fivemack (fivemack) wrote,
fivemack
fivemack

Hath the world enough woodchips?

The Guardian reported today that there was a plan to convert the Drax 4GW power station to burning biofuel - mostly wood chips - by the end of 2015, assuming the subsidies regime was favourable. I have shares in the company that operates the power station, and I should sell them if, as it appears, the company management has been taken over by purple aliens from beyond the planes of rationality.

Expensive modifications to the turbines have increased the thermal efficiency to 40%, so this is 10GW of thermal power to be obtained from woodchips. Which appears to be (caloric content from here) half a ton of dry woodchips a second: and they'll have to be dry, since wet woodchips would explode impressively in that hot a furnace.

There are ships available capable of carrying 125,000 cubic metres of woodchips (I confess I'm not quite sure why people want to ship wood chips by the fifty Olympic swimming-pools-full; isn't it easier to build the paper or chipboard factory near the forest?); wood chips have a density of about 250kg per cubic metre when packed in ships, so you're talking about one ship that size docking daily.

Swedish short-rotation willow coppice is about nine tons per hectare per year, so you need about fifteen thousand square kilometres of the stuff : half of Belgium. Most reasonably accessible half-Belgiums are not really available to be repurposed for growing flammable trees; Drax refuse on grounds of 'commercial confidence' to say where they're planning to source the wood-chip from, so I would tend to assume it would come from Borneo with an admixture of baby orangutans.
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