It was the first power plant in the world to employ oil shale as its primary fuel.

Gas is also the primary fuel we use to heat our homes, and will remain so until well into the 2020s.

U-235 is the world's primary nuclear fuel and is usually used in light water reactors.

America's primary fuel is hydrogen, with oxygen to bum it.

Coal is the primary fuel used in this unit, but oil can also be used.

Propane is the primary fuel for hot air balloons.

As a byproduct, it will also make one of the primary fuels for atom bombs.

The chain of power generated from a primary fuel like natural gas can be followed.

Secondly, balanced use must be made of different kinds of primary fuel.

Studies show that where coal is a primary fuel, high levels of urban pollution may result.