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Matt Ridley is the author of provocative books on evolution, genetics and society. His books have sold over a million copies, been translated into thirty languages, and have won several awards.

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The biomess

Making electricity from burning wood is bad for the economy and the environment

My column in the Times on 20 June 2013:

 

In the Energy Bill going through Parliament there is allowance for generous subsidy for a huge push towards burning wood to produce electricity. It’s already happening. Drax power station in Yorkshire has converted one of its boilers to burn wood pellets instead of coal; soon three of its six boilers will be doing this and the power station will then be receiving north of half a billion pounds a year in subsidy. By 2020, the Government estimates, up to 11 per cent of our generating capacity will be from burning wood.

This is a really bad idea. It will cost a fortune, worsen air pollution, exacerbate dependency on foreign energy and increase greenhouse gas emissions compared with burning gas and maybe even with burning coal. All these are in direct contradiction of the Energy Bill’s ostensible purpose. Yet “biomass” is trumpeted as a key part of the Government’s strategy to keep the lights on and combat climate change.

It is also a retrograde step, taking us back towards the days when we relied on plant growth for most of our energy. According to Tony Wrigley’s recent book, Energy and the English Industrial Revolution, firewood provided a third of Britain’s energy under Elizabeth I, more than draught animals, human muscle-power, wind, water or coal. By the time of Queen Victoria, firewood’s contribution had fallen to 0.1 per cent.

This astonishing change was key to the industrial revolution. To sustain an industrial economy requires far more energy than can be obtained from even the fastest-growing trees, crops or from horses. Britain would have stagnated in the early 1800s if it had not tapped almost inexhaustible supplies of coal to replace the need to fell trees and grow oats for horses. By 1850 England was each year burning coal equivalent in energy terms to the maximum output of a forest one and a half times the country’s land area. Thanks to coal, that deforestation could begin to be reversed. By 2000, Britain’s forest cover had trebled since its low point in 1900.

Under the Government’s plan, biomass power stations will soon be burning much more wood than the country can possibly produce. There is a comforting myth out there that biomass imports are mainly waste that would otherwise decompose: peanut husks, olive pips, bark trimmings and the like. Actually, the bulk of the imports are already and will continue to be of wood pellets.

It is instructive to trace these back to their origin. Reporters for The Wall Street Journal recently found that the two pelleting plants established in the southern US specifically to supply Drax are not just taking waste or logs from thinned forest, but also taking logs from cleared forest, including swamp woodlands in North Carolina cleared by “shovel-logging” with giant bulldozers (running on diesel). Local environmentalists are up in arms.

The logs are taken to the pelleting plants where they are dried, chopped and pelleted, in an industrial process that emits lots of carbon dioxide and pollutants. They are then trucked (more diesel) to ports, loaded on ships (diesel again), offloaded at the Humber on to (yet more diesel) trains, 40 of which arrive at Drax each day.

Yet until recently the Government was in denial about all this diesel. “No net emissions during production are assumed,” it said in its 2007 Biomass Strategy. More recently, it has admitted that the energy costs of transporting biomass can be up to “46 per cent of the energy generated by combustion at the power station” if shipped from afar.

Storing the pellets is not easy. If too dry, they spontaneously burst into flames, as happened at Tilbury last year. The Health and Safety Executive warns that stored wood pellets also produce carbon monoxide, which can suffocate in a confined space.

Burn the pellets and you produce smoke. The Committee on the Medical Effects of Air Pollutants says airborne particulates kill more people than road traffic accidents. It is no accident that the Renewable Heat Incentive, designed to subsidise us replacing gas boilers with wood burners for central heating, is not available in cities because it could break air-quality limits. To put it more bluntly, your Government has decided that there is not enough pollution in the countryside.

Moreover, soot — or “black carbon” as scientists now call it — has recently been shown to have a much bigger impact on climate than previously thought. “Global atmospheric absorption attributable to black carbon is too low in many models and should be increased by a factor of almost 3,” reads the key paper published this month. Because burning gas does not produce soot, this is another black mark against wood.

As for carbon dioxide, clear-felling a forest is like raiding the carbon bank. Wood is the most carbon-rich fuel of all — more so than coal and much more so than oil or gas. The biomass industry and the Government respond that trees regrow, so reabsorbing from the atmosphere the CO2 emitted when they were burnt. The Government’s 2012 UK Bioenergy Strategy says that wood burning “results in lower total GHG [greenhouse gas] emissions than leaving the wood unharvested”.

But it only achieves this result by measuring the effect over 100 years. That’s how long it takes on average for the forest to regrow. And this assumes that you do not then cut it down again, or you are back to square one.

Over 20 or 40 years, study after study shows that wood burning is far worse than gas, and worse even than coal, in terms of its greenhouse gas emissions. The effect on forest soil, especially if it is peaty, only exacerbates the disparity. The peat dries out and oxidises.

Yet the Government persists in regarding biomass burning as zero-carbon and therefore deserving of subsidy. It does so by the Orwellian feat of defining sustainability as a 60 per cent reduction in emissions from fossil fuels. As Calor Gas puts it: “This is a logical somersault too far, conveniently — for the sake of cherry-picking the technology — equating 40 per cent to 0 per cent.” (Calor Gas supplies rural gas and is understandably miffed at being punitively treated while a higher- carbon rival industry is subsidised. See here, here and here) Moreover, unlike gas or coal, you are pinching nature’s lunch when you cut down trees. Unfelled, the trees would feed beetles, woodpeckers, fungi and all sorts of other wildlife when they died, let alone when they lived. Nothing eats coal.

So, compared with gas, the biomass dash is bad for the climate, bad for energy security and dependence on imports, bad for human health, bad for wildlife and very bad for the economy. Apart from that, what’s not to like?

 

Postscript: For those who objected to my comment that wood produces more carbon dioxide than coal, please see the following short note from the Partnership for Policy Integrity (http://www.pfpi.net/carbon-emissions):

 

"Burning biomass emits more CO2 than fossil fuels per megawatt energy generated:

1. Wood inherently emits more carbon per Btu than other fuels

2.  Wood is often wet and dirty, which degrades heating value Typical moisture content of wood is 45 – 50%, which means its btu content per pound is about half that of bone dry wood. Before “useful” energy can be derived from burning wood, some of the wood’s btu’s are required to evaporate all that water.

3.  Biomass boilers operate less efficiently than fossil fuel boilers (data from air plant permit reviews and the Energy Information Administration)

  • Utility-scale biomass boiler: 24%
  • Average efficiency US coal fleet: 33%
  • Average gas plant: 43%"