The Power of Wave Energy

wavepowerPhoto: unknown

Who can fail to be awestruck when they witness a huge wave crashing into the shore? You stand among boulders spraying diamond drops of rainbow colored water in all directions, transfixed by the raw power that you see unfolding before your eyes – but until now it’s been a power that man had never learned to harness. Those breakers generate awesome amounts of energy as they pound the shoreline.

Consider the vastness of the oceans that cover so much of our planet and the influence that they exert even over the moon. This boundless and immeasurable energy is constantly renewable and begs to be utilized for lighting and heating. Fossil fuels may be slowly diminishing around the globe but the ocean is vast and timeless.

In March 2000, the world’s first commercial wave power station came online on the Scottish island of Islay, feeding electricity generated by the ebb and flow of the sea into the island Grid and supplying power for four hundred local homes. It was only a small beginning, but the technology has since moved on by leaps and bounds.

limpetPhoto: website

The Land Installed Marine Powered Energy Transformer (LIMPET) was an example of a commercial wave energy converter designed to operate on the shoreline. Waves entering a concrete tube alternately compress and decompress the air within which rotate the blades of the Wells turbine housed within the tube.
Because these blades can uniquely turn whatever the direction of the airflow the generation of electrical power from it is constant. This amazing device was the brainchild of Professor Alan Wells and Allan Thompson who together founded WAVEGEN back in 1992, pioneering research in the design and manufacture of wave power systems.

Their estimates showed that the seas off Scotland could provide enough energy to supply the whole of the British Isles three times over and that worldwide the seas could easily supply more than double the energy needs of the entire planet for the foreseeable future.

As Allan Thompson said at the time – ‘This is a big day. Wave power has joined the important group of commercially viable competitive and clean forms of sustainable energy available to the world market. Limpet is an important milestone, here to prove that energy can be commercially extracted from our vast ocean resources.’

Of course L.I.M.P.E.T. was only small in scale, only producing 500kw of electricity, but much larger machines have since been developed, providing far greater returns. Marine Current Turbines Ltd. Developed a new Tidal Wave Generator, Seagen which was trailed in Scotland’s Loch Linnhe in 1994.

seagenPhoto: website

Over the next decade, the technology was refined to the point that the company installed the largest offshore generator in the world, SeaGen, at Strangford Lough in Northern Ireland in 2008. This 1.2 meagawatt turbine is claimed to be the largest grid-connected marine renewable energy system in the world, the first to have exceeded 1000 hours of operation, and has so far sent 800mw of power into the national electricity grid.

Tidal wave generators are apparently twice as efficient as wind powered turbines and there are some massive schemes planned around the world. One such is the UK’s Severn Barrage. The river Severn has an enormous tidal surge twice a day, more than big enough to generate massive amounts of electricity.

severn barragePhoto: website

The 20 billion pound Barrage would mean building a 10 mile long dam between Cardiff and Somerset. This would act as a bridge between England and Wales and should be operational for up to 200 years. It would be largest ever renewable energy project on earth. A total of 214 40MW turbines would be operating when the tide turned generating electricity.

The tidal turbines would generate as much electricity as three nuclear power stations, enough for 5-6% of the current electricity needs of England and Wales, and equivalent to 8 large coal-fired power stations. Only one large scale commercial tidal power station in the world exists today – La Rance Tidal Power Plant in Brittany, which has been in operation for over 40 years without mechanical breakdown.

big dam,Photo: website

We must not forget that hydro-electric power in nothing new. Dams have been built all over the world for this purpose. Some are truly massive, and the world’s second largest, on the border between Brazil and Paraguay, in 2008 produced 95billionKwh – enough power for 90% of Paraguay’s and 20% of Brazil’s annual requirement. Yet even electrical power on this scale is nowhere near enough.

OsmosisiPhoto: website

Scientists have long been aware of the process known as osmosis, and that this provides yet another method of generating power. Osmosis is the movement of water through a semi-permeable membrane exactly how plants absorb moisture through their leaves. When fresh water meets salt water, for instance where a river runs into the sea, energy is released.

This energy can be used to generate power. The world’s first osmotic power plant is to be found at Tofte in Norway. Worldwide it is estimated that this process could produce as much electricity as the total power requirements of China in 2002.

plantPhoto: website

In the osmotic power plant, fresh water and salt water are kept in separate chambers, divided by an artificial membrane. Salt molecules in the sea water pull the freshwater through the membrane at a rate equivalent to a significant waterfall, which is then fed through a power generating turbine.

waterfallPhoto: Josey Shwaa

Waterfalls are also great natural providers of power, and in the USA, plans are in place for the installation of 850+ turbines within the Niagra river and falls, again generating huge amounts of power. Water is, let’s face it, everywhere on the planet and capable of providing endless ‘green’ power for the foreseeable future, if mankind will only learn to take full advantage of it.

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