It is argued: (i) that the harvesting of terrestrial solar radiation to perform useful work is at least an order of magnitude more efficient when carried out by solar-thermal or solar-photovoltaic processes than when carried out by way of biomass conversion and (ii) that, therefore, biomass energy is unlikely to compete successfully with inanimately harvested solar energy except of course in restricted niche applications. (C) 2009 Elsevier Ltd. All rights reserved.