Advantages

• Reliability. Tidal power/energy is more predictable than solar or wind energies. Rise and fall of tides is more cyclic than random weather patterns.

• Renewable. Tidal energy will not run out very soon (something like 2 billion years, when all of the oceans will boil, because our planet's orbit will get too close to the sun). Tidal energy is free, non-polluting, no waste is produced.

• Security. Barrages or small dams in general, can protect nearby cities or ship ports from dangerous tides during a storm, or at least reduce the damage done.

• Efficiency. Tidal turbines are up to 80% efficient in converting tidal energy to usable electricity. This is much higher than solar or wind energy generators. Compare this to your car engine, which is about 30% efficient at converting fuel in your tank to actual energy applied to the road.

Disadvantages

• Environmental Damage. There is considerable effect on the ecosystem. The exchange of water volume between a basin and the sea is reduced, this leads to the potential for increased pollution, because pollution is left accumulating in the basin. Also, because the exchange of volume is reduced, salinity of the basin decreases and sediment accumulation increases. Basically, anything we place in the water can and does affect the ecosystem.

• Fish population. Even with the best barrage designs, fish mortality rate per pass through the barrage is about 15%. Solutions to resolves this problem have either failed or are too impractical and too expensive.

• Time of day. Tides are predictable, but power stations only generate power when the tide is flowing in or out of the basin, which only happens during certain times of the day.

• Economical. Startup costs to build a tidal energy plant is high, but the maintenance costs are very low. This means that you will not see profits for a few years, causing some investors to back out of the project. This can be seen as both an advantage and disadvantage, depending upon desired profit returns.

Underwater tidal power

free-flow – свободный, безнапорный virtually – практически in development – в стадии разработки side effects – побочные эффекты predict – предсказать current – течение underway – в процессе исполнения adjust – приспосабливаться stocky – низкий, приземистый

nacelle/pylon flange – обтекатель pylon – опора tailcone/nosecone – хвостовой/носовой конус hub – центр, основа shaft seal – сальник вала (уплотнение вала против утечки жидкости, газа) bearing – шейка вала (часть вала, опирающаяся на подшипник) coupling – соединение, стыковка

Some people just don't like the look of windmills or wind turbines outside their window. A number of companies are working on solving this problem. A company called Verdant Power came up with an idea of placing "wind" turbines underwater. This new free-flow hydropower technology converts kinetic energy of deep water into usable electricity.