Special Features - Catching the tide

Making waves - Scottish company, Rotech, is developing a prototype of a bi-directional tidal turbine.

Catching the tide
(08/02/08)

An innovative tidal turbine is making waves in the energy industry.

Renewable energy debate

Climate change and the rising price of oil has pushed renewable energy to the forefront of the energy debate. Scottish company Rotech, has followed that agenda, deploying their skills and experience in offshore oil work to develop a prototype of a bi-directional turbine.

Rotech Director, Dr Donald Stewart, explains: "We have much of the necessary infrastructure already here in Scotland, the technology and expertise needed for working in the challenging ocean environment, and equipment such as heavy-lift vessels is available in the North Sea unlike in many other parts of the world."

Tidal energy vs wind

The Rotech Tidal Turbine, or RTT, is like a windmill but takes energy from the movement of water rather than air.

"Tidal energy has a number of advantages over wind," explains Stewart, "because the energy source is predictable. We know when we will harvest the energy, and for how long, a major advantage when planning energy production."

Also, the impact on the environment is better. "A one megawatt tidal turbine will be much smaller than a wind turbine," Stewart continues, "in terms of the materials used it's much less, and our impact on wildlife is less. Passing fish will experience the turbine as an obstruction, no different to a cliff, and swim around it. And the RTT in particular is totally submerged so it's completely invisible from the surface."

Efficient design

Rotech have licensed the technology to Lunar Energy Ltd, and together with Lunar have signed a deal with E.On, the world's largest investor-owned power company. The aim is to create an energy farm off the coast of Wales, showcasing the concept with the aim of developing a commercial field.

Aside from the engineering innovation of the bi-directional turbine, the device design is incredibly efficient. "Our intention is that all the working components are in a removable cassette," explains Stewart, "which can be lifted onto a ship and brought to land for maintenance. Because the turbine is out of the wave zone where the highest extremes of energy are experienced, we don't have to protect the turbine from the constant wear and tear of the waves."

With approaches from a large Korean utilities company planning a 300-megawatt farm for 2012, Rotech's shift from oil to water looks like the smart move.

Related links

Tidal energy projects in the UK