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47-735: This region was originally covered with dense forests and meandering rivers. In the course of urbanization and lignite open pit mining , large areas were deforested and many rivers and streams canalised or diverted. The Leipzig Bay is bounded to the north by the Düben Heath , to the east by the River Elbe , to the south by the Ore Mountain Foreland and the Central Saxon Hills , and by the River Saale to

94-474: A fuel for steam-electric power generation . Lignite combustion produces less heat for the amount of carbon dioxide and sulfur released than other ranks of coal. As a result, lignite is the most harmful coal to human health. Depending on the source, various toxic heavy metals , including naturally occurring radioactive materials , may be present in lignite and left over in the coal fly ash produced from its combustion, further increasing health risks. Lignite

141-560: A fuel for poor people compared to higher value hard coals. In Germany, briquettes are still readily available to end consumers in home improvement stores and supermarkets. An environmentally beneficial use of lignite is in agriculture. Lignite may have value as an environmentally benign soil amendment , improving cation exchange and phosphorus availability in soils while reducing availability of heavy metals, and may be superior to commercial K humates. Lignite fly ash produced by combustion of lignite in power plants may also be valuable as

188-732: A moist, mineral-matter-free basis. The energy content of lignite consumed in the United States averages 15 MJ/kg (13 million BTU/ton), on the as-received basis. The energy content of lignite consumed in Victoria, Australia, averages 8.6 MJ/kg (8.2 million BTU/ton) on a net wet basis. Lignite has a high content of volatile matter which makes it easier to convert into gas and liquid petroleum products than higher-ranking coals. Its high moisture content and susceptibility to spontaneous combustion can cause problems in transportation and storage. Processes which remove water from brown coal reduce

235-524: A proposed alternative for a future hydrogen economy . Reciprocating steam engines have been used for mechanical power sources since the 18th Century, with notable improvements being made by James Watt . The very first commercial central electrical generating stations in New York and London, in 1882, also used reciprocating steam engines. As generator sizes increased, eventually turbines took over due to higher efficiency and lower cost of construction. By

282-430: A result of increased temperatures and pressures underground. Lignite forms from peat that has not been subjected to deep burial and heating. It forms at temperatures below 100 °C (212 °F), primarily by biochemical degradation. This includes the process of humification, in which microorganisms extract hydrocarbons from peat and form humic acids, which decrease the rate of bacterial decay. In lignite, humification

329-413: A soil amendment and fertilizer. However, rigorous studies of the long-term benefits of lignite products in agriculture are lacking. Lignite may also be used for the cultivation and distribution of biological control microbes that suppress plant pests. The carbon increases the organic matter in the soil while the biological control microbes provide an alternative to chemical pesticides. Leonardite

376-421: Is a hardened, gem-like form of lignite used in various types of jewelry. Germany is the largest producer of lignite, followed by China , Russia , and United States . Lignite accounted for 8% of all U.S. coal production in 2019. – no data available Steam-electric power generation A steam–electric power station is a power station in which the electric generator is steam -driven: water

423-418: Is a soft, brown, combustible sedimentary rock formed from naturally compressed peat . It has a carbon content around 25–35% and is considered the lowest rank of coal due to its relatively low heat content . When removed from the ground, it contains a very high amount of moisture , which partially explains its low carbon content. Lignite is mined all around the world and is used almost exclusively as

470-563: Is a soil conditioner rich in humic acids that is formed by natural oxidation when lignite comes in contact with air. The process can be replicated artificially on a large scale. The less matured xyloid (wood-shaped) lignite also contains high amounts of humic acid. Reaction with quaternary amine forms a product called amine-treated lignite (ATL), which is used in drilling mud to reduce fluid loss during drilling. Lignite may have potential uses as an industrial adsorbent . Experiments show that its adsorption of methylene blue falls within

517-520: Is brownish-black in color and has a carbon content of 60–70 percent on a dry ash-free basis. However, its inherent moisture content is sometimes as high as 75 percent and its ash content ranges from 6–19 percent, compared with 6–12 percent for bituminous coal . As a result, its carbon content on the as-received basis (i.e., containing both inherent moisture and mineral matter) is typically just 25-35 percent. The energy content of lignite ranges from 10 to 20 MJ/kg (9–17 million BTU per short ton ) on

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564-536: Is called slacking or slackening . Most lignite is used to generate electricity. However, small amounts are used in agriculture , in industry , and even, as jet , in jewelry . Its historical use as fuel for home heating has continuously declined and is now of lower importance than its use to generate electricity. Lignite is often found in thick beds located near the surface, making it inexpensive to mine. However, because of its low energy density , tendency to crumble, and typically high moisture content, brown coal

611-720: 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. Worldwide, most electric power is produced by steam–electric power plants. The only widely used alternatives are photovoltaics , direct mechanical power conversion as found in hydroelectric and wind turbine power as well as some more exotic applications like tidal power or wave power and finally some forms of geothermal power plants. Niche applications for methods like betavoltaics or chemical power conversion (including electrochemistry ) are only of relevance in batteries and atomic batteries . Fuel cells are

658-461: Is heated, evaporates , and spins a steam turbine which drives an electric generator. After it passes through the turbine, the steam is condensed in a condenser . The greatest variation in the design of steam–electric power plants is due to the different fuel sources. Almost all coal , nuclear , geothermal , solar thermal electric power plants, waste incineration plants as well as many natural gas power plants are steam–electric. Natural gas

705-734: Is inefficient to transport and is not traded extensively on the world market compared with higher coal grades. It is often burned in power stations near the mines, such as in Poland's Bełchatów plant and Turów plant , Australia's Latrobe Valley and Luminant 's Monticello plant and Martin Lake plant in Texas. Primarily because of latent high moisture content and low energy density of brown coal, carbon dioxide emissions from traditional brown-coal-fired plants are generally much higher per megawatt-hour generated than for comparable black-coal plants, with

752-414: Is much less than atmospheric pressure, the condenser generally works under vacuum . Thus leaks of non-condensable air into the closed loop must be prevented. Plants operating in hot climates may have to reduce output if their source of condenser cooling water becomes warmer; unfortunately this usually coincides with periods of high electrical demand for air conditioning . If a good source of cooling water

799-415: Is not available, cooling towers may be used to reject waste heat to the atmosphere. A large river or lake can also be used as a heat sink for cooling the condensers; temperature rises in naturally occurring waters may have undesirable ecological effects, but may also incidentally improve yields of fish in some circumstances. In the case of a conventional steam–electric power plant using a drum boiler ,

846-492: Is partial, coming to completion only when the coal reaches sub-bituminous rank. The most characteristic chemical change in the organic material during formation of lignite is the sharp reduction in the number of C=O and C-O-R functional groups. Lignite deposits are typically younger than higher-ranked coals, with the majority of them having formed during the Tertiary period. Lignite is often found in thick beds located near

893-404: Is withdrawn from the bottom of the condenser. The adjacent image is a diagram of a typical surface condenser. For best efficiency, the temperature in the condenser must be kept as low as practical in order to achieve the lowest possible pressure in the condensing steam. Since the condenser temperature can almost always be kept significantly below 100 °C where the vapor pressure of water

940-418: The critical pressure ) to maintain supercriticality and there are issues with corrosion. Steam–electric power plants use a surface condenser cooled by water circulating through tubes. The steam which was used to turn the turbine is exhausted into the condenser and is condensed as it comes in contact with the tubes full of cool circulating water. The condensed steam, commonly referred to as condensate .

987-596: The railway network was dependent on lignite either through steam trains or electrified lines mostly fed with lignite derived power. As per the table below, East Germany was the largest producer of lignite for much of its existence as an independent state. In 2014, about 12 percent of Germany's energy and, specifically, 27 percent of Germany's electricity came from lignite power plants, while in 2014 in Greece , lignite provided about 50 percent of its power needs. Germany has announced plans to phase out lignite by 2038 at

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1034-593: The reclamation of old lignite pits and mining facilities and their conversion into recreation areas, especially north and south of Leipzig. By flooding some the open-cast mines many new lakes have been and are being created in the Leipzig Basin, which are gradually changing the face of the landscape. 51°00′00″N 13°00′00″E  /  51.0000°N 13.0000°E  / 51.0000; 13.0000 Lignite Lignite (derived from Latin lignum meaning 'wood'), often referred to as brown coal ,

1081-443: The thermodynamic efficiency of the system. This reduces plant operating costs and also helps to avoid thermal shock to the boiler metal when the feedwater is introduced back into the steam cycle. Once this water is inside the boiler or steam generator , the process of adding the latent heat of vaporization begins. The boiler transfers energy to the water by the chemical reaction of burning some type of fuel. The water enters

1128-404: The 1920s any central station larger than a few thousand kilowatts would use a turbine prime mover. The efficiency of a conventional steam–electric power plant, defined as energy produced by the plant divided by the heating value of the fuel consumed by it, is typically 33 to 48%, limited as all heat engines are by the laws of thermodynamics (See: Carnot cycle ). The rest of the energy must leave

1175-420: The area remains saturated with water, which covers dead vegetation and protects it from atmospheric oxygen. Otherwise, peat swamps are found in a variety of climates and geographical settings. Anaerobic bacteria may contribute to the degradation of peat, but this process takes a long time, particularly in acidic water. Burial by other sediments further slows biological degradation, and subsequent transformations are

1222-406: The boiler through a section in the convection pass called the economizer . From the economizer, it passes to the steam drum, from where it goes down the downcomers to the lower inlet water wall headers. From the inlet headers, the water rises through the waterwalls. Some of it is turned into steam due to the heat being generated by the burners located on the front and rear waterwalls (typically). From

1269-511: The compass, linking the Leipzig Bay with other parts of the country. Only inland shipping has no direct access to this region, although work on the unfinished Elster-Saale Canal began in the mid 20th century. The Leipzig region is historically, culturally and economically of huge importance to Central Germany . Although open-cast mining continues in the area, it is also being developed from an environmental and tourist perspective, through

1316-484: The efficiency of the plant is fundamentally limited by the ratio of the absolute temperatures of the steam at turbine input and output, efficiency improvements require use of higher temperature, and therefore higher pressure, steam. Historically, other working fluids such as mercury have been experimentally used in a mercury vapour turbine power plant, since these can attain higher temperatures than water at lower working pressures. However, poor heat transfer properties and

1363-402: The geothermal steam is very corrosive or contains excessive suspended solids. Nuclear plants also boil water to raise steam, either directly passing the working steam through the reactor or else using an intermediate heat exchanger. After the steam is conditioned by the drying equipment inside the drum, it is piped from the upper drum area into an elaborate set up of tubing in different areas of

1410-931: The governments of Japan and Australia has begun extracting hydrogen from brown coal. The liquefied hydrogen will be shipped via the transporter Suiso Frontier to Japan. The largest lignite deposits in North America are the Gulf Coast lignites and the Fort Union lignite field. The Gulf Coast lignites are located in a band running from Texas to Alabama roughly parallel to the Gulf Coast. The Fort Union lignite field stretches from North Dakota to Saskatchewan . Both are important commercial sources of lignite. Lignite can be separated into two types: xyloid lignite or fossil wood , and compact lignite or perfect lignite. Although xyloid lignite may sometimes have

1457-881: The land has been restored to full productivity. A bond (not necessary in this form) for mine reclamation is required in the US by the Surface Mining Control and Reclamation Act of 1977 . The Latrobe Valley in Victoria , Australia , contains estimated reserves of some 65 billion tonnes of brown coal. The deposit is equivalent to 25 percent of known world reserves. The coal seams are up to 98 m (322 ft) thick, with multiple coal seams often giving virtually continuous brown coal thickness of up to 230 m (755 ft). Seams are covered by very little overburden (10 to 20 m (33 to 66 ft)). A partnership led by Kawasaki Heavy Industries and backed by

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1504-473: The latest. Greece has confirmed that the last coal plant will be shut in 2025 after receiving pressure from the European Union and plans to heavily invest in renewable energy . Lignite was and is used as a replacement for or in combination with firewood for home heating. It is usually pressed into briquettes for that use. Due to the smell it gives off when burned, lignite was often seen as

1551-407: The lignite is removed, restoration involves grading the mine spoil to as close an approximation as practical of the original ground surface (Approximate Original Contour or AOC). Subsoil and topsoil are restored and the land reseeded with various grasses. In North Dakota , a performance bond is held against the mining company for at least ten years after the end of mining operations to guarantee that

1598-498: The obvious hazard of toxicity have ruled out mercury as a working fluid. Another option is using a supercritical fluid as a working fluid. Supercritical fluids behave similar to gases in some respects and similar to liquids in others. Supercritical water or supercritical carbon dioxide can be heated to much higher temperatures than are achieved in conventional steam cycles thus allowing for higher thermal efficiency . However, these substances need to be kept at high pressures (above

1645-421: The plant in the form of heat. This waste heat can be removed by cooling water or in cooling towers . ( cogeneration uses the waste heat for district heating ). An important class of steam power plants is associated with desalination facilities, which are typically found in desert countries with large supplies of natural gas . In these plants freshwater and electricity are equally important products. Since

1692-746: The range of activated carbons currently used by industry. Jet is a form of lignite that has been used as a gemstone. The earliest jet artifacts date to 10,000 BCE and jet was used extensively in necklaces and other ornamentation in Britain from the Neolithic until the end of Roman Britain . Jet experienced a brief revival in Victorian Britain . Lignite begins as partially decayed plant material, or peat. Peat tends to accumulate in areas with high moisture, slow land subsidence , and no disturbance by rivers or oceans – under these conditions,

1739-414: The risk of spontaneous combustion to the same level as black coal, increase the calorific value of brown coal to a black coal equivalent fuel, and significantly reduce the emissions profile of 'densified' brown coal to a level similar to or better than most black coals. However, removing the moisture increases the cost of the final lignite fuel. Lignite rapidly degrades when exposed to air. This process

1786-422: The subsurface beds. Topsoil and subsoil must be properly removed and either used to reclaim previously mined-out areas or stored for future reclamation. Excavator and truck overburden removal prepares the area for dragline overburden removal to expose the lignite beds. These are broken up using specially equipped tractors ( coal ripping ) and then loaded into bottom dump trucks using front loaders . Once

1833-418: The surface condenser removes the latent heat of vaporization from the steam as it changes states from vapor to liquid. The condensate pump then pumps the condensate water through a feedwater heater , which raises the temperature of the water by using extraction steam from various stages of the turbine. Preheating the feedwater reduces the irreversibilities involved in steam generation and therefore improves

1880-409: The surface. These are inexpensive to extract using various forms of surface mining , though this can result in serious environmental damage. Regulations in the United States and other countries require that land that is surface mined must be restored to its original productivity once mining is complete. Strip mining of lignite in the United States begins with drilling to establish the extent of

1927-401: The tenacity and the appearance of ordinary wood, it can be seen that the combustible woody tissue has experienced a great modification. It is reducible to a fine powder by trituration , and if submitted to the action of a weak solution of potash , it yields a considerable quantity of humic acid . Leonardite is an oxidized form of lignite, which also contains high levels of humic acid. Jet

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1974-550: The valleys of the Saale , White Elster , Mulde , and Pleiße rivers. The Leipzig Bay was formed during the Tertiary period. When the Ore Mountains and Vogtland were uplifted, a basin was formed as a compensating movement, into which weathering material from the mountain ranges was deposited. As a result of the creation of bogs and variable flooding , organic material was also deposited in this basin, which in turn

2021-547: The waterwalls, the water/steam mixture enters the steam drum and passes through a series of steam and water separators and then dryers inside the steam drum . The steam separators and dryers remove water droplets from the steam; liquid water carried over into the turbine can produce destructive erosion of the turbine blades. and the cycle through the waterwalls is repeated. This process is known as natural circulation . Geothermal plants need no boiler since they use naturally occurring steam sources. Heat exchangers may be used where

2068-536: The west. The conurbation formed by the two cities of Leipzig and Halle lies in the centre of the Leipzig Bay. Other important towns are Delitzsch , Eilenburg , Merseburg and Borna . The Leipzig Bay is a Young Drift landscape and the southernmost part of the North German Plain . The landscape is essentially a plain broken only by low eminences such as the Hohburg Hills and dissected by

2115-501: The world's highest-emitting plant being Australia's Hazelwood Power Station until its closure in March 2017. The operation of traditional brown-coal plants, particularly in combination with strip mining , is politically contentious due to environmental concerns. The German Democratic Republic relied extensively on lignite to become energy self-sufficient , and eventually obtained 70% of its energy requirements from lignite. Lignite

2162-496: Was also an important chemical industry feedstock via Bergius process or Fischer-Tropsch synthesis in lieu of petroleum, which had to be imported for hard currency following a change in policy by the Soviet Union in the 1970s, which had previously delivered petroleum at below market rates. East German scientists even converted lignite into coke suitable for metallurgical uses ( high temperature lignite coke ) and much of

2209-546: Was overlaid by sediments . Brown coal or lignite was formed from these deposits, which is covered by layers of sand and loess . The landscape is very well served by communications. A cardioid ring motorway runs around the Leipzig-Halle conurbation, the so-called Central German Loop ( Mitteldeutsche Schleife ). Leipzig/Halle Airport is an important transport hub in the eastern German states. Railway lines and Bundesstraßen (federal roads) run in all directions of

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