Many companies have announced plans to build plants that would take in material like wood chips, garbage or crop waste and so on.
Virtually any material containing hydrogen, carbon and oxygen could potentially be turned into motor fuel. That includes plastics, construction debris, forest and lawn trimmings, wood chips, wheat straw and many other types of agricultural waste.
In Montreal, for instance, Enerkem, plans to use arsenic-contaminated utility poles from the provincial electric company.
About 28 small plants are in advanced planning, under construction or, in a handful of cases, already up and running in test mode, says Matthew L Wald, writing in New York Times.
On Wednesday, the Los Angeles County Regional Planning Commission approved a plan by BlueFire Ethanol to build a $30 Lancaster, California; construction will start soon, the company said.
A bigger operation, Iogen, has been running a demonstration plant in Ottawa since 2004 that can turn wheat straw into ethanol. It was expected to build a plant in Idaho but has suspended work to focus attention on a plant in Saskatchewan. "It would be our view that there are substantial challenges in scaling up a big new biochemical process," said Brian Foody, the president.
Still potential controls on global warming gases would heighten the appeal of these fuels, since many of them would add little new carbon dioxide to the atmosphere.
The Energy Department early last year picked six projects as most likely to succeed, and offered each of them tens of millions of dollars. Iogen's Idaho project was among them; so was a plant in Kansas proposed by a Florida company, Alico, that has also been abandoned.
It is not as if only the small companies, counting on billions in taxpayer subsidies, are trying their hand in the non-conventional sector.
Biggies too are exploring such option. General Motors has invested an undisclosed sum in two companies to turn crop wastes into ethanol.
DuPont, one of the world's largest chemical companies, has joined forces with a company called Genencor, announcing plans to commercialize a process for making ethanol from the non-edible parts of corn and sugar cane. They plan to invest $140 million over three years.
In making their announcement, the companies estimated the worldwide market for fuels made by methods like theirs would eventually reach $75 billion, dwarfing the scale of today's bio-fuels produced from food crops like corn and sugar cane.
The dream of making fuel from plants is almost as old as the internal combustion engine. Henry Ford himself was fascinated by the idea, and it re-emerges in periods of fuel scarcity and high prices. These days, advancing technology has made the notion more plausible.
Big technological hurdles do remain though. Even if they can be solved, no one is sure what unintended consequences will emerge or what it will really cost to produce this type of fuel.
Still it is going to be a vigorous effort from now on.