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Question 1

State one problem associated with generating electricity form ocean waves

Answer 1

Intermittency of wave energy sources.

Reliability of wave energy sources.

Question 2

Renewable energy sources have the potential to deliver a significant proportion of our energy needs in the future. 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

Answer 2

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

Question 3

There are significant wind energy resources available in and around Northern Ireland. State one main reason why we need good energy storage facilities if we are to make optimum use of the available wind energy resources.

Answer 3

Energy supplies from renewable souorces (wind/solar/tidal) tend to be unreliable and/or intermittent

Question 4

describe how pumped hydro storage system operates.

Answer 4

Pumped hydro storage

It utilises renewable energy to pump water up to the high dam / reservoir.

It uses the gravity fed water supply to turn turbines

whenever there is a lull in renewable power

Question 5

State one other method of energy storage.

Answer 5

Compressed air energy storage (CAES)

Question 6

The flow diagram shown in the figure below illustrates the stages of a typical Compressed Air Energy Storage (CAES) system. In the space provided, outline the operation of the system making reference to each stage

Answer 6

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.

Question 7

Pumped hydro energy storage is another type of energy storage facility.
Discuss two features of locations for pumped hydro energy storage that are required to make it cost-effective.
1.
2.

Answer 7

1. Availability of existing water facilities (lakes/reservoirs) to avoid the
   need for excavation with associated costs and environmental impact.
2. A suitable head height so that there is sufficient potential energy stored in the upper facility to drive a turbine and generate electricity.
3. Proximity to transmission lines. The facility needs to connect to the grid as cheaply as possible. Installing new transmission networks causes environmental and social issues as well as adding to cost.