|
|
 | |
 | |
| |
|
Press Releases :
Events News :
Photography :
Q & A |
|
| |
|
|
|
|
Biomass :
Geo-energy :
Hydroelectric :
Solar :
Tidal :
Wave :
Wind
| |
|
| |
|
| Questions about Tidal energy |
What is tidal energy?
How does tidal power work?
Is it possible to alter the timing of electricity production to allow for peak demand times?
Does there need to be a substantial difference between high and low tide height?
How much electricity is produced by tidal power?
Is tidal power reliable?
What is the visual impact of the technology?
What is the environmental impact of the technology?
| Answers about Tidal energy |
Question: What is tidal energy?
Tidal energy exploits the natural rise and fall of coastal tidal waters, caused primarily by the interaction of the gravitational fields of the earth-moon-sun system. The coastal water line fluctuates twice daily (high and low tide), alternatively filling and emptying natural basins along the shoreline. The currents flowing into and out of these basins can be exploited to produce electricity.
Question: How does tidal power work?
The technology is similar to that used in traditional hydroelectric power plants. A dam is put across a tidal bay or estuary, with gates and turbines installed along it. When there is a sufficient difference between the height of water on either side of the dam, the gates are opened. Water then flows through the turbines, which turns an electric generator to produce electricity. Electricity can be produced in this way by water flowing into and out of a bay. As there are two high and low tides every 24 hours or so, tidal electricity production is characterised by periods of maximum generation every 12 hours.
Question: Is it possible to alter the timing of electricity production to allow for peak demand times?
In periods of low electricity demand, the turbines can be used to pump extra water into the basin behind the barrage. This water can then be released when demand is at its highest, allowing the tidal plant to function with some of the characteristics of a 'pumped storage' hydroelectric facility.
Does there need to be a substantial difference between high and low tide height?
Yes, in order to produce practical amounts of electricity, a difference of at least five metres between high and low tide is required. There are only about 40 sites in the world with this magnitude of tidal range, including some on the west coast of the UK. The higher the tides, the more electricity can be generated from a given site, and the lower the cost of electricity produced.
How much electricity is produced by tidal power?
If all reasonably exploitable estuaries were utilised, the annual generation of electricity from UK tidal power plants would be 50TWh, equivalent to about 15 per cent of the current UK electricity consumption.
Is tidal power reliable?
Although tidal power is variable, it is reliable and predictable and can make a valuable contribution to an electricity grid which utilises power from a variety of sources.
What is the visual impact of the technology?
One example of the technology is La Rance Tidal Barrage, Brittany, France. The system used consists of a dam 330m long which also serves as a highway bridge linking St.Malo and Dinard, and a 22kmē basin with a tidal range of eight metres. It incorporates a small lock to allow passage for small craft.
What is the environmental impact of the technology?
Tidal energy and tidal stream energy do not result in the emission of gases responsible for global warming or acid rain associated with fossil fuel generation.
Changing tidal flows by artificial means such as dams could have an impact on aquatic and shoreline ecosystems as well as navigation and recreation, which is why detailed coastal surveys and Environmental Impact Assessments take place as part of the planning process.
Information supplied by the DTI 'It's only natural' campaign
Notes to editors:
About 'It's only natural'
The UK Government has committed to renewable energy by signing up to international agreements such as the Kyoto Protocol, which means we are now legally bound to reduce greenhouse gas emissions to 12.5 per cent below 1990 levels by 2012. In addition, it has also set targets that by 2010, 10 per cent of the UK's electricity will come from renewable energy and that the percentage will increase to 20 per cent by 2020.
Currently just 3.86 per cent of the UK's electricity comes from renewables, so there is a lot of work to be done. This document is part of our campaign to provide you with more information about renewable energy sources such as wind, solar, biomass, wave and tidal power and why they are so important to the UK, to help us meet our international commitments and enable us to become a more sustainable nation.
For more information contact:
Aby Billi or Victoria Stainton, Porter Novelli
Tel: 01295 224533 or 01295 224397
Email: Firstname.lastname@cpn.co.uk
| |
