Breaking waves

Elaine Maslin

July 1, 2016

Danish firm Wavestar has a fixed installation wave energy concept, which could also incorporate wind turbines and even solar power, says CEO Laurent Marquis. 

The core concept involves a row of half submerged buoys or floats, attached to a fixed platform. The floats rise and fall with the waves, producing energy via hydraulics into a generator. When the waves are too strong, the floats are lifted out of the water. 

The Wavestar concept was invented by sailing enthusiasts Niels and Keld Hansen. In 2009, a half scale 600kW machine, using two 5m-diameter floats, was installed and then grid connected in 2010. Over four years, it produced 45.4 MW of energy, with 88% uptime, according to the firm.  

The company has formed an industrial consortium for commercial testing of its first full scale 1MW Wavestar, including STX in France and JDN, to make the machine. 

Marquis told the European Ocean Energy Conference in Edinburgh earlier this year that some €40 million (US$45 million) has been invested to get the company to where it is today. “We believe we need to invest the same amount again, if not more, to be commercial,” he says. 

The company has been through a learning curve. “[We] broke floats in the beginning,” Marquis says. “There were failures due to failings in structure. Cracks in welding. The lifting system to take the system out of the water, a rolling screw, issues with that. [There was a] small fire in the machine because of electrics overheating. After all these failures, we found solutions to prevent it from happening again. Now we want to build bigger, with 20 floats,” he says. “The complexity increases as it gets bigger. Twenty floats means more hydraulic oil, more control systems. There is a focus on improving performance and decreasing cost by optimizing the structure.” 

A new hydraulic power take off system has been developed by Wavestar and Aalborg University for this unit, using four generators at 160kW and two at 200kW, to support variable capacity, with an optimized control system. A jackup structure is also planned to be used for sites with high tidal range.

The company aims to produce a full scale, 1MW using a C6-1000 device, by 2019 at Belgian site owned by Parkwind, with commercial units by 2022. The family behind the Danfoss brand is a main shareholder in the company. 

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