Wind power

Wind farms

The most common way of getting energy from the wind is through setting up 'wind farms'.

How they work:

• wind turbines generally have 3 blades and they rotate at 10-30 revolutions per minute

• the blades face into the wind, the wind forces them to go round, which then spins a shaft inside the turbine, which is connected to a generator which produces the electricity.

Advantages:

• electricity is produced in an environmentally friendly way: no chemical or radioactive emissions

• ground on which the turbines are positioned can still be used for agricultural purposes, e. g. as sheep grazing

• if the turbines need to be taken down, there is no damage to the environment and no residues are left behind

Disadvantages:

• ruin the landscape because they generally have to be positioned on hills to get the maximum benefits of the wind

• take up much more space to produce the same amount of energy as other methods such coal-firepowered stations

• can be costly to maintain

• the noise generated from wind turbines

• the turbines can cause some slight electromagnetic interference, which can cause interference with television signals and some communications equipment

The costs:

• electricity produced by this method is more expensive than that produced by other means

The future:

• The initial costs of setting these kinds of farms up is the main obstacle at the moment, but this could be an avenue to explore.

Solar Power

How it works:

• The photovoltaic effect (photo cells convert sunlight directly into electricity). Photovoltaic cells (PV's) used as roof tiles.

• Designing buildings to collect the heat: large glass windows, heating water pipes (painting them black and putting them in a 'greenhouse' type insulator).

Advantages:

• no extra land space is needed

• can also be situated in urban areas, where there is plenty of available space

• easy to install

• replace the need for other materials, such as tiles

• generate more electricity than is needed at certain times in the day, so can be sold back to local electricity companies

Disadvantages:

• depend on changeable weather

• costly installation

The costs:

• Expensive though reduced by 90% since 1970.

The future:

• within 10 years photo voltaic cells are likely to be competitive with conventional power sources.

• more large-scale projects are to be centrally funded with an energy-efficiency programs devised alongside it.

Geothermal Energy

How it works:

• Geothermal that is 'Earth's heat'. The centre of the Earth is hot (current estimates are 5,500º C at the core just over 6, 500 km below the crust (about as hot as the surface of the sun). The upper 3 m of the Earth's surface nearly constantly stay at a 10-16º C throughout the year.

Ways of tapping geothermal energy:

• direct use (1) directly for heating buildings (2) district heating - the system of supplying communities with hot water or heating.

• geothermal heatpumps - using a series of pipes to circulate fluid through the warm ground. In the winter when the ground is warmer than the buildings above, the liquid absorbs heat from the ground, which is then concentrated and transferred to the buildings.Inthe summer, when the ground is cooler, the pump transfers heat from the buildings back into the ground.

• electricity production using a turbine driven by steam, which then drives a generator.

The advantages:

• no fossil fuel burning is required.

• emit only excess steam and very few trace gases (1000-2000 times less carbon dioxide than fossil fuel power plants)

• take up very little land compared to traditional fossil-fuel plants

• advanced drilling techniques minimise the impact of drilling wells

• electricity produced more 'available' as fossil-fuelled power plants produce electricity 65-75% of the time compared to 90% from geothermal power plants

• geothermal heat pumps can be used nearly anywhere

The costs:

• the savings on electricity can outweigh the cost of installing and running the system.

• in agriculture (such as to heat greenhouses) heating costs can be cut by up to 80%.

• are slowly becoming competitive with that from traditional power plants.

The future

• to drill deeper and circulate water through the hot dry rock found 3-5 miles under the surface

• to identify deep geothermal aquifers

• to venture even deeper and try to utilise the hottest source of all - the molten and semi-molten magma of theEarth's core.