The Habitable PlanetHabitable Planet home page

Unit 10: Energy Challenges // Glossary

A diesel-equivalent, processed fuel derived from biological sources (such as vegetable oils), that can be used in unmodified diesel-engine vehicles.
British thermal unit (Btu)
A unit of heat. One Btu is the energy required to raise one pound of water by one degree Fahrenheit at a constant pressure of one atmosphere.
A chemical substance consisting of a lattice of one type of molecule trapping and containing a second type of molecule.
A flammable, colorless, slightly toxic chemical compound with a distinctive perfume-like odor. Also known as ethyl alcohol, drinking alcohol, or grain alcohol, in common usage it is often referred to simply as alcohol.
fast breeder
A fast neutron reactor designed to breed fuel by producing more fissile material than it consumes.
Capable of sustaining a chain reaction of nuclear fission.
The rate at which new material is added to or removed from the stock.
fuel cells
An electrochemical energy conversion device that produces electricity from external supplies of fuel (on the anode side) and oxidant (on the cathode side). Fuel cells differ from batteries in that they consume reactant, which must be replenished, while batteries store electrical energy chemically in a closed system.
A process that converts carbonaceous materials, such as coal, petroleum, petroleum coke or biomass, into carbon monoxide and hydrogen.
geothermal gradient
The rate of increase in temperature per unit depth in the Earth.
Compounds formed by the union of water with some other substance.
Chemical compounds containing carbon and hydrogen as the principal elements. Oil is composed primarily of hydrocarbons.
General term designating the water or other fluid entering a system.
methane hydrates
Natural formations consisting of mounds of icelike material on or just below the sea floor containing large amounts of methane trapped within a lattice of icelike crystals.
non-renewable resource
A natural resource such as coal or mineral ores that is not replaceable after its removal.
oil shale
A general term applied to a fine-grained sedimentary rock containing enough organic material (called kerogen) to yield oil and combustible gas upon distillation.
A mineral or an aggregate of minerals from which a valuable constituent, especially a metal, can be profitably mined or extracted.
The rock and dirt that overlie a mineral deposit and that must be removed before the mineral deposit can be extracted by surface mining.
Producing an electric current as the result of light striking a metal; the direct conversion of radiant energy into electrical energy.
renewable resources
Supplies of biological organisms that can be replaced after harvesting by regrowth or reproduction of the removed species, such as seafood or timber.
source rock
A rock rich in organic matter which, if heated sufficiently, will generate oil or gas.
In ecological cycles and models, the amount of a material in a certain medium or reservoir.
tar sands
Sandy deposits containing bitumen, a viscous petroleum-like material that has a high sulfur content.
thermal maturation
A process in which as rock layers press down on buried deposits, geothermal energy heats the peat and reduces its oxygen and hydrogen content, converting it to coal.
uranium enrichment
A process that results in an increase in the amount of the fissionable isotope of uranium in a given mass of uranium. Used mostly for nuclear weapons, naval propulsion, and smaller quantities for research reactors.

top of page


© Annenberg Foundation 2017. All rights reserved. Legal Policy