Energy Resources: Wave power

Wave Power - energy from the wind on the sea

Introduction How it works More details Advantages Disadvantages Is it renewable?

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 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!

A company called Wavegen now operate a commercial wave power station called "Limpet" on the Scottish island of Islay,
>> more details in their website....

>>View a simulation
from the Greenpeace website, with a good animation of how "Limpet" works

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 and down in the waves, as the hinges bend they pump hydraulic fluid which drives generators.

Find out more, including an interactive model, videos and technical details at www.oceanpd.com

Pelamis offshore wave generator from Ocean Power Delivery

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.