# 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 Remember that energy costs are changing all the time so this is probably out of date even as I write it and will almost certainly be by the time you read it!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 the UK at the moment (November 2012) the price of petrol is about 135p a ltre and diesel about 140p a litre. (Compare these with the costs in October 2007 when petrol for cars cost about 98p/litre and autogas about 44 p/litre. Diesel was a little more expensive than petrol (101 p/litre)). The prices depend on which petrol station you go to! 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.

In Mongolia (2012) the prices are roughly half those in the UK). 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) how quickly we would get our money back after the initial investment, the pay-back time
(f) the problems of decommissioning the power station when it has reached the end of its useful life

### 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.

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

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.

### 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.

### 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.