Submitted by :
Rupinder Kaur

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Thermal power station
A thermal power station is a power plant in which the prime mover is steam driven.
Water is heated, turns into steam and spins asteam turbine which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated; this is known as a Rankine cycle. The greatest variation in the design of thermal power stations is due to the different fuel sources. Some prefer to use the term energy center because such facilities convert forms of heat energy into electrical energy. Some thermal power plants also deliver heat energy for industrial purposes, for district heating, or for desalination of water as well as delivering electrical power.
Almost all coal, nuclear, geothermal, solar thermal electric, and waste incineration plants, as well as many natural gas power plants are thermal. Natural gas is frequently combusted in gas turbines as well as boilers. The waste heat from a gas turbine can be used to raise steam, in a combined cycle plant that improves overall efficiency.
Power plants burning coal, oil, or natural gas are often referred to collectively as fossil-fuel power plants. Some biomass-fueled thermal power plants have appeared also.
Non-nuclear thermal power plants, particularly fossil-fueled plants, which do not use co-generation are sometimes referred to as conventional power plants.
Environmental impact of Fossil Fuels power plant
It includes the consideration of issues such as land use, waste management and water and air pollution caused by the extraction and processing of oil shale.
1.) Land use and waste management
• Surface mining and in-situ processing requires extensive land use. Mining, processing and waste disposal require land to be withdrawn from traditional uses, and therefore should avoid high density population areas
• Oil shale mining reduces the original ecosystem diversity with habitats supporting a variety of plants and animals. After mining the land has to be reclaimed. However, this process takes time and cannot necessarily re-establish the original biodiversity.
• Disposal of mining wastes, spent oil shale (including semi-coke) and combustion ashes needs additional land use.
According to the study of the European Academies Science Advisory Council, after processing, the waste material occupies a greater volume than the material extracted, and therefore cannot be wholly disposed underground. According to this, production of a barrel of shale oil can generate up to 1.5 tons of semi-coke, which may occupy up to 25 % greater volume than the original shale. The mining and processing of 1000 million tons of oil shale in Estonia has created about 360-370 million tons of solid waste, of which 90 million tons is a mining waste, 70–80 million tons is a semi-coke, and 200 million tons are combustion ashes.
• The waste material may consist of several pollutants including sulfates, heavy metals, and polycylic aromatic hydrocarbons (PAHs), some of which are toxic and carcinogenic. To avoid contamination of the groundwater, the solid waste from the thermal treatment process is disposed in an open dump (landfill or "heaps"), not underground.
• As semi-coke consists of, in addition to minerals, up to 10 % organics that may pose hazard to the environment owing to leaching of toxic compounds as well as to the possibility of self-ignition
2.) Water management
Mining influences the water runoff pattern of the area affected.
• The thermal processing of oil shale needs water for quenching hot products and the control of dust..
Depending on technology, above-ground retorting uses between one and five barrels of water per barrel of produced shale oil In situ processing, according to one estimate, uses about one-tenth as much water.
• Water represents the major vector of transfer of oil shale industry pollutants. One environmental issue is to prevent noxious materials leaching from spent shale into the water supply .The oil shale processing is accompanied by the formation of process waters and waste waters containing phenols, tar and several other products, heavily separable and toxic to the environment.
3.) Air pollution management
Burning coal is a leading cause of smog,acid,rain, global warming, and air toxics.
In an average year, a typical coal plant generates:
• 3,700,000 tons of carbon dioxide (CO2), the primary human cause of global warming--as much carbon dioxide as cutting down 161 million trees.
• 10,000 tons of sulfur dioxide (SO2), which causes acid rain that damages forests, lakes, and buildings, and forms small airborne particles that can penetrate deep
into lungs.
• 500 tons of small airborne particles, which can cause chronic bronchitis, aggravated asthma, and premature death, as well as haze obstructing visibility.
• 10,200 tons of nitrogen oxide (NOx), as much as would be emitted by half a million late-model cars. NOx leads to formation of ozone (smog) which inflames the lungs, burning through lung tissue making people more susceptible to respiratory illness.
• 720 tons of carbon monoxide (CO), which causes headaches and place additional stress on people with heart disease.
• 220 tons of hydrocarbons, volatile organic compounds (VOC), which form ozone.
• 170 pounds of mercury, where just 1/70th of a teaspoon deposited on a 25-acre lake can make the fish unsafe to eat.
• 225 pounds of arsenic, which will cause cancer in one out of 100 people who drink water containing 50 parts per billion.
• 114 pounds of lead, 4 pounds of cadmium, other toxic heavy metals, and trace amounts of uranium.