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Alstom and the Conquest Of the Ocean
Next Steps for the Development of Renewable Energy


Rob Stevenson

3D rendering of Alstom's 1-megawatt tidal turbine.
There is considerable potential for the tidal energy market, estimated at between 50 and 100 gigawatts worldwide. The early markets are in northern Europe (the west coast of France and the Scottish coastline of the U.K., in particular). Alstom (Levallois-Perret, France) believes this market alone accounts for 10 percent of the potential market. In fact in the U.K., the 2011 Tidal Current Resource and Economics report suggests a total capacity of 20.6 terawatts per hour per year, which could practically be extracted from the 30 key tidal stream sites in the U.K. That 20.6 terawatts per hour figure equates to 3 percent of the U.K.'s forecasted electricity needs in 2050.

In terms of maturity, tidal stream energy is one of the more advanced marine energy technologies (after offshore wind) that is available to developers, and the first European tenders are expected in the near future. Last year, Alstom bought TGL Ltd. to gain access to their 1-megawatt electricity and 500-kilowatt tidal turbine and associated technologies, which were already being tested off the coast of Orkney, Scotland.

Developing, Testing Technology
The acquisition was finalized by the deployment of a 1-megawatt, full-scale tidal turbine at the European Marine Energy Centre's (EMEC) tidal test site in Orkney, on the same tripod support structure used to deploy the 500-kilowatt device. Alstom teams continue to test the 1-megawatt tidal turbine as part of the Energy Technologies Institute ReDAPT (Reliable Data Acquisition Platform for Tidal) project. The turbine is being tested in different operational conditions off Orkney over an 18-month period.

This project as a whole will help the company gather valuable information over a wide range of conditions, allowing the Alstom ocean teams to improve the product design, reliability and performance. The aim of this project is to demonstrate the effectiveness of the new, efficient and reliable turbine design, which would be a huge step toward the commercialization of this power solution.

During the summer, the turbine reached its capacity of 1 megawatt, and has now generated more than 130 megawatt-hours of electricity on the grid. This shows a reliability and performance in line with its design models, allowing the team to move on to demonstrate that the turbine can run independently. This year will also be a milestone for the turbine's endurance. The turbine will be in place, apart from during maintenance checks, for 20 years once it is in commercial operation. Alstom has to prove that it can operate successfully for extended periods of time.

Installation is a Costly, Challenging Process
The technology allows the turbine to be installed or uninstalled in just 30 minutes (using relatively small boats), maximizing the time it spends producing electricity and minimizing the cost of deployment and maintenance for the operator.

On site, it uses a patented winch and clamp design that winches the nacelle down to its seabed support structure and locks it in place. The system avoids the need for specialist high-capacity lift vessels and for divers.

Another major competitive advantage for the turbine stems from the way the system yaws. Tidal streams do not always turn through 180°. As the tide turns four times each day, the turbine has to be able to turn with it, positioning itself to face directly into the flow at the optimum angle to extract the maximum energy potential.

This also means that the initial placement of the foundation does not have to be perfectly aligned with the tidal flow. To continue this article please click here.

Rob Stevenson has more than 30 years of international management experience in the power generation sector across a wide variety of fuel mixes. He possesses a deep knowledge of the U.K. electricity market and is an enthusiastic supporter of the marine energy industry, while maintaining a realistic outlook on its prospects. Stevenson is currently vice president of the Alstom ocean energy business, having previously been the chief executive officer of Tidal Generation Ltd. He manages an integrated ocean team based in Bristol, England, and Nantes, France.

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