Plants are not as efficient as you might think in capturing solar energy. Current photovoltaic panels can capture more energy per square meter — quite a bit more in fact — than biomass crops that are being suggested as feedstock for ethanol. This is not a reason to dismiss biomass crops, but with the ever growing competition for land, it should certainly be taken into account when evaluating renewable energy options. Alfred Spormann, a professor in micro-biology at Stanford, explains the conversion process and discusses potential for improvement using genetic engineering.