Power Station Efficiency

Factors which affect the efficiency of power stations include fuel type (brown coal, black coal, gas) the load factor (full load, part load) and the technology employed. The figure is generally quoted as sent out efficiency.

 

For cogeneration or CHP (combined heat and power) plants, the total efficiency or energy utilisation factor can be quoted

 

The efficiency of Australian coal power stations has risen over time.

 

Selected 1988 national average thermal efficiencies are shown below.
 

Country	Coal	Gas
Australia	33.3	31.1
Canada	36.8	43.1
West Germany	35	32.4
Italy	35.5	14.31
Japan	38.4	43.6
Sweden	17.3	-
UK	36.8	45.6
USA	36.9	31.6

  Energy Balances of OECD Countries 1987 - 1988, IEA/OECD, 1990  

The highest efficiencies are being achieved by combined cycle plants. In a combined cycle plant, surplus heat from  a gas turbine is used to produce steam which in turn drives a steam turbine. Efficiencies of over 50% are routinely achieved and efficiencies approaching 55% are possible.
 
Increasing efficiencies are being achieved with conventional single cycle plants. The use of supercritical conditions and a cold final cooling water source allows a power station in Denmark to attain over 45% efficiency, the world's highest for an operational, single cycle, large coal-fired plant.

 

A number of advanced technologies are being developed including CFBC, PFBC, IGCC and IDGCC.

 

In cogeneration or combined heat and power (CHP) plants waste heat is utilised, typically for district heating or for an industrial process. Total efficiencies of 80% are typical.