Tidal-stream (tidal) energy is a renewable form of energy produced by harnessing the kinetic energy of marine currents created by the rise and fall of the tides and converting it into electricity. To-date, tidal energy development remains largely in the demonstration stage and the development community has not rallied behind any one foundation technology. The distinguishing challenge for tidal development is the required installation technique and the uncertainty surrounding their performance in environments where the seabed has been stripped of most of its sediment and the underlying bedrock is left exposed due to the high energy currents common to locations suitable for turbine deployment. Shallow foundations, or gravity-based structures (GBS), are one of the leading foundation solutions for tidal turbines because they can be easily installed in these demanding environments; however, like offshore wind turbines, tidal turbines are subjected to predominantly horizontal loads. This paper describes the results from a combined horizontal and vertical load test conducted on a novel footing geometry designed to maximize penetration into the seabed. An onshore test site was selected based upon geologic similarity to possible offshore developments. The results of this study outline the importance of achieving footing penetration during turbine installation.
John Barrett, P.E., Kenneth Gavin, Ph.D., C.Eng. and Tom Doyle, Ph.D.
Keywords: gravity-based structures, GBS, shallow foundations, tidal
Publisher: DFI