P3: Energy Resources (Y10 - Autumn 1)

Question 1

🟠 Percentage of the world’s energy usage consumption

Answer 1

• 31% Oil
• 31% Coal
• 24% Gas
• 7% Hydroelectricity
• 4% Nuclear
• 3% Other Renwables

Question 2

🟠 What happens inside a power station?

Answer 2

In a coal or oil fired power stations, and most gas fired power stations, the burning fuel heats water in a boiler. This produces steam. The steam drives a turbine that turns an electricity generator. Coal, oil, and gas are fossil fuels that come from long-dead animals and plants.

Question 3

🟠 What is the definition of a biofuel?

Answer 3

A biofuel is a fuel taken from any living or recently living organisms. Animal waste is an example of biofuel. Biofuels can be used instead of fossil fuel in modified engines for transport and in generators at power stations. Biodiesel uses waste vegetable oil and plants such as rapeseed. Other examples of biofuels are ethanol (from fermented sugar cane), straw, nutshells, and woodchip.

Question 4

🟠 What are the two qualities of Biofuel (+ explanation)

Answer 4

A biofuel is:

• Renewable: because it’s biological source either regrows (vegetation) or is continually produced (sewage/rubbish). This means it is used at the same rate that it is replaced.
• Carbon Neutral: because, in theory the carbon that the living organism takes in from the atmosphere as carbon dioxide can balance the amount that is released when the biofuel is burnt.

Question 5

🟠 What is Nuclear Power?

Answer 5

Nuclear fuel takes energy from splitting lots of different atoms. Every atom contains a positively charged nucleus surrounded by electrons.

Question 6

🟠 What happens in a Nuclear Power Station?

Answer 6

The fuel in a nuclear power station is uranium (or plutonium). The uranium fuel is in sealed cans in the core of the reactor. The nucleus of a uranium atom is unstable and can be spilt into two. Energy is transferred from the nucleus when this happens. Because there are lots of uranium atoms in the core, it becomes very hot.

The energy of the core is transferred by a fluid called the coolant that is pumped through the core.

Question 7

🟠 Comparing a Nuclear Power Station to a Fossil Fuel Power Station

(Fuel)
(Energy Released Per Kilogram Of Fuel)
(Waste)
(Greenhouse Gas Emissions)

Answer 7

Nuclear Power Station:

• Fuel: Uranium or Plutonium
• Energy Released Per Kilogram Of Fuel: 300,000 MJ (=about 10,000 x energy released per kg of fossil fuel)
• Waste: Radioactive waste that needs to be stored for many years
• Greenhouse Gas Emissions: No - because uranium releases energy without burning

Fossil Fuel Power Station:

• Fuel: Coal, Oil, Gas
• Energy Released Per Kilogram Of Fuel: 30 MJ
• Waste: Non-radioactive waste
• Greenhouse Gas Emissions: Yes - because fossil fuels produce gases such as carbon dioxide when they burn

Question 8

🟠 What is used to generate Wind Power?

Answer 8

A wind turbine is an electricity generator at the top of a narrow tower. The force of the wind drives the turbine’s blades around, this turns a generator. The power generated increases as the wind speeds also increase. Wind turbines can be unreliable because when there is little or no wind they do not generate any electricity at all.

Question 9

🟠 What is used to generate Wave Power?

Answer 9

A wave generator uses the waves to make a floating generator move up and down. This motion turns the generator so it generates electricity. A cable between the generator and the shoreline delivers electricity to the grid system.

Wave generators need to be able to withstand storms, while they also don’t produce a constant supply of electricity. Also, lots of cables (and buildings) are needed along the coast to connect the wave generators to the electricity grid which can, in turn, destroy areas of the coastline, while tidal flow patterns can affect marine wildlife and habitats.

Question 10

🟠 What is used to generate Hydroelectric Power (HEP)?

Answer 10

Hydroelectricity can be generated when rainwater that’s collected in a reservoir (or water in a pumped storage scheme) flows downhill. The flowing water drives turbines that turn electricity generators at the bottom of the hill.

Question 11

🟠 What is used to generate Tidal Power

Answer 11

A tidal power station traps water from each high tide behind a barrage. The high tide can then be released into the sea through turbines. The turbines drive generators in the barrage.

One of the most promising sites for a tidal power station in Britain is the Severn estuary. This is because the estuary rapidly becomes narrower as you move up-river from the open sea. Soit funnels the incoming tide and makes it higher.

In some coastal areas, electricity is generated by the tidal flow passing through undersea turbines on the sea bed. Underwater cables are used to connect these turbines to the national grid.

Question 12

🟠 When are Solar Panels useful (pros+cons)

Answer 12

Todays’s solar energy cells convert less than 10% of the solar energy they absorb into the energy transferred by electricity. They can be connected together to make solar cell panels

• They are useful where only small amounts of electricity are needed (e.g in watches and calculators) or in remote places like small, cut-off islands.
• They are very expensive to install, but have no maintenance costs
• Lots of solar panels are needed, along with lots of sunshine to generate enough power to be useful. Solar panels can be unreliable in areas where the Sun is often covered by clouds.

Question 13

🟠 When are Solar Power Towers useful (pros+cons)

Answer 13

A solar power tower uses thousands of flat mirrors to reflect sunlight onto a big water tank at the top of the tower. The mirrors on the ground surround the base of the tower.

• The water in the tank is turned into steam by the heating effect of the solar radiation directed at the water tank.
• The steam is piped down to ground level, where it turns electricity generators
• The mirrors are controlled by a computer so that they track the Sun

A solar power tower in a hot, dry climate can generate more than 20MW of electrical, which is enough to power a few thousand homes.

Question 14

🟠 What is Geothermal Power and how does it work?

Answer 14

Geothermal energy comes from energy released by radioactive substances deep within the Earth.

• The energy transferred from these radioactive substances heats the surrounding rock.
• So energy is transferred by heating towards the Earth’s surface.

Geothermal power stations can be built in volcanic areas or where there are hot rocks deep below the surface. Water gets pumped down to these rocks to produce steam. Then the steam that is produced drives electricity turbines at ground level.

Sometimes geothermal energy can be used directly under buildings, such as using underground heat floe for underfloor heating e.c.t.

Question 15

🟠 Energy Sources used for Electricity

Answer 15

• 46% Gas
• 31% Coal
• 16% Nuclear
• 5% Other Fuels and Renewables
• 1% Oil
• 1% Hydro

Question 16

🟠 What are the problems with Fossil Fuels?

Answer 16

When coal, oil, or gas is burnt, greenhouse gases such as carbon dioxide are released. The amount of these gases in the atmosphere is increasing, and most scientists believe that this is causing more global warming and climate changed. Some electricity comes from oil-fired power stations. People use much more oil to produce fuels for transport.

Burning fossil fuels can also produce sulphur dioxide, which is a gas that can cause acid rain. The sulphur can be removed from a fuel before burning it, to stop acid. For example, natural gas has it’s sulphur impurities removed before it is used.

Question 17

🟠 Nuclear Power Advantages and Disadvantages

Answer 17

Avantages:

• No greenhouse gases (unlike fossil fuels)
• Much more energy is transferred from each kilogram of uranium or plutonium fuel than from fossil fuel

Disadvantages:

• Used fuel rods contain radioactive waste, which gas to be stored safely for centuries
• Nuclear reactors are safe in normal operation, however an explosion in a reactor could release radioactive material over a wide area. This would affect this area, and the people living there, for many, many years

Question 18

🟠 Renewable Energy Resources Advantages

Answer 18

Advantages:

• They will never run out because they are always being replenished by natural processes
• They do not produce greenhouse gases or acid rain
• They do not create radioactive waste
• They can be used where connection to the National Grid is uneconomical. For example, solar cells can be used for road signs and to provide people with electricity in remote areas

Question 19

🟠 Renewable Energy Resources Disadvantages

Answer 19

Disadvantages:

• Renewable energy resources are not currently able to meet the world demand. So fossil fuels are still needed to provide some of the energy demand
• Wind turbines create a whining noise that can upset people nearby, and some people consider them unsightly.
• Tidal barrages affect river estuaries and habitats of creatures and plants there
• Hydroelectric schemes need large reservoirs of water, which can affect nearby plant and animal life. Habitats are often flooded to create dams
• Solar cells need to cover large areas to generate large amounts of power
• Some renewable energy resources are not available all of the time and can be unreliable (e.g no solar power at night, no wind power without high winds).

Question 20

🟠 Reliability problems with Hydroelectric, Wind/Waves, Tidal and Solar

Answer 20

Hydroelectric - Upland reservoir could run dry

Wind/Waves - Wind and waves too weak on very calm days

Tidal - Height of tide varies both on a monthly and yearly cycle

Solar - No solar energy at night, and variable during the day

Question 22

🟠 Key points about Capital Costs for resources

Answer 22

Key points include:

• Capital costs are lowest for gas-fired power stations and greatest for wind power and nuclear power, including decommissioning costs (i.e taking stations out of use)
• Overall costs including fuel costs are lowest for hydroelectricity, and greatest of offshore wind farms.

The costs of new energy facilities are usually passed on to consumers through increased fuel bills. Energy saving schemes such as low-energy light bulbs in your home would reduce the need for more power stations. Schemes such as improved home insulation reduce the demand for non-renewable energy resources (e.g gas). Home owners pay upfront and eventually get their money back through reduced fuel bills.

Question 23

🟠 How are demands for electricity met?

Answer 23

The variable demand for electricity is met by

• Using nuclear and coal-fired power stations to provide a constant amount of electricity (the base load demand)
• Using gas-fired power stations and pumped-storage schemes to meet daily variations in demand and extra demand in winter
• Using renewable energy resources when demand is high and when the conditions for renewable energy generation are suitable (e.g when wind turbines are used at high wind speeds)
• Using renewable energy resources when demand is low to store energy in pumped storage schemes

Question 24

🟠 The key parts of a Coal Power Station (processes)

Answer 24

• Tractor-Scraper: Organises the coal into piles to be sent into the station
• Industrial Furnace: Where the coal is burned and the heat is made to boil the water
• Boiler Tubes: Transfers the water at high pressure speeds as it heats up
• Cooling Lake: Where the hot water is sent to to cool down and then to be re-used
• Turbine: It turns and therefore runs the generator
• Generator: The generator contains a rota, which spins and makes a flow of electrons
• Step-Up Transformer: This steps up the voltage just before it goes out on the grid