Environmental Physics Wiki

=IB Physics=

<!--Topic 8: Energy, power and climate changeItalic text

8.1 Energy degradation and power generation
'''8.1 Energy degradation and power generation '''

Topic 8: Energy, power and climate change
8.1 Energy degradation and power generation


 * 8.1.1 State that Thermal Energy may be completely converted to work in a single process, but that continuous conversion of this energy into work requires a cyclical process and the transfer of some energy from the system.


 * Thermal energy may be completely converted to work in a single process, but that continous conversion of this energy into work requires a cyclical process and the transfer of some energy from the system.


 * 8.1.2 Explain what is meant by degraded energy.


 * degraded energy - in any process that involves energy transformations, the energy that is transfered to the surroundings (thermal energy) is no longer available to perform usefull work.


 * 8.1.3 Construct and analyze energy flow diagrams (Sankey diagrams) and identify where the energy is degraded.


 * Sankey diagrams are a specific type of flow diagram, in which the width of the arrows is shown proportionally to the flow quantity. They are typically used to visualize energy or material transfers between processes.Commonly used to visualize the energy accounts or material flow accounts on a regional or national level. Sankey diagrams put a visual emphasis on the major transfers or flows within a system. They are helpful in locating dominant contributions to an overall flow and as such are popular during times of resource scarcity.


 * 8.1.4 Outline the principal mechanisms involved in the production of electrical power.


 * Electric power is defined as the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt.
 * When electric current flows in a circuit, it can transfer energy to do mechanical or thermodynamic work. Devices convert electrical energy into many useful forms, such as heat (electric heaters), light (light bulbs), motion (electric motors), sound (loudspeaker) or chemical changes. Electricity can be produced mechanically by generation, or chemically, or by direct conversion from light in photovoltaic cells, also it can be stored chemically in batteries.

8.2 World Energy Sources 


 * 8.2.1Identify different world energy sources


 * Most of the world's energy resources are from the sun's rays hitting earth - some of that energy has been preserved as fossil energy, some is directly or indirectly usable e.g. via wind, hydro or wave power.
 * The term solar constant is the amount of incoming solar electromagnetic radiation per unit area, measured on the outer surface of Earth's atmosphere, in a plane perpendicular to the rays.s.
 * Some energy sources include:
 * Fossil Fuels
 * Nuclear Power
 * Hydropower
 * Biomass and biofuels
 * Wind power
 * Solar power
 * Geothermal


 * 8.2.2 Outline and distinguish between renewable and non-renewable energy sources


 * Renewable energy sources can be replenished in a short period of time. The five renewable sources used most often are:
 * o biomass - including wood and wood waste
 * o water (hydropower)
 * o geothermal
 * o wind
 * o solar


 * Nonrenewable energy sources come out of the ground as liquids, gases and solids. Right now, crude oil (petroleum) is the only naturally liquid commercial fossil fuel. Natural gas and propane are normally gases, and coal is a solid. Coal, petroleum, natural gas, and propane are all considered fossil fuels because they formed from the buried remains of plants and animals that lived millions of years ago.  Uranium ore, a solid, is mined and converted to a fuel.  Uranium is not a fossil fuel.   These energy sources are considered nonrenewable because they can not be replenished (made again) in a short period of time.  Renewable energy sources can be replenished naturally in a short period of time.


 * 8.2.3 Define the Energy Density of a fuel


 * In energy storage application the energy density relates the mass of an energy store to its stored energy. The higher the energy density, the more energy may be stored or transported for the same amount of mass. In the context of fuel selection, that energy density of a fuel is also called the specific energy of that fuel, though in general an engine using that fuel will yield less energy due to inefficiencies and thermodynamic considerations—hence the specific fuel consumption of an engine will be greater than the reciprocal of the specific energy of the fuel.


 * 8.2.4 Discuss how choice of fuel is influenced by its energy density




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 * 8.2.5 State the relative proportions of world use of the different energy sources that are available


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 * 8.2.6 Discuss the relative advantages and disadvantages associated with various energy sources


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8.3 Fossil Fuel power production


 * 8.3.1 Outline the historical and geographical reasons for the widespread use of fossil fuels


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 * 8.3.2 Discuss the energy density of fossil fuels with respect to the demands of power stations


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 * 8.3.3Discuss the relative advantages and disadvantages with the transportation and storage of fossil fuels


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 * 8.3.4State the overall efficiency of power stations fuelled by different fossil fuels


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 * 8.3.5Describe the environmental problems associated with the recovery of fossil fuels and their use in power stations.


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8.4 Non-Fossil Fuel and Production


 * 8.4.1Describe how neutrons produced in a fission reaction may be use to initiate further fission reactions (chain reactions)


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 * 8.4.2Distinguish between controlled nuclear fission (power production) and uncontrolled nuclear fission (nuclear weapons)


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 * 8.4.3Describe what is meant by fuel enrichment


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 * 8.4.4Describe the main energy transformations that take place in a nuclear power station. Discuss the role of the moderator and the control rods in the production of controlled fission in a thermal fission reactor


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 * 8.4.5Discuss the role of the heat exchanger in a fission reaction


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 * 8.4.6Describe how neutron capture by a nucleus of Uranium-238 results in the production of a nucleus of Plutonium 239


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 * 8.4.7Describe the importance of plutonium-239 as a nuclear fuel


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 * 8.4.8Discuss safety issues and risks associated with the production of nuclear power


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 * 8.4.9Outline the problems associated with producing nuclear power using nuclear fusion


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 * 8.4.10Solve problems on the production of nuclear power


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 * 8.4.11Distinguish between a photovoltaic cell and a solar heating panel


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 * 8.4.12Outline reasons for seasonal and regional variation in the solar output incident per unit area of the Earth’s surface


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 * 8.4.13 Solve problems involving specific applications of photovoltaic cells and solar heating panels


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 * 8.4.14Distinguish between different hydroelectric schemes


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 * 8.4.15Describe the main energy transformations that take place in hydroelectric schemes


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 * 8.4.16Solve problems involving hydroelectric schemes


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 * 8.4.17Outline the basic features of a wind generator


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 * 8.4.18Determine the power that may be delivered by a wind generator, assuming the wind kinetic energy is completely converted into mechanical energy, and explain why this is impossible.


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 * 8.4.19Solve problems involving wind power


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 * 8.4.20Describe the principle of operation of an oscillating water column (OWC)


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 * 8.4.21Determine the power per unit length of a wavefront, assuming a rectangular profile for the wave


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 * 8.4.22Solve problems involving wave power


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