Whilst welcoming the actions being taken by some universities to generate their own electricity, may I sound a note of caution about the large scale use of woodchip as an energy source.

Let's be clear, there are supplies of wood that can safely be used as fuel, and burning it in an efficient CHP is better than burning it in a domestic fire, even a closed wood burning stove.

But there are limits, and we ought to be proceeding with caution. The 'sustainable' supplies are obviously not infinite. Plans for very large power stations are being put forward around the UK that will burn millions of tonnes of woodchip. If we exceed the capacity of UK forestry to meet demand, we cause imports or expansion of UK forestry. Imports reduce the carbon savings of using woodchip, expansion of UK forestry competes with food production and if monoculture plantations are involved, impacts negatively on biodiversity.

A quick survey has found that large woodchip power stations are in planning or construction that will provide over 1200MWe capacity. None of them are CHP, so they suffer the same inherent problems of inefficiency through wasted heat as any centralised power station. The expected fuel consumption of just these large power stations is 20-30 million tonnes per annum, that's more than the UK's entire annual wood production.

It's also worth pointing out that as UK electricity consumers we all pay a levy for 'renewable' electricity. That levy finds its way back to the generators in the form of Renewable Obligation Certificates. But not all renewable electricity has the same carbon intensity. Biomass and in particular biofuel electricity have the highest (worst) carbon intensity. Wind, hydro, wave and solar are much lower. If the UK gets a high proportion of its renewable electricity from energy crops, i.e. biomass, then the green levy paid by consumers is buying a smaller carbon reduction than if cleaner technologies like wind had taken a bigger share of the market.

This 'rush to wood' as a power source is stimulated by the levels of subsidy under the Renewable Obligations Order. Burning biomass gets 50% more subsidy than on-shore wind and hydro-electric power, and the same as offshore wind.

I believe UK energy policy should recognise that there should be a limit on the total amount of wood consumed by the energy sector. Otherwise, the generous subsidies currently on offer will lead to massive over-consumption and environmental damage, and our carbon emissions will not reduce as much as they could. Building large woodchip power stations looks like another instance of lock-in which will close the electricity market to truly clean technologies and starve them of public research funding.