Renewable Energy Sources

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Chapter 9 : Renewable Energy Sources

Renewable Energy arrow_upward

  • Renewable Energy is energy which comes from natural resources such as:
    • Sunlight
    • Wind
    • Rain
    • Tides
    • Geothermal heat
  • Renewable means naturally replenished.
  • About 19% of global final energy consumption came from renewables, with 13% coming from traditional biomass.
  • Renewable energy replaces conventional fuels in three distinct areas.
    • Power generation
    • Heating
    • Transport fuels

    Forms of Renewable Energy arrow_upward

  • There are various renewable energy sources that are classified as:
    • Wind Power
    • Hydro Power
    • Solar Energy
    • Biomass
    • Biofuel
    • Geothermal Energy
    • Ocean Energy

    Wind Power arrow_upward

  • Wind is a form of solar energy.
  • It is caused by uneven heating of atmosphere by the Sun, irregularities of the earth’s surface, and rotation of the earth.
  • The amount and speed of wind depends on the Earth’s terrain and other factors.
  •  Advantages:
    • Wind is free.
    • Wind farms need no fuel.
    • Produces no waste or greenhouse gases.
    • The land beneath can still be used for farming.
  • Disadvantages:
    • Not always predictable.
    • Changing landscape.
    • Can kill birds - migrating flocks tend to like strong winds.
    • Noisy: A wind generator makes a constant, low, "swooshing" noise day and night.

    Hydro Power arrow_upward

  • Water flows from a high potential energy (high ground) to lower potential energy (lower ground).
  • This potential energy difference is partially converted into electric energy through the use of a generator.
  • Hydroelectric energy is a term usually reserved for large-scale hydroelectric dams.
  • Examples:
    • The Grand Coulee Dam in Washington State and the Akosombo Dam in Ghana.
  • There are two major designs in use that utilize water to produce electricity.
    • Hydroelectric Dams
    • Pumped-Storage Plant

    Solar Energy arrow_upward

  • Solar energy is the energy derived from the sun through the form of solar radiation.
  • Solar technologies are broadly characterized depending on the way they capture, convert and distribute solar energy.
  • Passive Solar:
    • Include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties.
  • Active Solar:
    • Include the use of photovoltaic panels and solar thermal collectors to harness the energy.
  • Applications:
    • Solar powered electrical generation relies on photovoltaic and heat engines.
    • Space heating and cooling through solar architecture.
    • Solar hot water, solar cooking.
    • High temperature process heat for industrial purposes.

    Biomass arrow_upward

  • Biomass (plant material) is a renewable energy source because the energy it contains comes from the sun.
  • Through the process of photosynthesis, plants capture the sun's energy.
    • When the plants are burned, they release the sun's energy they contain.
    • In this way, biomass functions as a sort of natural battery for storing solar energy.
  • As long as biomass is produced sustainably, with only as much used as is grown, the battery will last indefinitely.

  • Biofuel arrow_upward

  • Liquid biofuel is usually either bio-alcohol such as bioethanol or oil such as biodiesel.
  • Bioethanol is an alcohol made by fermenting the sugar components of plant materials and it is made mostly from sugar and starch crops.
  • With advanced technology being developed, cellulosic biomass, such as trees and grasses, are also used as feedstock for ethanol production.
  • Bioethanol is widely used in the USA and in Brazil.
  • Biodiesel is made from vegetable oils, animal fats or recycled greases.
    • Biodiesel can be used as a fuel for vehicles in its pure form.

    Geothermal Energy arrow_upward

  • Geothermal Energy is energy obtained by tapping the heat of the earth itself, both from kilometers deep into the Earth's crust in volcanically active locations of the globe or from shallow depths.

  • Ocean Energy arrow_upward

  • Oceans cover more than 70% of Earth's surface.
  • Oceans are the world's largest solar collectors.
  • The ocean can produce two types of energy.
  • Thermal Energy:
    • The sun's heat warms the surface water a lot more than the deep ocean water, and this temperature difference creates thermal energy.
  • Mechanical Energy:
    • Sun affects all ocean activity, tides are driven primarily by the gravitational pull of the moon, and waves are driven primarily by the winds.
    • A barrage (dam) is typically used to convert tidal energy into electricity by forcing the water through turbines, activating a generator.
    • Mechanical energy is the energy that is possessed by an object due to its motion or due to its position.

    Future of Nuclear Power arrow_upward

  • Nuclear Power is and will remain an important energy resource, especially as world energy use climbs inexorably and the proportion of electricity in it increases.
  • Half a century's experience in harnessing the power of the atom has provided a good basis for going forward with newer technologies for nuclear power generation and for managing the associated wastes.
  • No energy conversion technology producing electricity is without risks or environmental effects.
  • All the implications of all the available options need to be examined carefully.
  • Nuclear power is the only energy-producing industry which takes full responsibility for all its wastes and fully costs this into the product.
  • With sustainable development as the prevailing ethic, nuclear energy has much to offer in the context of the resources supplying it and because it is environmentally benign, all wastes are contained and managed.
  • Nuclear power offers the world a felicitous coincidence of environmental virtue and necessity in the provision of large-scale, base-load electricity.
  • However, public acceptance remains the key factor influencing its future, and perhaps intelligent citizens who already have knowledge and experience of nuclear medicine will be able to give a lead in changing that positively.

  • Review of Current Technology arrow_upward

  • Boiling water reactors and pressurized water reactors.
    • Only 2 commercial designs in the US.
  • Use of thermal energy from nuclear fission to generate steam, power a turbine and produce electricity.
  • Only use Uranium-235 as a fuel source.
  • Single pass systems generate large amounts of radioactive wastes.

  • Advantages of Nuclear Energy arrow_upward

  • Substantial base load energy producing capability.
  • No greenhouse gas emissions during operation.
  • Does not produce air pollutants.
  • The quantity of waste produced is small.
  • Small number of major accidents.
    • Only one (TMI)
  • Low fuel costs.
  • Large fuel reserves.
  • Ease of transport and stockpiling of fuel.
  • Future designs may be small and modular.

  • Nuclear Safety remains a Challenge arrow_upward

  • Public continues to be wary of nuclear power due to Chernobyl, Three Mile Island and Japan accidents.
  • Nuclear plants are vulnerable to terrorist attacks.
  • Both nuclear fission and nuclear fusion reactions can be used to generate large amounts of energy for destructive purposes.
  • When an atom of 235U is bombarded by a neutron:
    • It splits into atoms of cesium (Cs) and rubidium (Rb), releasing a large amount of energy and three additional neutrons.
    • These neutrons, if not controlled, can then cause more 235U atoms to split, leading rapidly to a nuclear explosion (A-bomb).
  • Fusion reactions release energy when two lighter nuclei combine to make a heavier nucleus.

  • Problems with Nuclear Energy arrow_upward

  • Safety,
  • Waste Disposal,
  • Possibly disastrous accidents,
  • Nuclear waste dangerous for thousands of years unless reprocessed,
  • Risk of nuclear proliferation associated with some designs,
  • High capital costs,
  • Long construction periods largely due to regulatory delays,
  • High maintenance costs,
  • High cost of decommissioning plants,
  • Radioactive waste storage,
  • Finite amount of Uranium for fuel.

  • Conclusion arrow_upward

  • Nuclear energy will stay with human society.
  • It is no longer a matter of debate whether there will be new nuclear plants in the industry’s future.
  • Now, the discussion has shifted to predictions of how many, where and when.
  • Further research work is needed to ensure safe operations of nuclear plants and measures to take care of nuclear waste.

  • Thank You from Kimavi arrow_upward

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