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Dictionary of Energy

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bubble tower

by a decline or collapse; e.g., the U.S. stock market bubble of the late 1990s fueled by “dot.com” offerings. [So called because such an economic boom is bound to come to an end because of fundamental problems, like a bubble bursting.] 2. Environment. an option in the Kyoto Protocol that allows a group of countries to meet their targets jointly by aggregating their total emissions. The member states of the European Union currently utilize this option.

bubble tower Oil & Gas. a distillation tower in which the rising vapors pass through layers of condensate, bubbling under caps on a series of plates.

bubbling fluidized bed see FLUIDIZED BED


bucket Hydropower. one of a set of blades, scoops, or containers employed in a water wheel or water turbine to capture the force of flowing water so that it can be employed to generate power.

bucket thermometer Measurement. a watertemperature thermometer whose bulb is surrounded by an insulated container, used to measure ocean temperatures.

bucket-wheel excavator Mining. a poweroperated shovel consisting of a series of buckets attached to a wheel, which allows for continuous digging; the buckets scoop up material, then empty it onto a conveyor.

buckwheat coal see COAL SIZING.

bucky ball or buckyball Materials. a large molecule of 60 carbon atoms resembling a soccer ball; an extremely durable material that is the third known form of pure carbon (in addition to graphite and diamonds). [So called in tribute to Buckminster “Bucky”


budget 1. see CARBON BUDGET. 2. see ENERGY BUDGET.

buffalo Biological Energetics. a general name for several species of oxen in the family Bovidae, including the water buffalo (Bubalus bubalis, B. carabenesis) which has been used as a draft animal since ancient times.

buffer factor Climate Change. the ratio of the instantaneous fractional change in the partial pressure of CO2 exerted by seawater to the fractional change in total CO2 dissolved in the


bulk power

ocean waters. Used to study the relative distribution of CO2 between the atmosphere and the ocean, and to measure the amount of CO2 that can be dissolved in the mixed surface layer. Also called Revelle factor because of its description by the noted U.S. oceanographer


Buffon, Comte de 1707–1788, French scientist and author whose views influenced future naturalists, such as Jean-Baptiste, Lamarck and Charles Darwin. In his monumental Historie Naturelle, a 44-volume encyclopedia, Buffon described everything then known about the natural world.

bug dust Coal. a term for fine particles of coal or other material left over from a boring or cutting operation; e.g., cutting the coal face by drill or machine.

building-associated symptoms another


building code see CODE.

building envelope HVAC. a collective term for all the components of a building that enclose its conditioned space and separate conditioned spaces from unconditioned spaces (e.g., an unheated garage) or from outside air.

building-integrated Photovoltaic. describing the design and integration of photovoltaics into a building envelope, typically in place of conventional building materials.

building-related illness (BRI) Health & Safety. a specific disease that has identifiable symptoms and whose cause can be directly attributed to toxic agents within a given building; may be an infectious disease such as Legionnaires’ disease, an allergic condition such as asthma, or a toxic condition such as carbon monoxide or asbestos poisoning. See


bulb turbine Conversion. a type of water turbine in which the entire generator is mounted inside the water passageway as an integral unit with the turbine.

bulk boat History. a wooden barge used for bulk transportation of oil in the early period of the U.S. oil industry.

bulk power Electricity. the actual power and the infrastructure (generating plants, transmission lines, interconnections with

bulk terminal



neighboring systems, and associated equipment) producing power that is made available for sale on the wholesale power market or directly to retail customers. Similarly, bulk system, bulk market, and so on.

bulk terminal Oil & Gas. a facility that receives petroleum products by tanker, barge, or pipeline, and stores them for eventual shipment to refineries or other marketing outlets. Also, bulk station.

bullet train Transportation. 1. a name for Japan’s Shinkansen train, the world’s first high-speed railway system (1964). 2. any such high-speed train.

bundling Economics. 1. a process or policy in which multiple products or services (e.g., gas, electricity) are combined into a single package that is sold at a set package price. 2. a process in which all electricity generation, transmission, and distribution services provided by one entity for a single charge. Thus, bundled rate, charge, service, and so on.

bunker Storage. a tank or other container used to store fuel for later use in a furnace or engine, especially such a storage unit on a ship. Thus, bunkering. [Originally a term for a receptacle used to hold coal on a steamfired ship.]

bunker coal Coal. coal consumed by ocean steamers, tugboats, ferries, or other steam watercraft; so called because stored in bunkers before use.

bunker fuel Oil & Gas. a term for marine fuel, especially for international shipping.

Bunsen burner Consumption & Efficiency. a gas burner having an adjustable air inlet that allows the heat of the flame to be modified; widely used in laboratories. [Developed by German chemist Robert Wilhelm Bunsen, 1811–1899.]

burden Environment. a term for the total mass of a gaseous substance of concern in the atmosphere.

Bureau of Land Management an agency within the U.S. Dept. of the Interior that administers more than 260 million surface acres of federal and Indian lands, located primarily in 12 Western states.

burnable poison Nuclear. a nuclide of large neutron absorption cross section, such as boron, that is incorporated into a nuclear reactor’s fuel, to compensate for loss of reactivity as fuel is consumed and fission-product poisons accumulate.

burner Consumption & Efficiency. any device used for the final conveyance of a combustible gas, or a mixture of gas and air, to the combustion zone.

burner reactor Nuclear. a nuclear reactor with little or no fertile material; thus there is no conversion of fertile material into fissile material.

burnertip Consumption & Efficiency. a term for the ultimate point at which natural gas is used by a consumer; e.g., a furnace, cooking device, or engine. Thus, burnertip price.

burning mirror History. a legendary ancient weapon using solar energy, described as a giant parabolic mirror of polished metal combined with a large series of smaller mirrors to generate a powerful beam of heat; supposedly invented by Archimedes and used to defend the harbor of Syracuse against a Roman siege by setting fire to the Roman ships from shore.

burning speed Chemistry. the speed at which an area of burning gas travels through a combustible gas mixture toward the unburnt gas. Also, flame velocity. Distinct from flame speed, which is the sum of the burning speed and displacement velocity of the unburned gas mixture.

burning spring History. a historic term for a natural gas vent in the earth, which could be ignited by a flame or by lightning.

burnout Nuclear. in a water-cooled reactor, a term for a rupture in fuel cladding, with a release of fission products into the coolant, caused by localized heat buildup.

burnup Nuclear. a measure of the consumption of nuclear fuel in a reactor, usually expressed as the ratio of the fissile material consumed to that originally present.

Burqan (Al Burqan) Oil & Gas. an important oil field in southern Kuwait, the site of one of the first major discoveries in this region (1938); hundreds of wells here were destroyed or set afire by Iraqi forces during the Gulf War in 1991.


burst see SOLAR BURST.

Burton, William 1865–1954, U.S. chemist and oil industry executive who developed a thermal cracking process that doubled the yield of gasoline from crude petroleum. This evolved into the first commercially successful process for cracking crude oil into gasoline and other products.

bus Transportation. 1. short for omnibus; a large, elongated motor vehicle that is fitted with seats and used as a public conveyance. 2. Electricity. a noninsulated conductor used to carry a large current or to make a common connection between several circuits. 3. Communications. a high-speed structure in a computer system that is shared by the processor, memory, and peripherals, transferring data between them.

busbar Electricity. the power conduit of an electric power plant; the starting point of the electric transmission system.

busbar cost Electricity. the cost of producing 1 kilowatt per hour of electricity and delivering it to, but not through, the transmission system.

Bush, Vannevar 1890–1974, U.S. engineer whose work in the 1940s laid the groundwork for the Internet. He described a theoretical machine called a memex, which would enhance human memory by allowing the user to store and retrieve documents connected by associations (a form of linking similar to what is known today as hypertext).

business as usual (BAU) Economics. 1. a prediction or projection of future conditions on the assumption that there will be no significant changes in current, normal operating conditions. 2. specifically, an estimate of a company’s emissions under normal operating circumstances. Depending on the scope of the BAU scenario, this may incorporate some emission reduction regulatory controls, including carbon taxes.

bus rapid transit (BRT) Transportation. a program that seeks to improve bus service by reducing travel time and providing enhanced rider convenience.

butadiene Chemistry. a colorless gas that is a commercially important compound used in making nylon, latex paints, and synthetic rubbers (buna rubber).


bypass system

butane Oil & Gas. a colorless, highly flammable gas; it occurs in natural gas and is produced by cracking petroleum; widely used as a fuel for lighters and other household products, as a component of LPG (liquefied petroleum gas), as a gasoline additive, and for other industrial purposes.

butene another name for BUTYLENE.

butterfly effect Earth Science. an expression developed by U.S. meteorologist Edward Lorenz to describe the concept of uncertainty and chaos in weather forecasting. He said that something as small as a butterfly flapping its wings in China could change the weather in the U.S. a few days later, because the butterfly would move a little bit of air that moved more air, and so on until the moving air reached the other side of the world. This effect, known technically as the “sensitive dependence on initial conditions”, is the essence of chaos.

button cell Storage. a miniature battery having a circular cross-section in which the overall height is less than the diameter.

buttress dam Hydropower. a dam consisting of a watertight upstream face supported at intervals on the downstream side by a series of flat or curved supports (buttresses) that resist the forces of the reservoir water. Typically employed in a valley to hold back a wide river or lake.

butylene Chemistry. the alkene hydrocarbon group C4H8, including three known isomeric forms; all are flammable and easily liquefied gases. Used mainly in making synthetic rubbers.

buyback tariff Economics. a price paid to the owner of a distributed energy (DE) resource for electricity that is sold back to the electricity grid.

buythrough Economics. an agreement between a utility and customer to import power when the customer’s service would otherwise be interrupted.

BWR boiling water reactor.

bypass diode Photovoltaic. a diode connected across one or more solar cells in a photovoltaic module in such a way that the diode will conduct if the cells become reverse biased.


system Hydropower. a

structure in

a dam

that provides a route

for fish (e.g.,


migrating salmon) to move safely through or around the dam without going into the turbine units. A collection and bypass system collects and holds the fish approaching the dam for later transportation.

byproduct or by-product Materials. a secondary or additional product resulting from

58 byte

an industrial process, especially a useful material that can be employed in a subsequent process. Thus, byproduct fuel.

byte Communication.




of bits (discrete items


data) represent-

ing a transmission character. usually







C carbon; Celsius (centigrade); coulomb.

C3 plant Biological Energetics. a plant that produces a three-carbon compound during photosynthesis; a classification that encompasses the greater percentage of plant species on earth, including trees and most important food crops, such as rice, wheat, barley, soybeans, potatoes, beans, and other vegetables.

C4 plant Biological Energetics. a plant that produces a four-carbon compound during photosynthesis; a classification that includes a small percentage of plant species, mainly tropical and subtropical grasses such as the agricultural crops corn (maize), sugarcane, millet, and sorghum. Because of the different photosynthetic processes of C3 and C4 plants, global warming and increased carbon dioxide levels can affect their relative abundance and distribution on earth, though precisely in what manner is not certain.

cable car Transportation. 1. an engine-driven continuous track used to carry coupled bulktransport cars; historically one of the first steps to replace horses with mechanical power in urban transit systems, but now limited to a few locations (e.g., San Francisco, Wellington, NZ). 2. a similar conveyance suspended from an overhead cable, as for transportation across a canyon or up a mountainside. Thus, cable railway or tramway.

cable tool Mining. a bottom-hole tool in which the drilling bit is connected by cable with the machine on the surface, allowing a percussive action to drill the boreholes. Thus, cable-tool drilling.

cable tool drilling Oil & Gas. an older type of oil well drilling in which the hole is drilled by dropping a sharply pointed bit on the bottom of the hole. The bit is attached

to a cable and the cable is picked up and dropped repeatedly to deepen or drill the hole.

cable yarding Biomass. the process of transporting cut logs to a landing or yarding area by means of an overhead cable and winch system.

CADDET Centre for the Analysis and Dissemination of Demonstrated Energy Technologies (est. 1988); an international information network that informs decision-makers about renewable energy and energy-saving technologies that have been successful in other countries. Part of the International Energy Agency.


cadmium Chemistry. a rare element having the symbol Cd, the atomic number 48, an atomic weight of 112.4, a melting point of 320.9°C, and a boiling point of 767°C. It is a white, ductile metal obtained from zinc ores, and is used as an anticorrosive and in making alloys. Compounds of cadmium are widely used as components of nickel cadmium batteries and as solar energy materials; e.g., cadmium sulfide (CdS), cadmium telluride (CdTe).

cadmium hydroxide Storage. an active material used at the negative electrode of a nickelcadmium battery.

CAES compressed air energy storage.

CAFE Transportation. Corporate Average Fuel Economy; a U.S. standard officially defined as the sales-weighted average in miles per gallon achieved by a manufacturer’s fleet of passenger cars or light trucks having a gross vehicle weight rating of 8500 lbs. or less, manufactured for sale in a given model year. Enacted in 1975 as a part of the Energy Policy Conservation Act.

cage Mining. an enclosed or semi-enclosed structure in a vertical mine shaft, similar to an elevator car, that is used for transporting personnel and materials.

caking Coal. the fact of coal becoming fused together in a coherent, solidified mass when heated. Thus, caking character, caking test.

caking coal Coal. a type of coal that softens and then cakes upon heating, producing a hard, gray cellular mass of coke.




calcination Materials. the heating of a solid to a high temperature, below its melting point, to create a condition of thermal decomposition or a phase transition other than melting or fusing. Also, calcining.

calculating engine Communication. a name for either of two machines designed in the 1820s by English scientist Charles Babbage, the table-making difference engine or the more ambitious analytical engine, a flexible, punch-card controlled general purpose calculator, embodying many features found in the modern computer. The machines were never actually built due to a lack of funds.

caldera Earth Science. a large, more or less circular volcanic crater, usually resulting from the collapse of underground lava reservoirs, having a diameter that is many times greater than that of the vent.

Calder Hall Nuclear. the world’s first commercial nuclear power station (opened in 1956), a complex of four reactors in West Cumbria on the coast of northwest England. British Nuclear Fuel closed this facility in 2003.

Callendar, G. S. 1897–1964, British engineer who was the first to empirically connect rising carbon dioxide concentrations in the atmosphere and the increase in the earth’s temperature.

caloric Thermodynamics. 1. having to do with heat transfer, or the measurement of this. 2. a theoretical substance once thought to be the source of the phenomenon of heat. See

CALORIC THEORY. 3. Biological Energetics. having to do with calories or the calorie content of a given food.

caloric theory (of heat) History. a historic concept of heat as a substance that flows into a body as it is heated and flows out as it is cooled; from about 1800 onward this was refuted by Count Rumford, Joule, Mayer, Clausius, and others, and then replaced with the concept of heat as the kinetic energy of molecules.

caloric value Biological Energetics. the sum of the calories provided by the energy-contain- ing nutrients in a given food: i.e., protein, carbohydrate, fat, and alcohol. Because carbohydrates contain some fiber that is not digested and utilized by the body, the fiber component is usually subtracted before calculating the caloric value.

calorie Measurement. a unit of energy, defined as the amount of heat transfer required to raise the temperature of one gram of pure water by one degree Celsius (from 14.5°C– 15.5°C) at standard atmospheric pressure (sea level); equivalent to 4.184 J. Used as a description of the energy content of a given food. Also called a small calorie in contrast with a KILOCALORIE or large calorie (1000 small calories).

calorific value see CALORIC VALUE.

calorimeter Measurement. an instrument that is used to measure the amount of heat generated during a physical process such as burning, change of state, or friction. See BOMB


calorimetry Measurement. the measurement of heat transfer.

Calvin cycle Biological Energetics. the complete route that carbon travels through a plant during photosynthesis. [Named for U.S. biochemist Melvin Calvin, 1911–1977.] Also called the Calvin-Benson cycle. RSee next page.

CAM (plant) Biological Energetics. crassulacean acid metabolism; a descriptive term for plants that close their stomata during the day to reduce water loss and open them at night for carbon dioxide uptake.

camel Biological Energetics. an animal used historically for transportation, especially in desert regions of Africa, the Middle East, and central Asia; either the one-hump Bactrian camel (Camelus dromedarius) or the two-hump dromedary (Camelus dromedarius).

CAN Climate Action Network (est. 1979); a global network of over 280 nongovernmental organizations (NGOs) working to promote government and individual action to limit human-induced climate change to ecologically sustainable levels.

canal Transportation. 1. an artificial waterway that is dug to connect two adjacent bodies of water to allow for the passage of shipping between them. 2. a similar waterway dug to conduct water across an extent of land for irrigation or drainage.

canary Coal. 1. a small songbird of the finch family, having bright yellow plumage and often kept as a pet. For centuries caged canaries were brought into coal mines to signal


RCalvin cycle The metabolic pathway by which carbon dioxide (CO2) is incorporated

into carbohydrate. Nobel Laureate Melvin Calvin had a major role in elucidating this cyclic series of enzyme-catalyzed reactions. The enzyme RuBisCO (ribulose bisphosphate carboxylase/oxygenase) catalyzes the initial reaction of CO2 with a five-carbon compound ribulose-1, 5-bisphosphate (RuBP). The resulting 6-carbon intermediate splits into two copies of a 3-car- bon compound that is converted in subsequent steps to the carbohydrate glyceraldehyde-3- phosphate. Some of this product exits the pathway to be used for synthesis of more complex carbohydrates or other carbon compounds. The rest is converted back to RuBP (the substrate for the initial CO2 fixation reaction), completing the cycle. Most carbon compounds in the biosphere are derived from the carbohydrate product of the Calvin Cycle. The abbreviated structure of a typical carbohydrate is (H–C–OH)n. Due to unequal sharing of electrons in a C–O bond, the carbon atom in CO2 is electron deficient relative to a carbon atom in a carbohydrate, that bonds with only one oxygen atom. Carbon in CO2 is thus said to be more oxidized, while carbon in a carbohydrate is more reduced. The Calvin Cycle does not directly utilize light energy, but is part of the process of photosynthesis. Some Calvin cycle reactions require ATP (adenosine triphosphate), a compound that functions in energy transfer, and NADPH (reduced nicotinamide adenine dinucleotide phosphate), a source of hydrogen atoms for reduction reactions. ATP and NADPH are formed during light-energized reactions of photosynthesis.

Joyce Diwan

Rensselaer Polytechnic Institute

the presence of dangerous gases, the idea being that a canary would succumb quickly to the gas and thus warn the miners to get out. 2. canary in a coal mine. based on this practice, a metaphor for an early warning of oncoming danger or disaster.

cancer Health & Safety. a collective term for a wide variety of diseases that are generally characterized by improperly regulated cell growth and differentiation, resulting from specific alterations in the function of one or more genes. Various forms of cancer have been linked to environmental pollutants.



candela Lighting. the SI unit of luminous intensity, symbol cd; it is equal to the luminous intensity in a given direction of a source that emits monochromatic radiation of frequency 540 × 1012 Hz and that has a radiant intensity in the direction of (1/683) W per steradian. [From the Greek word for candle.]

candle Lighting. 1. a cylinder of wax or other solid fuel, with a central wick that burns to produce light. 2. an older name for the CAN- DELA or CANDLEPOWER units of measure.

candlepower Lighting. a unit formerly used for measuring the light-radiating capacity of a lamp or other light source. One candlepower represents the radiating capacity of a light with the intensity of one international candle, or about 0.981 candela as now defined.

candlepower distribution Lighting. a curve that represents the variation in luminous intensity in a plane through the light center of a lamp or luminaire; each lamp or lamp/ luminaire combination has a unique set of candlepower distributions that indicate how light will be spread.

CANDU Nuclear. Canadian Deuterium Uranium (Reactor); a pressurized heavy-water, natural-uranium power reactor designed in the 1960s by a partnership between Atomic Energy of Canada Limited and the HydroElectric Power Commission of Ontario, as well as several private industry participants.

cannel coal Coal. 1. a variety of nonbanded, fine-grained, highly volatile coal derived mainly from spores and other plant remains, characterized by a dull to greasy luster and conchoidal fracture. 2. a former term for any coal that burns with a steady luminous flame.

Canola oil Biomass. another name for RAPE- SEED OIL, especially as used in commercial food products. [Short for “Canadian oil”.]

canopy (cover) Ecology. 1. the leafy cover or top layer formed by the uppermost branches of trees in a forest. 2. another term for LEAF


cap Economics. 1. a supply contract between a buyer and a seller, according to which the buyer is assured that they will not have to pay more than a given maximum price. 2. the maximum amount of a pollutant that


can be emitted under a specific regulatory

regime. 3. SEE CAP-AND-TRADE. 4. see EMIS- SIONS CAP.

capacitance Electricity. the ability of conductors separated by dielectric material to store energy in the form of electrically separated charges; a value described as the ratio of a quantity of electricity to a potential difference.

capacitative Electricity. having to do with or employing capacitance or a capacitor.

capacitor Electricity. an electric circuit element used to store an electric charge temporarily, consisting in general of two metallic plates separated and insulated from each other by a dielectric (e.g., air or mica).

capacity Electricity. 1. the electrical charge effectively stored in a primary or secondary battery and available for transfer during discharge. Usually expressed in amperehours (Ah) or milliampere-hours (mAh). 2. Transportation. the maximum number of vehicles per hour that a highway can carry under normal driving conditions; exceeding this level will tend to produce congestion and delays rather than greater traffic volume.

capacity factor Conversion. the ratio of the actual energy output of an energy converter (power plant or wind turbine) to the energy that could have been generated at continuous full-power operation over a specified period of time.

cap and trade Policy. an emission trading program in which the government creates a fixed number of allowances and requires regulated sources to surrender them to cover actual emissions. RSee next column.

capillarity Physics. the general behavior of fluids acting with surface tension on interfaces or boundaries, by which the fluid is either elevated or depressed.

capillary Physics. a thin hollow tube through which a liquid can rise by means of capillary action (see next).

capillary action Physics. the attraction of the surface of a liquid to the surface of a solid, which either elevates or depresses the liquid depending upon molecular surface forces; e.g., crude oil clings to the surface of each pore in a rock formation, making it difficult to recover the oil.



Rcap and trade A policy to limit overall emissions from a group of sources in a

cost-effective manner by using market forces. A fixed number of allowances, equal to the desired cap on total emissions, are distributed or sold to participating firms. Each firm must retire allowances corresponding to its emissions for that time period. Firms that find abatement more difficult can purchase excess allowances from others that reduce emissions more cheaply. Such trades benefit both firms while reducing overall compliance costs. When supply meets demand for allowances, in theory, the market price reflects the marginal cost of abatement among the firms, the cap is met, and total costs are minimized. The idea of using a system of tradable property rights to manage emissions was first articulated by economist Tom Crocker and political scientist J. H. Dales in 1966 and 1968, respectively. In practice, the 1990 U.S. Clean Air Act Amendments initiated a cap and trade program for sulfur dioxide emissions to combat acid rain. Since then, emissions trading has been used in California’s RECLAIM program and for nitrogen oxide emissions in the Northeastern states. Recently, the European Union began a cap-and-trade program for carbon dioxide emissions. Several countries, most notably New Zealand, use a similar program of individual transferable quotas to manage allowable catch of fish stocks. Cap and trade is most effective when abatement costs are disparate, individual emissions are easily measured, and their environmental impacts are not significantly affected by the location of the source.

Carolyn Fischer

Resources for the Future, USA

capital Economics. 1. the buildings, equipment, tools, and other manufactured items used in producing goods and services. Thus, capital asset, capital stock, and so on. 2. an accumulation or supply of financial assets.

capitalism Economics. an economic system in which capital assets are chiefly held by private individuals and companies rather than by public or quasi-public entities, and in which prices and the production and distribution of goods are chiefly determined by conditions in the marketplace rather by government policy.



carbon-14 dating

capping Oil & Gas. 1. the process of sealing or closing a borehole, such as a spouting gas or oil well, to prevent the escape of fluids.

2.the device used to accomplish this closure.

3.Mining. the overburden situated atop a valuable seam or bed of mineral.

cap rock Mining. 1. consolidated barren rock material overlying a mineral or ore deposit, which must be removed before mining; e.g., a layer of hard rock overlying a coal bed. 2. Oil and Gas. an impervious layer of rock overlying an oil or natural gas deposit.

captive Electricity. 1. a term for a customer who does not have a reasonable alternative to buying power from the local utility. 2. a battery that has an immobilized electrolyte (that is, gelled or absorbed in a material). 3. Mining. a mine that produces coal for direct use by the same company that owns the mine, rather than its being marketed to others. Thus, captive coal.


caravel History. a historic type of small sailing vessel, usually with lateen sails on two or three masts; used in the Middle Ages and later and noted especially for its use by explorers of Portugal and Spain; e.g., the exploration of the west coast of Africa and the voyages of Columbus.

caravel Portuguese caravels entering Lisbon harbor, 15th century (detail).

carbide Materials. any of various compounds made up of carbon and another element (other than hydrogen); typically a metal such as iron, calcium, tungsten, silicon, or boron; usually produced by heating the reacting substances in an electric furnace.

carbide lamp Mining. a miner’s lamp burning acetylene that forms as a result of charged calcium carbide and water; widely used historically but now largely superseded by electric lamps.

carbide nuclear fuel Nuclear. a ceramic formulation of uranium in the form of uranium or plutonium monocarbide or dicarbide that has desirable thermal conductivity characteristics; used in advanced reactors that operate at very high temperatures.

carbohydrate Biological Energetics. a collective term for chemicals composed of carbon, hydrogen, and oxygen and typically having a hydrogen-to-oxygen ratio of 2:1; e.g., sugars such as glucose or xylose, starches, and cellulose or hemicelluloses.

carbon Chemistry. a very common nonmetallic element having the symbol C, the atomic number 6, an atomic weight of 12.01115, and a melting point about 360°C; the active element of photosynthesis and the key structural component of all living matter. RSee next page.

carbon-12 Chemistry. an isotope of carbon that has a stable nucleus; it is the naturally occurring, dominant form of carbon and thus makes up most of the carbon found in nature. Carbon-12 is the basis of the atomic weights of other elements (12C = atomic weight 12).

carbon-14 Chemistry. a naturally occurring, radioactive isotope of carbon; commonly used in demonstrating the metabolic path of carbon in photosynthesis and in dating ancient materials (see next).

carbon-14 dating Measurement. a widely used method for estimating the age of an ancient carbonaceous specimen by measuring the radioactivity of its carbon-14 content; this will indicate how long ago a once-living artifact ceased to be in equilibrium with the atmosphere. Carbon-14 is continuously produced by cosmic-ray bombardment and decays with a half-life typically described as 5568 years; dating is accomplished by


Rcarbon Carbon is the sixth most abundant element in the universe and is unique

due to its dominant role in the chemistry of life and in the human economy. It is nonmetallic element having the symbol C, the atomic number 6, an atomic weight of 12.01115, and a melting point about 360°C. There are four known allotropes of carbon: amorphous, graphite, diamond, and fullerene. A new fifth allotrope of carbon was recently produced, a spongy solid called a magnetic carbon “nanofoam” that is extremely lightweight and attracted to magnets. Due to carbon's unusual chemical property of being able to bond with itself and a wide variety of other elements, it forms nearly 10 million known compounds. Carbon is present as carbon dioxide in the atmosphere and dissolved in all natural waters. It is a component of rocks as carbonates of calcium (limestone), magnesium, and iron. The fossil fuels (coal, crude oil, natural gas, oils sands, and shale oils) are chiefly hydrocarbons. The isotope carbon-12 is used as the basis for atomic weights. Carbon-14, an isotope with a half-life of 5730 years, is used to date such materials as wood and archeological specimens. Organic chemistry, a major subfield of chemistry, is the study of carbon and its compounds. Because carbon dioxide is a principal greenhouse gas, the global carbon cycle has become a focus of scientific inquiry, and the management of carbon dioxide emissions from the combustion of fossil fuels is a central technological, economic, and political concern.

Cutler Cleveland

Boston University

comparing the carbon-14 activity per unit mass of the specimen with that of a contemporary sample.

carbonaceous Chemistry. containing or composed of carbon.

carbonaceous coal Coal. coal derived from the accumulation of undecayed plant matter.

carbon arc Electricity. an electrical discharge between two carbon electrodes; used in welding and in high-intensity lamps. Thus, carbon

(arc) lamp.

carbonate Chemistry. 1. a compound formed by the reaction of carbonic acid with either a metal or an organic compound. See CARBONIC ACID. 2. relating to or containing such a compound.


carbon cycle

carbonate pump Earth Science. a process in which various organisms in the ocean (phytoplankton and zooplankton species) form calcium carbonate (CaCO3) skeletal coverings. When these organisms die, some fraction of this CaCO3 is eventually remineralized back to calcium and carbonate ions in the deeper parts of the water column and in sediments. This carbon cycle or pump leads to a reduction in surface ocean levels of dissolved inorganic carbon (DIC) and alkalinity; an increase in the strength of the pump will serve to increase levels of CO2 in surface water.

carbon black Materials. a black colloidal substance consisting wholly or mainly of amorphous carbon, produced commercially by thermal or oxidative decomposition of hydrocarbons. Used as a reinforcing agent in rubber products, as a black pigment in inks, paints and plastics, in the manufacture of dry-cell batteries and electrical conductors, and in high-temperature insulating material.

carbon budget Climate Change. the balance of the exchanges of carbon between carbon reservoirs (atmosphere, oceans, biota, fossil fuel deposits, soils, and society) in the carbon cycle. It is defined in terms of a “balance sheet” of gains and losses of carbon in the atmosphere, where fossil fuel combustion is a gain of carbon, while forest regrowth is a loss. The net of gains and losses produces an increase or decrease in the level of atmospheric carbon dioxide concentrations. Thus, carbon debt or deficit, carbon purchase, carbon surplus, and so on.


carbon compensation depth Earth Science. the level in the ocean below which the solution rate of calcium carbonate exceeds its deposition rate; i.e., the preservation of calcium carbonate shells is negligible.

carbon conversion factor Measurement. the amount of carbon per unit mass of a fuel (e.g., kg/ton).

carbon cycle Environment. 1. the movement of carbon among its reservoirs by various chemical, physical, geological, and biological processes. The major reservoirs are the atmosphere, terrestrial biosphere (usually