Surf's up - harnessing the power of the waves
The world's first wave farm opened off the coast of Portugal in November 2007 in what supporters of clean energy hope will be the start of new era in harnessing the vast power of the oceans.
Compared to wind and solar energy, wave power is still in the early days of its development. As a new form of alternative energy it faces the same obstacles that these other renewables have had to tackle, including improving their efficiency and producing electricity that is cheaper than that that produced from fossil fuels.
"What people shouldn't forget is that we're harvesting a resource that hasn't' been harvested before," says Peter Madigan, of the British Wind Energy Association (BWEA) that represents the British wind and wave power industry.
"People shouldn't judge the projects for what they are at the moment, but rather look to their potential. The resources off the coast of the UK and many other parts of the world are enormous."
Numerous companies are developing devices that can capture the awesome power of the oceans' waves and turn them into electricity. There are two types of energy that can be harnessed - wave and tidal power - with variations on the design of barrages and buoys the most common means. These machines take the energy from the motion of the waves near the surface of the water.
The devices used in the wave farm off the coast of Agucadoura, Portugal have been built by a Scottish company called Pelamis Wave Power ("pelamis" is Latin for "sea snake").
Resembling huge, red steel tubes similar in size to train carriages, these "snakes" are linked together in a row. Pointing in the direction of the oncoming waves, the waves travel down the length of the three tubes (each one is 140-meters long) making them bob up and down, while a hydraulic system harnesses this movement, driving generators to produce electricity. Each "snake" is anchored to the sea bed and the electricity transferred to the electric grid via a cable. Pelamis has said that each machine can generate the electricity for 500 homes each year.
It is early days for the technology, with a number of other methods and devices being trialed across the world; wave-power rich areas of the world include the western coasts of Scotland, northern Canada, southern Africa, Australia, and the northeastern and northwestern coasts of the United States.
The go-ahead has been given for a commercial demonstration project called Wave Hub that will operate off the coast of Cornwall, southwest England. It will act as a testing ground for a number of wave energy devices and it is estimated will produce 20 megawatts of electricity, enough to power 7,500 homes.
"It will be an experimental venture with a number of different companies tendering their devices to be included, but it is still a real project. In the next few years we will probably see most of these demonstration projects coming online, says Madigan.
Life under the ocean waves
The majority of wave power projects have been anchored a few miles off-shore and their effects on the immediate environment and eco-system remains uncertain.
"We're really only just seeing the first few projects, so we don't have much background knowledge of their ecological impact. What we do have the benefit of is seeing the impact of off-shore wind farms, so hopefully we can head any problems off at the pass," says Madigan.
However, other methods of hydro-electric power, such as tidal barrages are not without their own environmental implications. Spanning river estuaries they force the tidal water through turbines to activate a generator.
According to Greenpeace, the UK government plan to construct a tidal barrage across the Severn estuary in the UK has the potential to supply 4.4 percent of the country's electricity needs, but the scheme was met with a warning by the UK's Sustainable Development Commission in October 2007. The independent watchdog on sustainable energy clamed that a tidal energy system in the area would mean the loss of habitat for rare species in the Severn estuary.
"We are excited about the contribution a Severn barrage could make to a more sustainable future, but not at any cost," says Jonathon Porritt, Chair of the Sustainable Development Commission.
"Any development must be publicly-led as a project and publicly-owned as an asset, in order to ensure that the government takes full responsibility for taking a sustainable, long-term approach."
Large-scale hydro-electric projects, especially dams, have often come under fire for their ecological damage.
The Three Gorges dam in China was designed to end the floods in the basin of the Yangtze and provide power for the country's growing economic boom. Already 1.3 million people have been displaced and Chinese officials have admitted future problems associated with the dam could include conflicts over land shortages, land erosion and landslides on the steep hills around the dam, which could mean hundreds of thousands more people could be displaced.
Perhaps the grandest mega-project is the proposal to dam the Red Sea. A team at Utrecht University in the Netherlands looked at the possibility of building a wall 150-meters high, one-kilometer thick and 60-miles long stretching between Yemen and Eritrea.
While the authors of the report suggest it has the potential to create 50 gigawatts of CO2-free electricity for energy-impoverished Middle Eastern and northeast African countries, the plan has been derided as an ecological catastrophe with Peter Bosshard, policy director of the International Rivers Network calling it "a completely ludicrous proposal" in the New Scientist.
What do you think? Have your say and join the debate
I think we should make fewer dams and more wave farms. Wave farms cost less and don't affect people and the environment.