Government subsidy is increasing the focus on renewable energy, within which tidal energy has the advantage of being both efficient and predictable. The UK is a world leader in this field, and has some of the most promising naturally occurring sites. The challenges of the underwater location and the distance of generation sites from the transmission network have thus far prevented effective ways of harnessing this energy source.
There is great variation in the concepts which are being developed and no industry standard approach has yet emerged. Tidal energy, despite its potential and conceptual promise has not yet been proved to be economically viable. The cost of tidal energy needs to be reduced to between 10 percent and 20 precent of its current cost to be fully competitive with traditional types of generation. Innovative next generation concepts show the most potential for being able to reach these targets in terms of simplicity, flexibility and cost.
Flexible moorings for tidal current turbines offer advantages in both installation and maintenance but require careful consideration in the design phase. Until the tidal energy sector builds up its own body of experience in flexible moorings, the best information is likely to come from other marine industries.
Respected international agencies have begun to extend their existing guidelines for design, maintenance and safety to the marine energy sector. These guidelines have many common themes but many differences of definition and standards. Reflecting pace of new technology and trends, the guidelines tend to focus on principles and encourage a case by case approach.
Elastomeric mooring tendons (widely used in the yachting and navigation buoy industries) have excellent properties allowing significantly greater compliance than traditional types of mooring line as well as potentially reduced costs and a maximisation of energy generation. They are not a panacea and their practicality and economic feasibility need to be evaluated on a case by case basis according to the particular circumstances and location. Intrinsic uncertainties about the performance and lifetime upkeep of the elastomeric technology means that only experience will tell whether it is the best option for tidal current turbines.