Back to P1 Home
P1 L) Renewable Energy Sources – Water Energy
P1 L) Renewable Energy Sources – Water Energy
There are many different ways that we can generate electricity from water. Some include hydroelectric power, wave powered turbines and tidal power.
Hydroelectric Power
An example of a hydroelectric power station is the Three Gorges Dam in China. The majority of hydroelectric power stations work by building a dam across a river, which floods a valley creating a reservoir of water. The water in the reservoir behind the dam has gravitational potential energy. Water from the reservoir is let through the dam at a controlled rate. As the water goes through the dam, energy is transferred from the gravitational potential energy stores of the water to the kinetic energy stores of the water. This moving water turns turbines, which generates electricity. Workers at hydroelectric power stations can change the volume of water that is let through the dam depending on current electricity demand; if there is an increase in demand for electricity, more water can be let through the dam, which turns the turbines more, thus generating more electricity (the opposite will happen when demand is lower).
An example of a hydroelectric power station is the Three Gorges Dam in China. The majority of hydroelectric power stations work by building a dam across a river, which floods a valley creating a reservoir of water. The water in the reservoir behind the dam has gravitational potential energy. Water from the reservoir is let through the dam at a controlled rate. As the water goes through the dam, energy is transferred from the gravitational potential energy stores of the water to the kinetic energy stores of the water. This moving water turns turbines, which generates electricity. Workers at hydroelectric power stations can change the volume of water that is let through the dam depending on current electricity demand; if there is an increase in demand for electricity, more water can be let through the dam, which turns the turbines more, thus generating more electricity (the opposite will happen when demand is lower).
An advantage of hydroelectric power stations is that they can respond to changes in electricity demand as we can change the amount of water that is let through the dam. Also, hydroelectric power stations have very low running costs. A final advantage is that it is a useful way to generate electricity in remote areas.
However, the initial costs of hydroelectric power stations are huge. The Three Gorges Dam in China cost around 180 billion yuan, which is around £18 billion. Also, there is a severe impact on the environment because a significant amount of land behind the dam is flooded. This will cause humans and animals to be displaced. In addition, the flooding of land causes large quantities of carbon dioxide to be produced because the vegetation that has been flooded will rot/ decompose (the carbon dioxide is produced because the microorganisms breaking down the vegetation respire). Carbon dioxide is a greenhouse gas, which leads to the enhanced greenhouse effect/ climate change. Furthermore, a drought may reduce the amount of water in the reservoir, which may mean that there will not be enough water to generate electricity. However, the reservoirs behind the dams hold huge reserves of water, so it is very unlikely that a hydroelectric power station would completely run out of water. Another negative is that there are only certain locations that are suitable to build hydroelectric power stations.
However, the initial costs of hydroelectric power stations are huge. The Three Gorges Dam in China cost around 180 billion yuan, which is around £18 billion. Also, there is a severe impact on the environment because a significant amount of land behind the dam is flooded. This will cause humans and animals to be displaced. In addition, the flooding of land causes large quantities of carbon dioxide to be produced because the vegetation that has been flooded will rot/ decompose (the carbon dioxide is produced because the microorganisms breaking down the vegetation respire). Carbon dioxide is a greenhouse gas, which leads to the enhanced greenhouse effect/ climate change. Furthermore, a drought may reduce the amount of water in the reservoir, which may mean that there will not be enough water to generate electricity. However, the reservoirs behind the dams hold huge reserves of water, so it is very unlikely that a hydroelectric power station would completely run out of water. Another negative is that there are only certain locations that are suitable to build hydroelectric power stations.
Wave Powered Turbines
We can turn wave energy into electricity by having lots of small wave turbines that are each connected to a generator. Water/ waves passing the turbines causes them to spin, which generates electricity.
We can turn wave energy into electricity by having lots of small wave turbines that are each connected to a generator. Water/ waves passing the turbines causes them to spin, which generates electricity.
No pollution is produced when the wave-powered turbines generate electricity.
However, wave-powered turbines tend to be unsightly and spoil a view. Also, they are unable to respond to an increase in electricity demand as electricity generation is dependent on the size and force of the waves (small waves will result in low electricity generation, and large waves will result in high electricity generation). Furthermore, the initial cost of wave-powered turbines are high, and they tend to generate small amounts of electricity. Another negative is that wave-powered turbines disturb the seabed, which can affect habitats and become a hazard to boats.
However, wave-powered turbines tend to be unsightly and spoil a view. Also, they are unable to respond to an increase in electricity demand as electricity generation is dependent on the size and force of the waves (small waves will result in low electricity generation, and large waves will result in high electricity generation). Furthermore, the initial cost of wave-powered turbines are high, and they tend to generate small amounts of electricity. Another negative is that wave-powered turbines disturb the seabed, which can affect habitats and become a hazard to boats.
Tidal Power
Tidal power has the potential to generate a significant amount of electricity. Tidal power can be turned into electricity by using a tidal barrage, which is a dam that is built across a river estuary (an estuary is where a river meets the sea). The water level in an estuary will rise and fall with the tide. The tidal barrage contains turbines that are connected to generators. When the tide comes in, it fills up the estuary and turns the turbines in the tidal barrage. The barrage traps the water on the river side and lets the water through at a controlled rate whilst the tide is receding (going out to sea).
Tidal power is a renewable energy resource as the tides are caused by the gravitational pull of the moon and the sun; we will always have tides. Also, tidal barrages do not produce any pollution when they are generating electricity. Furthermore, we can predict the heights of tides and at what time they will occur with a good degree of accuracy, which means that we can predict how much electricity will be generated. However, the height of tides does vary throughout the year, which means that the amount of electricity generated will also vary throughout the year. The running costs of tidal barrages are low.
A negative of tidal barrages are that the initial costs are very high. Also, the barrage can affect boats going between the river and the sea. Furthermore, it can look unsightly and effect wildlife. A final negative is that the tidal barrage will not generate electricity at 4 times during the day when the water level is the same on the seaside and the river side.
Tidal power has the potential to generate a significant amount of electricity. Tidal power can be turned into electricity by using a tidal barrage, which is a dam that is built across a river estuary (an estuary is where a river meets the sea). The water level in an estuary will rise and fall with the tide. The tidal barrage contains turbines that are connected to generators. When the tide comes in, it fills up the estuary and turns the turbines in the tidal barrage. The barrage traps the water on the river side and lets the water through at a controlled rate whilst the tide is receding (going out to sea).
Tidal power is a renewable energy resource as the tides are caused by the gravitational pull of the moon and the sun; we will always have tides. Also, tidal barrages do not produce any pollution when they are generating electricity. Furthermore, we can predict the heights of tides and at what time they will occur with a good degree of accuracy, which means that we can predict how much electricity will be generated. However, the height of tides does vary throughout the year, which means that the amount of electricity generated will also vary throughout the year. The running costs of tidal barrages are low.
A negative of tidal barrages are that the initial costs are very high. Also, the barrage can affect boats going between the river and the sea. Furthermore, it can look unsightly and effect wildlife. A final negative is that the tidal barrage will not generate electricity at 4 times during the day when the water level is the same on the seaside and the river side.