Eleven leading scientists including Jon Foley (2000) have identified five sources of renewable biofuels that can meet substantial energy needs without threatening food production or causing land to be cleared for cultivation. Their study, published in Science, addresses two major concerns that have colored recent debates about the sustainability of biofuels.
Emmett Duffy (2006) is co-leading an initiative to develop algae-based biofuel; the effort aims to create energy from renewable resources while attacking pollution. 
Long seen as a means to reduce carbon dioxide emissions from transportation, biofuels may be less "green" than anticipated if put to greater use, according to Bob Howarth (2000) and Alan Townsend (2001). Their work was featured in the