This time, the goal is mass-transit buses that run on fuel cells and batteries.

Mobile Energy Solutions LLC of Conifer (MES) has finished designs for the hybrid, alternative energy, fuel cell- and battery-operated buses, and awaits federal funding to begin assembling a prototype bus.

The company also is building a new, 13,000-square-foot headquarters and manufacturing facility on 3.25 acres at 16360 Table Mountain Parkway in the Coors Technology Center in Golden.

"We own the tooling," CEO Dale Hill said. "It's our design and it's proprietary to us. We have room on the property to ultimately go to 46,000 square feet and be able to handle 300 to 500 buses a year."

MES is one of a handful of companies nationwide pursuing fuel-cell and battery-operated buses, said Leslie Eudy, senior project leader in the hydrogen technology center at the National Renewable Energy Lab in Golden.

"They're definitely cutting-edge, prototype technology," Eudy said.

Buses using fuel cells and batteries still have obstacles, ranging from the cost -- some being tested in California cost $3 million apiece -- to what is the optimum combination for fuel cells matching the weight and durability of batteries, Eudy said.

Ultimately, research on fuel-cell buses can be carried over into the automobile market, she said.

MES is part of a team of 16 organizations, including Sabre Engineering, which is based in Englewood; the Martin Marietta Composites Division and the Birmingham-Jefferson County Transit Authority. The buses will be tested in Connecticut; Birmingham, Ala.; and Columbia, S.C.