Energy Resources

What is the formula for efficiency?

(energy used usefully / total energy input) x 100

What is a Sankey Diagram?

A diagram showing how all the energy in a system is transferred into different stores. Start off as one arrow that splits into two or more points.

Define a renewable energy resource.

A resource that either replenishes itself or can be replaced within a human’s lifetime.

Define a non-renewable energy resource.

A resource that either doesn’t replenish itself and cannot be replaced within a human’s lifetime.

Give examples of non-renewable resources (4).

• Natural gas

• Coal

• Oil

• Nuclear

Give examples of renewable resources (6).

• wind power

• solar power

• geothermal energy

• hydro-electric power

• biomass

• tidal power

What are natural gas, coal and oil examples of?

Fossil fuels.

How much of UK electricity did / do fossil fuels:

• used to make up?

• now make up?

• Used to make up around 70-80%

• Now makes up less than 40%

How is electricity generated in a fossil fuel power station? (3 steps)

• A fuel is burnt (coal / oil / natural gas) in a furnace. This heats water in a boiler and generates steam

• Steam passes through a pipe to a turbine. This is made to rotate by the steam’s high pressure.

• The turbine’s axle is connected to an electrical generator. This spins and generates electricity.

What are the different energy transfers occurring in a fossil fuel power station? 

Chemical —> thermal —> kinetic —> electrical

How is electricity generated in a wind turbine?

• Wind transfers kinetic energy to turbine, causing the blades to spin.

• Turbine connected by shaft to generator. Kinetic energy causes generator to spin and generate electricity.

What are the energy transfers in a wind turbine?

Kinetic —> electrical

What does the gearbox in a wind turbine do?

It increases the slow rotational speed of the blades to the high speed required by the generator to produce electricity efficiently.

How is light energy converted to electricity in solar panels?

• Photons in sunlight strikes a sheet of silicon (a semi-conductor). Transfers its energy to electrons in silicon atoms.

• If photon has enough energy, it can break electron loose from atomic bond, causing it to become a free electron

How does hydro-electric power generate electricity?

• A dam creates a reservoir. Water runs through pipes sloping down to a turbine, which begins spinning.

• The spinning turbine turns a generator, which generates electricity. 

What are the energy transfers in HEP?

Gravitational potential —> kinetic —> electrical

How does tidal power generate electricity?

Same way as HEP.

How does geothermal power generate electricity?

• Cold water pumped into hot rocks through pipes - returns to surface as hot water / steam

• Steam spins a turbine

• Spinning turbine turns a generator, which generates electricity.

What are the advantages of wind power? (3)

• Renewable - wind replenishes itself

• Do not produce GHGs or other pollutants

• Low maintenance costs after initial construction.

What are the disadvantages of wind power? (4)

• Weather-dependent - amount of generated electricity depends on wind speed

• High initial construction costs

• Visual pollution (not nice to see) and noise pollution (noisy)

• Can cause harm to wildlife, e.g. birds 

What are the advantages of solar power? (3)

• Renewable - Sun is virtually limitless resource

• No GHGs or other pollutants produced

• Low maintenance costs after initial construction

What are the disadvantages of solar power? (5)

• Weather-dependent - unreliable, depends on weather

• High initial construction costs

• Inefficient - don’t convert all sunlight into electricity

• Take up lots of space

• Manufacturing of solar panels can release pollutants

What are the advantages of hydro-electric power? (4)

• Renewable - water is a renewable resource

• Doesn’t produce any GHGs or other pollutants

• Valves can be opened quickly to increase electricity generation when demand is high

• Low maintenance costs after construction

What are the disadvantages of hydro-electric power? (4)

• Extremely high construction costs

• Negative environmental impact - can flood areas, disrupt fish migration patterns, and rotting vegetation in reservoirs can release GHGs, e.g. methane

• Limited suitable locations - can only be built in places with suitable geography

• Output can be reduced in periods of drought

What are the advantages of tidal power? (5)

• Renewable - water is a renewable resource

• Reliable - tides are consistent

• Predictable - tides are regular

• Produces no GHGs or other pollutants

• Low maintenance costs after construction

What are the disadvantages of tidal power? (4)

• High construction costs

• Limited locations - limited to coastal areas w/ large tidal ranges

• Can flood land, destroy habitats, disrupt marine life and fish migration.

• Can impede shipping and other maritime activities

What are the advantages of geothermal power? (5)

• Renewable - heat from Earth’s core is renewable

• Reliable - can run 24/7 and aren’t weather-dependent

• Produce extremely little GHGs and other pollutants

• Low maintenance costs after construction

• Require little space to produce significant amount of power

What are the disadvantages of geothermal power? (3)

• Location-specific - can only be built in specific locations where hot rocks are close enough to the Earth's surface, e.g. Iceland

• High construction costs

• Environmental issues - in drilling, GHGs trapped underground can be released, and can cause seismic activity

• What is the formula for power?

• Using the same formula, what is the formula of energy transferred?

• Using the same formula, what is the formula of time?

• Power = energy transferred / time

• Energy transferred = power * time

• Time = energy transferred / power

• What is the unit of power?

• What does one of this unit mean?

• Watts

• 1 Watt = 1 Joule per second