A Dictionary of Energy

Martin Counihan

• Publisher: Routledge
• Year: 2019
• ISBN:
  9780429560569
• Edition: 1
• Topic: Business
• Subtopic: Energy Industry
• Index: Business

Originally published in 1981. Every aspect of Energy – production, conversion and use - is discussed and explained in this unique dictionary. Comprehensive and well-illustrated entries cover fossil and other types of chemical fuel; hydro-electric and nuclear power; energy conservation; solar energy of every kind; wind, wave and tidal power. Every type of nuclear reactor is described, with emphasis on the energy technologies that have the greatest relevance and future promise.

The first section is devoted to a careful explanation of the units used, with conversion tables; key concepts are precisely defined. The closing sections comprise tables of international energy statistics and a short bibliography. This is an excellent introduction and invaluable reference work for general readers, students and all workers in energy and energy-related fields.

absolute zero The lowest temperature to which any substance could conceivably be cooled, and at which it would contain no remaining energy in the form of heat. Absolute zero is close to –273 C and is by definition the zero of the Kelvin temperature scale (0 K).

absorption cycle A thermodynamic cycle sometimes used to run heat pumps for refrigeration or air conditioning. Since it may be driven by heat energy rather than mechanical or electrical energy, the absorption cycle can be a useful alternative to the more familiar vapour compression cycle, and absorption cooling systems have been developed which run from solar heat and from industrial waste heat.

Figure 1 The absorption cycle.

The cycle makes use of two fluids, namely a refrigerant (which might be, for example, ammonia) and an absorbant (say, water). The right-hand side of Figure 1 is at high temperature and pressure, with the refrigerant condensing to give out heat; the left-hand side is at lower pressure and temperature so that heat is taken into an evaporator within the space being cooled. To complete the cycle, the evaporated refrigerant is allowed to dissolve in the absorbant and is subsequently driven off from it again at higher pressure in another container (the generator) which is heated. The pump between the absorber and the generator expends very little energy (much less than the pump in a vapour compression cycle), most of the input power being the heat applied to the generator.

The absorption cycle can in practice give coefficients of performance (c.o.p.) of about one-third those possible with the vapour compression cycle, i.e. the c.o.p. is typically around unity. In circumstances where the generator heat is in effect free the absorption cycle is competitive and its technical development is progressing rapidly.

absorptivity (sometimes called absorptance, or absorptive power) When radiation falls onto a surface, some is reflected and some absorbed; the proportion absorbed is the absorptivity of the surface. It may vary according to the wavelength of the radiation, and so may be different between visible light and radiant heat. Absorptivity may also change somewhat with temperature.

The absorptivities of materials are valuable data for the design of buildings and rooms for energy efficiency and comfort. It can be shown that the absorptivity of a surface is equal to its emissivity, i.e. surfaces which are good at absorbing heat are also good at emitting it by radiation. For tabulated figures, see emissivity.

AC See alternating current.

accumulator (1) a storage cell which accumulates electrical energy in chemical form, i.e. a battery. The term ‘accumulator’ is used especially of lead-acid batteries such as those used in automobiles. (2) A reservoir of cooling water used in certain emergency core-cooling systems for nuclear reactors. The water is held under pressure in the accumulator and would automatically flow into the reactor core to cool it if there were a loss-of-coolant accident.

acetylene A gas (C₂H₂) which was often used as a fuel for lighting before electricity became widely available. It remains important in oxyacetylene burners for cutting and welding metals at temperatures which can exceed 3,000 C.

actinides The collective name given to a series of chemically similar metallic elements which includes those which are valuable for nuclear fission energy production and those sustaining, by radioactivity, the earth’s internal heat.

The actinides are listed in Table 1, together with their atomic numbers and the range of mass numbers covered by the known isotopes of each actinide. For the most stable isotopes, the symbol and half-life are given.

Table 1 The actinides

It is significant that the elements of higher mass number tend to be those with the shortest half-lives, i.e. to be the least stable. The only actinides sufficiently long-lived to be found in nature in large amounts are near the top of the table, i.e. thorium and uranium. All but these two are extremely rare or non-existent on the earth. Because of the heat of their radioactivity uranium and thorium are vital to the earth’s overall energy balance and have had a powerful influence on long-term geophysical processes. The commercial significance of uranium and thorium reserves has been greatly enhanced by the roles which they may play in nuclear fission fuel cycles.

Several of the man-made actinides have found applications in industry, medicine and communications. Some, like americium, are used as sources of particular types of radiation in industry, while others such as californium provide radiotherapy. Others are used in isotopic power generators which produce electricity from decay heat and have been used to power satellites, navigation buoys, heart pacemakers and other devices for which regular fuelling is not possible.

Chemically, the actinides are mildly toxic, as are other heavy metals like lead and mercury. They are of special danger, however, because of the combined effect of (a) their radioactivity, and (b) their tendency when absorbed by the body to become concentrated in certain vital areas such as the bone marrow. This concentration means that relatively tiny amounts of, say, ²³⁹Pu may cause serious illness by radiation damage to delicate organs or by carcinogenesis.

As a by-product of nuclear fission energy, dangerously large amounts of radioactive actinides are produced, and their disposal is one of the main technical difficulties for fission energy. A form of nuclear incineration has been proposed which could, in principle, reduce the dangerous actinides to safety within a relatively short time, but it is doubtful if this will be workable in the near future. See also nuclear waste, transuranic elements.

actinium A chemical element (atomic number Ζ = 89, symbol Ac) which is one of the group of elements known collectively as the actinides. Actinium occurs naturally in minute amounts, mainly the isotope ²²⁷Ac, as part of the decay chain of uranium (²³⁵U).

actinium series The series of nuclides which forms the decay chain of the nuclide ²³⁵U down ultimately to ²⁰⁷Pb (i.e. from uranium to lead). The mass numbers of the actinium series are of the general form A = 4n + 3, where n is an integer between 51 and 58 inclusive.

adenosine triphosphate (ATP) The organic substance which transfers the energy used for muscular contraction by animals. In the body of an average adult there will be about 75 g of ATP present at any instant of time, but the rate of production and consumption in the body tissues is such that he will actually use more like 75 kg of ATP per day, expending energy at a rate of about 150 W.

adiabatic When a system undergoes a process without any flow of heat out of the system, or into it, then the process is said to be adiabatic.

advanced gas-cooled reactor See AGR.

Advisory Committee on Reactor Safeguards (ACRS) A committee of the US Atomic Energy Comm...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Original Title Page
• Dedication
• Original Copyright Page
• Contents
• Figures
• Preface and acknowledgments
• Units
• Dictionary of Energy
• International energy statistics
• Bibliography