Methods of Electricity Generation of Energy within the UK and Their Impact upon the Environment - Term Paper Example

"Methods of electri generation of energy within the UK and their impact upon the environment". Introduction: The generation of electri is the process of conversion of energy stored in natural fuels to electrical energy. The process is based on the induction principle formulated in 1831 by the English scientist Michael Faraday and the American scientist Joseph Henry independent of one another. The fundamental principles remained unchanged but many sources to generate electricity were exploited. These methods are being subjugated to keep a concern with the environment at first place, the disposal of resultant waste products and efficient energy conversion next to it. This is related to provide a cost effective technology so as to meet the growing demands of various levels of consumers. Almost every product at some or the other stages during its manufacture or sale require the use of electricity. In UK different groups of consumers, use electricity as- Sector Electricity Use, GWh (2004) Percentage Industry 117,149 34.45% Transport 8,034 2.36% Domestic 115,526 33.97% Public administration 20,924 6.15% Commercial 74,215 21.83% Agriculture 4,194 1.23% Total 340,043 100% (http://www.aepuk.com/need_info.php#4) To meet these demands enhancements in the methods of electricity generation are being implemented keeping the merits and de-merits of the technology in terms of environmental concern. To reduce the damages caused to the environment the conservation of energy becomes important. Changing trends emphasise on using renewable, sustainable energy sources, an alternative to fossil fuels, the use of low or no carbon technologies to reduce the environmental hazards (the IET Energy principles, www.theit.org/factfiles). There are basically two main sources to derive electricity- A. Non-renewable Resources includes: 1. Nuclear Power Station- A fissionable material like Uranium is used to generate heat in the core of the reactor. This heat is passed away by a coolant liquid or gas, which is then used to generate steam. The fission reaction emits neutrons, controlled by a set of rods made of a material capable of absorbing neutrons. Lowering this rod can shut down the reactor in emergencies. To protect the operators "biological shield", consisting of concrete several metres thick, surrounds the powerful radioactive reactor. (Microsoft Encarta Encyclopedia 1993-2004 Microsoft Corporation). In UK its use is increased from 8.5% (1992) to 10% (1998) for electricity production (the IET Energy principles, www.theit.org). 2. By burning fossil fuels- a. Natural Gas: Gas provides 39% of electricity and 70% heat at homes in UK (parliamentary Office of Science and Technology, postnote, February 2007 number 280). UK is now venturing into; Combined Cycle Gas Turbine (CCGT) natural gas technology is used to generate electricity. This is not only efficient in its energy providing feature but also cost-effective, reliable and on top environmentally sounds. The process comprises of fuelling of gas turbines by natural gas, which heats water into steam. It is the steam that rotates an electricity generator. (http://www.edfenergy.com/about-us/energy-generation/story-power-generation.shtml) b. Coal: It was the mainstay of electricity generation in UK, accounting for one-third of the UK's electricity; this has reduced from two-third from 1990s. It is estimated that one-third of the existing stations will close down by 2015 in compliance to the law made to restrict SO2 emissions (Parliamentary Office of Science and Technology, postnote, February 2007 number 280). The coal is finely grinded as face powder in pulverizing mills and mixed with warm air blown into furnace, here it burns like a gas. The power station has furnace as its largest structure which is lined with water pipes to extract maximum heat from the burning fuel. Water in the pipes is converted to high-temperature and high-pressure steam. This steam is supplied to the turbine where heat energy is converted to mechanical energy. The low-temperature, low-pressure steam at the output of the turbine has to be condensed into water and pumped back into the boiler to close the cycle. This requires large quantities of cooling water equivalent to 230,000 cubic metres (50.6 million gallons) per hour for a 2,000 MW station (1 MW equals 1 megawatt) (Microsoft Encarta Encyclopaedia 1993-2004 Microsoft Corporation). Normally power stations are built on the river banks to get a constant supply of water else the water has to be recycled. Cooling towers help to remove the waste heat by throwing it in the atmosphere. Then extraction of ash is done to remove sulphur impurities and flue gases. These gases are forced up to the tall chimney to be released in the atmosphere (Microsoft Encarta Encyclopaedia 1993-2004 Microsoft Corporation). The process is not only exhausting the natural resources but also causing environmental hazard. The coal is solely made up of carbon which when burnt produces CO2 gas apart from this it also emits sulphur and nitrogen causing "smog" and "Acid rain" (Parliamentary Office of Science and Technology, postnote, February 2007 number 280). The normal permissible % of this gas is 1% but exceeding the limits cause "Green House Effect" and in turn leads to Global Warming causing the increase in the temperature of the earth. This causes melting of snow, henceforth rise in the sea-level (Microsoft Encarta Encyclopaedia 1993-2004 Microsoft Corporation). The use is decreased from 29% (1992) to 18% (1998) for electricity production. "The economic impacts of climate change have been reviewed in the Stern Report, published in 2006. The Kyoto Protocol is a policy statement signed by the majority of the world's national governments. It binds them to reduce greenhouse gas emissions and thus avert the worst consequences of climate change". http://uk.encarta.msn.com/encyclopedia_781533545/electricity_generation.html 3. Petroleum: The use is decreased from 36% (1992) to 33% (1998) for electricity production(the IET Energy principles, www.theit.org/factfiles B. Renewable Energy Source: Contribute only 4.2% of electricity generation but it is growing in proportions. Efforts are being underway to combine heat and power (CHP) so that the heat emitted as the by-product of electricity generation can be utilized (Parliamentary Office of Science and Technology, postnote, February 2007 number 280). 1. Wind: Moving air has kinetic energy. Wind turbines reduce its speed and extract energy to convert it into mechanical energy. In UK they are installed offshore as well as onshore. This mechanical energy helps in the development of torque and rotates the rotor. The shaft of the rotor through the gearbox drives an electric generator. Underground electrical cables collect the electrical energy to pass it to the local network station. http://uk.encarta.msn.com/encyclopedia_781533545/electricity_generation.html 2. Solar: The solar energy is harvested in photovoltaic (PV) devices made up of semi-conductors capable of converting about 15 % of solar radiation directly into DC electricity. This has to be converted into AC (alternating current) before it is fed into the mains. If mass installation is done then it becomes cost-effective method of electricity generation. Moreover it can be installed on the buildings also just near the point of demand. 3. Hydroelectric power: This contributes to the non-polluting energy. The Kinetic energy of falling water is first converted into the mechanical energy of turbines and then into electrical energy. The water is allowed to flow out of the reservoir at peak times, driving generators and supplementing the electrical supply. This enables the power station to keep running at a more uniform level (Microsoft Encarta Encyclopaedia 1993-2004 Microsoft Corporation). The process requires lot of water and with increasing population a threat of draught is always there. In UK the electricity generation by this process is 0.2% (1992 & 1998) (the IET Energy principles, www.theit.org/factfiles) . 4. Marine Power: This technology exploits the water power in the marine environment. The tidal power caused by the gravitational pull of the moon. The Marine Current Turbines (MCT) are similar to wind turbines, here the underwater currents turn the blades. The tidal currents are highly predictable and therefore this technology has bright future. 5. Biomass: The methane gas is produced from the agriculture/ cattle waste. This is used as bio-fuel. Microbial fuel cell (MFC) Cysteine acts as a chemical oxygen scavenger. This serves as a substrate for electricity generation. MFC generates power at the anode with reduction of oxygen at cathode. (Water Research, March 2005). Conclusion: All the technologies used to generate electricity also generate CO2. around 30% of CO2 emission comes from the electricity generation (parliamentary Office of Science and Technology, postnote, February 2007 number 280) These emissions occur either directly from the plants or indirectly at any non-operational phase of the life cycle. Technologies using fossil fuels (Coal, Oil, Gas) contribute to the largest carbon footprint as carbon is their main constituent, and they are burnt during the operation. Where as the non-fossil fuel based technology such as wind, solar energy, water energy, biomass and nuclear energy do not emit CO2 during operation. Conventional coal combustion system emits.1,000gCO2eq/kWh. Gasification can reduce this to Read More