The detractors of renewable energies are painting a broad brush in condeming the growing of renewable energy crops on soils that can produce food. This is to simplistic a picture, the question has to be about efficiency.  The right crop on the right soil type with the right climate to maximise the biomass output per hectare has to be the goal of meeting both the energy and food crisis that the world is facing.

As an example once established Elephant grass in the UK requires only minimal inputs and has the potential to produce 15 to 20 times more energy per hectare than wheat in the form of biomass. If you then convert the biomass to electricity, and use the waste heat from generation to enhance the growth rates of edible crops under controlled environment glasshouse’s then the result in a more efficient use of  each hectare of cropped land in terms of the suns energy captured and utilised.