DETROIT - General Motors is looking at how it can use natural gas as 'an enticing alternative' to gasoline.

'In the near term, we can use compressed natural gas in internal-combustion engines,' said Larry Burns, GM vice president of research and development in a July 31 posting on the GM FastLane blog. 'Midterm, we can leverage natural gas to create electricity for the Volt and future variants. In the long term, natural gas could be an excellent source for making hydrogen for fuel cell vehicles, either at the filling station or in people's homes.'

Burns was careful not to lay out a specific timetable for rolling out natural-gas vehicles in the U.S.

'While we are not ready to commit to a future production plan, we are taking a serious look at natural gas in the U.S. as yet another way to diversify our portfolio of affordable and sustainable transportation energy solutions,' Burns said.

One intriguing idea he brought up is to offer flex-fuel vehicles that could be powered by either natural gas or gasoline. 'Just as owners of our flex-fuel ethanol/gasoline vehicles have two fuel choices, purchasers of natural gas/gasoline vehicles could also buy either fuel.'

But Burns stopped short of saying which GM vehicles would be most appropriate for such a setup.

He also warned that the infrastructure needs to be upgraded to accommodate such vehicles. 'If natural gas is to make a measurable impact, many vehicles need to use it, and it must be readily available,' Burns said. 'Collaboration with the energy industry and governments is key. Governments will likely need to provide incentives to encourage early adoption of the technology and to jump-start the fueling infrastructure.'