  As the demand for electricity and the need for power systems flexibility
grow, it is crucial to exploit more reliable and clean sources of energy to
produce electricity when needed most. Tidal lagoons generate renewable
electricity by creating an artificial head difference between water levels on
the seaside, driven by tides, and water levels inside the basin, controlled by
flow through the structure. Depending on the level of seawater, power
generation from a tidal lagoon can be controlled, i.e. shifting power
generation in time. This paper aims to investigate the operation of a tidal
lagoon in response to fluctuating electricity prices. By developing an optimal
operation model of a tidal lagoon, its schedule in the day-ahead wholesale
electricity market was optimized to achieve maximum revenue. The Swansea Bay
tidal lagoon was used as a case study. It was demonstrated that by exploiting
the flexibility offered by the tidal lagoon, it can achieve a higher revenue in
the day-ahead market, although their total electricity generation is reduced.
