BOULDER, CO - If all goes as planned, nine out of 10 vehicles in the City of Boulder's fleet will run on some type of alternative fuel within a few years, according to Boulder & County News.

Joe Castro, who manages Boulder's fleet, said the city's goal last year was to make sure that 60 percent of new vehicles purchased could use some sort of alternative fuel.

This year, the goal is 90 percent. Given that the fleet's average vehicle age is seven years, that means that within just a few years, the overwhelming majority of the vehicles the city owns will either be hybrids or capable of getting by on biodiesel or ethanol.

Just a couple of years ago, Castro said, finding alternative-fuel versions of some cars was tough. When gas prices hit their peak over the last year, he said, that started to change.

"Now that more manufacturers are providing alternative fuel vehicles, we can cover a lot more of our needs," he said. "Prior to 2009 we had a hard time finding light-duty trucks with alternative fuel options. In 2009, you're seeing a lot more light-duty trucks with E85 ethanol"— that is, gasoline that's 85 percent ethanol.

The city's fleet includes cars and trucks that are hybrids or vehicles that burn ethanol or biodiesel — a version of diesel that's generated from organic sources such as vegetable oil.

Ethanol — much of which comes from corn — has drawn plenty of criticism as a fuel source. Detractors say growing corn or soy for fuel displaces land that could be used to make food. And, they say, it's an inefficient way of producing energy.

Drew Bascue, Boulder's transportation sustainability coordinator, said he's aware of those concerns.

However, he said, the city's analysis of those fuels shows they're still cleaner than the pure-petroleum alternative. And better technologies —such as ethanol made from the more environmentally friendly switchgrass   — promise even better results.

And since the infrastructure for delivering those kinds of fuels already exists, he said, it makes sense for the city to use them.

"We're showing that there's a demand here," he said. "We're showing that there's a business case for a continued growth in the vehicles — and it's an indirect force showing that there's a market for the next-generation biofuels."