Optimising the Operation of Tidal Range Schemes

Abstract

Marine renewable energy, including tidal renewable energy, is one of the less exploited sources of energy that could contribute to energy demand, while reducing greenhouse gas emissions. Amongst several proposals to build tidal range structure (TRS), a tidal lagoon has been proposed for construction in Swansea Bay, in the South West of the UK, but this scheme was recently rejected by the UK government due to the high electricity costs. This decision makes the optimisation of such schemes more important for the future. This study proposes various novel approaches by breaking the operation into small components to optimise the operation of TRS using a widely used 0-D modelling methodology. The approach results in a minimum 10% increase in energy output, without the inclusion of pumping, in comparison to the maximum energy output using a similar operation for all tides. This increase in energy will be approximately 25% more when pumping is included. The optimised operation schemes are used to simulate the lagoon operation using a 2-D model and the differences between the results are highlighted.

Implementation of a Full Momentum Conservative Approach in Modelling Flow Through Tidal Structures

“…Neglecting any tidal variations that could develop over the rest of the year, this neap-spring tidal cycle was presumed to be sufficient for this assessment. The estimated annual (neap-spring averaged) energy was then calculated by extrapolating the simulation results over the period of one year [15]. The total electricity generated for the baseline scenario was estimated to be about 578 GWh/year, which was consistent with predictions for past studies [2,13,49].…”

“…The transfer of mass is included in the continuity Equation (1) through local sink and source terms. The operation of the lagoon can be optimised to generate the maximum energy [15]. Since this is outside the scope of this study, only a typical two-way generation scheme (as suggested by Tidal Lagoon Plc [29]) was considered herein.…”

“…In all cases, the models have provided useful predictions for a variety of designs and operations, including: investigation of the regional hydrodynamics, sediment transport and water quality, optimisation of power generation efficiency and coastal flood risk assessment. More recently, there have been several studies undertaken on modelling tidal lagoons in the UK, including studies: on Swansea Bay lagoon [2,[13][14][15], North Wales lagoons [16] and Cardiff lagoon [13,17] to name but a few. Adcock et al [18] discussed the open boundary problem that can occur due to the operation of large TRSs, such as barrages in an estuary.…”

“…On the other hand, sometimes simplified numerical models can prove more effective than expensive 2D models. For example, Aggidis et al [20] and Xue et al [15] both showed that 0-D models are useful tools for assessment of power production and are commonly used for operational optimisation of TRSs. However, there are certain aspects of TRSs, such as bed erosion and turbine performance, that require a much more detailed approach to numerical modelling [21].…”

The Potential for Tidal Range Energy Systems to Provide Continuous Power: A UK Case Study

“…The short-term storage capabilities possessed by tidal power plants is facilitated by the degree of control in scheduling different modes of operation. Combined with the predictable and reliable nature of the tidal resource, this flexible control can unlock economic opportunities [7,8].…”