Wave Energy Project
In Japan
Wave Energy Project
In Japan
Japan has been the country of which the research and construction of wave power stations are extensively developed. It has built more than 10 power stations successively including the floating oscillating water column device, fixed oscillating water column device and pendulum device. The characteristic of Japan-made device lies in its higher reliability but lower efficiency.
In 1978, a united experimental research was conducted in a floating device called Haiming, which was reconstructed by a ship in a length of 80m and width of 12m, jointly by Japan Ocean Science Center and other countries including U.S, England, Norway, Swede and Canada. The device included 13 oscillating water column air chambers. The first stage of experiment was conducted from 1978 to 1979, which parallel experiment were simultaneously proceeded on three diverse types of device made by Japan, England and U.S. The second stage of experiment was conducted from 1985 to 1986 aiming to improve the generation efficiency, mitigate the solidity and weight of the sets and generation distribution under the sea and mooring system. The generation efficiency on Haiming was disappointed, only 6.5%. But as a large-scale international cooperation project, the contribution of Haiming lies not only in the technical achievements, but also the promotion of wave energy research in the worldwide.
In 1983, one set of 40kW on-shore oscillating water column pilot power station was built in Japan jointly by Japan Ocean Science Center and the ship manufacturer and Fuji Power, and a winter power generation experiment was conducted with the total investment of 80 million Japan Yuan. The site selection was placed on a rock with inner concave. After the completion of underground foundation, the framework of steel structure of air chamber was erected, and then the concrete was poured. The width of air chamber was 8.1m; depth was 5m. A symmetrical wing turbine with the diameter of 1.3m was equipped to the two ends of 40kW horizontal generator sets. When the wave height reached 4m, the output efficiency of power station was 40kW, the average output was 11.3kW and the total efficiency was 11%. After the experiment, the turbine generator sets was dismantled due to the difficulty of management, but the air chamber structure still remained in good situation.
Furthermore, one set of pendulum wave-activated power station with the installed capacity of 5kW was built in Japan in 1983 by Japan Shilan Industrial University. A swing gate that can be swing back and forth of the water channel was utilized to absorb the wave energy in the power station. The hydraulic device was its damping. Two sets of single-direction functional hydraulic pump were utilized to drive the generator to absorb the wave energy in the whole period. The width of swing was 2m, the max. pivot angle was ¡À30 for the power station. The normal output was 5kW and the total efficiency was 40% while the wave height was 1.5m and the period was 4s, which was one of the power stations with the highest efficiency. Moreover, another sameness device was built in Westpu Harbor to provide heating water for the housing of fisherman.
In 1988, another set of oscillating water column demonstration power station was designed and constructed on the shore 99 miles away eastern to Tokyo. 10 pieces of steel pipe in the diameter of 1.5m was arranged in the air chamber of power station, which was erected in a place meters before the wave embankment. When the water column inner the air chamber raised, air would be compressed to a constant pressure tank in a diameter of 7m through the air-discharging pipe. When the water level inner the air chamber declined, air in the outside would be injected into the air chamber through the air suction valve, and vice versa. A 30kW conventional impulse turbine generator sets with a steady output and average output of 6kW was connected to the air storage tank to produce electricity for the nearby farm. It was scheduled to conduct the generation experiment in a period of 7 years in the power station, which has been operation in normal condition for 10 years.
Japan Harbor Technology Research Institution built a wave breaker oscillating water column power station in 1989. The caisson of wave breaker was a chest-type air chamber, in front of which was the plate for prevention of orifice possible to flow in the wave. The wave contacting width of caisson was 20m; the thickness was 24.5m; the height was 27m. The generator was connected to two symmetrical turbines in the diameter of 1.3m with which the capacity of 60kW. The electricity was utilized for the demonstration water heater, fish breeding by warm water and navigation buoys. The efficiency for air chamber was about 50%; the efficiency for turbine was about 30-40%; and the total efficiency was in the region of 10-30%. Large amounts of measuring sensor was arranged in more than 100 places in the power station in order to obtain the data information of wave, load, pressure, motion and electricity. The total investment was over 700 million Japan Yuan. The charges for the turbine generator sets were over 60 million Japan Yuan.
Backward duct wave energy device was an innovative work in Japan proposed by a famous wave energy inventor, which was a back extending floating oscillating water column system. The opening of air chamber was locating in the backward of the floating body and back to the wave. Such brave design can make full use of the energy of floating body obtained from vibration and swing, and the back extending air chamber can be adjusted with the length conveniently in order to cater to variable wave, which will be of great significance for the small wave and shallow water area. On-sea test was conducted on the device in 1987. Soon afterwards, this device was developed jointly with GIEC (Guangzhou Institutes of Energy Conversion, Chinese Academy of Sciences).
Japan Ocean Science Center started its research and construction of another wave energy device called huge whale in the early of 1990s, which was a developed backward duct floating device. The shape looked like a huge whale. The air chamber of the device was designed to the front part of the structure. The long body not only can make use to absorb the wave energy, but also can be comprehensively utilized to be a combined system including wave power generation, fish breeding on sea and tour resources. The device has completed its manufacturing in 1998 and put into operation in the open sea. The device in the width of 30m, length of 50m, was equipped with one set of 10kW, one set of 50kW and 2 sets of 30kW power generator.