Biofuel can become a credible alternative to fossil fuels only if it can be derived from non-food sources. Most of these “second-generation” technologies are still at lab stage. But there is now increased pressure to quickly move towards full commercial introduction.
The technologies vary. Cellulosic ethanol produced from waste wood or weeds such as switch-grass, by either enzymes or thermo-chemical reactions breaking down the cellulose and turning it into sugar to be converted into ethanol, is perhaps the technology offering the strongest hopes of relatively rapid success in the US. But cost is a problem.
Currently, cellulosic ethanol two or three times more expensive than corn ethanol, which is already struggling to compete with cane ethanol from Brazil.
In Europe, where car-drivers have switched to diesel-fuelled machines, there is more emphasis on biomass-to-liquid (BTL) technologies that produce synthetic biodiesel from wood biomass using the Fisher Tropsch process. Choren, a German company backed by Shell, Volkswagen and Daimler Chrysler, is one of the leaders of this technology. Last week, Choren inaugurated the world’s first commercial BTL plant in Freiberg, Saxony. It may be a year before the plant reaches its full annual capacity of 18 million liters.
Other technologies abound. BP and Dupont have been engaged in a joint venture to develop bio-butanol as an alternative to ethanol.
A genetically modified corn, using an enzyme from the stomach of a cow, has been developed by scientists at Michigan State University. The development should allow the corn to be processed into ethanol without the use of synthetic chemicals.
Researchers from the US National Science Foundation claimed to have achieved the first direct conversion of lignocellulose, a material found in plant stems, from plants into a petrol-like fuel. The process involves the rapid heating of cellulose in the presence of catalysts and then cooling it to create many of the components of petrol, including toluene and naphthalene.
Trials are on of a new method of extracting jatropha oil that produces 20% more than current technologies, says the developer Jatropha Biofuels Technologies. The process, which uses high- pressure gas to extract the oil, can extract up to 30% of the weight of each jatropha seed.
Algae is a feedstock with the greatest theoretical potential. Most research into algae has focused upon converting it into ethanol. However, scientists at the US Department of Energy's Argonne National Laboratory have suggested it could also be converted into hydrogen gas. They are looking at algae which contains an enzyme called hydrogenase, which creates small amounts of hydrogen gas. The aim is to remove the catalyst from the hydrogenase and use it during photosynthesis.
Despite frenetic research, second-generation biofuels may not be able to pick up the slack from crop-based biofuel fast enough. The US Energy Information Administration says second-generation biofuels would fall short of US government expectations. Instead of producing 21bn gallons a year by 2022, it was likely only 17.5bn gallons would be possible, leaving ethanol production overall some 3.5bn gallons a year short of its target.