Sea trials soon for fledgling wave power technology

May 1, 2011

Norwegian mechanical engineer Julius Espedal had his first real brush with the forces of nature when undergoing offshore safety induction and emergency training in the UK back in 1999. Now he is getting reacquainted with them as his company Langlee Wave Power gears up for the first sea test of its new device this autumn. Espedal discusses the rationale behind this technology and progress to date.

If there is one sure thing we can predict in life it is the coming and going of waves. Global energy producers are waking up to the power of nature as an alternativesource of energy, particularly the forces of wind and sea – and are turning their gaze, albeit some believe too slowly, towards offshore renewables technology.

Waves are now being recognised as a dependable energy source with the potential to become a substantial industry. This energy is more stable and has better potential than wind power due to higher energy density.

The renewables industry can learn from oil & gas engineering, but often there has been reluctance from companies as they strive to do things differently. When designing the Wave Energy Converter (WEC) Langlee Wave Power turned to proven oil & gas technology and offshore standards. Another key was to ensure the design was available for mass production in any region and suitable for quick installation to any offshore location.

The WEC is a floating structure, which utilises horizontal wave movements, harnessing it into energy set around a simple steel tubular structure. The lightweight device is securely moored to the seabed and laps up wave movement through large water wings which swing along with the waves. The two water wings move in opposite directions providing optimal power efficiency which is converted into electricity through special generators, which are directly connected to the water wings.

A scale model of Langlee's larger, 250kW (25m x 25m) E2 converter took place last year at Aalborg University in Norway. A new 1:20 scale model was built for the test, based on engineering work carried out through 4Subsea and Aker Solutions. In the model, the power take-off system was simulated with microprocessor controlled electric motors, one on each water wing. The control system was designed to respond dynamically to the incoming wave, with various control parameters used to increase the power production.

A power efficiency of 35% was documented in the target wave conditions. Stability, movements and mooring forces were measured toverify the computer models, demonstrating the E2 has been designed to survive a 100-year storm. The calculated yearly production for one E2 installed at the European Marine Energy Centre in Orkney is 1GWh, which would power 250 homes. This has given Langlee the confidence to proceed to this autumn's sea test.

The steel framework meets offshore compliance standards (DNV-OSS-312) with standard steel quality (S355/NV36) and is constructed with offshore surface treatment. The joints are made of steel castings which boast excellent fatigue and fabrication properties. Each module has been designed for streamlined fabrication by local industries, allowing easy construction, outfitting as well as minimum maintenance. This has the added advantage of cutting down on transportation costs.

Langlee will ensure the framework is constructed to high standards by having quality assurance programmes in place for companies' compliance. Once the device is built onshore, it is towed to site for hookup to the sea bed. When installed, Langlee will also set up operational and maintenance contracts to ensure the long life of the device.

The structure is environmentally friendly and is designed to work with 100mm of marine growth which will attract fish, and with a no fishing zone around the installation it will become a natural habitat for marine life.

Langlee initially focused on the large converter for use in the North Sea and similar hostile environments. However as progress with utility companies and gridconnection has been slower in the UK than first expected, the company was encouraged to refocus its business plan and its technology. Its smaller, 50kW (15m x 15m) E1 converters are ideally suited for small island communities facing energy challenges, but without the big waves experienced in Scotland.

By bringing forward its more flexible device, Langlee has been able to open up brand new markets to wave power and it thinks there are huge opportunities to supply small islands in temperate regions with efficient wave power solutions.

As the E1 model works in smaller waves, power from the seas starts to become a real alternative for islands without grid connections. The cost of energy will be competitive with power from diesel generators. This could be an exciting new future, empowering island communities that have suffered at the hands of a volatile energy supply.

Langlee has signed a licence agreement with Turkish partner Unmaksan, part of the Altintas Group, for a 600kW test farm off Turkey, which has backing from the local authorities. In Turkey, 80% of energy is imported, mainly gas from Russia, with energy demand growing at a rate of 8% annually.

One of the attractions of this model is that it will be supporting the local economy. Local yards will build the bulk of the infrastructure, while the generator and control system will be delivered from Norway. OE


In brief

  • Statkraft is cementing its place as one of the leading trading and aggregators of wind power in the UK, after signing a new power purchase agreement with Dong Naturgas worth around £160 million. The two-year agreement sees Statkraft purchasing 50% of the production of Dong’s Burbo Bank, Gunfleet Sands, Walney and London Array offshore wind farm projects.
  • Marine Current Turbines, developer of the pioneering SeaGen offshore tidal energy turbine, believes it is on course to install one of Scotland’s first tidal energy farms by 2014 after securing an lease agreement from the UK’s Crown Estate for a four-turbine facility in Kyle Rhea, a strait of water between the Isle of Skye and the Scottish mainland.
  • CTC Marine has returned to Germany to continue installating subsea inter-array power cables on the Bard Offshore 1 wind farm utilizing the Maersk Recorder with its CMROV 4 jet trenching ROV. In a campaign that follows on from last year and is expected to last up to seven months, CTC Marine is installing 80 inter-array power cables in total on this development in the German Bight.
  • The bearings division of oil & gas sector polycrystalline diamond cutters provider US Synthetic has been awarded a $186,000 grant by the US Department of Energy under its renewable energy program for a joint investigation into the potential role of PCD thrust bearings as an enabling technology for underwater marine hydrokinetic turbine generators.
  • Danish manufacturer Vestas plans next year to test a prototype of its biggest ever offshore wind turbine – 187m from seabed to tip, and with a rotor diameter of 164m. Anders Soe-Jensen, president of Vestas Offshore, said he expects serial production to start 1Q 2015.


About the Author

Julius Espedal
is founder and CEO of Norway's Langlee Wave Power. He sold Frontec, a company he started up in 2001 to import custom-made components for the Scandinavian electronics industry, to bankroll the 2006 launch of Langlee and focus on the development and commercialisation of a groundbreaking wave power system. Espedal has held product development and management posts with a number of Norwegian companies. He also spent time with Cambridge Management Consulting in the UK supporting the reorganization of a North Sea oil company





 



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