Clean Energy Fuels Corp., a provider of natural gas fuel for transportation and developer of natural gas refueling stations, says it delivered 43.7 million gallons of natural gas during the first quarter, up 23% from the 35.5 million gallons delivered during the first quarter of 2011.

Also, revenue for the first quarter rose to $73.6 million, up from $65.3 million for the first quarter of 2011.

"Significant fuel cost savings and environmental benefits are driving the transition to natural gas fueling," says Andrew J. Littlefair, Clean Energy's president and CEO. "To support this transition, we are diligently working on building out 'America's Natural Gas Highway.' We also continue to monitor the development of new natural gas engines for the heavy-duty trucking market. We believe we are approaching an inflection point when these elements all come together."

The company's calculation of "gallons delivered" includes its compressed natural gas (CNG), liquefied natural gas (LNG) and renewable natural gas (RNG), as well as the gallons associated with providing O&M services to its customers.