewable”, they say. Those trees also absorbed carbon dioxide while they were alive so they believe it is only fair that its release when the tree dies is considered carbon-neutral. And in their power plants, Drax says they mainly burn waste wood, the twigs and branches that are left when trees are cut down trees for timber. Clearing the waste helps to prevent wildfires and the waste would have decomposed anyway, which also releases carbon into the atmosphere. Burning just speeds up that process. If that doesn’t convince you, consider this: they primarily cut the trees down in Canada and the US, then burn them in the UK. By a trick of emissions accounting, there are no emissions in the UK then, right? [1]

Well. Decomposition releases carbon slower than combustion, and managed forests with logging and re-planting typically have lower carbon absorption than just leaving trees alone. It also doesn’t matter where carbon is emitted for it to impact climate change. And, following several BBC investigations, Drax actually does burn timber from forests that is not a waste product.

Nonetheless, the UK government bought in, big. Tax-payers have funded £7 billion of subsidies to Drax in the last ten years to top up its revenues from the energy market. The subsidy payments they received in 2023 contributed £23 to every household’s bill [2], which would make up almost 3% of typical electricity bills as of June 2024 [3]. Yet the government remains steadfast in their commitment to Drax.

This is illustrated in a peculiar parliamentary debate in December 2022, when some Conservative MPs and opposition allies argued that something didn’t seem quite right about burning trees to generate “renewable” power.

“The whole life cycle emissions of carbon dioxide per kilowatt-hour (kWh) are 41 grams for solar, 11 to 12 grams for wind and 948 grams for coal. For forest biomass, they are 1,079 grams…more carbon is being put into our atmosphere currently than when we were burning coal,” began Selaine Saxby.

Sammy Wilson pointed out that “had we used gas, we would have had 50% [lower] carbon emissions.” Sir Roger Gale discussed the carbon cost of shipping, adding “is it not an irony that we are shipping stuff across an ocean into the United Kingdom … when we are trying to control the use of domestic carbon products?”

After the back and forth among Saxby’s supporters, interrupted briefly by a fire alarm test, Graham Stuart, the Energy and Climate Minister, came to the government’s defence and effectively shut down the debate. While most of his speech sounded like it was lifted from a Drax lobbyist’s talking points, parts of his response reveal the reason the government continues this charade, eleven years after Drax’s biomass facilities were commissioned.

He mentions flexibility. Drax’s power plants are dispatchable at any time of the day and are more reliable than wind and solar for providing baseload power and peak demand. While batteries or other electricity storage can help to manage renewable energy variability, this can increase system costs.

He also highlights Drax’s substantial contribution to the UK’s power generation. Drax’s 2.6-gigawatt biomass electricity plant is the largest plant in the UK and represented around 4% of national electricity generation in 2023.

A UK biomass researcher told me that Drax “has the government over a barrel” when renegotiating its expiring subsidies. This substantial portion of dispatchable electricity will be difficult to replace and their operations are not profitable without government support.

Offshore wind is the main renewable generation technology that can compete with the scale of Drax’s facilities, but these projects now take a decade to develop. Even if a facility could be built tomorrow, the grid connections to get this electricity to where people live are backlogged by several years. For the time being, we may be stuck with Drax if we want to avoid electricity blackouts given its significance to the energy system.

Another reason Mr Stuart did not highlight was Drax’s cost and availability relative to gas. While at £0.20/kWh [4], this is higher than renewable generation and historical wholesale prices, the UK and Europe were experiencing an energy crisis due to gas shortages following Russia’s invasion of Ukraine. The average wholesale price was ~£0.20/kWh [5] over 2022 and £0.24/kWh for the month of December, making Drax a more financially attractive and geopolitically secure option than gas at the time.

The UK’s gas crisis has since eased and wholesale electricity prices have reduced to £0.06/kWh on average this year [5]. Drax once again is a significantly over-priced electricity option.

Instead of extending Drax’s subsidies, the British government could use this reprieve to take the environmental and financial costs of Drax’s wood-burning more seriously.

It could instead fund grid upgrades and reduce permitting difficulties that contribute to connection delays for renewable projects. It could also support low-carbon generation innovations and system-wide long-duration energy storage to manage peak demand. Surely by 2027, we can come up with cheaper and cleaner ways to produce power in the UK than a glorified log fire.

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[1] In a quirk of carbon accounting, emissions from burning wood for energy are counted in the country where the tree is cut down, regardless of whether that tree is then exported somewhere else to be burned. Further reading here.

[2] £687 million of subsidy payments in 2023 from Drax’s annual filing (notes 2.2 and 3.3), divided by 29.7 million domestic electricity customers, UK energy smart meter statistics, 2023.

[3] Based on the UK’s Latest price cap of £881 per year for electricity (prices and typical consumption).

[4] Based on £2.5 billion of generation revenue and 12.3 TWh of generation in 2023, again from Drax’s annual filing; these figures include hydroelectric electricity generation, 6.5% of Drax’s production.

[5] Wholesale data is expensive to purchase, Energy Stats (https://energy-stats.uk/) is a helpful free data source.