OCR 21st Century Science Unit P3b Revision Generating energy

Generators (dynamos) 21/04/2017 Electricity 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?

Using primary energy sources in power stations 21/04/2017 1) A fuel is burned in the boiler 2) Water turns to steam and the steam drives a turbine 3) The turbine turns a generator – if you want more electricity you have to burn more fossil fuels 4) The output of the generator is connected to a transformer 5) The steam is cooled down in a cooling tower and reused

Efficiency of Power Stations 21/04/2017 Heat Heat Heat 15J Boiler Turbine Generator 100J 50J 5J 85J 35J 30J Heat Kinetic Electrical

Nuclear power stations 21/04/2017 These 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.

Radioactive Waste - Ionisation 21/04/2017 Radiation 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.

Radioactive Contamination 21/04/2017 Simply 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 Events Video of risks from polonium 210

Other ways of generating electricity 21/04/2017 Can we drive the turbine directly without burning any fossil fuels? Here are some examnples...

21/04/2017 Wind Power

Wave Power 21/04/2017

Hydroelectric Power 21/04/2017

The National Grid 21/04/2017 Electricity reaches our homes from power stations through the National Grid: Power station Step up transformer Step down transformer Homes If 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.

Decommiss-ioning costs Which power station? 21/04/2017 Type of power station Commiss-ioning costs Running costs (p per KWh) Decommiss-ioning costs Life span (years) Coal £650 million 4 £100 million 40-80 Oil £700 million 12 Gas £800 million 6 30-40 Nuclear £2 billion 3 £500 million Which power station is the most expensive to build and why? Give one advantage of coal power stations Why is nuclear fuel cheaper than oil? Overall, which power station is the most expensive?

Matching supply and demand… 21/04/2017 Hydroelectric power station might “kick in” here “Baseline” power stations

Solar Panels and Thermal Towers 21/04/2017 What are the advantages and disadvantages of solar power?

Using Solar Energy in remote places 21/04/2017 Using Solar Energy in remote places

Words – steam, Iceland, volcanic, turbines, hot rocks Geothermal Energy 21/04/2017 Geothermal 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

Non-renewable energy sources 21/04/2017 Advantages Disadvantages Cheap fuel costs Costs a lot of money to decommission a nuclear plant Good for “basic demand” Coal, oil, gas and nuclear Reliable Fuel will run out Short start-up time for gas and oil Pollution – CO2 leads to global warming and SO2 leads to acid rain Nuclear produces little pollution

Renewable energy sources summary 21/04/2017 Advantages Disadvantages Zero fuel costs Unreliable (except for hydroelectric) Don’t produce pollution Wind, tidal, hydroelectric and solar Expensive to build Hydroelectric is good for a “sudden” demand Tidal barrages destroy the habitats of wading birds and hydroelectric schemes involve flooding farmland Solar is good for remote locations (e.g. satellites)

Electricity Supply in the UK 21/04/2017 Notice that, due to all these advantages and disadvantages, we use a variety of sources of energy in the UK: