The new engines will have to burn far more cleanly than those now in use.

It burns cleanly and can end the air-pollution problems caused by gasoline fuel.

Compressed natural gas, again due to the fact that it burns cleanly, also comes out well.

They burn much more cleanly than their predecessors and produce electricity in the bargain.

"It burns cleanly, smells pleasant; it's a good thing to start a spell with."

But on the whole, I'd say it's easier to handle than gasoline, and it certainly burns cleanly.

When lit, the wick should burn cleanly all the way up to the highest flame it can make.

It is also much easier to burn cleanly than gasoline.

Most of the growth in demand is coming from power plants that run on natural gas, which burns more cleanly than other fossil fuels.

Natural gas, which burns far more cleanly than coal or oil, has become the Clinton Administration's favorite fuel.