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Energy Sources - Coggle Diagram

- - - - Coal ranks as one of the world's main forms of fuel.It is the dirtiest of all fossil fuels,it is cheap,abundant and available.The three main types of coal are:
        bituminous coal,the most important coal used for generating electricity,making coke and producing heat;
        anthracite coal,which has value as a fuel,because it burns slowly,producing a lot of heat and very little smoke;
        lignite,which contains a great deal of moisture and produces less heat than anthracite and bituminous coal.
      - Wood was once man's main fuel.
      - Peat,like lignite,contains a great deal of moisture and therefore is a poor fuel.
    - - They include crude oil which is found in areas that are,or once,were,covered by oceans.Microorganisms that sank to the bottom of the ocean were covered by sediment,sediment changed into rock and the organic matter changed into oil.
        
        Petroleum:black gold
        
        Petroleum,or crude oil,is often called black gold because it is so valuable to mankind.It comes from the Earth as a dark flammable liquid which consists of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds.A fossil fuel is formed when large quantities of dead organisms,zooplankton and algae are buried and undergo intense heat and pressure.Petroleum is derived mostly by drilling for oil.It is used in a large number of consumer products,from petrol and kerosene to asphalt and chemical reagents used to make plastics and pharmaceuticals.It is estimated that the world consumes about 88 million barrels each day.They can have a negative impact on the Earth's biosphere,releasing pollutants and greenhouse gases into the air and damaging ecosystems through events such as oil spills.
    - - They include natural gas coming from wells which are drilled deep underground.It is an ideal fuel.When burned,it gives off almost twice as much heat as the common manufactured gases,and leaves no ash or other waste.
- - - - Atoms are made up of Protons,neutrons and electrons.The most fissionable atom is an isotope of uranium known as uranium 235(U-235),which is used in most types of nuclear reactors today.U-235 is relatively rare.Besides U-235,the most common non fossil fuel is plutonium 239.
    - - Most power plants burn fuel to produce electricity.Fission takes place inside the reactor.At the centre of the reactor is the core,which contains uranium fuel.Fission generates heat in a reactor just as coal generates heat in a boiler to boil water into steam.The steam turns huge turbine blades.As they turn,they drive generators that make electricity.Afterwards,the steam changes back into water and cools in a separate structure at the power plant called cooling tower,so that it could be used again and again.Nuclear power provides about 6% of the world's energy and 13-14% of the world's electricity.The radioactive waste the nuclear industry collects is highly hazardous to people and wildlife.
- - - - The electricity produced from the sun's rays is called solar energy.The sun sends out a never-ending stream of radiant energy.Most of this energy is called sunlight.The amount of solar energy streaming towards the Earth in only one day equals the energy that is produced by burning 550 tons of coal.Solar energy can be produced directly from the sun:
        by absorbing the heat and storing it to be used,for example for heating buildings and water;
        by converting sunlight to electricity using photovoltaic cells.
        This area is constantly being improved by research and development,and production costs are being reduced.Solar energy is captured by two types of solar panel systems called solar photovoltaic and solar thermal systems.The word photovoltaic comes from "photo"(light) and "voltaic"(electricity).Photovoltaic cells are made of special materials called semiconductors such as silicon.Basically,when light strikes the cell,a certain portion of it is absorbed within the semiconductor material.Absorbed light transferred to the semiconductor of the PV cell,then can be collected for external use.
    - - It is obtained by damming rivers and utilising the potential energy stored in water.Hydroelectric dams are very expensive to build,but the water comes free of charge,and there is no waste or pollution.
    - - It is a form of energy that comes from the ocean and the method is similar to a hydroelectric power plant.When waves come into the shore,they can be trapped in reservoirs behind dams.
    - - It is gas produced by most mammals when they digest their food.Biogas can be used instead of natural gas for heating and cooking.
    - - It is organic material which has stored sunlight in the form of chemical energy.They include wood,wood waste,straw,manure,sugar cane.Biomass is a renewable energy source because the energy it contains comes from the sun.
    - - Man has expolited the wind for thousands of years and by medieval times there were hundreds of windmills in the UK and Holland.Some were used for turning millstones that crushed grain into flour.Today,wind power is also used as another renewable energy source using wind turbines.Harnessing the wind is highly dependent upon weather and location.Therefore it is convenient to install wind turbines in very windy places.A wind turbine is a machine made of two or three propeller-like blades called the rotor which is attached to the top of a tall tower.As the wind blows it spins the rotor,the energy of the movement of the propellers gives power to a generator,that make electricity.Wind turbines are 30 metres tall to allow the rotor to catch more wind energy.The turbines are built with a device that turns the rotor so that it always faces the wind.The electrical energy can also be stored in batteries.Places where there are a number of wind turbines clustered together are called wind farms.
    - - The adjective geothermal originates from the two Greek terms geo,meaning earth,and thermos,meaning hot.Geothermal energy is generated and stored in the Earth.It is the energy that determines the temperature of matter.It originates from the original formation of the planet(20%) and from the radioactive decay of minerals(80%).The geothermal gradient,drives a continuous conduction of thermal energy in the form of heat from the core to the surface.Geothermal energy has been used in hot springs for bathing since Paleolithic times and for heating building since ancient Roman times,but it is now better known for electricity generation.Geothermal power is cost-effective,reliable,sustainable,and environmentally friendly,but is limited to areas near tectonic plate boundaries.The Earth's geothermal resources are theoretically more than adequate to supply the energy needs of the population.Drilling and exploration for deep resources is very expensive.