Using the ebb and flow of the tide
On the sea, there is not only a steady flow of powerful wind but also a flow of sea water which is caused by the tide. “Skwid”, that combines a windmill and a water wheel, is the world’s first offshore electricity generating equipment that uses both the wind force and the tide. It is developed by a Japanese company that deals with oil and gas production in a submarine oil field. Aiming for its completion in the spring of 2014, the facility is currently under construction off the sea of Kyushu, and it is scheduled to begin its operation in the autumn of the same year after some test runs. It is located about 1.5 kilometers away from its nearest island, and the water depth there is about 50 meters.
“Darrieus windmill” that can efficiently generate electricity with wind from any direction © MODEC, Inc
The power generator of Skwid is at the center of the yellow floating body, and it stabilizes itself using the underwater wheel as its weight © MODEC, Inc
The windmill of Skwid is about 50 meters high from the water surface, the water wheel about 16 meters of depth underwater, and they are attached and rotated centering the single axis which is mounted perpendicular to the water surface. The electricity generator is located between the windmill and the water wheel, with its output at 500 kilowatt. It is capable of serving about 300 households.
A traditional wind power generator needs to adjust its blade angle before start rotating, so it cannot operate without any external power source. On the other hand, Skwid can start turning windmill with the power generated by the tide. For this reason, it can be the first to start generating electricity even when surrounding plants stop operating from a catastrophic disaster.
Between the floating body and the generator, a special type of rubber is used in order to prevent transmitting wave movement
© MODEC, Inc
Many remote islands in Japan depend on diesel power stations within its land, because it is not easy to carry electricity from distant locations. If Skwid can be placed near these under-populated islands, the amount of oil consumption can be cut down dramatically. There are many islands in the world that are in a similar situation, so if Skwid is to be put into actual use, it can advance the practical use of natural power sources even in those lands.
Energy of the future
Testing Skwid’s wind power generation on the land © MODEC, Inc
The sea wind is stable in strength and direction, since it does not get affected by surrounding geographical feature. Although offshore wind power is popular in Europe, the type of facility that is most used is the one that gets fixed to the seabed, so it is limited to locations where the water depth is less than 50 meters. The floating wind power facility is a technology apt to Japan where there are only limited areas of shallow sea waters. If this new type of wind power station becomes practical in use, it would not only be the source of Japan’s future energy, but it would arouse an increase of wind force usage throughout the world.
(January 2014)