RENEWABLE ENEGRY

• Renewable energy


  Energy sources that are replenished in a short time
• Mechanical energy


  • Kinetic energy (energy of motion) and potential energy (stored energy)
• Conversion of mechanical energy

  Potential energy to kinetic energy, kinetic energy to electrical energy, electrical energy to heat energy
• Solar energy conversion


  • Solar cells, solar water heating, solar furnaces
• Natural sources of energy

  • Solar, wind, hydroelectricity, tidal
• Wind speed increases


  More energy can be extracted from the wind turbine
• Every minute, enough solar energy arrives at the Earth to meet our demands for a whole year
• Hydroelectricity


  • Generates power very quickly, unlike other power stations
  • Electricity can be generated constantly
• Ocean Thermal Energy Converter (OTEC)


  A system that extracts heat from the upper part of the ocean, converting some of the energy to useful work, and rejecting the remainder to the cooler deep region
• Ocean Thermal Energy Converters (OTEC)


  • They are essentially pollution free
  • They make use of the sun, which replenishes the internal energy of the ocean surface with its radiation
• Fossil Fuels


  Coal, oil and gas which provide about 66% of the world's electrical power and 95% of the world's total energy demands
• How fossil fuels work

  1. Fuel

  2. Burn to make steam

  3. Steam turns turbines

  4. Turbines turn generators

  5. Electrical power sent around country
• Coal


  • Crushed to a fine dust and burnt
  • Provides around 28% of our energy
• Oil and Gas


  • Can be burnt direct
  • Oil provides 40% of energy
  • Natural gas provides around 20% of the world's consumption of energy
• How nuclear power works

  1. Fission or fusion makes heat

  2. Heat water to make steam

  3. Steam turns turbines

  4. Turbines turn generators

  5. Electrical power sent around country
• Nuclear Reactors


  • Must have strategic arrangement for removing thermal energy from the reactor and a scheme for controlling the energy output
• Russia, France and England have successfully operated nuclear breeder reactor electric power plants
• Plutonium


  Extremely dangerous, has chemical effects on the body, radioactive and decays by emitting alpha particles which are among the most damaging nuclear particles to the internal organs of the human body
• Nuclear Fusion


  Occurs when two light nuclei are fused together to form a heavier nucleus and energy is released
• Nuclear Power Stations in Britain

  • Built on the coast and sea water is used for cooling the steam
  • Carbon dioxide gas is blown through the reactor to carry the heat away
• At Chernobyl, in Ukraine, they did not have a sophisticated system to automatically shut down the reactor if things got out of hand. The reactor overheated, melted and excessive pressure blew out the containment system before they could stop it. Then, with the coolant gone, there was a serious fire. Many people lost their lives.
• Geothermal Energy


  Energy from heat inside the earth
• How Geothermal Energy is extracted

  1. Drilling to the rock

  2. Injecting water into the entrance and recovering the steam formed when the water contacts the hot dry rock
• Law of Conservation of Energy


  Energy is neither created nor destroyed in any given physical system. One kind of energy may be converted easily into another such as potential to Kinetic type or chemical to electrical form, while the total energy always remains the same.
• Law of Conservation of Energy

  • Bullet leaving a gun
  • Kinetic energy of a wheel lifting water
  • Chemical reaction in a voltaic cell
• The following is also an example of transformation of different forms of energy into heat and power: Oil burns to make heat -> Heat boils water -> Water turns to steam -> Steam pressure turns a turbine -> Turbine turns an electric generator -> Generator produces electricity -> Electricity powers light bulbs -> Light bulbs give off light and heat
• It is difficult to imagine spending an entire day without using energy. In a home where electricity supplies all of the energy requirements, the average energy consumption is: Air conditioner and heater (50%), Water heater (20%), Lighting and small appliances (10%), Refrigerator (8%), Other (5%), Ovens and stoves (4%), Clothes dryer (3%)
• Because of the limited amount of nonrenewable energy sources on Earth, it is important to conserve our current supply or to use renewable sources so that our natural resources will be available for future generations.
• Energy conservation is also important because consumption of nonrenewable energy sources contributes to environmental problems such as air pollution and global warming.
• Fossil fuels contain the same constituents - hydrogen and carbon - as those found in fresh biomass
• Environmental impacts pose a significant distinction between biomass and fossil fuels
• When a plant decays, it releases most of its energy back into the atmosphere
• Fossil fuels are locked away deep in the ground and do not affect the earth's atmosphere unless they are burned
• Rising world fuel prices, the growing demand for energy, and concerns about global warming are the key factors driving the increasing interest in renewable energy sources and in biomass in particular
• Biomass


  The best alternative energy source as it is available in large amounts and production of some form of energy from biomass is also less costly
• The use of renewable energy is not new
• Biomass that could normally present a disposal problem is converted into electricity and other useful energy alternative
• Biomass is considered to be one of the key renewable resources of the future at both small- and large-scale levels
• Biomass already supplies 14 per cent of the world's primary energy consumption, and for three quarters of the world's population living in developing countries biomass is the most important source of energy
• With increases in population and per capita demand, and depletion of fossil-fuel resources, the demand for biomass is expected to increase rapidly in developing countries