• Fuel delivery, storage and processing;
• Combustion & waste processing;
• Power generation, transmission and distribution.
  

Fuel delivery, storage and processing: - this is not a focus in this site but clearly involves technology and efficiencies in terms of getting the fuel to the plant, storing it and in some cases carrying out any pre-combustion processing. The chief fossil fuels used in power generation are coal, oil and gas and each presents its own challenges for transportation and storage. Oil and gas require containment and oil requires pumping from storage to furnace. Coal is more easily stored but is always crushed to provide higher surface area and more uniform size. Interim storage may compact the coal (typically 6 mm) to avoid spontaneous combustion. Before combustion the coal is further crushed until it is a fine powder. All fuels including coal especially when crushed require significant safety measures to prevent spontaneous or accidental ignition/combustion.

Combustion & waste processing; this is the key aspect in the context of the Stern Review since it relates to the generation of greenhouse gases, excess heat and much waste, the processing of which requires energy. The combustion stage involves the same chemistry as respiration and so demands that oxygen is available to enable the oxidation of the fuel to release energy. Various methods are used mostly involving the air to be forced to mix with the fuel for combustion. The heat may then be used to superheat steam which is used to turn the turbine (e.g. most coal or oil stations) or the hot fuel/air mixture itself may be used to turn the turbine in the case of a gas fuelled “Combined Cycle Power station”. (see animations).

Whilst the fuel and air are input to the furnace, the products of the combustion: oxides of carbon, nitrogen and sulphur along with soot and ash all need to be removed, along with considerable amounts of unused heat. Thermal Power stations are not very efficient and 60% would be regarded as good. The excess heat removal results in e.g. the cooling towers we see at many power stations. In order to remove the oxides and particles from the exhaust gases, power stations have various types of “scrubber”. To date more focus has been on removing the oxides of sulphur and nitrogen given their poisonous nature and because they give rise to acid rain. Recent focus has however included removal of carbon oxides and to improving the efficiency overall.

Power generation, transmission and distribution: again not a focus in this site, but well developed technology and engineering illustrates some excellent application of science. The use of heat to move gases, (steam, combustion gases or a mixture of both) is used to turn a turbine which in turn “drives” a generator. The “generator” uses Faraday’s observation that moving a magnet through a coiled conductor “induces” a current. Generator design develops this idea and enables an alternating current to be produced on a continuous basis in number of phases. Commercial, industrial and domestic use of electricity is very high and to avoid huge currents being sent from power station to final destination, the transmission stage uses transformers to scale up the voltage and reduce the current and deliver power to “local” sub-stations. This is fortunate since passing large currents through conductors generates heat and would demand very thick and strong conductors as well as wasting energy. From the sub-station, power is then distributed in the local area with the voltage stepped down again to e.g. 240 volts (UK).
Linked sites provide detail of technological aspects of the plant and processing equipment used which are similar to other industrial sites and include combustion chambers, conveyors, pumps, pressure vessels, heat exchangers and considerable control technology. Specific additions include turbines, generators, transformers and of course cooling towers