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Distributed systems

The conversion of raw materials into usable energy (electricity or heat) and storage of the energy produced, are two very important aspects of everyday life. Whilst most of the electricity generated is converted from primary energy sources (fossil, nuclear, hydro), there are many other techniques increasing in popularity. 

The most important is the conversion of sunlight into electricity using solar cells. Solar power stations are now feeding power into local electricity distribution networks. Solar collectors are used to harnessing the heat of the Sun to heat water or buildings. Fuel cells are becoming a commercial reality for generating electricity in a variety of applications. Substantial effort has been devoted to exploring the generation of electric power from the effect of gaseous plasma or liquid metal moving through a magnetic field, also known as magnetohydrodynamics. Thermoelectric and thermionic conversion processes are being investigated for possible use in space vehicles.

Batteries are used for both energy conversion and storage. Improved technology is leading to longer life and better performances. Battery storage plants are now used for load levelling applications in power systems. Hydrogen is a useful energy resource but its role in the future is more likely to be in the area of energy storage and transportation. 

Energy can be stored by other than chemical means. These include: mechanical energy storage, primarily flywheels; capacitor banks, which are used for reactive power compensation or for supplying a large amount of energy in a very short time for pulsed power applications; inductive energy storage; compressed air energy storage in natural underground caverns and aquifers; superconducting magnet energy storage which is often used for power system control; and thermal energy storage using phase change materials, solar ponds, hot water tanks or ice.

The INSPEC database provides comprehensive coverage of developments in these areas. Papers can be found in Section A (Physics Abstracts: Chapters A8630 and A8640) and Section B (Electrical and Electronics Abstracts: Chapter B8400). The main energy conversion and storage processes and their relevant INSPEC classification codes are:

Energy conversion

  • Electrochemical conversion, general A8630D, B8410
  • Primary cells A8630E, B8410C
  • Secondary cells (inc. lead-acid batteries) A8630F, B8410E
  • Fuel cells (inc. molten carbonate, solid oxide and phosphoric acid fuel cells) A8630G, B8410G
  • Photoelectric conversion; solar cells A8630J, B8420
  • Phototelectrochemical conversion A8630K, B8410
  • Magnetohydrodynamic energy conversion A8630L, B8430
  • Thermoelectric conversion (inc. alkali metal thermoelectric converters) A8630M, B8460
  • Thermionic conversion A8630N, B8460
  • Photosynthesis (inc. bioenergy conversion) A8630P
  • Chemical energy conversion (inc. coal gasification) A8630Q
  • Thermal energy conversion (inc. heat engines, heat pumps and ocean thermal energy conversion) A8630R
  • Photothermal conversion (inc. solar collectors, solar ponds, space heating and refrigerators) A8630S, B8460

Energy storage

  • Mechanical (inc. flywheels and compressed air energy storage) A8640C, B8470
  • Thermal (inc. solar ponds and tanks, phase-change materials) A8640F
  • Chemical A8640H
  • Hydrogen energy A8640K
  • Capacitor storage (inc. capacitor banks) B8470
  • Inductive energy storage B8470
  • Superconducting magnet energy storage B8470

Relevant Inspec Thesaurus terms include:

Energy conversion terms:

  • bioenergy conversion
  • chemical energy conversion
  • direct energy conversion
  • fuel cells
  • heat engines
  • heat pumps
  • magnetohydrodynamic conversion
  • ocean thermal energy conversion
  • photoelectrochemical cells
  • photothermal conversion
  • primary cells
  • radioisotope thermoelectric generators
  • secondary cells
  • solar absorber-converters
  • solar cell arrays
  • solar cells
  • solar energy conversion
  • solar heating
  • solar ponds
  • thermionic conversion
  • thermoelectric conversion
  • thermoelectric devices

Energy storage terms:

  • battery storage plants
  • capacitor storage
  • compressed air energy storage
  • energy storage
  • energy storage devices
  • flywheels
  • hydrogen economy
  • inductive energy storage
  • mechanised energy storage
  • superconducting magnet energy storage
  • thermal energy storage

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