Finally A Practical Way To Harvest Energy From Our Oceans

Deriving power from the movement of the tides has long been considered a target for alternative energy strategists. In some parts of the world, like Canada’s Bay of Fundy, tidal changes measure 50 feet in height while 160 billion tonnes of seawater flows in and out twice a day. However, the technology derived so far has been largely impractical to implement in the vast majority of coastal areas. Now a new UK company, in conjunction with Oxford University has approached the challenge in a fresh way and may just have brought tidal energy into the mainstream.

Kepler Energy, which was born out of the research of the Oxford University Department of Engineering Science, has patented a tidal power system which mitigates a number of the disadvantages associated with traditional technologies. Known as THAWT for Transverse Horizontal Axis Water Turbine, the major innovation is the horizontal design of the turbines. This is contrasted with the standard vertical “propeller” type turbine which is essentially an underwater wind turbine and requires a significantly deeper body of water in which to operate. This necessitates more expensive installation and maintenance while also limiting the regions of the world where it is applicable. Additionally, the relatively small profile of the horizontal turbines results in less materials costs and leads to minimal drag generated by the water and thus fewer parasitic losses.

THAWT: these new horizontal water turbines from Kepler Energy are several times more efficient than previous methods of tidal energy harvesting.THAWT: these new horizontal water turbines from Kepler Energy are several times more efficient than previous methods of tidal energy harvesting.

The horizontal turbines will operate individually, but are designed to most efficient when installed as a sort of turbine fence with many units linked together. As the water flows past the fence, a head of water is produced that increases the turbines’ efficiency. The extent of this increase is proportional to the length of the fence. The design has few moving parts submerged in the water, instead containing the majority of the system within dry columns which increases reliability, ease of maintenance, and instrument shelf life. The performance of the turbines was assessed first using computer models and then by real world tests: they were found to be the most efficient harnessers of tidal energy ever devised.

The company’s proposal is to install a 0.6 mile long tidal fence in the Bristol Channel on England’s southwest coast by 2021. The installation is projected to cost $224 million, a relative pittance when compared with many large scale industrial projects, and generate a peak of 30 megawatts. If successful, this could account for a whopping 5% of the energy demands of the UK. Future proposals for up to 6 miles of fence installed in the channel could yield five or six hundred megawatts, the equivalent of a small nuclear reactor.

Here’s a short video of a scale model of the rotor in action:


With global population set to hit eight billion shortly and increasing industrialization leading energy demand to increase at an even more rapid rate, alternative power sources will be a constant source of scientific inspiration. To see a new technology emerge that leads to such a dramatic increase in efficiency is remarkable and gives us hope that we may still find an acceptable balance between fossil fuels and renewables before it is too late.

Via News Daily.