Abstract
Wave energy is one of the most promising renewable energies. Practical use of wave energy conversion technology requires that the following conditions are all satisfied at some acceptable level: (1) durability against wave load, (2) workability in setting and maintenance, (3) high performance of energy gain, and (4) reduction of total cost. In order to meet these conditions, the authors have proposed a float-type WECs each of which consists of a float, rack & pinion, ratchet mechanism and electric generator, and works by utilizing gentle vertical motion of the water in a chamber of the chambers array laid along the direction of the wave propagation. The layout of the chambers array is accomplished by laying chambers array in the cross shore direction in the near shore, which makes it possible to lay multiple WEC devices and therefore to gain a lot of energy from limited length of the shore line. The present paper gives the dynamics model of the above mentioned WEC system, and the results of the calculations supposing the practical use. The calculation covers both time series of the vertical motion of the float, tension of the shaft of rack & pinion, torque required to turn the generator, and the occurred electric power including the sum of the multiple WECs, and the time averaged energy gain.