Tidal Energy

Eco Sustainable Village

Energy production with Wave Power

Introduction

Ocean waves are caused by the wind as it blows

across the sea. Waves are a powerful source of

energy. The problem is that it's not easy to harness

this energy and convert it into electricity in large

amounts. Thus, wave power stations are rare.

How it works

There are several methods of getting energy from waves,

but one of the most effective works like a swimming pool

wave machine in reverse. At a swimming pool, air is

blown in and out of a chamber beside the pool, which

makes the water outside bob up and down, causing

waves. At a wave power station, the waves arriving cause

the water in the chamber to rise and fall, which means that

air is forced in a and out of the hole in the top of the

chamber.

We place a turbine in this hole, which is turned by the air rushing in and out. The turbine turns a

generator.

A problem with this design is that the rushing air can be very noisy, unless a silencer is fitted to the

turbine. The noise is not a huge problem anyway, as the waves make quite a bit of noise themselves.

More details

Once you've built it, the energy is free, needs no fuel and produces no waste or pollution.

One big problem is that of building and anchoring something that can withstand the roughest conditions at sea, yet can generate a reasonable amount of power from small waves.
It's not much use if it only works during storms!

Another method

A company called Ocean Power Delivery are developing a

method of offshore wave energy collection, using a floating tube

called "Pelamis". This long, hinged tube (about the size of 5

railway carriages) bobs up a and down in the waves, as the

hinges bend they pump hydraulic fluid which drives generators.

Advantages

	The energy is free - no fuel needed, no waste produced.
	Not expensive to operate and maintain.
	Can produce a great deal of energy.

Disadvantages

	Depends on the waves - sometimes you'll get loads of energy, sometimes nothing.
	Needs a suitable site, where waves are consistently strong.
	Some designs are noisy.
	Must be able to withstand very rough weather.

Is it renewable?

Wave power is renewable.

TAPCHAN wave energy device

Teamwork Techniek a Netherlands based organisation have an exciting new product for harnessing the power of the waves, they claim that their product, the Archemedes Wave Swing (AWS), is competitive with other energy generation technologies. The concept is a simple system of connected air chambers utilising a flywheel effect, using the heave of the sea to produce electrical energy. Sea heave is caused by the action of the wind on the water surface, in turn wind energy is caused by solar energy but with waves during the process of conversion the energy is concentrared more and more, from 100w/m2 upto a level of 100kw per wave front. Also wave energy is reliably present even during calm periods, unlike wind energy proper, so wave energy can also be considered as stored wind energy. Where a wind turbine produces on average 20% of it's rated capacity, the AWS produces 50%. The AWS is completely under the water surface and doesn't use the surface wave for energy generation. The effect of this is that the design is simplified and doesn't need to cope with the extremes brought about by surface storms, a great advantage when compared with surface wave type generators, resulting in less extreme stresses, and a gentler operating environment. Their three chamber design produces 8mw. Teamwork expect a cost of 9 to 15 cents per kwh for the AWS and a global coastal potential of 20,000 kilometres (70,000 households at Dutch consumption levels), where six systems can be installed per kilometre . Within this total global coastal length, an existing electricity grid infrastructure is present near about 10% of the coast, they have then worked out an economical market potential of 1000 kilometres, dependant on available infrastructure, extent of market and selling price per kwh. The product will be marketed and installation begun by the year 2000. It is planned that the pilot project will be built in Portugal using EEC funding from the Thermie project and that subsequent development and builds are not planned to be subsidised in this way, however the experience gained will reduce the cost of subsequent implementation. Teamwork will be the knowledge base and not the actual manufacturers or installers of the hardware, building is an offshore project of large mass and dimensions. For once with this type of project, there is confidence in the potential for success.

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