2 Natural ResourcesA natural resource is a feature of Earth that benefits people.Earth’s natural material resources are things like air, fresh water, and soil.
3 16.2 Electricity from fossil fuels A nonrenewable resource is not replaced as it is used.Because it takes so long for these resources to form, someday we will not have enough fossil fuels to produce the electricity we need.The three major fossil fuels are coal, oil, and natural gas.16.2 Electricity from fossil fuelsVideo clip on fossil fuels
4 Electricity from renewable resources (often called alternative energy sources) A renewable resource can be replaced naturally in a relatively short period of time.The Sun and wind are renewable resources that can be used as energy sources.
5 Electricity from renewable resources It is also possible to use:moving water (hydroelectric)hot spots near Earth’s surface (geothermal)tides to produce electricity.Let’s look at some of these!
12 Advantages Once the dam is built, the energy is virtually free. No waste or pollution produced. Much more reliable than wind, solar orwave power. Water can be stored above the dam readyto cope with peaks in demand. Hydro-electric power stations can increaseto full power very quickly, unlike otherpower stations.Electricity can be generated constantly.
13 DisadvantagesThe dams are very expensive to build. However, many dams are also used for flood controlor irrigation, so building costs can be shared. Building a large dam will flooda very large area upstream, causing problemsfor animals that used to live there. Finding a suitable site can be difficult –the impact on residents and theenvironment may be unacceptable. Water quality and quantity downstreamcan be affected, which can have animpact on plant life.
14 Windmills are built together in a “wind farm.” Wind powerWindmills are built together in a “wind farm.”
19 AdvantagesWind is free, wind farms need no fuel. Produces no waste or greenhouse gases.The land beneath can usually still be used for farming.Wind farms can be tourist attractions. A good method of supplying energy to remote areas.
20 Disadvantages The wind is not always predictable – some days have no wind.Suitable areas for wind farms are often nearthe coast, where land is expensive.*Some people feel that covering the landscapewith these towers is unsightly.Can kill birds - migrating flocks tend tolike strong winds. Splat!Can affect television reception if you live nearby. Noisy. A wind generator makes a constant,low, "swooshing" noise day and night,which can drive you nuts. An entire wind farm makes quite a racket!
21 Solar powerSeveral ways to use the sun for power!
22 Solar cells to make electricity like your solar calculator does.
23 Solar power plants that can produce large amounts of electricity instead of for one house. Info on picture
25 We even use solar power in orbit We even use solar power in orbit! Why would that be a good way to power satellites?Video clip on solar power
26 AdvantagesSolar energy is free - it needs nofuel and producesno waste or pollution.In sunny countries, solar powercan be usedwhere there is no easy way to getelectricity to a remote place.
27 Disadvantages*Doesn't work at night.*Very expensive to build solarpower stations. Solar cells cost a great dealcompared to the amountof electricity they'll producein their lifetime.*Can be unreliable unless you'rein a very sunny climate.
29 Turbines are placed underwater like with a dam Turbines are placed underwater like with a dam. Tidal turbines have to spin 180 degrees because the tide switches directions 4 times a day!Video clip on tidal power
30 Once you've built the dam, tidal power is free. AdvantagesAdvantagesOnce you've built the dam, tidal power is free.It produces no greenhouse gases or other waste.It needs no fuel.It produces electricity reliably.Not expensive to maintain.Tides are totally predictable.
31 Disadvantages Very expensive to build. Affects a very wide area - the environment is changed for many miles upstream and downstream. *Many birds rely on the tide uncovering the mud flats so that they can feed. *Only provides power for around 10 hours each day, when the tide is actually moving in or out. *There are very few suitable sites for tidal power stations.
36 Advantages Nuclear power costs about the same as coal, so it's not expensive to make.Does not produce smoke or carbon dioxide,so it does not contribute to the greenhouse effect.Produces huge amounts of energy fromsmall amounts of fuel. Produces small amounts of waste. Nuclear power is reliable.
37 Disadvantages Although not much waste is produced, it is very, very dangerous. It must be sealed up and buried for manyyears to allow the radioactivity to die away. Nuclear power is reliable, but a lot of moneyhas to be spent on safety –if it does go wrong, a nuclear accidentcan be a major disaster.
38 Geothermal energyThe earth has lots of heat inside!