Income optimisation of a fleet of tidal lagoons

Tidal lagoons represent a form of renewable electricity generation that remain untested. In the UK, a perceived lack of value for money to the consumer triggered the government's rejection of a recent plan to build and operate a system of six tidal lagoons along the west coast of England and Wales. Tidal energy benefits from a high degree of predictability in its resource, as well as flexibility with regards to the control of the constituent hydraulic structures. An adaptive operation can utilise these factors in order to optimise the operation of a tidal lagoon. We explore here the potential to optimise economically by targeting generation periods to match high demand in the day-ahead energy market, increasing the return on electricity sold. Gradient-based optimisation techniques are applied to a finite difference 0D model of a fleet of seven idealised tidal lagoons.For the generation of site-specific inputs, the model is in turn coupled with Thetis, a coastal ocean modelling framework based on the finite element engine Firedrake. An adjustment is made to the price signal which reflects the presence of tidal lagoons in energy market trading. Results converge towards a system which utilises the inherent phase difference of the operation of the tidal lagoons to limit price reduction and make significant gains in income when optimising the entire fleet. The high variability of site conditions present in the tidal lagoon fleet is also highlighted, emphasising the importance of flexibility in tidal lagoon operation and design.