Abstract
The UK has an enormous potential for tidal range energy. With the threat of global warming and the decline of the North Sea oil industry, national energy focus is shifting towards this form of renewable energy. Following in the footsteps of the first tidal barrage scheme in La Rance, the 320MW Swansea bay lagoon scheme has recently been given governmental approval (BBC News, 2015). Like existing projects, this lagoon will use the bulb turbine, which has been the standard device for tidal range projects for the last 50 years. One of the reasons these have continued to be chosen is because they are a proven technology, however, since the first project in the 1960’s, turbine technologies have evolved and altered in a plethora of new designs. The aim of this research is to investigate and evaluate these new designs numerically using a marking criteria to determine their suitability. Out of the designs examined the Archimedes Screw proved the most promising for further research, due to the reduced cost, simplistic design and environmentally friendly nature. Through the use of computational fluid dynamics (CFD), a variety of screw turbine designs were evaluated, each investigating a different geometric parameter, which affects the overall performance of the device. The trends found due to altering these values proved that the design of a screw turbine and a screw pump are fundamentally different. The designs, which both increased the volume of flow in each screw bucket and decreased the surface area of the turbine in contact with the flow proved the best. This device in tidal lagoons offers; superior pumping ability; longer operational per tide cycle and can perform well in water with a high silt content (which is expected in tidal lagoons). However, it is necessary to perform further research and model testing to fully analyse the power potential of a full sized device.