That's the bottom line because, if it was really beyond petroleum, it would be offering some new and different fuel.

So volume is not really a fully accurate way to represent fuel efficiency between two different fuels.

This allows a reasonable comparison between vehicles using different fuels.

A calculator for comparing the costs of different fuels is on the institute's Web site, www.pelletheat.org.

A frequently used and cost-efficient method is to convert a plant to run on a different fuel.

The rules allow for a variety of different fuels in a bid to encourage more efficient cars.

Information about converting a vehicle or engine to run on a different fuel than the one it was originally designed for.

He did many experiments with different fuels and cases.

He said experts continue to debate the merits of the different fuels.

Emission intensities may also be used to compare the environmental impact of different fuels or activities.