Final Report On Submerged Cylinder Wave Energy Device

Abstract

A first overall assessment of the submerged cylinder device has been prepared, from which at outline design for the principal components has been produced. A budget estimate for this design has been made, including allowances for annual operation and maintenance charges. The efficiency characteristics of the device have been determined from selected tank tests. With these efficiencies, the energy captured by each cylinder of an array has been estimated. Allowances have been made for the probable energy losses in each component through to the National network at Perth. On the basis of the preliminary specification for the device agreed in June 1979, at the end of Stage 1 of this Contract, the price of electricity delivered to the network is estimated to be 11. 4 p/kWh. This assumes a 5% discount rate and a 20 year operating life. A number of improvements to the reference design are already clear. Principally its tuned frequency should be increased so that the efficiency characteristics match the wave spectrum more closely. This single improvement in gross output appears sufficient to reduce the unit cost to about 8.5 p/kWh because of the significance of annual maintenance charges on the net annual revenue from sales of electricity. There is considerable scope to improve the design. Other power take off and energy transfer techniques deserve attention, and there is scope to rationalise the mooring and foundation arrangements. Because of the nature of its working environment, the same philosophy of using proven components or reasonable derivatives therefrom should be retained. The stable behaviour of the device in all sea conditions studied, and its high efficiency in the more persistent waves, confirm that this further step towards a comprehensive design of the basically simple, efficient and robust system is justified.