Beyond gasoline conservation measures, U.S. President George Bush has called for diversifying America's energy supply through increases in alternative fuel production.

But experts warn the country is not capable of delivering in the quantities requested, at least today.

And some in the industry worry what effect the continued decrease in oil prices will have on new high-profile renewable energy efforts.

In his annual State of the Union speech, President Bush said, "it is in our vital interest to diversify America's energy supply, and the way forward is through technology." In addition to calling for fuel conservation, the President requested a dramatic increase in the amount of ethanol and other alternative fuels produced, setting a target of 35 billion gallons in 2017.

Many in the industry were quick to note that current technology is not able to meet the President's targets, and delivering would require advanced technologies not yet available.

"Producing 35 billion gallons of ethanol a year would require putting an additional 129,000 square miles of farmland - an area the size of Kansas and Iowa - into corn production, which is not very likely," said Philip E. Clapp, president of the National Environmental Trust. Clapp's comments echo recent concerns from environmentalist Lester R. Brown (see Cleantech.com's Corn ethanol crisis looming, says watchdog.)

Many believe the emerging technology of cellulosic ethanol, derived from the fermentation of waste or other organic matter, could be the answer to meeting at least part of the President's targets.

David Friedman, research director of the Union of Concerned Scientists, said his group has calculated that the country could possibly produce 18 billion gallons of conventional ethanol by 2017.

"If 18 billion gallons came from corn ethanol, then the remaining 17 billion gallons must come from cellulosic ethanol or other renewable fuels by 2017."

Yet the industry is a long way from cellulosic ethanol production in commercial volumes, cautioned a trade analyst.

"Certainly when you start to look at the new [bio-engineered] crops and think about cellulosic, and perhaps non-ethanol like biobutanol technologies, it's possible," Ron Pernick of industry analyst firm Clean Edge told Cleantech.com.

"From our analysis, looking and talking with people in the field, we're probably a good five years away. There's a lot of money going into biofuels. Perhaps we'll see an unexpected technology breakthrough that people haven't considered. I think we can get there with certain technologies, but it does take time."

Technology and timing risks aside, others were concerned that history might repeat itself if falling oil prices counteracted the current emphasis on renewables.

"In the 1970s, Jimmy Carter proposed creating a giant alternative fuels industry, too. Three years later, oil prices fell and the whole thing went bust," noted Philip E. Clapp, president of the National Environmental Trust.

Stewart Sonnenfeldt, VP of corporate development for Practical Instruments, a solar concentration vendor, was also concerned that falling oil prices could undermine interest in renewable energy.

"The biggest threat to this industry is oil going down to $40 a barrel. The stuff that motivates people is what's visible. If the price of oil comes down and stays down, you'll see a lot of the momentum come off of this," he told Cleantech.com.

Venture capitalist Ray Lane of Kleiner Perkins Caufield & Byers, addressing an investor conference in Palm Springs just before the President's State of the Union speech, acknowledged "suppliers do have control over short term prices in oil," but said he didn't think any effort by OPEC to thwart the renewable energy industry could last.

"In the late 70s and early 80s, we didn’t have China and India coming online. I don’t think China is going to slow its economy down."

Concerns about execution aside, some industry watchers applauded the new solidarity shown by American lawmakers.

"We saw a shift from a country that was divided in its views on energy and the environment to this past year when both sides of the aisle came together and unified in a green approach for the country. This is a unique point in history," noted cleantech investor Ira Ehrenpreis, general partner of Technology Partners.

"This is no longer an issue about a tradeoff between the environment and the economy. I think both sides recognize that we're unified in our view that pushing innovation in cleantech helps both the economy and the environment," he told Cleantech.com.