Rachel Wuest Period 5

Tenth-century British idea First major one was in St. Malo, France in the 1960’s Second major one in Canada in 1982 Most favourable topography: North coast of France, Bay of Fundy (Canada), and Northeastern United States

So basically how this works… For starters, you build a dam across the entrance of a bay or a similar water body The flood tide runs turbines to open the dam The water floods in, turning more turbines, creating electricity When the bay is filled, the dam closes When the tide retreats, there is more water in the bay than there is in the ocean The dam is opened once again, and the water goes back into the ocean, again, turning turbines (that are reversible)

Three uses… Wave – (pictures in last slide). Kinetic energy exists in the moving waves of the ocean and can be used to power a turbine. Water enters a chamber and forces the air out of the chamber. The moving air spins a turbine which can turn a generator. When the wave goes down, air flows through the turbine and back into the chamber through doors that are normally closed. Tidal – (discussed first). When tides comes into the shore, they can be trapped in reservoirs behind dams. Then when the tide drops, the water behind the dam can be let out just like in a regular hydroelectric power plant. In order for this to work well, you need large tides. An increase of at least 16 feet between low tide to high tide is needed. One plant in France makes enough energy from tides to power 240,000 homes. Ocean thermal – Power plants can be built that use difference in temperature to make energy.

Yes, it does make electricity and heat. It can move large turbines if the tide is large enough, but this type of energy probably could not be used in small machines.

Earliest evidence – 900 A.D. First modern-era plant (about 10 mW turbine) (France) – 1960’s Second modern-era plant (about 16 mW turbine) (Canada)

Making the plant is the most expensive part (about $3-$15 billion  ), but running, maintaining it, and repairing it are relatively cheap About £1m/mW ($1.50/mW) to produce Uses from 2,200 – 8,000 mW plants, the more mW, the more expensive

St. Malo, France

Canada

Once you built the plant, power is free. No transportation carbon emissions It produces no green house gases or other waste No need for fuel Very dependable Very predictable

VERY expensive to build Large environmental impact, both upstream and downstream Limited sites Only provides power for about 10 hours Blocks navigation Impedes fish migration

Grandest proposal is the 8640-Megawatt Severn Tidal Barrage proposal. Suggested to dam the Severn Estuary between Wales and England. The tidal range in the Severn is upwards to 40 feet in places and the potential power from a barrage could provide 12% of the United Kingdom’s requirements.

Won’t be expensive to use Limits power use (~10 hours) Low greenhouse gas emissions No extra transportation needed

Sources Cited dal_power.htm dal_power.htm /tidal-power-tidal-energy-facts.html /tidal-power-tidal-energy-facts.html