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.

Flat | Top-Level Comments Only

I'll refer you to the excellent and recently disbanded RCEP, who produced a short report on Biomass as a Renewable Energy Source.

In short, your numbers aren't unrealistic, but the assumption that all the biomass needs to come from abroad doesn't hold. From what I can gather, the UK is heading for a forestry wood glut at the moment, which could support the industry for a while, and in the longer-term could support 20% of agricultural land being used for biomass production.

2.50
Figure 2-I illustrates the anticipated wood production from forests in Britain from 1994 to 2021. Supply is predicted to increase over the next couple of decades, peaking at about 10 million tonnes per year above current demand by 2020.

2.51
We expect that much of the extra 10 million tonnes per year of production by 2020 will be available as biomass fuel for energy, and that the supply will then fall to a level dependent on the competitivity of the UK industry. Long-term supply cannot be predicted but it is likely to be significantly higher than the current availability of 1.3 million tonnes per year.

And later:

4.49 In this scenario for moving towards 16GW from biomass, energy crops would not be needed before 2010. The first two stages of the four-stage approach described by Bauen89 and discussed in chapter 2 (paragraph 2.41) and below would continue until 2017 at which time forestry, straw and energy crops would provide roughly comparable inputs. After 2020, energy crops would become the dominant source.

4.50 Assuming, as before, that 1hectare of land yields 10odt of wood per year, the implied land that would have to be under energy crop cultivation at any time is indicated by Figure 4-IV. The land required for energy crops would rise from 1 million hectares in 2020 to 5.5 million hectares in 2050.

That's an extremely good and interesting report. The main conclusion I draw from it is that it needs policy stability in order to work.

Hath the world enough woodchips?

How much wood would a woodchipper chip?

Re: How much wood would a woodchipper chip?