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Deniz Cinalioğlu 10-U Coal Crude Oil Naturel Bitumen Natural Gas Oil Shale Peat Nuclear Hydropower Peat Biomass Solar Energy Geothermal Energy Wind Energy Tidal Energy Wave Energy Ocean Thermal Marine Current Energy Hydrogen Coal gasification Deniz Cinalioğlu 10-U Renewable is the term used for forms of energy that can be regenerated, or renewed, in a relatively short amount of time. The regeneration process may be continuous and immediate, as in the case of direct solar radiation, or it may take some hours, months or years. This is the case of wind energy (generated by the uneven heating of air masses), hydro energy (related to the sun- powered cycle of water evaporation and rain), biomass energy (stored in plants through photosynthesis), and the energy contained in marine currents. The energy contained in fossil fuels – coal, oil and natural gas – likewise comes also from the sun's energy, but it was stored in plants millions of years ago, and once used, it cannot be regenerated on a human time scale. They are examples of non renewable energy sources. The earth's remaining fossil fuel reserves can probably provide us with energy for another 100 to 500 years, but this is an insignificant amount of time in terms of the whole past history of human civilisation and of its future. Deniz Cinalioğlu 10-U Coal (non renewable): It is a fossil fuel, and was formed from the remains of plants that were buried and subjected to high presure and heat. It is largely or almost entirely composed of carbon with varying amounts of mineral matter. After the plants die and buried, the chemical changes gradually lower the oxygen and hydrogen content of the cellulose molecules, CH₂O. Coal matures through four stages; lignite, subituminous, bituminous and anthracite. Each stage has a higher Carbon-to- Oxygen and Carbon-to-Hydrogen ratio. The energy available from the combustion of a given mass of coal increases as the Carbon content increases. Crude Oil (non renewable): A thick, flammable, yellow-to-black mixture of gaseous, liquid, and solid hydrocarbons that occurs naturally beneath the earth's surface, can be separated into items including natural gas, gasoline, naphtha, kerosene, fuel and lubricating oils, paraffin wax, and asphalt. It is used as raw material for a wide variety of products. Deniz Cinalioğlu 10-U Deniz Cinalioğlu 10-U 10-U Naturel Bitumen (non renewable): Natural bitumen and extra-heavy oil are closely related types of petroleum, but differ from the petroleum. They have small amounts of the paraffins, and relative enriched heavy molecules, leading to increased density and viscosity. Of these molecules, the asphaltenes are very large and has such non-hydrocarbons as nitrogen, sulphur, oxygen, and metals, in particular nickel and vanadium. The result of the this composition creates problems more than the problems of conventional petroleum with respect to exploitation, transportation, storage, and refining. This is the reason for the increased cost of extraction and processing and the physical limitations on production capacity. Deniz Cinalioğlu 10-U Natural Gas (non renewable): Natural gas liquids (NGL’s) are hydrocarbons that exist in the reservoir as constituents of natural gas. These are recovered as liquids in separators, field facilities or gas-processing plants. Natural gas liquids include (but are not limited to) ethane, propane, butanes, pentanes, natural gasoline and condensate; they may include small quantities of non- hydrocarbons. Oil shale (non renewable): It does not contain oil nor is it commonly shale. The organic material is mainly kerogen, and the "shale" is usually a relatively hard rock, called marl. Properly processed, kerogen can be converted into a substance somewhat similar to petroleum. However, to be changed into an oil- like substance, it must be heated to a high temperature. By this process the organic material is converted into a liquid. This liquid must be further processed to produce an oil which is said to be better than the lowest grade of oil produced from conventional oil deposits, but of lower quality than the upper grades of conventional oil. Peat (non renewable): Peat is soil material consisting of partially decomposed organic matter; found in swamps and bogs in various parts of the temperate zone. It is formed by the slow decay of successive layers of aquatic and semiaquatic plants, e.g., sedges, reeds, rushes, and mosses. Peatland is defined as follows: for land to be identified as peatland, the depth of the peat layer, excluding the thickness of the plant layer, must be at least 20 cm on drained, and 30 cm on undrained land. Deniz Cinalioğlu 10-U Nuclear Energy (renewable) Deniz Cinalioğlu 10-U Hydropower (renewable): Obtained by storing the water in reservoirs (dams) and utilizing the potential energy or channelizing the water flow for energy generation. Deniz Cinalioğlu 10-U 10-U Biomass(renewable): Residues, forestry, industrial, woody, agricultural, aquatic crops, animal and plant wastes are currently the main sources of bio-energy . A variety of fuels can be made from biomass resources, including the liquid fuels ethanol, methanol, biodiesel, Fischer-Tropsch diesel, and gaseous fuels such as hydrogen and methane. It is an important form of stored energy. Methods for Getting Energy from Biomass: Wood burning Gassification This process, usually using would produce a flammable gas mixture of hydrogen, carbon monoxide, methane and other non flammable by products. This is done by partially burning and partially cooking the biomass (using the heat from the limited burning) in the presence of charcoal (a natural by-product of burning biomass). The gas can be used instead of petrol and reduces the power output of the car by 40%. It is also possible that in the future this fuel could be a major source of energy for power stations. Deniz Cinalioğlu 10-U Anaerobic Digestion/Gasification If a specially formulated mixture of bacteria is added to biomass and water in a sealed container (so that no oxygen can enter it) the contents soon ferment. The product of this fermentation is mainly methane (a flamable gas which is the same as the gas you burn at home) which is an excellent fuel. This process removes biomass from dirty water and may be used in a water treatment plant. Fermentation If the biomass used is (or can be converted into) mostly sugar, then yeast can be added. The fermentation that follows produces alcohol which is a very high energy fuel that makes it very practicle for use in cars. This has been tried succesfully in Brazil. Deniz Cinalioğlu 10-U Solar Energy (renewable): With the exception of nuclear, geothermal and tidal energy, all forms of energy used on earth originate from the sun’s energy. Although sunshine can be collected by solar arrays and used to heat a home or supply its hot-water needs, the unconcentrated rays are not strong enough for efficient power generation. The amount of solar radiation available at the Earth's surface is about 1kW thermal energy per square metre. The idea of using large numbers of reflective panels called heliostats or multi- faced mirrors to concentrate solar radiation has an ancient history dating as far back as 212BC when Archimedes in ancient Syracuse is said to have used polished shields to focus light onto the sails of the Roman ships to burn them. Theoretically, by using mirrors and lenses, the temperature of the sun's surface can be reached. While photovoltaic cells produce electricity directly, solar thermal technologies produce hot air, water and steam for industry. They can also provide energy to photolytically process fuels and chemicals and destroy dangerous materials. Deniz Cinalioğlu 10-U 10-U In new housing areas, use of solar systems can cut the demand for fossil fuel by as much as 70%. Deniz Cinalioğlu 10-U Geothermal Energy (renewable): Geothermal energy is the natural heat of the earth stored deep below the earth's surface. When the earth was formed 5 billion years ago from a cloud of hot gas, it was very hot indeed. Ever since then the earth has been cooling down, loosing it's heat to the cold reaches of space. However a lot of this heat still remains and can be used as a source of energy for the ever increasing demands of civilisation. The energy is found near areas where volcanic activity has taken place, either recently or many years ago. It can be in the form of steam, hot liquid, or hot dry rock. There are many ways of getting the energy to the surface in a usefuk form. Wells drilled deep into the ground bring steam and hot water to the surface There is enough energy for us to consume as much energy as we do now for the next 35 billion years. The only problem is getting to all this energy and converting it efficiently. It is estimated that at present we can only reach enough energy to supply the world's energy needs for one year. This is because of the limits of current geothermal technology and the disperse nature of the energy we can reach. Geothermal energy is currently cheaper than nuclear power and comparable to some conventional energy generation methods, geothermal power is ecenomic enough to warrant it's continued use and developement. Deniz Cinalioğlu 10-U Wind Energy (renewable): The power contained in the wind represents a vast source of energy. There are approximately 20,000 wind turbines connected to the electricity network in operation worldwide. Only a very small amount of wind energy can be used because of technological and also social limitations. The wind turbine vanes use the flowing movement of the air to rotate an electrical generator similar to that in a hydropower station. The actual power being generated is directly linked to the windspeed such that if the windspeed dropped by 10 percent, there will be a 30 percent decrease in available energy. The numerous factors that influence the windspeed include local geographical effects such as ground roughness and the height of the airflow. Deniz Cinalioğlu 10-U Deniz Cinalioğlu 10-U Marine current energy (renewable): The global marine current energy resource is mostly driven by the tides and to a lesser extent by thermal and density effects. The tides cause water to flow inwards twice each day (flood tide) and seawards twice each day (ebb tide) with a period of approximately 12 hours and 24 minutes (a semi-diurnal tide), or once both inwards and seawards in approximately 24 hours and 48 minutes (a diurnal tide). In most locations the tides are a combination of the semi-diurnal and diurnal effects, with the tide being named after the most dominant type. The strength of the currents vary, depending on the proximity of the moon and sun relative to Earth. Generally the marine current resource follows a sinusoidal curve with the largest currents generated during the mid-tide. The strength of the marine currents generated by the tide vary, depending on the position of a site on the earth, the shape of the coastline and the bathymetry (shape of the sea bed). Along straight coastlines and in the middle of deep oceans, the tidal range and marine currents are typically low. Generally, but not always, the strength of the currents is directly related to the tidal height of the location. However, in land-locked seas such as the Mediterranean, where the tidal range is small, some variable marine currents exist. Deniz Cinalioğlu 10-U Deniz Cinalioğlu 10-U Ocean Thermal (renewable): It is common since that if the oceans have sunlight shining on them for up to fifteen hours a day, they are going to be warmed up by this process. In a way this thermal energy (the energy of heat) is solar energy. The oceans make excellent traps for this energy. One of the main advantages is that the oceans do not cool very quickly and therefore, energy can be extracted from them during the night. This is obviously not the case with traditional solar energy technologies. To work effectively, energy conversion from fluids (water in this case) needs a supply of hot and cold water. In the tropical and subtropical regions of the world there is a big difference in temperature between the temperature of the ocean at the surface and at depth. Basically, hot water is pumped in to the plant from the surface of the ocean and cold water is pumped in from the ocean depths. This source of hot and cold fluid drives a heat engine (an engine that runs on energy flow from hot to cold). Below is a basic diagram showing what goes on. Deniz Cinalioğlu 10-U Deniz Cinalioğlu 10-U Wave Energy (renewable): Waves supply many sportsmen and women with a great deal of entertainment and excitement, but out at sea their awesome power can smash ships apart or flip them on their backs. Waves tens of meters high with wavelengths of more than one hundred meters are common in the atlantic and pacific oceans. This energy will exist as long as there are large expanses of water on earth and could supply huge amounts of energy but as yet there are no large scale commercial organizations to exploit them. Deniz Cinalioğlu 10-U Deniz Cinalioğlu 10-U Deniz Cinalioğlu 10-U Deniz Cinalioğlu 10-U Deniz Cinalioğlu 10-U Deniz Cinalioğlu 10-U Deniz Cinalioğlu 10-U Tidal energy (renewable): Most countries have concentrated on the use of capturing structures to create artificial reservoirs that can be used to control the natural tidal flow. It was concluded that building a permeable barrage across an estuary(arm of the sea which extends to the opening of the river) minimizes the cost of civil structures for the quantity of energy that can be produced. Complete closure of estuaries would be achieved by placing a series of prefabricated sections, or caissons, made from concrete or steel which could be floated and then sunk into position. Tidal barrages would consist of gates and turbine generators. During the ebb tide water is allowed to flow through the gates. When water level becomes high the gates are closed. Storage of water allows a head of water (i.e. difference in vertical height of water levels) to be created as the flood tide progresses seaward of the barrage. Once a sufficient head has been created, water is allowed to flow back through the turbines to generate electricity. In this respect a tidal energy barrage is no different to a low-head hydro-electric dam. Deniz Cinalioğlu 10-U Deniz Cinalioğlu 10-U Hydrogen: Hydrogen has a potential as a fuel. It has an advantage over fossil fuels in that the only product of hydrogen hydrogen combustion is water, fossil fuels produce carbon dioxide in addition to water. H₂(g)+1/2o₂(g)=H₂O(l) Currently, hydrogen is maintained from the treatment of natural gas with steam CH₄(g) + H₂O(g)=3H₂(g) + CO(g) but this is not economical. Therefore new ways to maintain hydrogen are being searched. Production of hydrogen from water is possible; by electrolysis of water,thermal decomposition of water, thermochemical decomposition of water and biological decomposition of water. This energy source is not a very common one as it is quite new. Coal Gassification: It is the most economical way of converting dirty coal into clean burning gaseous fuel. It involves four steps. -hydrogasification (high temperature and pressure): C(coal)+H₂O(g)=CO(g)+H₂(g) -catalytic”” increase of H₂: CO(g)+ H₂O(g)=CO₂(g)+H₂(g) -removal of CO₂, H₂: desulfurisation (removal of impurities, H₂S) -catalytic methanation: 3H₂(g)+CO(g)=CH₄(g)+H₂O(g) H₂O(g) is removed and CH₄(g) is called synthetc natural gas. Advantages of coal gassification include the prevention of pollution by sulfur dioxide, but the process requires %30 of the energy content of coal for conversion!
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