Microgeneration

Question 1

Microgeneration definition:

Answer 1

The small scale generation of heat and power

Question 2

Microelectricity technologies:

Answer 2

Solar PV
Wind turbines

Question 3

Microheat technologies:

Answer 3

Solar thermal
Biomass
Heat pumps

Question 4

4 Benefits of microgeneration

Answer 4

1. Reduced energy cost
2. Contribution to environmental targets
3. Enhanced security of supply for home user
4. Potential for income

Question 5

Components in a heat pump and their roles:

Answer 5

1. The evaporator - refrigerant in liquid form cooler than external environment, takes in heat, changes state to a gas
2. The compressor - gas is compressed as work is done on the gas by the compressor, raising its thermal energy
3. The condenser - gas is hotter than external environment, heat is lost to environment and gas turns to a mixture of liquid and gas
4. The expansion valve - mixture of gas and liquid does work on the expansion valve allowing it to compress lowering its thermal energy back to original temperature

Question 6

Advantages and disadvantages of an air source heat pump:

Answer 6

Advantages:
1. Easily installed
2. Lower cost than ground source heat pump
3. Does not require a large area to be installed

Disadvantages:
1. Air temperature can vary a lot
2. Noise is given off

Question 7

Advantages and disadvantages of a ground source heat pump:

Answer 7

Advantages:
1. Relatively consistent temperature range
2. Repayment periods are shorter as it is a more effective system (higher COP)

Disadvantages:
1. Larger upfront costs
2. Large area required to excavate to install infrastructure

Question 8

Coefficient of performance calculation:

Answer 8

COP = heat produced by heat pump / energy consumed by heat pump

( COP = Qc / W )

Question 9

3 types of closed loop ground source heat pumps

Answer 9

Horizontal loop

Vertical loop

Pond loop