Roaring Fork currently has four Gillig CNG buses with tank assemblies from Agility Fuel Systems, using Type III cylinders from Worthington-SCI, with delivery of the remaining 18 set to occur in July.

A new facility is scheduled to begin operations this spring, and the agency just received its first 30 Gillig CNG buses in February.

Today, the maturation of alternative fuels has made it easier for transit agencies to implement programs than it was for early adopters in the 1990s. Even still, there are many lessons to learn from the early pioneers, including being aware of possible infrastructure and training investments.

Elkhart, Ind.-based TMC Group Inc. has added the Delray Beach, Fla.-based Stallion Bus Industries' 30-passenger Pony and 40-passenger Stallion buses to its product offerings, company officials reported.

Roughly 14 percent of transit buses currently on the road run on natural gas. Demand is growing, according to industry experts, with natural gas engines specified for about 25 percent of all new bus orders.

Several projects are in the planning stages, many of them on the West Coast. Although funding is once again a common hurdle, with financial support hinging on tight application deadlines, transit agencies are pushing ahead.