P1.4.1 Generating Electricity

Question 1

How are energy sources used to generate electricity?

Answer 1

In some power stations an energy source is used to heat water. The steam produced drives a turbine that is coupled to an electrical generator.

Question 2

Give three energy sources and how they are used.

Answer 2

1. Fossil fuels (coal, oil and gas) which are burned to heat water or air.
2. Uranium or Plutonium, when energy form nuclear fission is used to heat water.
3. Biofuels that can be burned to heat water.

Question 3

Explain how wind power can generate electricity.

Answer 3

Wind Power involves putting up lots of windmills up in exposed places like on moors or round coasts. Each wind turbine has its own generator inside it. The electricity is generated directly from the wind turning the blades, which turn the generator.

Question 4

Evaluate wind power to generate electricity.

Answer 4

+ There is no permanent damage to the environment.
+ There’s no pollution so it’s environmentally friendly.
+ It’s renewable.
+ No fuel costs and there are minimal running costs.
- However the initial costs are quite high.
- Visual pollution and you need many to generate the same amount of electricity as a fossil fuel station - they would over a lot of ground and effect the scenery.
- Noise pollution - affecting people who live near them.
- Unreliable as they depend on the weather i.e. there’s no power when the wind stops and it’s impossible to increase supply when there’s extra demand.

Question 5

Explain how solar power can generate electricity.

Answer 5

Solar cells generate electricity currents directly from sunlight.

Question 6

Evaluate solar cells to generate electricity.

Answer 6

+ There’s no pollution produced.
+ Solar cells are often the best source of energy for small appliances that don’t require much electricity.
+ Small-scale production of electricity may be useful in some areas, locally and for uses such as roadside signs.
+ In sunny countries solar power can be a very reliable source of electricity and can still be cost-effective in cloudy countries like Britain.
+ The energy is free and running costs almost nil.
- They depend on the weather which is unreliable and they only work in the daytime.
- Initial costs are high.
- 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 vale of the electricity generated.

Question 7

Explain how hydroelectric power can generate electricity.

Answer 7

Hydroelectric power usually requires the flooding of a valley by building a big dam. Rainwater is caught and allowed out through turbines.

Question 8

Evaluate hydroelectric cells to generate electricity.

Answer 8

+ It can be useful to generate electricity on a small scale in remote areas.
+ There is no pollution.
+ It can provide an immediate response to an increased demand for electricity.
+There’s no fuel and minimal running costs.
+ There’s no problems with reliability….
- …. except in times of drought.
- Initial costs are quite high.
- There is a big impact on the environment due to the flooding of the valley (rotting vegetables release methane and carbon dioxide) and possible loss of habitat for some species.
- The reservoirs can also look very unsightly when they dry up.

Question 9

Explain how pumped storage can be useful.

Answer 9

Pumped storage is a means of storing energy for later use. In pumped storage, ‘spare’ night-time electricity is used to pump water up to a higher reservoir. This can then be released during periods of peak demand or to supplement the steady delivery from the big power stations.

Question 10

Explain how wave power can generate electricity.

Answer 10

You need lots of small wave-powered turbines located around the coast. As waves come in to the shore they provide an up and down motion which can be used to drive a generator.

Question 11

Evaluate wave power to generate electricity.

Answer 11

+ There is no pollution.
+ There are no fuel costs and minimal running costs.
+ Wave power can be very useful on small islands.
- Wave power is unlikely to provide energy on a large scale.
- Initial costs are high.
- They are fairly unreliable, as waves depend on the wind.
- Visual pollution.
- They might be a hazard to boats.

Question 12

Explain how tidal power can generate electricity.

Answer 12

Tidal barrages are big dams built across river estuaries, with turbines in them. As the tide comes 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.

Question 13

Evaluate tidal power to generate electricity.

Answer 13

+ There is no pollution.
+ Tidal power has the potential to generate a significant amount of energy.
+ Tidal barrages are a good way to store energy for peak demand.
+ There are no fuel costs and minimal running costs.
+ Relatively reliable - they happen twice a day without fain as the source of the energy is in the gravity of the Sun and the Moon.
- However, the hide of the tide is variable and they on’t work when the water level is the same either side of the barrage - this happens four times a day because of the tides.
- They prevent free access by boat.
- Visual pollution.
- They alter the habitat of the wildlife.
- They can only be used in some of the most suitable estuaries.

Question 14

Explain the process of generating geothermal energy.

Answer 14

In some volcanic areas hot water and steam rise to the surface. The steam can be tapped and used to drive turbines. This is known as geothermal energy.

Question 15

Evaluate geothermal energy.

Answer 15

+ There are no environmental problems.
+ In some places, geothermal heat is used to heat buildings directly, without being converted to electrical energy.
- However, there aren’t very many suitable locations for power plants.
- The cost of building a power plant is often high compared to the amount of energy we can get out of it.

Question 16

Of all the fossil fuel power stations, which has the shortest start-up time?

Answer 16

Gas-fired power stations.

Question 17

Explain how biofuels can generate electricity and where they come from.

Answer 17

Biofuels are renewable energy resources that are used to heat up water, where the steam produced turns a generator. Biofuels can be solids, liquids or gases. You can get biofuels from organisms that are still alive or from dead organic matter.

Question 18

Evaluate the use of biofuels to generate electricity.

Answer 18

+ Biofuels are a relatively quick and ‘natural’ source of energy.
+ They are supposedly carbon neutral.
- However, this is excluding the full energy that goes into the production.
- In some regions, large areas of forest have been cleared to make room to grow biofuels, resulting in lots of species losing their natural habitat.
- The decay and burning of this vegetation also increases CO2 levels and methane emissions.

Question 19

Which fuel to all fossil fuels release and what impact does this carry on the earth?

Answer 19

All fossil fuels release carbon dioxide into the atmosphere, which adds to the greenhouse effect and contributes to global warming.

Question 20

Burning which fuels, releases which gas, that causes which type of rain? What is the effect of this and how can it be reduced?

Answer 20

Burning coal and oil releases sulfur dioxide, which causes acid rain. Acid rain can be harmful in destroying habitats (trees, soil, lakes etc) as well as buildings.
Acid rain can be reduced by taking the sulfur out before the fuel is burned, or cleaning up the emissions.

Question 21

Mining for which fuel causes visual pollution?

Answer 21

Coal-mining makes a mess of the landscape, especially ‘open-cast mining’.

Question 22

What dangerous risk does the use of oil as a fossil fuel have on habitats?

Answer 22

Oil spillages cause serious environmental problems, affecting mammals and birds that live in and around the sea.

Question 23

Evaluate nuclear power.

Answer 23

+ Nuclear power is a clean burning fuel.
+ Nuclear fuel, e.g. uranium is relatively cheap
- The overall cost of nuclear power is high due to the cost of the power plant and final decommissioning.
- The nuclear waste is very dangerous and difficult to dispose of.
- Nuclear power carries the risk of a major catastrophe.

Question 24

What is the purpose of carbon capture and storage?

Answer 24

Carbon capture and storage (CCS) is used to reduce amount of CO2 building up in the atmosphere and reduce the strength of the greenhouse effect.

Question 25

How does carbon capture and storage work?

Answer 25

CCS works by collecting the CO2 from power stations before it is released into the atmosphere. 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.

Question 26

CCS is new _ _ _ _ _ _ _ _ _ _ that’s _ _ _ _ _ _ _ _ _ _ quickly. _ _ _ ways of storing CCS are being _ _ _ _ _ _ _ _.
Give two examples of this.

Answer 26

CCS is new technology that’s developing quickly. New ways of storing CCS 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.

Question 27

When evaluating different methods of generating electricity, what seven things might you need to consider?

Answer 27

1. How much it costs to set up.
2. Running or fuel costs.
3. How much power it can generate.
4. Environment issues and impact on local communities.
5. Location issues.
6. The overall set-up and decommissioning times.
7. Reliability issues