Environmental and energy glossary
Acid rain: Precipitation that has become acidic -- that is, has a low pH factor -- caused by the emission of sulfur oxides from fossil-fuel burning power plants.
Alternative fuels: A popular term for "non-conventional" fuels used for transportation and derived from natural gas, such as propane and compressed natural gas, or biomass materials such as methanol or ethanol.
Attic fan: A fan mounted on an exterior wall in an attic wall that transfers warm attic air to the outside.
Attic vent: A passive or mechanical device used to ventilate an attic space, primarily to reduce heat buildup and moisture condensation.
A biofuel made by combining animal fat or
vegetable oil (such as soybean oil or recycled
restaurant grease) with alcohol that can be
directly substituted for diesel as a stand-alone
fuel -- often called B100, for 100 percent
biodiesel. It also can be used as an additive
-- often called B20, for 20 percent bio-diesel.
Biodiesel can generally be used in vehicles
manufactured after 1994.
Biofuels are renewable liquid fuels -- primarily
ethanol and biodiesel -- made from plant matter
rather than fossil fuels. Biofuels can help
reduce air toxics emissions, greenhouse gas
buildup and dependence on imported oil, while
supporting United States agriculture.
A type of renewable fuel that includes trees
and other crops and residues, solid waste,
sewage and liquid fuels derived from agricultural
products. Some of the common energy sources
derived from biomass are landfill gas, anaerobic
digester gas, methane and biofuels including
biodiesel, bio-oil and ethanol.
thermal unit (Btu): The amount of heat
required to raise the temperature of 1 pound
of water 1 degree Fahrenheit. A Btu is equal
to 252 calories.
The term can be expressed two ways. Expressed
as a "small calorie," it means the amount
of heat required to raise the temperature
of 1 gram of water 1 degree Celsius. Expressed
as a "large calorie" or "kilogram-calorie,"
it represents the amount of heat required
to raise 1 kilogram (1,000 grams) of water
1 degree Celsius. When the term is capitalized
it indicates a kilogram-calorie.
A colorless, odorless noncombustible gas present
in the earth's atmosphere. It is designated
with the formula CO2 and is formed by the
combustion of carbon and carbon compounds
(such as fossil fuels and biomass), by respiration
(a slow combustion in animals and plants)
or by the gradual oxidation of organic matter
in the soil.
A colorless, odorless but poisonous combustible
gas with the formula CO. Carbon monoxide is
produced in the incomplete combustion of carbon
and carbon compounds such as fossil fuels
(coal, petroleum) and their products (liquefied
petroleum gas, gasoline) and biomass.