Presentation on theme: "OCR 21st Century Science Unit P3b Revision"— Presentation transcript:
1 OCR 21st Century Science Unit P3b Revision Generating energy
2 Generators (dynamos)21/04/2017Electricity is convenient because it can be transmitted over long distances and can be used in many ways. But how is it generated? We need to use a “generator”:Basically, a generator works by spinning a magnet near a coil of wire. That’s useful, but how do we get this magnet to keep spinning?
3 Using primary energy sources in power stations 21/04/20171) A fuel is burned in the boiler2) Water turns to steam and the steam drives a turbine3) The turbine turns a generator – if you want more electricity you have to burn more fossil fuels4) The output of the generator is connected to a transformer5) The steam is cooled down in a cooling tower and reused
4 Efficiency of Power Stations 21/04/2017HeatHeatHeat15JBoilerTurbineGenerator100J50J5J85J35J30JHeatKineticElectrical
5 Nuclear power stations 21/04/2017These work in a similar way to normal power stations:The main difference is that the nuclear fuel is NOT burnt. This means that they produce less pollution but they do produce radioactive waste instead.
6 Radioactive Waste - Ionisation 21/04/2017Radiation is dangerous because it “ionises” atoms – in other words, it turns them into ions by “knocking off” electrons:Alpha radiation is the most ionising (basically, because it’s the biggest). Ionisation causes cells in living tissue to mutate, usually causing cancer.
7 Radioactive Contamination 21/04/2017Simply being “irradiated” by a radioactive material doesn’t have to be dangerous – for example, we have background radiation around us all the time. However, being “contaminated” is far more dangerous. Consider the example of Alexander Litvinenko who was poisoned with polonium-210:Timeline of EventsVideo of risks from polonium 210
8 Other ways of generating electricity 21/04/2017Can we drive the turbine directly without burning any fossil fuels? Here are some examnples...
12 The National Grid21/04/2017Electricity reaches our homes from power stations through the National Grid:Power stationStep up transformerStep down transformerHomesIf electricity companies transmitted electricity at 230 volts through overhead power lines there would be too much energy loss by the time electricity reaches our homes. To ensure this doesn’t happen, electricity companies transmit electricity at higher voltages instead.
13 Decommiss-ioning costs Which power station?21/04/2017Type of power stationCommiss-ioning costsRunning costs(p per KWh)Decommiss-ioning costsLife span (years)Coal£650 million4£100 million40-80Oil£700 million12Gas£800 million630-40Nuclear£2 billion3£500 millionWhich power station is the most expensive to build and why?Give one advantage of coal power stationsWhy is nuclear fuel cheaper than oil?Overall, which power station is the most expensive?
14 Matching supply and demand… 21/04/2017Hydroelectric power station might “kick in” here“Baseline” power stations
15 Solar Panels and Thermal Towers 21/04/2017What are the advantages and disadvantages of solar power?
16 Using Solar Energy in remote places 21/04/2017Using Solar Energy in remote places
17 Words – steam, Iceland, volcanic, turbines, hot rocks Geothermal Energy21/04/2017Geothermal energy can be used in _______ areas such as ______. In a geothermal source cold water is pumped down towards ____ _____. The water turns to steam and the steam can be used to turn ______. In some areas the _____ rising at the surface can be captured and used directly.Words – steam, Iceland, volcanic, turbines, hot rocks
18 Non-renewable energy sources 21/04/2017AdvantagesDisadvantagesCheap fuel costsCosts a lot of money to decommission a nuclear plantGood for “basic demand”Coal, oil, gas and nuclearReliableFuel will run outShort start-up time for gas and oilPollution – CO2 leads to global warming and SO2 leads to acid rainNuclear produces little pollution
19 Renewable energy sources summary 21/04/2017AdvantagesDisadvantagesZero fuel costsUnreliable (except for hydroelectric)Don’t produce pollutionWind, tidal, hydroelectric and solarExpensive to buildHydroelectric is good for a “sudden” demandTidal barrages destroy the habitats of wading birds and hydroelectric schemes involve flooding farmlandSolar is good for remote locations (e.g. satellites)
20 Electricity Supply in the UK 21/04/2017Notice that, due to all these advantages and disadvantages, we use a variety of sources of energy in the UK: