Changes

'''Fuel''' traditionally is a substance that may be burned to produce [[energy]] (heat, light, or power).  In more recent times fuelds can also be [[nuclear]], and these do not require burning to produce energy.  The chief property of fuel is its caloric value - the amount of heat produced by complete combustion of a unit mass of its volume.

'''Fuel''' traditionally is a substance that may be burned to produce [[energy]] (heat, light, or power).  In more recent times fuels can also be [[nuclear]], and these do not require burning to produce energy.  The chief property of fuel is its caloric value - the amount of heat produced by complete combustion of a unit mass of its volume.

Some fuels that have been found and used throughout history include [[wood]], animal and vegetable oil, [[peat]], [[coal]], and dried dung.

Some fuels that have been found and used throughout history include [[wood]], animal and vegetable oil, [[peat]], [[coal]], and dried dung.

Common fuels today are [[petroleum]] and [[natural gas]].

Common fuels today are [[gasoline]], diesel, fuel oil and [[natural gas]], along with [[coal]] and nuclear power.

Many fuels also have a number of incombustibles, such as ash, that could cause air pollution and have unhealthy or even toxic qualities from fuel production.

Many fuels also have a number of incombustibles, such as ash, that could cause air pollution and have unhealthy or even toxic qualities from fuel production.

The New American Desk Encyclopedia, Penguin Group, 1989

The New American Desk Encyclopedia, Penguin Group, 1989

[[Category:Energy]]

[[Category:Energy]]