Combined wind and current generator due

This Savonius unit is under construction by Mitsui Ocean Development and Engineering Company (MODEC) and is scheduled to be installed later this year.

The unit comprises a floating circular base that is moored out at sea. Above this is a Darrieus vertical axis wind turbine that extends to 47m above the waterline. Below the waterline and installed on the same vertical axis is the current turbine that comprises bucket shaped rotors. This has a diameter of 15m and which extends below the waterline by about the same amount. The two turbines are connected to a central generator that is housed in the floating support unit. The wind turbine is mounted flexibly in order to isolate it to a certain extend from any wave motions.

The generator is claimed to produce 1.5 MW of electric power which will be carried ashore by a connecting cable. This prototype unit will be moored off the south west coast of Japan when completed and is aimed to be the prototype of larger units that should create a higher efficiency system to harness renewable energy.

By combining wind and current power it is anticipated that the unit will be able to produce power on a more continuous basis that wind turbines alone and it will also produce a more concentrated power source in crowded ocean waters. It should also reduce the costs of installation compared with seabed structures and it can be brought into harbour for maintenance rather than incur the high cost of maintenance in the open sea, as happens with fixed structures.

Further information: www.modec.com

By Dag Pike