Electricity production

When the fuel—typically coal or natural gas—burns, chemical energy is released as heat. The goal of the power plant is to convert as much of this energy as possible into electricity. The critical step in this process is to trap the heat given off in the combustion reaction. Water is the material of choice for this process 

It is interesting to wonder how the design of power plants would change if something with a much smaller heat of vaporization replaced water. 

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Potential fusion appHcations other than electricity production have received some study. For example, radiation and high temperature heat from a fusion reactor could be used to produce hydrogen by the electrolysis or radiolysis of water, which could be employed in the synthesis of portable chemical fuels for transportation or industrial use. The transmutation of radioactive actinide wastes from fission reactors may also be feasible. This idea would utilize the neutrons from a fusion reactor to convert hazardous isotopes into more benign and easier-to-handle species. The practicaUty of these concepts requires further analysis. 

Two of these cycles have an electrolysis step. Although one of the purposes of the thermochemical cycles is to avoid electrolysis and the associated iaefftciencies of electricity production, the electrolysis steps proposed use much less electrical energy than water electrolysis. The Mark 13 is regarded as the most advanced thermochemical cycle, with overall efficiency of about 40%, including the electrolysis step (164). 

Underwriters Laboratories (UL) is an independent, nonprofit organisation that develops standards for safety in electrical products. UL 746 A, B,... 

The widespread availabiHty of electrical energy completely transformed modem society and enabled a host of breakthroughs in manufacturing, medical science, communications, constmction, education, and transportation. Centralized fossil fuel-powered, steam-turbine-based power plants remain the dominant means of electricity production. However, hydropower faciHties such as the 1900-MW Hoover Dam Power Project located on the Arizona—Nevada border, commissioned by the U.S. Bureau of Reclamation during the 1930s, have also made significant contributions. 

Tidal Power. Tidal power is caused by the gravitational pull of the sun and especially the moon, as they pull at the earth. Reacting to this pull, the ocean s waters rise, causing a high tide where the moon is closest. The difference between low and high tide can range from a few cm to several meters. Harnessing tidal power for electricity production by the use of dams requires a tidal difference of at least 4.5 m, a requirement met at few locations in the United States. Thus, the principal demonstration sites of tidal power are in Canada, China, and France. 

Fig. 7. Biofuels and biomass electricity production. Courtesy of the National Renewable Energy Laboratory.

One of the primary concerns of all power plants is to ensure high electricity production and reduce hazardous and waste substances. In that way green electricity could be produced. It is essential to monitor the presence and movement of impurities in various measuring sites in air, water and soil [1]. The presence of hazardous species in these eco-systems, even at low-mg/1 levels, has negative effects for nature and human beings [2, 3]. 

From an economic standpoint, electricity production from a new natural gas plant versus a newly built coal-fired plant heavily favors natural gas, because natural gas-fired plants are cheaper to build. However, older coal-fired plants built 20 to 30 years ago are often more profitable than newly built gas plants, because — among other reasons — coal is cheaper than natural gas, and the older plants have long since paid for their capital investments through depreciation. 

In electrical power stations a new measure of the performance is the amount of CO2 produced per unit of electricity generated, i.e. A = kg(C02)/kWh this quantity can be non-dimensionalised by writing A = A( 16/44)(LCV) where (16/44) is the mass ratio of fuel to CO2 for methane and (LCV) in its lower heating value. However, presenting the plant s green performance in terms of A directly allows the cost of any tax on the carbon dioxide to be added to the untaxed cost of electricity production most easily. 

The sources of biofuels and the methods for bioenergy production are too numerous for an exliaustive list to be described in detail here. Instead, electricity production using direct combustion, gasification, pyrolysis, and digester gas, and two transportation biofuels, ethanol and biodiesel, are discussed below. 

In the United States about 3 percent of all electricity produced comes from renewable sources of this a little more than half comes from biomass. Most biomass energy generation comes from the lumber and paper industries from their conversion of mill residues to in-house energy. Municipal solid waste also is an important fuel for electricity production approximately 16 percent ot all municipal solid waste is disposed of by combustion. Converting industrial and municipal waste into bioenergy also decreases the necessity for landfdl space. 

Most electricity from biofuels is generated by direct combustion. Wood fuels are burned in stoker boilers, and mill waste lignin is combusted in special burners. Plants are generally small, being less than 50 MW in capacity. There is considerable interest in combustion of biomass in a process called cofiring, when biomass is added to traditional fuels for electricity production. Cofiring is usually done by adding biomass to coal, but biomass also can be cofired with... 

In electric power systems, it is essential to have permanent control of the power in electricity production, transportation, and consumption. Because of speed and reliability requirements, electric power systems were the first large systems to use a variety of automatic control devices for the protection of different parts of the system. 

The United States is the world leader in geothermal electricity production, with about 2850... 

Some geothermal power plants use a combination of flash and binai y cycles to increase the efficiency of electricity production. An initial flash creates steam that drives a turbine then the binai y cycle is run, using either the hot water remaining after the initial flash or the hot exliaust from the turbine. 

The main advantage of geothermal energy is that it can be exploited easily and inexpensively in regions where it is abundantly available in hydrothermal resen/oirs, whether it is used for electricity production or for dircct-usc heat. Gcothcrmally produced electricity from dry-steam sources is vei y cheap, second only to... 

Rader, N. (1998). Green Buyers Beware A Critical Review of Green Electricity Products. Washington, DC Public Citizen. 

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