P1 4 Generating Electricity

Question 0

How is electricity generated in coal, oil, gas fired stations?

Answer 0

The burning fuel heats the water in the boiler which produces steam. The steam drives a turbine that turns the electricity generator.

Question 1

What is most of the energy you use generated by?

Answer 1

Power stations

Question 2

What are coal, oil and gas? What are they made from?

Answer 2

Fossil fuels

From long-dead biological material

Question 3

How is electricity produced in some gas-fired power stations?

Answer 3

The natural gas is burned directly in a gas turbine engine and the heated wit produces a powerful jet of hot gases and air which drive the turbine.

Question 4

What is a biofuel?

Answer 4

Any fuel obtained from living or recently living organisms such as animal waste, wood chip, ethanol, straw .etc.

Question 5

Give the advantages and disadvantages of a biofuel?

Answer 5

Advantages:
It is renewable
It is carbon neutral

Disadvantages:
It can take up a large amount of land

Question 6

What is meant by renewable?

Answer 6

The energy source will never run out.

Question 7

What is meant by carbon neutral?

Answer 7

The carbon dioxide produced can be balanced out with the carbon taken in

Question 8

What are the fuels used in a nuclear power station?

Answer 8

Uranium (plutonium)

Question 9

What is nuclear fission?

Answer 9

When the nucleus of a uranium atom is unstable and splits into two.

Question 10

How is the electricity obtained from a nuclear power station?

Answer 10

As there are a lot of uranium atoms, the core becomes very hot.
The energy of the core is transferred by a fluid - coolant and is pumped through the core.
The coolant is very hot when it leaves the core. It flows through a pipe to a heat exchanger and back to the core.
The energy of the coolant is used to turn water into steam and drives turbines to turn electricity generators.

Question 11

Which releases more energy in a given time - nuclear power stations or fossil fuel stations?

Answer 11

Nuclear power stations (x1000)

Question 12

How does wind power generate electricity?

Answer 12

The wind turbine is an electricity generator on top of a tall tower. The force of the wind drives the turbine blades around and turns the generator.

Question 13

How can the power generated increase in a wind turbine?

Answer 13

When the wind speed increases

Question 14

How does wave power generate electricity?

Answer 14

The wave generator floats on top of the waves and move up and down. This motion turns the generator so generates electricity. A cable between the generator and the shore delivers electricity to the grid system.

Question 15

How can we generate electricity through hydroelectric power?

Answer 15

When water is collected in a reservoir or in a pumped storage scheme and flows downhill, the water drives turbines that turn electricity generators at the foot of the hill.

Question 16

How is electricity generated through tidal power?

Answer 16

The tidal power station traps water from each high tide behind a barrage. Then the high tides are released into the sea through turbines and drive the generators in the barrage.

Question 17

How is electricity generated through the sun?

Answer 17

Solar a are used to convert the sun’s energy into electricity.

Question 18

What are the disadvantages and advantages of solar cells?

Answer 18

Advantages: 
Useful where we only need small amounts of electricity or remote places 
Renewable
Disadvantages:
They are expensive 
We need plenty of sunshine/ lots of them

Question 19

How is electricity generated through geothermal energy?

Answer 19

Energy comes from the energy released by radioactive substance is deep inside the earth. Water is pumped into the hot rocks underground and produces steam to drive turbines and generate electricity.

Question 20

What are the disadvantages and advantages of fossil fuels?

Answer 20

Advantages:
They do not produce radioactive decay

Disadvantages:
They let carbon dioxide and other greenhouse gases into the atmosphere which causes global warming
They are non-renewable
They produce sulfur dioxide which can cause acid rain

Question 21

What can be used to stop carbon dioxide emissions into the atmosphere?

Answer 21

Carbon capture and storage (CCS) old oil and gas fields are used to store carbon dioxide.

Question 22

What are the advantages and disadvantages of nuclear power?

Answer 22

Advantages:
No greenhouse gases
Much more energy from each kg of uranium
Disadvantages:
Used fuel rods contain radioactive waste
An explosion can take place and can release radioactive material which can stay for many years.

Question 23

What are the disadvantages and advantages of renewable energy sources?

Answer 23

Advantages:
They are renewal
They don't produce greenhouse gases
They do not create radioactive waste
They can be used in remote places

Disadvantages:
Wind turbines are noisy and unattractive
Tidal barrages affect the habitats of creatures and plants there
Hydroelectric schemes can affect habitats
Solar cells are expensive and will need to cover large areas to supply large amounts of power

Question 24

What is the national grid?

Answer 24

A network of cables and transformers that distributes electricity to out homes from distant power stations and renewable energy generators.

Question 25

What does The National Grid also contain?

Answer 25

Transformers

Question 26

What are the transformers? What are their roles?

Answer 26

Step-up transformers - to step the voltage up to the grid voltage
Step-down transformers - to step the grid voltage down for use at homes and offices.

Question 27

What does the electrical power supplied to any device depend on?

Answer 27

The appliance’s current an voltage.

Question 28

Which does what? Which transformers raise/lower the current/voltage?

Answer 28

The step-up transformers lower the current and raise the voltage whereas the step-down transformer does vise-versa.

Question 29

Why is it important to raise the voltage?

Answer 29

So that less current is needed to transfer the same amount of power. Energy losses due to the heating effect of the current is also reduced. More efficient.

Question 30

State the disadvantages of underground cables.

Answer 30

• More expensive
• Much more difficult to repair
• Difficult to bury where they cross rivers, roads and canals.

Question 31

What are the disadvantages of overhead cables?

Answer 31

• Spoils landscapes
• Can affect health
• Electric and magnetic fields might affect people

Question 32

What does the start-up time depend on?

Answer 32

The type if power station

Question 33

Give the order from shortest to longest start-up time?

Answer 33

Natural gas
Oil
Coal
Nuclear

Question 34

Why are renewable energy resources unreliable?

Answer 34

The amount of energy they generate depends on the conditions.

Question 35

How can a hydroelectric, wind and wave, tidal and solar energy resource be unreliable?

Answer 35

Hydroelectric - upland reservoir could run dry
Wind/wave - can be too weak on calm days
Tidal - height of tides vary on a monthly and yearly cycle
Solar - no solar energy at night and variable during day

Question 36

How is the variable demand for electricity met?

Answer 36

• Using nuclear, coal and oil-fired power stations to provide a constant amount of electricity.
• Using gas-fired power stations and pumped-storage schemes to meet daily variations in demand and extra demand in the winter.
• Using renewable energy sources when demand is high and renewables are in operation.
• Using renewable energy sources when demand is low to store energy in pumped storage schemes.

Question 37

What is base-load?

Answer 37

A constant supply of electricity

Question 38

Which power stations meet the base-load demand?

Answer 38

Coal, nuclear and oil-fired

Question 39

Why is CCS not used a lot?

Answer 39

It’s expensive