Energy resources and methods of generating electricity

This is also Electricity section 7.

Doc Brown's Physics Revision Notes

Suitable for GCSE/IGCSE Physics/Science courses or their equivalent

What energy resources are used for generating power


See also

The 'National Grid' power supply, small scale supplies, transformers

and

 Energy resources & uses, general survey & trends, comparing sources of renewables, non-renewables


Know and understand that in some power stations an energy source is used to heat water.

  • Know that the steam produced drives a turbine that is coupled to an electrical generator.

  • Know and understand that the flow of water and wind can be used to drive turbines directly.

    • Know that renewable energy sources used in this way include, but are not limited to, wind, waves, tides and the falling of water in hydroelectric schemes and all involve converting FREE kinetic energy into electrical energy using a generator. None of these schemes needs a fuel, or produces any kind of chemical pollution on the site, and all are 'green' in terms of not consuming fossil fuels ie carbon dioxide, but they may have quite an environmental impact. All these methods can contribute to National Grid of electricity supply.

  • Energy resources (more detailed notes on other pages):

    • Non-renewable energy sources

      • These energy resources are finite and will run out eventually, there are major associated environmental issues BUT at the moment, most of our useful energy is derived from them. These are historically, and to the present day, the major energy sources for large power stations.

      • e.g. Coal (mainly carbon), crude oil (certain hydrocarbon fractions), natural gas (mainly methane) and nuclear fuels (based on the metals uranium and plutonium).

    • Renewable energy sources

      • e.g. biofuels, geothermal, hydroelectric, solar radiation, tidal changes, wave action, wind turbines

      • Theoretically these energy resources will never run out and generally speaking their environmental impact is not as great as non-renewables, but they only provide a small % of our energy needs at the moment and can be unreliable like the wind.

      • Most of these energy sources, apart from hydroelectric schemes and a few tidal barrage sites, are deployed on an experimental or small commercial scale.

      • Renewable energy resource technology should be the cheapest to run with no primary fuel costs.

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Methods we use to generate electricity

chemical energy store (fossil fuel) or nuclear energy store ===> heat energy (steam) ===> kinetic energy (turbine blades) ===> electrical energy (generator)

OR renewable energy stores:

sunlight == solar panel ==> electrical energy

The figures for the UK electricity generation for 2017 are: Natural gas 40%, coal 7%, renewables (wind, solar, hydroelectric) 30%, nuclear 21% and 2% from other sources. This is part of a good trend as we become less reliable on fossil fuels.

  • Appreciate that various energy sources can be used to generate the electricity we need.

  • Appreciate the need to carefully consider the advantages and disadvantages of using each energy source before the decision to decide which energy source(s) would be best to use in any particular situation.

  • Know that electricity is distributed via the National Grid.

  • You are expected to use your skills, knowledge and understanding to:

    • evaluate different methods of generating electricity,

      • you should be able to evaluate different methods of generating electricity given data including start-up times, costs of electricity generation and the total cost of generating electricity when factors such as building and decommissioning (removing everything of an old power station) are taken into account.

        • You must also be able to consider the reliability of different methods.

        • There are other general issues such as environmental impact - pros and cons for the local community (eg jobs versus environmental damage, visual impact), how long will it take to build?, at what cost versus eventual power output?, planning delays etc.

        • Ideally you would want to site a large fossil fuel/nuclear power station as near as possible to the major/bulk users AND in the case of coal, near a coal mine, since power line transmission involves wasted energy (see National Grid section).

        • Large scale tidal and river/lake hydroelectric schemes and geothermal power plants all need very specific geographical locations.

        • For safety reasons, nuclear power plants are sited in remote locations, often near the coast.

        • Small scale power generation with solar cells and wind turbines can be sited anywhere, but larger wind farms need to be in a windy area eg on low hills or out at sea.

      • Knowledge of the actual values of start-up times and why they are different is not needed, but you must appreciate that the implications of such differences in start-up times are important.

    • evaluate ways of matching supply with demand, either by increasing supply or decreasing demand,

      • you should be aware of the fact that, of the fossil fuel power stations, gas-fired have the shortest start-up time.

        • Power station generator start up times: Nuclear >> coal fired > gas-fired

        • By coincidence (or maybe not?), this order is also paralled by the capital costs, decommissioning costs,

      • you should also be aware of the advantages of pumped storage systems in order to meet peak demand, and as a means of storing energy for later use. See the section on hydroelectricity.

    • compare the advantages and disadvantages of overhead power lines and underground cables.

  •  Know and understand that the flow of water and wind can be used to drive turbines directly.

    • Know that renewable energy sources used in this way include, but are not limited to, wind, waves, tides and the falling of water in hydroelectric schemes and all involve converting FREE kinetic energy into electrical energy using a generator. None of these schemes needs a fuel, or produces any kind of chemical pollution on the site, and all are 'green' in terms of not consuming fossil fuels ie carbon dioxide, but they may have quite an environmental impact. All these methods can contribute to National Grid of electricity supply.

  • Know and understand that small-scale production of electricity may be useful in some areas and for some uses, eg hydroelectricity in remote areas, solar cells for roadside signs, remote telephone kiosks.

    • You should understand that while small-scale production can be locally useful because it is sometimes uneconomic to connect such generation to the National Grid.

  • You should know and appreciate that using different energy resources has different effects on the environment and these effects include:

    • the release of substances into the atmosphere,

    • the production of waste materials,

    • noise and visual pollution,

    • the destruction of wildlife habitats.

    • Also, you should know and understand that carbon capture and storage is a rapidly evolving technology.

      • To prevent carbon dioxide building up in the atmosphere we can catch and store it.

      • Know that some of the best natural containers are old oil and gas fields, such as those under the North Sea.

      • The idea is to capture the carbon dioxide from fossil fuel burning before it is released into the atmosphere and pump it to some suitable storage location.

      • Is it possible to feed the carbon dioxide to algae from which to derive a biofuel?

        • I do know that carbon dioxide from a fermentation process is fed into greenhouses to promote growth of crops like tomatoes! Can we do it on a bigger scale?

    • There are other ways to reduce carbon dioxide, principally by reducing electricity demand, so less fossil fuel is burned. You can reduce electricity demand in the home by insulation, better designed and more energy efficient appliances like washing machines, low energy light bulbs, turning off all devices/appliances not in use.

 


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Energy resources, and transfers, work done and electrical power supply revision notes index

Types of energy store - a comparison with examples explained, mechanical work done and power calculations

Conservation of energy, energy transfers, efficiency - calculations and Sankey diagrams gcse physics notes

Energy resources & uses, general survey & trends, comparing sources of renewables, non-renewables & biofuels

Renewable energy (1) Wind power and solar power, advantages and disadvantages gcse physics revision notes

Renewable energy (2) Hydroelectric power and geothermal power, advantages and disadvantages physics notes

Renewable energy (3) Wave power and tidal barrage power, advantages and disadvantages gcse physics notes

Comparison of methods of generating electricity

Greenhouse effect, global warming, climate change, carbon footprint from fossil fuel burning gcse physics notes

See also The Usefulness of Electricity gcse physics electricity revision notes


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