Washington, April 13 : Scientists have developed a new method that can rapidly produce low-cost biofuels from wood and grass.
Known as catalytic fast pyrolysis, the method has been developed by George Huber of the University of Massachusetts Amherst in the US.
By turning plant biomass such as wood and grasses into "green gasoline" using one simple step, the process would be much less expensive than conventional gasoline or ethanol made from corn.
Huber's method is for making biofuels from cellulose, the non-edible portion of plant biomass and a major component of grasses and wood.
At 10 to 30 dollars per barrel of oil energy equivalent, cellulosic biomass is significantly cheaper than crude oil.
But, ethanol production from cellulosic biomass currently involves multiple steps, including pretreatment, enzymatic or acid hydrolysis, fermentation, and distillation. Other processes for making biofuels have been hamstrung by similar multi-step methods. ow, Huber has come up with a technique for producing his "green gasoline" from biomass in one simple step by placing solid biomass feedstocks such as wood in a reactor, which is basically a high-tech still for thermal conversion of feedstock to gasoline.
He heats the feedstock by a technique known as catalytic fast pyrolysis, which means the rapid heating of the biomass to between 400 and 600 degrees centigrade, followed by quick cooling.
By adding zeolite catalysts to this process, gasoline range hydrocarbons can be directly produced from cellulose within sixty seconds.
According to Huber, this is a big improvement because it's all done in one single step, instead of several stages.
"Also, because of the high temperatures we use in the process, the residence time in our reactor is two to 60 seconds," he said.
"With cellulosic ethanol, your residence time is five to ten days, which means you have to have a huge reactor costing much more money. So we estimate that building a facility to use our process would be much less expensive," Huber added.
Using the current cost of wood in Massachusetts, which is 40 dollars per dry ton, as an example of the feedstock he can use in this process, Huber estimates that a gallon of green gasoline can be produced with his method for between 1 and 1.70 dollars.
"We've proven this method on a small scale in the lab," said Huber. "But we need to make further improvements and prove it on a large scale before it's going to be economically viable," he added.