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Renewables. Objectives. To look at alternative renewable forms of energy To analyse the pros and cons of each To evaluate the options facing the world today. Historical use. So renewables are not new.
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Objectives • To look at alternative renewable forms of energy • To analyse the pros and cons of each • To evaluate the options facing the world today
So renewables are not new • Water meant the new cotton mills of the 18th century were centred in the Pennines in England
Wind • Wind was used to drain the polders of the Netherlands and the marshlands of eastern England
Why renewables • 1. Sustainable • 2. Less/no pollution • 3. Specifically no CO2 emissions • 4. Greater self-reliance for all nations • 5. Not held hostage by oil producing nations/global prices • 6. Make use of waste.
Why not renewables • 1. Expensive • 2. Far less energy efficient than combustion of carbon based fuels • 3. Technology still in development • 4. Dependent on factors out of our control such as wind and sun etc. • 5. Biofuels use land needed for food production/destroy natural habitats. • 6. Technology reliant on rare earth metals of which China has currently a virtual monopoly • 7. Nuclear waste and fallout.
Nuclear • Not renewable, but at current levels of use sustainable
Nuclear Power • Pros • 1. Produces huge amounts of energy from small amounts of fuel • 2. Little associated production of CO2 • 3. Relatively cheap technology • 4. Proven • 5. Output can be controlled to meet need • 6. Provides fuel for nuclear warheads • Cons • 1. Disposal of high level nuclear waste • 2. Accidents such as Fukushima and Chernobyl have had devastating effects for populations • 3. Serious pollution associated with mining Uranium • 4. Dangers of transport of fuel and waste • 5. Terrorism targets • 6. Not as cheap as it is made out to be – many hidden costs • 7. Provides fuel for Nuclear warheads
Wind Where is this?
Windpower • Pros • No pollution • Can fit on small pieces of land such as waste • Small scale can be developed for installation in cities • Many parts of the world are windy • Can be placed out at sea • Cons • Unsightly • Noisy – especially large ones • Can only ever make a relatively small contribution • Don’t generate when it isn’t windy • Alleged danger to birds and even more so to bats
Hydroelectric Where is this?
Hydroelectric Power • Pros • Huge amounts of energy generated • Resource totally sustainable • No pollution • Often duel purpose – associated with drinking water reservoirs – so the dam would be there anyway • Can be controlled to meet demand • Cons • Large scale habitat destruction • Upstream silting • Downstream flow patterns reduced • Increased salination in estuaries • Loss of riverine habitat downstream • Sensitive to over exploitation of water resource
Tidal Power • Old – a medieval tide mill in England • New – an experimental tidal barrage in France Hold back water as tide falls and then allow water to flow through when difference in height is largest generating power.
Tidal power • Pros • No pollution • Generating potential massive: proposed Severn barrage could generate 25% of UK energy needs • Protection from storm surges • Cons • Massive loss of intertidal habitat • Disruption to shipping lanes • Siltation in upstream ports • Impacts on fish movements/nursery areas • Limited control over generation times
Wave Power • Pros • No pollution • Wave energy relatively constant • Generates in low wind conditions • Supply more constant • Minimal impact on habitats • Resistant to hostile sea conditions • Cons • Only at developmental stage • Relatively small scale • Dependent on seaboard • Some concerns about impacts on waves and natural coastal processes though all information suggests that this is insignificant.
Geothermal Can you name two places in the world where this is very important?
Geothermal • Pros: • Unpolluting • Allows direct access to heat in cold climates and thus cultivation of heat dependent plants • A fantastic resource • Cons • Very limited availability • Quite a high tech solution
Solar Power • Pros • No pollution • Can provide heating and warmth at relatively low light levels • Can be attached to roofs so minimising land take • Cons • Not very efficient at producing electricity – despite significant improvement • Not cost efficient • To produce large amounts of energy requires very large arrays using much land • Unpleasant chemicals used in their fabrication • Limited life span
Biofuels • Plant based oils such as sunflower, palm oil, rape seed oil, corn oil, possibly in the future biodiesel from algae • Ethanol from sugar cane • Wood • Methane produced by the fermentation of organic domestic waste, animal waste and sewage • Pellets made from waste wood paper and plastics
Biofuels • Pros • Carbon equal – most of this carbon dioxide was extracted from the atmosphere in recent years • Often use things of no other value • Save on waste disposal • Reduce contamination and pollution • Energy rich and production can be scaled to meet demand. • Cons • Huge loss of cropland and natural habitat to grow biofuels • Smelly processes • Cost of separating waste • Cost of fermenting sewage and organic waste • Cutting down trees • Toxins released when some wastes burnt.
Alternative • Saving energy • Combined Heat-Power schemes – generating electricity wastes energy as heat. This can be collected to heat local houses, factories etc. hence CHP • What others can you think of? • Do an energy audit and identify ways of saving energy
Background for audit • 1. Energy is measured in Joules • These are tiny amounts and useless for our purposes • Power is measured in Watts (W) • The energy used by an appliance is described in KiloWatt hours (KWhr) • This is the erngy used by an appliance of power 1KW in one hour = • If 1 W = 1 J/s How many J in 1 KWhr?
Physics • To work out the power rating of an implement (most already tell you). • 1. What is the size of the fuse in amps. This is the maximum current so take a bit off • 2. Voltage = 120V • Power = VI (voltage x current) • Now you have your power rating. • Divide by 1000 to get number of KW • Times by time used to get KWhrs.
Energy audit • 1. Try to calculate your household’s daily energy use. Electricity, gas and petrol (gasoline) separately. • 2. Identify ways of saving energy • 3. Suggest by how much each of these could reduce your household energy usage • 4. Try to put financial value on these savings • 5. Report back to the class • You may work in pairs – each pair only needs to do one household • You will need to know your parents’ spending on energy monthly • (8 point per section) in your report back to class I will assess clarity of explanation and any slides you use.
