Burning biomass. Part 1: Unintended consequences

If you were to travel by train from London to Manchester, as I did early last year, you might notice an intriguing sight as you approached your destination: a large freight train painted smartly in blue and silver, displaying the slogans “Powering tomorrow”, “Powering the northern powerhouse”, and “Carrying sustainable biomass for cost effective renewable power”.

If you were curious you might perhaps look up the name of the company displayed on the train, Drax. And you might be pleased to discover what seems to be an all-round good-news story: at the UK’s largest power station, located in Yorkshire, four out of six generation units have been converted from coal to biomass. They burn “compressed wood pellets sourced from sustainably managed working forests […] largely made up of low-grade wood produced as a by-product of the production and processing of higher value wood products, like lumber and furniture.”[1]

Those sleek trains with their specially constructed wagons are transporting 20,000 tonnes of pellets per day from Liverpool and ports on the east coast to the power station near Selby. The pellets, Drax tells us, lead to 80 % less carbon dioxide than coal, produce 12 % of the UK’s renewable energy, and support more than 20,000 jobs.[2] What’s not to like? Waste material is being put to good use, jobs are being created, and the UK is massively reducing its carbon footprint. A dirty fossil fuel – or so it seems ­– has been replaced by a clean, green fuel for the future.

But is this really the win-win solution it appears to be? If we were to follow one of those shiny blue and silver trains to its destination in Yorkshire, and study what actually came out of Drax’s smokestacks, the picture would be less rosy. And if we were to trace the journey of those wood pellets back to their source, an even more sinister story would emerge.

I’ll return to that story, the source of the pellets, in my next post. For now, let’s take a look at those smokestacks. The first crucial fact is that the emissions from burning wood pellets are no less harmful than those generated by burning coal. Biomass produces less of some pollutants, but more of others, most notably small particulates and volatile organic compounds.[3] Drax’s emissions of PM₁₀ particulates, which have extremely negative effects on human health, have risen substantially as it has converted to biomass.[4]

But even if it worsens local air pollution, surely the change from coal to biomass must have a positive impact on the global atmosphere? After all, decarbonization is the main rationale for the switch. Here, once again, the facts contradict the industry’s claims. Biomass-burning power plants emit at least as much CO₂ as coal, if not more. According to one study, biomass emits 150 % of the CO₂ of coal, and is less efficient in terms of CO₂ per megawatt of energy generated.[5] Another study states that “Because combustion and processing efficiencies for wood are less than coal, the immediate impact of substituting wood for coal is an increase in atmospheric CO₂ relative to coal.”[6] The carbon emitted in the production, transport and storage of the wood pellets exacerbates this impact.

These facts are not even especially controversial. So how can Drax justify its claims? Why is woody biomass being promoted as a “low-carbon” source of energy? Part of the answer is that, theoretically, the trees that are felled and turned into wood pellets are replaced by newly planted trees. These growing trees take carbon dioxide out of the atmosphere, supposedly balancing out the carbon released during combustion ­– a highly questionable assumption, given the time that it takes for trees to grow.[7] The other part of the answer is a loophole in the complex carbon accounting system established by the UN. According to these rules, emissions from biomass are only reported in the land-use sector (i.e. the carbon emitted when trees are felled), not in the energy sector (where they are burned). Since the UK gets 82 % of its wood pellets from the US, which is outside this accounting framework, the emissions related to this industry are simply not counted at all.

This has huge implications. As we all know, governments worldwide are under enormous pressure to reduce the carbon footprint of their countries without causing economic damage. The UK has recently committed to cutting greenhouse gas emissions “by the fastest rate of any major economy”, reducing them by at least 68 % (compared to 1990 levels) by 2030. The government boasts that “Over the past decade, the UK has cut carbon emissions by more than any similar developed country and was the first major economy to legislate for net zero emissions by 2050”, thus demonstrating our “leadership in tackling climate change”.[8]

It is no coincidence that the past decade – in which the UK has supposedly cut its emissions so dramatically – is also the decade in which biomass has become a major part of the country’s energy sector. In other words, the fact that emissions from biomass combustion are not counted is enabling us to meet our international climate obligations.

As well as trying to reduce its carbon output as part of the Paris Agreement, the UK is eager to demonstrate its commitment to renewable energy (which is not synonymous with low-carbon energy, though they often coincide). In 2009, the EU adopted a directive stipulating that 20 % of European energy needs had to be met with renewable energy sources by 2020. Since then, massive subsidies have been paid out all over Europe to support this development. In the UK in particular, a substantial proportion of this has gone to biomass. In 2018-19, for example, the UK government spent £1.5 billion to support biomass electricity, nearly three times the subsidy paid out for solar power.[9]

Are these subsidies justified? Is biomass (regardless of its carbon output) a truly renewable source of energy? That depends on how you define “renewable”. The EU directive contains a list rather than an explanation: renewable energy comes from “non-fossil sources”, i.e. “wind, solar, aerothermal, geothermal, hydrothermal and ocean energy, hydropower, biomass, landfill gas, sewage treatment plant gas and biogases”.[10] A report by the UK Parliament’s Select Committee on Energy and Climate Change gives greater clarity, stating that “Energy is renewable if it is derived from natural processes and replenished more rapidly than expended.”[11] Drax offers its own definition: “Renewable energy is produced from a resource that is infinite or can be replenished on a human timescale, such as the sun, wind, water or sustainably managed forests.”[12]

There is a critical difference between the time frames envisaged in these two definitions. A “human timescale” can surely mean whatever one wants it to mean: anything from half an hour to a millennium. If time were not an issue, and if an enormous amount of land were devoted to plantation forest, than perhaps it might eventually be possible to grow enough trees to replace those burned – considering volume alone, not forest quality. There is, however, no way that woody biomass can be replenished more rapidly than it is expended. A tree takes decades to grow, but only seconds to burn.

In short, wood pellets are neither a low-carbon nor a truly renewable energy source. In attempting to reach its internationally agreed targets and demonstrate climate leadership, the UK has invested heavily in a polluting and unsustainable form of power generation. Those smart new trains are taking us to a far less promising future than their optimistic slogans suggest. The question is whether, having set this juggernaut in motion, we have the power to stop it.

Kitmasterbloke on Flickr, https://creativecommons.org/licenses/by/2.0/legalcode

Shirokazan on Flickr,https://creativecommons.org/licenses/by/2.0/legalcode

Click here for the next thrilling instalment ...

 

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[1] https://www.drax.com/sustainability/what-is-biomass/

[2] https://forestscope.info/

[3] https://www.biofuelwatch.org.uk/2018/biomass-basics-2/

[4] https://www.biofuelwatch.org.uk/wp-content/uploads/Drax-and-air-quality-briefing-2.pdf

[5] https://www.pfpi.net/wp-content/uploads/2011/04/PFPI-biomass-carbon-accounting-overview_April.pdf

[6] https://iopscience.iop.org/article/10.1088/1748-9326/aaa512

[7] https://www.chathamhouse.org/2017/02/woody-biomass-power-and-heat

[8] https://www.gov.uk/government/news/uk-sets-ambitious-new-climate-target-ahead-of-un-summit#:~:text=A%20new%20plan%20aims%20for,decade%2C%20compared%20to%201990%20levels.&text=The%20Prime%20Minister%20has%20today,2030%2C%20compared%20to%201990%20levels

[9] https://www.nrdc.org/experts/sasha-stashwick/uk-must-end-biomass-electricity-subsidies-now#:~:text=In%202018%2D19%2C%20the%20UK,clean%20power%20to%20Britons%20today

[10] https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX%3A32009L0028

[11] https://publications.parliament.uk/pa/cm201617/cmselect/cmenergy/173/17305.htm

[12] https://www.drax.com/sustainability/what-is-renewable-energy/