Tidal-stream device undergoes final testing

The Neptune Proteus NP1000, from East Yorkshire-based Neptune Renewable Energy, was transferred by sea from Wear Dock in Sunderland and is now moored in William Wright Dock in Hull, where it is being fitted for deployment in the Humber Estuary.

When in place, it is anticipated that the Neptune Proteus NP1000 will be able to generate at least 1,000MWh/year. The company stated that this would be enough to power 1,000 homes.

Jack Hardisty, technical director of Neptune, told The Engineer in January that, once fully commercialised, there will no devices like it on the market.

‘We are not aware of any other device designed to capture the shallow-water resource,’ he said.

Weighing more than 150 tonnes and stretching to 20 metres long, with a beam of 14 metres, the Proteus NP1000 consists of a steel hull, a vertically mounted turbine and buoyancy chambers.

Nigel Petrie, chairman of Neptune, stated: ‘The key advantages that we believe set the vertical-axis Proteus apart from alternative solutions includes the fact that, at this stage, we are not aware of any similar device that is designed to capture the shallow-water resource in estuarine sites at significantly lower capital, and operation and maintenance costs.

‘Certainly, a major innovation is the cross-sectional shape that has been adopted for our patented design. The Proteus’ square turbine cross-section generated 30 per cent more electricity per unit channel width compared with circular turbines. Additionally, the flow-control shutters found in the Proteus increase the impacted length of the flow on the turbine, providing greater shaft torque and power outputs.’

Petrie said the Proteus demonstrator is the culmination of five years of intensive efforts. He admitted that the company had hoped to commission the Proteus at the start of the year, but the construction of the unit took longer than expected. Once deployed, the unit will undergo three months of trials in the Humber Estuary.

Neptune sees a number of practical benefits from focusing its efforts on estuarine locations such as the Humber. Specifically, the company points to the proximity of the generating capacity to the grid or distribution supply points, the absence of wave activity on the structure − as it can be moored in sheltered areas − and its proximity to land, which simplifies installation and maintenance.

Additionally, the company says the device can be towed to site using a small tug and, as a moored system, its environmental footprint is low, making it an attractive option in particularly sensitive locations.