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Wave and Tidal Power: An Introduction

TreeHugger likes to keep a keen eye on emerging sustainable and alternative energy technologies; while solar photovoltaics and wind farms are great (and getting better every day), the more ways we can produce energy without burning fossil fuels and other non-renewable sources, the better. One of the rising stars in the alternative energy game is wave and tidal power, and here is a quick introduction to what it is, how it works, and the designs we hope to be seeing more of soon.

While there are several different ways being developed to harvest the power of the wave and the tide, the basic idea remains fairly constant. Like clockwork, waves roll across oceans and other bodies of water (much like the sun always shines and the wind continues to blow); similarly, the tide comes in and the tide comes out each day. Harnessing this consistent power uses ideas from both current hydroelectric and wind turbine energy generation, but since water covers 2/3 of our planet, it can happen on a much larger scale.

One of the designs we like is by WaveEnergy [www.waveenergy.no] of Ålgård, Norway, which gets placed where an ocean break or sea wall would ordinarily belong (pictured). By creating a series of layered “reservoirs” up a carefully calculated slope, they have essentially digitized the potential energy of wave input. This is then converted to kinetic energy (by falling down), and this turns the turbine/generator; they estimate that a 500m breakwater generator can produce 150 kW of power. Not too shabby for just dropping it in the ocean instead of a pile of rocks, eh? There are more details about WaveEnergy (and a few other pretty interesting wave power implementations) here on TreeHugger [www.treehugger.com].

The other design that has piqued TreeHugger’s interest is a buoy system, illustrated at right by Ocean Power Delivery, Ltd. [www.oceanpd.com]’s system. They call their offshore wave energy converter the Pelamis, and it converts the energy created from bobbing up and down into energy we can use to power our homes, businesses, etc. A typical 30MW installation would occupy a square kilometer of ocean and provide sufficient electricity for 20,000 homes. Twenty of these farms could power a city of almost 500,000 people. Want to learn more about Pelamis? Check out this post over at TreeHugger [www.treehugger.com] for more details. Though wave power is just beginning to catch on, one thing is for sure: they aren’t just for surfing any more.