We designed the wave energy conversion system which consists of water chambers array aligned along the wave propagation direction and the float-type wave energy converters, each of which is installed in the chamber and utilizes the gentle up/down motion of the water in the chamber. This system aims to match conditions required for practical use, i.e., durability against wave load, workability in setting and maintenance, high performance of energy gain, and reduction of total cost. Calculation is made along our previous mathematical model, but consideration on the load resistance connected to the generator is added for the information to practical use. Also the effect of the total length of the systems set on the time history of the total energy is considered more strictly.
A rising demand for energy coupled with the problem of environmental pollution has led to investigations into potential of new energy resources. Wave energy is one of the most dependable and predictable sources of renewable energy available which is free from the variations present in wind or solar energy(Takahashi, S. (1993); Malm O., and Reiten A.(1985); Evans, DV. (1982)). Various mechanisms for extracting wave energy have been developed but not fully realized due to structural strength and economic problems.
For the practical use of wave energy, all the following factors should be satisfied at some level: durability of the device, workability (without difficulty in installation, maintenance and repair), high performance of energy gain, and low cost. The durability of the device includes those of both the external structure and the power converting portion of the device. It can be said with certainty that the lack of fulfilment of the above mentioned conditions is the main reason that the wave power conversion technology has not reached a commercially generating stage.
In order to meet these conditions, the first author et.al.(2013) designed the system which consists of water chambers array aligned along the wave propagation direction and the float-type wave energy converters each of which is installed in the chamber and utilizes the gentle up/down motion of the water in the chamber. In this system, neither the wall(s) of the chambers nor the energy conversion device(s) are exposed to the impulsive load due to water wave. Also since this system is profitable when set along the jetty or along a long floating body, installation and maintenance are done without difficulty and the cost is reduced. Waves near the jetty or a loosely moored long floating body will propagate toward the length of these structures. Therefore, an array of water chambers set along the jetty or a long floating structure is profitable in the sense that the outer wall is never exposed to severe wave loads.