James Bound, of Las Vegas' Public Works Department, fills his work vehicle with biodiesel fuel at the Northwest Fleet Operations Center on Monday. Bound uses the blend of diesel and 20 percent soybean oil for driving more than 200 miles a day. Photo by Ronda Churchill.

Known for its green felt and love of green bills, Las Vegas might be getting a new reputation -- home of green vehicles.

Out of the country's 50 largest cities, Las Vegas had the highest percentage of its municipal vehicles running on alternative fuels last year, according to a survey released Monday by a San Francisco-based company.

Las Vegas ran 63 percent of the city vehicles on alternative fuels such as biodiesel, hydrogen and compressed natural gas in 2006, according to the survey by SustainLane. The next-best city was Honolulu, with 51 percent of its vehicles on alternative fuels.

"At least in this area, Las Vegas is a leader. Other cities can learn something from Las Vegas' leadership," said Warren Karlenzig, chief strategy officer of SustainLane, which promotes smart planning in government.

Las Vegas as an environmental progressive bastion? Las Vegas, Nev., and not its namesake in New Mexico?

"We were surprised," Karlenzig said. "But there's a good reason for rankings and surveys -- to overcome perceptions that are not right."

But for city officials, who have been moving toward alternative-fuel vehicles since the early 1990s, the recognition is not such a surprise.

"People are beginning to understand we are a test-bed of innovation down here. It's more than a gambling mecca," said Dan Hyde, the city's fleet services manager.

The city's "fleet" is made up of about 1,500 vehicles, Hyde said.

Of those, 450 operate on a mix of diesel and soybean oil, called B20 biodiesel (20 percent is from soybean oil imported from the Midwest). Compressed natural gas runs 185 city vehicles; 10 use a combination of compressed natural gas and hydrogen. And then there's the one Honda the city leases that runs solely on hydrogen, which has zero emissions.

Other city vehicles use a cleaner, more oxygenated version of gasoline.

Hyde put the number of vehicles using alternative fuels at 87 percent, but he did not explain the discrepancy between his calculation and that of SustainLane.

He also pointed to work by the Community College of Southern Nevada, Clark County School District, and Clark County, which are all part of the Las Vegas Regional Clean Cities Coalition.

Hyde said the advantages for alternative fuel included help in meeting federal guidelines for air quality; reducing the foreign dependence on energy; and becoming a test-bed for new technologies.

"In order to prove a technology is viable, you have to put it under fleet operations in the most strenuous conditions," he said. "If it proves its worth, over a diversified fleet, it can be replicated in the general public."

The city's fleet includes cars, trucks, street sweepers, backhoes and trenchers.

With government incentives, biodiesel is cheaper than normal diesel right now, Hyde said. It also gives a boost in vehicle performance and is easier on engines, he said.

Karlenzig said the alternative fuels, which produce less pollution, would help reduce carbon emissions.

Launce Rake, spokesman for the Progressive Leadership Alliance of Nevada, said, "The fact that the city of Las Vegas ... has embraced alternative fuel vehicles is important to the community."

He said Las Vegas "has a mixed environmental history.

"We have relatively high population densities, which is a good thing. We're kind of perched on the precipice of an environmentally unsustainable community, because of our location in the Mojave desert. That's a bad thing," he said. "We're happy Las Vegas can claim positive feedback on any environmental issue. We'd like to see more of that."