Harnessing the powerful streams of water present in the oceans to produce energy is a very attractive idea. This energy source is extensive and available around the world. Water streams are not only renewable, but also a reliable force of nature that can continuously produce energy. To tame the power of water is a challenge, both when it comes to the waves at the water’s surface and subsurface currents.

Century-long tests

Back in the late 1800s and early 1900s American engineers tried to capture the power of water streams. The different engines that were tested along Southern California beaches never took off.

Although full-scale plants were built, none performed optimally. The structures did not survive the forces of the sea.

In 2008, the world’s first modern and large scale water power plant was built in Portugal, about 5 km off the coast. The goal was to create energy via wave power, a technology we have written about in the past. Wind power stored in the sea The Portuguese venture was abandoned after a few months because of technical difficulties. The company behind the project is now trying to improve wave power technology in a new project off the coast of Scotland. At the same time, what may be the world’s largest wave power plant is being built off the coast of Lysekil, Sweden. While the technology to get energy from wave power is being developed, another technology that offers hope is to use undersea turbines to harness fast-flowing currents.

Sea power is huge, both on and below the surface.

Power from underwater currents

The oceans produce large forces. In practice, it should be possible to harness energy from the surface, as in the facility to be built outside Lysekil, and from the seabed, and all depths in between. Facilities on the seabed have the advantage that the plants do not need to float, but can be built on solid undersea bedrock. The technology can, in simplified terms, be compared to wind turbines built on the seabed. One advantage of building plants on the bottom of the oceans is that water has a higher density than air. Even though water flows slower than air, it can generate more power. But there are challenges, both when it comes to building power plants underwater, and to avoid the destruction of equipment by violent ocean forces.

A Scottish technique

Scotland is on the forefront of harnessing undersea energy.

Scottish Power has already carried out preliminary tests of wave energy by lowering a giant underwater turbine in the fast-flowing coastal waters off Orkney. The single turbine generated one megawatt of electricity, enough to power about 500 households.

In June 2012, the company announced that a set of turbines would be located off the west coast of Scotland. And in Norway, and in other parts of the UK, there are attempts to produce electricity from underwater currents. The promised investment from Scottish Power will probably be the biggest in the world, where the target is to produce electricity for 5,000 households. It remains to be seen whether the efforts currently underway on wave energy at the surface or below it will bear fruit or not. But the potential is certainly there. The technique takes a long time to develop due to the enormous stresses for structures in the oceans. Moreover, the technology available today, for understandable reasons, has been more focused on building on land than at sea. Once the technical solutions to renewable power from the seas become available, there is vast potential for them to spread to many coastal countries in the world.

The article was published in November 2012