Sea Snakes Produce Power

Captain Nemo’s Dream: How Europe Draws Power from the Sea

By Steven Hill | Tuesday, February 23, 2010

While wind and solar power are the most common forms of renewable energy deployed in Europe, other energy forms are gradually being utilized and show impressive potential. One of these is power derived from the sea. Steven Hill, the author of "Europe's Promise," discusses how the EU is developing this unconventional alternative energy source.



arnessing the sea has long been the stuff of science fiction, the allure of seemingly limitless and continuous energy (unlike solar or wind, since the sun doesn’t always shine or the wind blow).

However, science fiction is becoming reality in Britain, Portugal, Spain and elsewhere.


With the services of a Scottish company, Portugal is the first country to pioneer an eye-popping new technology known as a “sea snake” or “energy eel.” Sea snakes are long, floating cylinders that bob semi-submerged in the waves and convert wave motion to electricity.


Europe has long led the world in marshaling power from the sea. The world’s first tidal station was the Rance Estuary dam, built in Brittany, France, in 1966.



Each sea snake is about 400 feet (120 meters) long and 11 feet in diameter and is composed of three or four segments linked together, end to end. The ocean’s constant wave motion causes them to undulate in the sea like a giant snake, up and down and side to side, the motion pumping fluid through pistons that drive generators, both of which are housed inside the cylinders.


The power produced is then fed into underwater cables and brought to land, the entire array composing a wave farm that provides energy that is inexhaustible and more predictable than wind or solar power.


Portugal’s first sea snake had three segments, producing over two megawatts of power, which met the electricity needs of an entire coastal village — some 1,500 homes. Now Portugal is planning to expand that to 30 segments capable of producing 20 megawatts of power, sufficient for 15,000 households, saving some 30 million tons of carbon emissions.


Scotland also has purchased four of the sea snake segments to produce three megawatts of power off the coast near the Orkneys, with talk of expanding to a 30-megawatt wave farm that would occupy a half square mile of ocean and provide sufficient electricity for 20,000 homes. Twenty of these farms could power a city the size of Edinburgh, the capital of Scotland.


Europe has long led the world in marshaling power from the sea. The world’s first tidal station was the Rance Estuary dam, built in Brittany, France, in 1966. The station harnesses an exceptional tide differential with a range of 27 feet to produce 240 megawatts of power for 100,000 homes.


In this age of oil uncertainty and unstable energy prices, Europeans are experimenting with all sorts of renewable energy and transportation options that previously had limited appeal.



But modern technology is allowing the futuristic promise of tidal energy to step up to a new level. Britain is pushing forward with a new tidal machine that has created a stir of excitement. Imagine taking a windmill, turning it on its side, and sinking it into the ocean.


That, in effect, is what engineers have done in the Bristol Channel, south of Wales, about a mile off the British coast. Sixty feet beneath the sea surface, 35-foot-long turbines turn 17.5 times a minute, generating renewable energy from the water’s current. Above the surface, only a white and red-striped tower is visible.


Just as dozens of windmills can be deployed in a field to create a wind farm, these underwater “seamills” create the possibility of grids of undersea turbines producing hundreds of megawatts of carbon-free power — an energy sea farm.


Europe is employing a whole array of these energy technologies and more. Italy, Iceland, Switzerland, Germany and Portugal are developing geothermal energy, which makes use of the earth’s interior heat to produce steam that rotates turbines. Italy has 95% of the EU’s installed capacity, and volcanic Iceland produces over 50% of its electricity from geothermal sources.


The EU overall is nearly on track for reaching its 2010 target of generating 21% of its electricity needs (excluding transportation) from renewable energy sources.


In 2007, Germany generated 14% of its electricity consumption from renewable energy, preventing 114 million tons of carbon dioxide emissions. Meanwhile, the United States generates a paltry 6% of electricity from renewables.


Portugal is the first to pioneer a new technology known as “sea snakes,” which are long, floating cylinders that bob semi-submerged in the waves and convert wave motion to electricity.



In this age of oil uncertainty and unstable energy prices, and with the urgency of Europe’s governments to meet their goals for sustainable energy and greenhouse gas reductions, Europeans are experimenting with all sorts of renewable energy and transportation options that previously had limited appeal.


Each country is deploying different technologies and acting as a laboratory for the others, plotting a meandering course toward the future. Motivated by the increasingly urgent crisis of global climate change, previously futuristic ideas now are seen to be within reach scientifically as well as economically.


Of course, such pronouncements and proclamations would be hot air without the funding to back them up. But substantial capital investments are being made — not only by governments, but also by venture capitalists, major banks, financial institutions and blue chip technology companies.


At a national energy summit convened by Chancellor Angela Merkel, Germany’s energy industry pledged to invest $50 billion in new renewable energy infrastructure by 2012, with $20 billion in the solar industry alone. On a per capita basis, that would be equivalent to the United States investing $180 billion, nearly $30 billion per year, in renewable energy — an unprecedented sum.


The outline of a low carbon economy is emerging, with Europe at the forefront. “Renewable energy is the source of energy for the future,” says Manuel Pinho, Portugal’s economics minister. “We think this can create an industrial revolution and a lot of opportunities for jobs and research, and we want to be ahead of the curve.”


That’s how Europe is viewing this — as a new industrial revolution. And it is at the lead of this revolution.


Editor's Note: This feature has been adapted from EUROPE'S PROMISE by Steven Hill, published by the University of California Press. Copyright 2010 Steven Hill. Reprinted with permission of the author.
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