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Comparative energy costs

With the use of energy so important in our world today it is important to compare the cost of the use of the different forms of energy.

This file gives you some ideas and data for you to work on. Remember that energy costs are changing all the time so this is probably out of date even as I write it and will almost certainly be by the time you read it!




In the developed world we use energy for three main things:
(i) for generating electricity
(ii) heating our homes
(iii) for travel

In thee UK at the moment (October 2020) petrol for cars costs about 120 p/litre and autogas about 44 p/litre. Diesel is a little more expensive than petrol (125 p/litre). The prices depend on which petrol station you go to!

Since writing this the prices have risen and now, at the start of 2011, it is difficult to find petrol for less than 122p/ litre with diesel costing at leat 2p/litre more. Autogas is supposed to be about 15-20% less efficient than petrol giving say 32 mpg on a car that usually does 40 mpg. There are many sites that will give you comparative costs for running a car on petrol and autogas.

A number of things have to be considered when comparing the cost of different ways of generating electricity:
(a) the initial cost of the power station or generating system
(b) the impact of the power station on the environment
(c) the cost per kWh of the electricity produced
(d) the environmental effects of the emissions from the power station such as greenhouse gases and radioactive waste
(e) the problems of decommissioning the power station when it has reached the end of its useful life



The effect on fuel prices in the UK of the corona virus pandemic of 2020 is shown by the accompanying photograph taken in the early morning of Wednesday 15th April 2020. It shows a drop of about 30p from their highest value (over 130p per litre) some years before. The enormous reduction in traffic and the susequent very much smaller demand for fuel during the crisis is the reason for this.

Wind power

Denmark provides 20% of all its energy by wind power (2007) so it is useful to look at some more details of this energy source.

Relative average energy costs per MWh (2011)  
Coal 30-100
Gas 50
Solar 45
Hydro 20
Nuclear 100
Wind 45

The cost of wind energy depends greatly on the speed of the wind. For the same wind farm the following table gives approximate relative costs for different wind speeds

Wind speed (m/s) Relative cost/kWh
7 10
8 7
9 5

Large wind farms have an "economy of scale". A 3 MW wind farm generates electricity that is one and a half times more expensive per kWh than one of 50 MW. The use of wind power has increased considerablty in the UK over the last five years with the construction of some very large wind farms particularly offshore.

Gas and electricity compared by cost

At the moment (2007) in the UK gas (natural gas for heating) is between 3 and 4.5 p/kWh and electricity between 10 and 14 p/kWh depending on how much you use..

Further comparisons between power stations

The costs are given (2004) in p/kWh. These are just for the generation they do not include the costs of setting up the power stations.


Gas fired 2.2
Nuclear fission plant 2.3
Coal-fired pulverised-fuel 2.5
Coal-fired circulating fluidized bed 2.6
Coal-fired integrated gasification combined cycle 3
Poultry litter-fired bubbling fluidized 6.8
Onshore wind farm 4
Wave and marine technologies 6

Comparative energy estimates

Jesse Aubusel of the Rockerfeller University New York has studied the cost of some forms of alternative energy. Here is a selection of some of his estimates:

Every car would need 10000 to 20000 square metres of biomass
One nuclear power plant generates as much energy as about 2500 square km of biomass
A wind farm the size of Texas, 780 000 square km would be needed to provide the energy needs of the United States (2005).
A lake 0.1 square km in area held behind a 60m high dam would be needed for each Canadian
A 1000 MW nuclear power plant would need 150 square km if it was to be replaced by solar cells.

For the full article see:
http://www.scientistlive.com/18389/renewable-energy-at-what- cost.thtml
 

A VERSION IN WORD IS AVAILABLE ON THE SCHOOLPHYSICS USB
 
 
 
© Keith Gibbs 2020