Sustainable biofuels move a step closer

New enzyme promises to speed delivery of second-generation biofuels made from waste biomass

So-called second-generation biofuels made from woodchips, corn stalks and other forms of waste biomass moved a step closer to commercial viability this week with the launch of the first enzyme for accelerating the creation of cellulosic ethanol.

Unlike conventional biofuels made from feedstocks such as corn and sugar cane, cellulosic ethanol can be made from waste biomass. Advocates of second-generation biofuels say they offer a much-needed alternative to using agricultural land to grow energy crops – a trend that environmentalist argue has led to higher food prices, growing pressure on water supplies and even increased carbon emissions as the result of forests being cleared to make way for energy crops.

The development of such biofuels has long been hampered by difficulties in breaking down the waste biomass for refinery, but biotech giant Genencor announced that it has solved the problem with the launch of the first commercial enzyme product for accelerating the breakdown of complex waste biomass and aiding the development of cellulosic enzyme.

Jack Huttner, vice president for biorefinery business at Genencor, said that the new Accellerase 1000 enzyme overcame one of the major stumbling blocks in the development of second-generation biofuels.

"Breaking down the biomass into fermentable sugars has been a major barrier to the development of second-generation biofuels for 10 years," he explained. " This enzyme is very effective at accelerating that process. It allows refineries to break down waste biomass products like wheat stalks, wood chips, newspapers and corn stalks – non-food raw materials that can be harvested in a more sustainable way."

The commercial availability of the enzyme removes one of the final scientific hurdles to development of second-generation biofuels, according to Huttner, who argued that infrastructure challenges now remain the final barrier to widespread adoption of the technology.

"Now the focus has to be on the engineering solutions," he argued. "The main challenge is integrating the refinery processes, bringing down the costs and delivering the supply chain."

Such a supply chain could see raw materials come from grasses, such as switch grass which requires no fertilizer or irrigation, waste from paper mills or wood chips from forest thinning activities.

Huttner said that once the supply of waste biomass is in place there is likely to be a surge in the development of second-generation biofuel refineries. "We'll see the first large-scale plants within five years and then, depending on the price of oil, I'd expect to see rapid adoption of the technology."

In related news, car giants Daimler and Volkswagen signalled their support for second-generation biofuels with the acquisition of a stake in biofuel company Choren.

The companies said the deal would support Choren's plans to develop biofuel to liquid (BTL) plants with 250m litres of capacity. BTL can be used in current diesel engines and is produced through the gasification of different kinds of organic feedstock or residual wastes that exclude competition with feedstocks.

Dr. Wolfgang Steiger, head of corporate development of drive systems at Volkswagen, said the fuel boasted significantly improved environmental credentials compared with conventional biofuels. "Compared with first-generation biofuels, [it] has a three times higher yield per unit area, it does not compete with food crops and enables up to 90 per cent reduction in green house gas emissions," he said.