Ship designer goes with Neptune’s flow
The OSD designed Neptune NP1000 full scale demonstrator tidal current generator.
IJmuiden based Offshore Ship Designer's first project in the marine renewable energy field will shortly be commencing on site trials in the UK's Humber estuary.
By applying its experience and design knowledge, the Dutch company has helped the UK’s Neptune Renewable Energy Ltd (NREL) to develop an innovative device to capture the potential of tidal stream energy. The Proteus NP1000 full scale demonstrator will harness tidal currents to produce at least 1,000 MWh/year of electrical energy.
Michiel Wijsmuller, managing director of OSD said, ‘There are plenty of innovative ideas on how to turn marine energy into usable power on the energy network. However, it takes solid marine engineering skills and design experience to turn these novel ideas into practical workable solutions, and that is where OSD comes in.
‘The basic and detailed design of the NREL patented concept was developed in OSD-IMT's offices in the UK. The target capital cost per megawatt of power generating capability of the device is very competitive with wind power generation and, unlike wind, tidal stream power is continuous and not intermittent.’
The original concept for the tidal current generator was developed at the University of Hull, where initial CFD, mathematical and physical modelling was carried out. In 2008 Neptune Renewable Energy Ltd was able to secure private investment to enable funding of the full scale demonstrator, and OSD turned the concept into reality with a full structural design to Lloyds Register approval, advice on equipment sourcing and building supervision.
The NP1000 is a catamaran type structure 20m in length, 14m wide and weighing more than 150 tons. It was built in Sunderland under the supervision of OSD-IMT and was transported by barge to Hull where performance trials to validate the concept will be undertaken.
Installed in the steel hull is a 6m by 6m vertical axis crossflow turbine mounted within a patented, asymmetrical Venturi diffuser duct. The vertical turbine shaft connects through a right angle gearbox to two permanent magnet DC generators mounted in an aluminium deck house. The power is cabled ashore and connected to the grid via industrial regenerative drives and control systems.
The device is designed so that almost all maintenance and component replacement can be carried out on site. The NP1000 will be moored in the free stream to minimise environmental impact and operates equally efficiently for both flood and ebb currents. The rotor is maintained at optimal power output by means of computer controlled shutters within the duct.
Future plans following full scale onsite tests are to install a further ten units in the Humber. There are at least ten more estuary sites around the UK, and hundreds worldwide, which potentially could support this new technology.
Says Wijsmuller, 'OSD aims to use its experience to help other renewable energy projects to develop. It is the ultimate in recycling, using existing experience and technology to move renewable energy from the innovation stage to real power production.'
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