Energy Storage

Question 1

State two problems associated with generating electricity from ocean waves. {1}

Answer 1

Indeterminacy of wave energy sources.

Reliability of wave energy sources.

Question 2

State one main reason why energy storage facilities are needed in order for us to make optimum use of renewable energy sources such as wind, solar, wave and tidal. {1}

Answer 2

Energy supplies from renewable energy sources (e.g. wind, solar, wave, tidal) tend to be unreliable or intermittent. {1}

Question 3

Identify the type of energy storage that uses two reservoirs and describe how the system operates. {4}

Answer 3

Pumped hydro storage. {1}

It utilities renewable energy to pump water up to the high dam / reservoir. {1}

It uses the gravity fed water supply to turn turbines {1}

whenever there is a lull in renewable power {1}.

Question 4

State one other method of energy storage. {1}

Answer 4

Compressed air energy storage (CAES) {1}

Question 5

Outline the operation of the CAES making reference to each stage. {5}

Answer 5

Energy from a renewable energy resource can be stored during periods of low energy demand (off peak) {1}.

Air is compressed by an electrically powered compressor {1}

And stored in mass quantity in an underground cavern {1}

For use in meeting periods of higher (peak load) {1}

When there is a demand the compressed air is released to drive a turbine connected to a generator to produce electricity. {1}

Question 6

Name the type of energy storage facility that uses reservoirs and describe how the system operates.

Type of facility {1}
Description. {4}

Answer 6

Pumped Hydro Energy Storage {1}

During off peak (low demand) times, renewable electricity from the grid is used to power pumps {1}

Which pump water from a lower reservoir to an upper reservoir {1}.

When demand increases the water from the upper reservoir is released down a pipe under high pressure {1}

This then spins turbines which drive generators to produce electricity {1}.

Question 7

State three factors that would make a potential location both beneficial as well as cost effective for pumped hydroelectric energy storage. {3}

Answer 7

Proximity to high voltage power transmission network. {1}

Service roads for construction, operation and maintenance. {1}

Lack of environmental concerns / objections. {1}