Tom Womack

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.