The first trickle of fuels made from agricultural waste is finally winding its way into the nation’s energy supply, after years of broken promises and hype promoting a next-generation fuel source cleaner than oil.

But as refineries churn out this so-called cellulosic fuel, it has become clear, even to the industry’s allies, that the benefits remain, as ever, years away.

The failure so far of cellulosic fuel is central to the debate over corn-based ethanol, a centerpiece of America’s green-energy strategy. Ethanol from corn has proven far more damaging to the environment than the government predicted, and cellulosic fuel hasn’t emerged as a replacement.

“A lot of people were willing to go with corn ethanol because it’s a bridge product,” said Silvia Secchi, an agricultural economist at Southern Illinois University.

But until significant cellulosic fuel materializes, she said, “It’s a bridge to nowhere.”

Cellulosics were the linchpin of part of a landmark 2007 energy law that required oil companies to blend billions of gallons of biofuel into America’s gasoline supply. The quota was to be met first by corn ethanol and then, in later years, by more fuels made with non-food sources.

It hasn’t worked out.

via Fuel Fix » Next generation of biofuels is still years away.