At the end of 2006, worldwide capacity of all wind turbines was close to 75 gigawatts, which represents around 1% of all electricity use in the world. Three quarters of that wind powered use comes from Europe. And the leaders with nearly 20% of their electricity coming from wind turbines are The Danes. Germany and Spain are placed 2nd and 3rd respectfully with about 10% of their energy being powered by the wind.

The major problem with wind - it's not always available when you need it. So to replace the unfulfilled need, non-renewable and also pollutant energy is used.

The United Kingdom one would think with its' island status and inclement weather, would be the leaders in wind power---not so much. Wind only accounts for 1% of the UK's energy needs, even though they have close to 2,000 wind turbines located both on and offshore.

The issue is where to store this renewable energy when it IS available. For the answer the world looks to the UK’s own, Professor Seamus Garvey. Garvey has introduced the idea of storing wind energy in flexible containers on the ocean floor, using Compressed Air Energy Storage (CAES).

CAES is easily explained by Garvey as a vast underground reservoir of wind energy. During peak hours, air is released from this reservoir which turns the turbines and produces energy to be used. Currently, CAES can only be found in 2 locations, Huntof, Germany and McIntosh, Alabama.

Garvey began his research on compressed air storage 2 years ago, but his love for wind power and wind turbines has been growing since childhood. In a moment of inspiration, Garvey realized that air could be compressed using a wind turbine or a wave-powered device.” Drawing a mass down within the blade of the piston itself compresses the air." he said.

So what exactly is the air being stored in? Garvey has invented a cone shaped bag (50 meters wide at the top to around 80 meters across at the base) and the bags are made of a combination of plastics. "A polyester reinforcement at the core with probably a polythene layer around that," Garvey said. The catch to this large zip-lock air-trapping bag, is that it must be kept in deep water (at least 600 meters or 1,696 feet deep) where the pressure is greatest.

Although there is an additional cost in fixing reinforcement cables and ballast, Garvey believes the future economic prospects for his invention are good. He plans to put the storage bags through smaller scale land-based tests, with four-meter diameter bags, to prove that his calculations are right.
The centrifugal force required to compress the air is too great for small wind turbines to cope with, so much larger turbines will have to be installed for the project to realize its goals.

Another problem...if the wind turbines are located in shallow water (like many of the UK's turbines are, in 40 meters of water or less) how can the air be placed into the storage bags, if the bags location must be at 600 meters? Garvey says a simple pipeline system from the turbines to the bags will solve this problem. Also, Garvey says the ocean contains steep ocean shelves off the west coast of France and Portugal and around the entire border of the Mediterranean. "You could put wind turbines on these shelves and within a few hundred meters, or kilometers you could be in 600-meter-deep water," he said.

Garvey has secured a grant from German's energy provider E.ON and he is confident that with the right funding the UK can achieve its goal of providing 20% of its energy from renewable sources by 2020.

Who knew that our dreaded friend the plastic bag who is know for littering the ocean could in fact be the answer for storing wind power underwater. Hopefully Garvey’s research produces outstanding results and revolutionizes the way wind energy is stored.

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