fuel!!!急

The solution :
天然氣 (後備燃料:柴油)

> Something about the Hong Kong power station

‧We cannot live a day in comfort without electricity. Our lighting, home appliances, computers, the mass transport systems (e.g. MTR and KCR trains), and numerous other machines are all powered by electricity. In Hong Kong, we are consuming over 3.8 × 1014J of electrical energy every day! In this module, you will learn how such a large amount of electrical energy is generated and transmitted.

In Hong Kong, electricity consumed is generated using coal, natural gas and nuclear energy as the sources.

‧Electricity generation in power plants

> Coal-fired power plants

‧ The power plants in Hong Kong use mainly coal and natural gas as fuel to generate electricity. The fuel releases chemical energy upon combustion; hot steam or gas is generated and used to drive turbines, thus converting part of the internal energy of the hot steam or gas into useful kinetic energy. Turning turbines then operate a generator to produce electricity. Examples of coal-fired power plants can be found in the Lamma Power Station of The Hongkong Electric Co., Ltd. (HEC) and Castle Peak Power Station of CLP Power Hong Kong Limited (CLP Power).

‧In Hong Kong, power plant generators are turned at a precise rate of 3000 rpm during operation to generate an AC of frequency 50 Hz. In order to withstand the tremendous force in rapid rotation and to optimize the output during operation, the design and construction of the generator is detailed and complex.

Although the actual construction of a power plant generator is complicated, it still relies on the basic principle of electromagnetic induction to generate electricity. Have you learnt this principle in physics lessons? When a coil is moved through a magnetic field, an induced current flows in the coil. You can also get an AC current with a simple AC generator found in a school laboratory. However, an AC generator that serves us every day in a power plant looks very different.

‧The related website : http://www.hk-phy.org/energy/power/print/elect_phy_print_e.html

> So the Hong Kong power station is using the Natural Gas .

‧Something about the Natural Gas

> Natural gas is a gaseous fossil fuel consisting primarily of methane but including significant quantities of ethane, propane, butane, and pentane—heavy hydrocarbons removed later on as condensate—as well as carbon dioxide, nitrogen, helium and hydrogen sulfide. It is found in oil fields (associated) either dissolved or isolated in natural gas fields (non associated), and in coal beds (as coalbed methane). When methane-rich gases are produced by the anaerobic decay of non-fossil organic material, these are referred to as biogas. Sources of biogas include swamps, marshes, and landfills (see landfill gas), as well as sewage sludge and manure by way of anaerobic digesters, in addition to enteric fermentation particularly in cattle.

Since natural gas is not a pure product, when non associated gas is extracted from a field under supercritical (pressure/temperature) conditions, it may partially condense upon isothermic depressurizing--an effect called retrograde condensation. The liquids thus formed may get trapped by depositing in the pores of the gas reservoir. One method to deal with this problem is to reinject dried gas free of condensate to maintain the underground pressure and to allow reevaporation and extraction of condensates.

Natural gas is often informally referred to as simply gas, especially when compared to other energy sources such as electricity. Before natural gas can be used as a fuel, it must undergo extensive processing to remove almost all materials other than methane. The by-products of that processing include ethane, propane, butanes, pentanes and higher molecular weight hydrocarbons, elemental sulfur, and sometimes helium and nitrogen.

‧The related website : http://en.wikipedia.org/wiki/Natural_gas

燃料. 天然氣 (後備燃料:柴油)