Renewable Resources (1)

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
Renewable resources can be used to generate electricity. Renewable energy resources will not run out, unlike fuels. Renewable energy does not have zero impact on the environment. There are advantages and disadvantages in the choice of any energy source. The use of renewable energy can save on fossil fuels and extend the lifetime of these non-renewable sources of energy.

Renewable sources of energy can be made to drive . The kinetic energy of the turbines then the , or dynamos. The generators convert energy into energy. Renewable energy resources will not run out, unlike fossil fuels.

Hydroelectric power is generated from the conversion of gravitational energy of stored into kinetic energy. The kinetic energy is then used to drive turbines. The turbines, in turn, drive the . Some countries have been able to use the landscape and wet to make use of hydroelectricity


(Hydroelectric Power : Scotland. Photo: M.Overy)

Until recently hydroelectric power was considered to be a source of energy. The production of electricity does not in itself release carbon into the atmosphere. However, hydroelectricity power requires large areas of to be flooded. When the plants and trees rot they release large amounts of carbon. Then these plants fall to the bottom of the lake and decay, without the presence of . This releases large amounts of methane. The methane is a gas. This gas can increase the rate of increase of global . The methane gas is released into the , as the water passes through the turbines. The water levels in reservoirs change with seasons. Plants which grow when the levels are are then covered, and sink below the water level and decompose. This increases the amount of methane released.

Other factors to be considered when constructing hydroelectric power stations include the effect on wildlife, and their , as the area is to make the reservoir. Land which could have been used for agriculture is also lost. Land used for homes of local is also lost. The effect of a changing can also affect the amount of water collected in reservoirs. There has been a drought in Arizona and Nevada for over six years. This has resulted in a significant drop in the levels at the Hoover .

Wind turbines use the energy of the wind to generate electricity.

(Wind Turbines: Palm Springs, California. (Photo: M.Overy) )

The wind drives the blades around which drives the turbines. The turbines then drive the generators. The wind must move past the blades, so not all of the kinetic energy can be removed from the air. The maximum of the wind turbines is 59%. There are less than 2000 wind turbines in the UK, providing over 2400 MW of power. There are savings on gases such as carbon , dioxide and nitrous emissions.

Large numbers of turbines are needed, covering large of land, to replace one conventional station.


(Wind Turbines: Palm Springs, California. (Photo: M.Overy) )

The output depends on a number of factors, such as location, the speed. Wind farms are likely to be found on or mountains and near the coast. These are places where the wind speeds are high.

Solar energy is a popular way of generating in many countries. This can be done using solar cells.


(Solar Cell Array for a home in Arizona. (Photo: M.Overy) )

Solar cells are made from semiconductor materials. These convert energy into electrical energy directly. The electrical energy can be fed into the National . In smaller installations, such a remote buildings, the electrical energy can be used to large batteries. The batteries can be used to drive appliances, during the day or at . The batteries can also be connected to inverters, which change DC into .

Solar cells are still expensive. The efficiency is still quite . Most commercial solar cells have efficiencies between 14 % and 16 % . The technology is slowly improving to increase the output .

Solar cells have many . They have been used in remote areas where electricity is not available. and space probes, calculators, garden lights, mobile devices, wrist watches, and water pumps can all be driven using solar cells

Another way of generating electricity is to use the solar energy directly to liquid.


(Solar Power Plant :Daggett, California, in the Mojave Desert. (Photo: M.Overy) )

The solar energy is reflected from hundreds of reflectors to a focus point. There is liquid in a special container at this point. The hot gases from the boiling liquid can then be used under pressure to turbines. These turbines then drive . There are powerful solar generators in many parts of the world. They are not suitable for places where there there are frequent or rainy days. The output also depends on the time of day, the of the year, and the position north or south of the Equator, known as the .

Need more information?

Solar Energy (Case Study)
Wind Energy (Case Study)
Environment Special (Case Study)