Energy production

Electricity is probably the most useful type of energy in the twenty first century and there are many ways in which we can produce it.

These fall into four groups:
(a) The direct conversion of another form of energy into electricity – such as solar cells

(b) Conversion of energy into heat by 'burning' a fuel and then using this heat to make steam in a power station which can then be used to drive a turbine, turn a generator and so generate electricity.
Examples of these fuels are coal, oil, gas, wood, straw and nuclear

(c) Conversion of energy into mechanical energy that will drive a generator and so generate electricity.
Examples of these types of energy are wind, waves, tides and hydroelectric power (HEP).
We may consider renovating old waterwheels like the one in the photograph and using them to generate electricity for our homes.

(d) Geothermal energy where steam coming out of the ground is used to drive a turbine, turn a generator and so generate electricity

Power station location and Environmental impact

There are many things to think about when planning and running a power station. Have a look at the following list that suggests some of the possible effects that any large-scale energy conversion plant could have on the surroundings.

1. Burning fossil fuels produces 'greenhouse gases' such as carbon dioxide

2. Wind farms are unsightly and noisy

3. Nuclear fission reactors produce nuclear waste which has to be disposed of and the risk of theft of by-products of the reaction such as plutonium could pose a terrorist threat

4. Flooding valleys for dam building and building a tidal barrage across an estuary to use the tides have enormous environmental impact due to the loss of habitat for many species of plants and animals as well as the possible loss of peoples' homes.

At present the biggest dam in the world is the Itaipú dam on the borders of Brazil and Paraguay. The dam is 7.76 km long, and 196 m high. The lake created by this is 170 km long and contains 29 billion tons of water. The energy production is enormous. The eighteen giant generating units can produce a maximum output of 12600 MW and a reliable output of 70 MWh per year.

5. At present the area of solar cells needed to generate even a modest amount of electrical energy is considerable. Many square kilometres would be needed.

There are plans to build a solar power plant in Portugal with a theoretical output of 116 MW from 2.5 km² of solar cells. This would be capable of supplying electricity to 130,000 households and would be visible from space.

6. The cost of building new power stations is very large. This is especially true of nuclear ones where the added safety considerations have to be considered.

7. There is also a problem of getting the energy from where it is generated to where it is needed. In the case of wind and waves the windiest places and those with the greatest wave energy are not close to the main centres of population. In Britain the 'best' places for this would be off the north west coast of Scotland – not a place where many people live!

8. Large power stations of any type are a 'blot on the landscape' and people don't usually want them near their homes. The photograph shows a geothermal power station in Iceland. Excellent in that it does not use fossil fuels and produces no ‘greenhouse gases’ but it does not look too good against the Icelandic landscape.

9. Power stations are very heavy structures and need to be built on ground that will not subside. This usually means rock and his limits the sites that can be chosen.

10. Power stations need cooling water to condense the steam that has been used in the turbines and so they must be built near large amounts of water such as lakes or the sea.

Energy resources

We must look to the future and think carefully about where the human race can obtain energy as we move towards the end of this century. Eventually the sources of energy based on the burning of 'fossil fuels' such as coal, oil and gas will be used up. We have to find some alternatives. There are a number of alternative or renewable sources of energy such a solar, wind, waves, geothermal, biomass, tides and HEP but at present their use is limited by lack of the right technology.

Something that we can all do to help the world energy stock is to try and conserve energy. This means using public transport if possible, turning off lights when we don't need them, campaigning for fewer lights on some roads (within safety limits of course), insulating our homes, supporting new designs for energy efficient houses and putting on a jumper rather than turning up the central heating!

The recycling of 'waste' rather than putting it all into landfill sites will also help. In the last twenty-five years this country has become much more concerned about recycling and many waste disposal sites claim to recycle up to 70% of all waste brought in.