Physics 1b

Questão	Responda
What are the non-renewable energy resources?	The non-renewable energy resources are the three fossil fuels and nuclear: 1) Coal 2) Oil 3) Natural gas 4) Nuclear fuels (uranium and plutonium).
What do we know about non-renewable energy resources?	1) They will all 'run out' one day. 2) They all do damage to the environment. 3) But they provide most of our energy.
What are the renewable energy resources?	The renewable energy sources are: 1) Wind 2) Waves 3) Tides 4) Hydroelectric 5) Solar 6) Geothermal 7) Food 8) Biofuels.
What do we know about renewable energy resources?	1) These will never run out. 2) Most of them do damage the environment, but in less nasty ways than non-renewable resources. 3) The trouble is they don't provide much energy and some of them are unreliable because they depend on the weather.
How can energy sources be burned to drive turbines in power stations?	Most of the electricity we use is generated from four non-renewable sources of energy (coal, oil, gas and nuclear) in big power stations, which are all pretty much the same apart from the boiler. 1) The fossil fuel is burned to convert its stored chemical energy into heat (thermal) energy. 2) The heat energy is used to heat water (or air in some fossil-fuel power stations) to produce steam. 3) The steam turns a turbine, converting heat energy into kinetic energy. 4) The turbine is connected to a generator, which transfers kinetic energy into electrical energy.
What are nuclear reactors?	1) A nuclear reactor power station is mostly the same as the one for fossil fuels, but with nuclear fission of uranium or plutonium producing the heat to make steam to drive turbines, etc. The difference is in the boiler. 2) Nuclear power stations take the longest time of all the power stations to start up. Natural gas power stations take the shortest time of all the fossil fuel power stations.
What is wind power?	1) This involves putting lots of windmills (wind turbines) up in exposed places like on moors or round coasts. 2) Each wind turbine has its own generator inside it. The electricity is generated directly from the wind turning the blades, which turn the generator to make the electricity.
What are the positives and negatives of using wind turbines?	1) There's no pollution (except for a little bit when they're manufactured). 2) But they do spoil the view. You need about 1500 wind turbines to replace one coal-fired power stations and 1500 of them cover a lot of ground - which would have a big effect on the scenery. 3) And they can be very noisy, which can be annoying for people living nearby. 4) There's also the problem of no power when the wind stops and it's impossible to increase supply when there's extra demand. 5) The initial costs are quite high, but there are no fuel costs and minimal running costs. 6) There's no permanent damage to the landscape - if you remove the turbines, you remove the noise and the view returns to normal.
How do solar cells generate electricity?	1) Solar cells generate electric currents directly from sunlight. Solar cells are often the best source of energy for calculators and watches which don't use much electricity. 2) Solar power is often used in remote places where there's not much choice (e.g. the Australian outback) and to power electric road sign and satellites.
What are the positives and negatives of using solar cells?	1) There's no pollution. (Although they do use quite a lot of energy to manufacture in the first place.) 2) In sunny countries solar power is a very reliable source of energy - but only in the daytime. Solar power can still be cost-effective even in cloudy countries like Britain. 3) Initial costs are high but after that the energy is free and running costs almost nil. 4) Solar cells are usually used to generate electricity on a relatively small scale. e.g. powering individual homes. 5) It's often not practical or too expensive to connect them to the National Grid - the cost of connecting them to the National Grid can be enormous compared with the value of electricity generated.
How is hydroelectric power generated?	1) Hydroelectric power usually requires the flooding of a valley by building a big dam. 2) Rainwater is caught and allowed through turbines which then turn the generator and make electricity.
What are the positives and negatives of making hydroelectric power?	1) There is no pollution (as such). 2) But there is a big impact on the environment due to the flooding of the valley (rotting vegetation releases methane and carbon dioxide) and possible loss of habitat for some species (sometimes the loss of whole villages). The reservoirs can also look very unsightly when they dry up. Putting hydroelectric power stations in remote valleys tends to reduce their impact on humans. 3) A big advantage is it can provide an immediate response to an increased demand for electricity. 4) There's no problem with reliability except in times of drought. 5) Initial costs are high, but there's no fuel and minimal running costs. 6) It can be a useful way to generate electricity on a small scale in remote areas.
How does pumped storage give an extra supply of electricity when needed?	1) Most large power stations have huge boilers which have to be kept running all night even though demand is very low. This means there's a surplus of electricity at night. 2) It's surprisingly difficult to find a way of storing this spare energy for later use. 3) Pumped storage is one of the best solutions. 4) In pumped storage, 'spare' night-time electricity is used to pump water up to a high reservoir. 5) This can then be released quickly during periods of peak demand such as at teatime each evening, to supplement the steady delivery from the big power stations. 6) Remember, pumped storage uses the same idea as hydroelectric power, but isn't a way of generating power - it's simply a way of storing energy which has already been generated.
How does waves power work?	1) You need lots of small wave-powered turbines located around the coast. 2) As waves come in to the shore they provide an up and down motion which can be used to drive a generator.
What are the positive and negatives of wave power?	1) There is no pollution. The main problems are spoiling the view and being a hazard to boats. 2) They are fairly unreliable, since waves tend to die out when the wind drops. 3) Initial costs are high, but there are no fuel costs and minimal running costs. Wave power is never likely to provide energy on a large scale, but it can be very useful on small islands.
How do tidal barrages work?	1) Tidal barrages are dams built across river estuaries, with turbines in them. 2) As the tide come in it fills up the estuary to a height of several metres - it also drives the turbines. This water can then be allowed out through the turbines at a controlled speed. 3) The source of energy is the gravity of the sun and the moon.
What are the positives and negative of tidal barrages?	1) There is no pollution. The main problems are preventing free access by boats, spoiling the view and altering the habitat of the wildlife, e.g. wading birds, sea creatures and beasties who live in the sand. 2) Tides are pretty reliable in the sense that they happen twice a day without fail, and always near to the predicted height. The only drawback is that the height of the tide is variable so lower (neap) tides will provide significantly less energy than the bigger 'spring' tides. They also don't work when the water level is the same either side of the barrage - this happens four times a day because of the tides. But tidal barrages are excellent for storing energy ready for periods of peak demand. 3) Initial coasts are moderately high, but there are no fuel costs and minimal running costs. Even though it can only be used in some of the most suitable estuaries tidal power has the potential for generating a significant amount of energy.
How is geothermal energy generated?	1) This is only possible in volcanic areas where hot rocks lie quite near to the surface. The source of much of the heat is the slow decays of various radioactive elements, including uranium, deep inside the Earth. 2) Steam and hot water rise to the surface and are used to drive a generator. 3) This is actually brilliant free energy with no real environmental problems.
What are the positives and negatives of geothermal energy?	1) It has no real environmental problems. 2) In some places, geothermal heat is used to heat buildings directly, without being converted to electrical energy. 3) The main drawback with geothermal energy is there aren't very many suitable locations for power plants. 4) Also, the cost of building a power plant is often high compared to the amount of energy we can get out of it.
How can biofuels be used to generate electricity?	1) Biofuels are renewable energy resources. They're used to generate electricity in exactly the same way as fossil fuels - they're burnt to heat up water. 2) They can be also used in some cars just like fossil fuels.
How are biofuels made and what can they be?	1) Biofuels can be solids (e.g. straw, nutshells and woodchips), liquids (e.g. ethanol) or gases (e.g. methane 'biogas' from sludge digesters). 2) We can get biofuels from organisms that are still alive or from dead organic matter - like fossil fuels, but from organisms that have been living much more recently. 3) E.g. crops like sugar cane can be fermented to produce ethanol, or plant oils can be modified to produce biodiesel.
How are fossil fuels a non-renewable energy sources linked to other environmental problems?	1) All three fossil fuels (coal, oil & gas) release CO2 into the atmosphere when they're burned. For the same amount of energy produced, coal releases the most CO2, followed by oil then gas. All this CO2 adds to the greenhouse effect, and contributes to global warming. 2) Burning coal and oil releases sulfur dioxide, which causes acid rain. Acid rain can be harmful to trees and soils and can have far-reaching effects in eco-systems. 3) Acid rain can be reduced by taking the sulfur out before the fuel is burned, or cleaning up the emissions. 4) Coal mining makes a mess of the landscape, especially "open-cast mining". 5) Oil spillages cause serious environmental problems, affecting mammals and birds that live in and around the sea. We try to avoid them, but they'll always happen.
How is nuclear power, a non-renewable energy resource linked to other environmental problems?	1) Nuclear power is clean but the nuclear waste is very dangerous and difficult to dispose of. 2) Nuclear fuel (i.e. uranium) is relatively cheap but the overall cost of nuclear power is high due to the cost of the power plant and final decommissioning. 3) Nuclear power always carries the risk of a major catastrophe like the Chernobyl disaster in 1986.
What are the disadvantages of biofuels?	1) Biofuels are a relatively quick and 'natural' source of energy and are supposedly carbon neutral. 2) There is still debate into the impact of biofuels on the environment, once the full energy that goes into the production is considered. The plants that grew to produce the waste (or feed the animals that produced the dung) absorbed CO2 from the atmosphere as they were growing. When the waste is burnt this CO2 is re-released into the atmosphere. So it has a neutral effect on atmospheric CO2 levels (although this only really works if you keep growing plants at the same rate you're burning things). Biofuel production also creates methane emissions - a lot of this comes from the animals. 3) In some regions, large areas of forest have been cleared to make room to grow biofuels, resulting in lots of species losing their natural habitats. The decay and burning of this vegetation also increases CO2 and methane emissions. 4) Biofuels have potential, but their use is limited by the amount of available farmland that can be dedicated to their production.
How can carbon capture reduce the impact of carbon dioxide?	1) Carbon capture and storage (CCS) is used to reduce the amount of CO2 building up in the atmosphere and reduce the strength of the greenhouse effect. 2) CCS works by collecting the CO2 from power stations before it is released into the atmosphere. 3) The captured CO2 can then be pumped into empty gas fields and oil fields like those under the North Sea. It can be safely stored without it adding to the greenhouse effect. 4) CCS is a new technology that's developing quickly. New ways of storing CO2 are being explored, including storing CO2 dissolved in seawater at the bottom of the ocean and capturing CO2 with algae, which can then be used to produce oil that can be used as a biofuel.
What factors do people have to think about when setting up a power station?	Because coal and oil are running out fast, many old coal - and oil-fired power stations are being taken out of use. Often they're being replaced by gas-fired power stations because they're quick to set up, there's still quite a lot of gas left and gas doesn't pollute as badly as coal and oil. But gas is not the only option. When looking at the options for a new power station, there are several factors to consider. How much it costs to set up and run, how long it takes to build, how much power it can generate, etc. Then there are also the trickier factors like damage to the environment and impact on local communities. And because these are often very contentious issues, getting permission to build certain types of power station can be a long-running process, and hence increase the overall set-up time. The time and cost of decommissioning (shutting down) a power plant can also be a crucial factor.
How can the set-up cost of power stations vary?	Renewable resources often need bigger power stations than non-renewable resources for the same output. And as you'd expect, the bigger the power station, the more expensive. Nuclear reactors and hydroelectric dams also need huge amounts of engineering to make them safe, which bumps up the cost.
How can the set-up/decommissioning time vary with different power stations?	These are both affected by the size of the power station, the complexity of the engineering and also the planning issues (e.g. discussions over whether a nuclear power station should be built on a stretch of beautiful coastline can last years). Gas is one of the quickest to set up. Nuclear power stations take by far the longest (and cost the most) to decommission.
How can the reliability of power stations vary?	All the non-renewable resources are reliable energy providers (until they run out). Many of the renewable sources depend on the weather, which means there pretty unreliable here in the UK. The exceptions are tidal power and geothermal (which don't depend on weather).
How can the running/fuel costs vary with different power stations?	Renewable sources usually have the lowest running costs because there's no actual fuel involved.
How can environmental issues vary with different power stations?	If there's a fuel involved, there'll be waste pollution and you'll be using up resources. If it relies on the weather, it's often got to be in an exposed place where it sticks out like a sore thumb. Atmospheric pollution from coal, oil, gas and others, though less so. Visual pollution from coal, oil, gas, nuclear, tidal, waves, wind and hydroelectric. Using up resources from coal, oil, gas and nuclear. Noise pollution from coal, oil, gas, nuclear and wind. Disruption of habitats from hydroelectric, tidal and biofuels. Disruption of leisure activities (e.g.boats) from waves and tidal. Other problems are cause by nuclear power (dangerous waste, explosions, contamination), Hydroelectric (dam bursting).
How do location issues vary with different power stations?	This is fairly common sense- a power station has to be near to the stuff it runs on. Solar - pretty much anywhere, though the sunnier the better. Gas- pretty much anywhere there's piped gas (most of the UK). Hydroelectric - hilly, rainy places with flood able valleys, e.g. the Lake District, Scottish Highlands. Wind - exposed, windy places like moors and coasts or out at sea. Oil - near the coast (oil transported by sea). Waves - on the coast. Coal -near coal mines,e.g. Yorkshire, Wales. Nuclear - away from people (in case of disaster), near water (for cooling). Tidal - big river estuaries where a dam can be built. Geothermal - fairly limited, only in places where hot rocks are near the Earth's surface.

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	Criado por Sophie Eileen Powell mais de 9 anos atrás