Report To Wave Energy Steering Committee On The State-Of-The-Art Of Moorings And Their Application To Wave Power Devices: Appendix 1, Costs
The costs of laying a mooring for a wave power device are made up of various parts, some of which such as laying and maintenance are time and weather dependent. In addition, the efficiency with which plant or vessels are utilised can be largely dependent on how they are employed on the wave power installation as a whole and not only on mooring activities. A number of operations to be carried out can greatly effect the unit cost, ie much greater cost savings per wave power device are likely to result if a large number of devices are to be installed consecutively as opposed to only one device. This mainly results from the differences in short and long-term charter rates for vessels and normally mobilization fees from and to the home port are also charged. In the case of relatively common vessels such as offshore supply vessels, this could be small since the home port could be local, however, with specialised craft such as crane barges and ocean going tugs, these may have to come from places like Rotterdam or even Singapore. In considering a very large wave power installation it is possible that such specialised craft as would be required would be owned by the Electricity Supply Authority and therefore operating costs would become part of the overheads. At present in arriving at a cost for mooring wave power devices we can only use predicted costs for equipment where it does not already exist and use current day rate charges for plant and craft on short-term hire. In the case of mobilization charges it is intended to ignore these and consider the mooring operation as commencing with all equipment and plant already located at the home base which for this exercise is assumed to be the Firth of Clyde.