While corn gets the headlines, companies are exploring a host of other potential fuel sources including sorghum stubble, citrus peel, timber scraps and even landfill trash.

Experts say it will be years before companies decide if those sources can be commercially viable, but the research is well under way. And some refinery production could be as little as two years away.

Ottawa-based Iogen Corp. has been producing ethanol from wheat, oat and barley straw for several years at its demonstration plant in Canada, and it plans to build a commercial-size version in Shelley, Idaho.

When it comes to things like switchgrass — mentioned prominently by Bush this year and last — success will depend on farmers learning how to grow new crops, said Anna Rath, director of business development for Ceres Inc., a biotechnology company in Thousand Oaks, California.

Crop-breeding technology developed over the past 70 years has increased corn yields more than fivefold, Rath said, and Ceres wants to be on the forefront of developing energy crops.

“The beauty is we now have the benefit of all of these technologies and so hopefully we should be able to make the same kind of improvements, but do it even a little more rapidly than what was done with corn,” she said.

So-called cellulosic ethanol is basically fuel made from plants or plant waste — something other than a corn kernel. Making fuel from this biomass is well-established, but it costs about twice as much as cooking up corn-based fuel, government researchers say.

Earlier this year, the Energy Department awarded US$385 million (euro284 million) to six companies hoping to build the nation’s first big biomass-to-fuel plants. The investment is part of the Bush administration’s goal of making cellulosic ethanol competitive by 2012.

Poet LLC, a privately owned ethanol producer based in South Dakota, has been making ethanol from corn for more than 20 years, but an US$80 million (euro59 million) grant will help the company adapt its Emmetsburg, Iowa, plant to make additional fuel out of corn stalks and fiber.

At Ceres, Rath said officials believe warm-season grasses such as switchgrass and miscanthus — perennials that grow in a variety of climates — will be the biggest contributor to the cellulosic ethanol industry.

The first versions, developed through conventional breeding methods, should be ready to sell to biorefineries by 2009, Rath said. Varieties created through “marker-assisted breeding,” in which scientists examine gene traits in seedlings, could be ready by 2012.