The more neutrons that are present in the nuclear reactor the more fission will produce thus more energy would be gained. This is called a chain reaction. to continue a chain reaction, minimum mass of uranium – 235 must be present. This is the critical mass. If the critical mass is not provided, the neutrons will escape. Also, the uranium could only capture the neutrons if they are slow. To do this, a moderator is used. This material surrounds the fuel rods (contains uranium – 235). The control rods are also used; these are present so that they can absorb excess neutrons, and they also ensure that the energy from the nuclear reaction is released in a slow and controlled rather than uncontrolled which would take place in a nuclear weapon.
The energy released is in the form of kinetic energy, which gets converted to thermal energy( in the moderator) as the neutrons are slowed down by collisions with the moderator atoms. A coolant is then used, which can extract this energy, and use I as a heat exchanger to turn water into steam at high temp. and pressure. The steam can then be used to turn the turbines, and finally producing electricity.
Brief Procedure:
Nuclear fission ----- Heat water to make steam ----- Steam turn turbines ----- Turbines turn generator ----- Electrical power
Energy transfer during the procedure:
nuclear energy --- kinetic energy of particles – thermal energy – kinetic energy of rotation --- electrical energy
Hydroelectricity
Introduction:
Hydroelectricity is the electricity produced by the movements of water, in other words, generated by hydropower. This is the production of power through the use of the gravitational force of falling or flowing water. Hydroelectricity is a form of renewable energy.
The procedure for the conversion of hydropower to electricity.
The water - typically held behind a dam - is forced through a turbine generator, which makes the generator spin. When the generator spins, magnets attached to the turbine portion move by magnets mounted on the generator walls just outside the turbine to produce electrical currents, which are harnessed as electricity.
Note: Gravitational potential energy is stored in the water above the dam. Since the water falls from a height, it would arrive at the turbines at high pressure, which means that a large amount of energy could be extracted from it.
Solar Power
Introduction:
Solar power generates electricity by using sunlight. Solar cells or photovoltaic cells are devices that convert radiant energy into the electrical energy, but this is direct. Sunlight can be converted to heat first and then to electricity. In this case it is indirect since the sunlight is used as a heat to boil water first and then provide electricity.
The procedure for the conversion of solar power to electricity.
Photovoltaic cell directly converts light energy into electricity at atomic level. This is due to the photoelectric effect that causes them to absorb photons of light and release electrons. When these free electrons are captured, electric current results, that is electricity (Passive solar)
Another way is to use the solar panels (Active solar); they are basically thermal collectors, which heats a liquid (water mainly) and then pass the heated liquid through the heat exchanger to produce heat for a building.
The energy transfer can be seen:
Solar Furnaces use a huge array of mirrors to concentrate the Sun's energy into a small space and produce very high temperatures.
Other uses include: Solar cells provide the energy to run satellites that orbit the earth.
Wind Power
Introduction:
Wind power generates electricity using the wind. There are two types of wind turbines; one is on a tower (horizontal axis turbine) and the other one is placed on the ground, vertical axis.
Different parts can be seen on the right, of the wind turbine from the diagram. The rotor or the propeller blade is the part which turns when the wind comes. This causes the coil of wire to rotate with the generator. The gearbox is present there so that the speed of the rotor would match the speed of the turbine. Simply, as the wind comes, the rotor rotates the turbine move which turn the generator.
Energy transfer:
Geothermal
Geothermal power is power extracted from heat stored in earth. This geothermal energy basically comes of the planet from radioactive decay of minerals, and from solar energy absorbed at the surface.
The hot rocks underground, heat the water to produce steam. When the earth is drilled down to the hot region, steams comes up which is purified and then it is used to drive the turbines which drive the generators producing electricity.
Note: How useful the geothermal energy is ,depends on how hot the water gets. This depends on how hot the rocks were to start with, and how much water we pump down to them.
Water is pumped down an "injection well", filters through the cracks in the rocks in the hot region, and comes back up the "recovery well" under pressure. It "flashes" into steam when it reaches the surface. If the steam is not purified then it would ruin the turbine blades.
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Wave Power
Wave power is the transport of energy by ocean surface waves, and the capture of that energy to do useful work — for example for electricity generation.
At a wave power station, the waves arriving cause the water in the chamber to rise and fall, which means that air is forced in and out of the hole in the top of the chamber. The turbine placed in this hole, is turned by the air rushing in and out. The turbine turns a generator.