The potential for tidal range energy systems to provide continuous power: a UK case study

A study published in the Journal of Marine Science and Engineering on our recent work on the operation capabilities of tidal range energy systems. The work was led by Lucas Mackie, in collaboration with Daniel Coles from Plymouth University and Matthew Piggott from Imperial College London. The study refines our tidal power plant optimisation framework to consider multiple schemes cooperating to maximise the value of the overall tidal range system. The study highlights the potential but also the limitations of the technology due to the nature of the resource

Abstract

The extraction of tidal energy from head differences represents a predictable and flexible option for generating electricity. Here, we investigate the generation potential of prospective tidal power plants in the UK. Originally conceived as separate projects, operating these schemes as a cooperative system could prove beneficial. Combined with the inherent operational flexibility of tidal range-based schemes, a notable tidal phase difference in selected sites allows for the system to spread power generation over a larger proportion of the day. Using depth-averaged modelling and gradient-based optimisation techniques, we explore how a flexible cumulative operation schedule could be applied to provide a degree of continuous supply if desirable. While fully continuous operation is not achieved, a number of different optimisation schedules deliver cumulative continuous supply for over half of the year. The average minimum cumulative power output on these days is consistently over 500 MW out of a total installed capacity of 6195.3 MW. Furthermore, by introducing financial incentives associated with reliable, baseload supply, we provide an economic assessment of the tidal power plant system. The daily minimum cumulative power output determines income in the modelled idealised baseload market, while excess supply is traded in an hourly variable wholesale energy market. Results indicate that subsidies would be required in order to make a pursuit of continuous generation financially advantageous over energy maximisation strategies.

Figure : Power output P(MW) and basin elevations η(m) of the tidal power plants.Example 1indicates a scenario where the holding periods are equal to 2 h for each scheme. Examples 2–4 display continuous generation optimised schedules, applying different examples of default alternative operation, defined as the operation schedule reverted to when the cut-off power cannot be achieved in the continuous generation case. Daily minimum power sold on the idealised Baseload Market (BM) is indicated in red.