The potential to use the UK’s high tidal ranges to generate power have been discussed for more than a century. Now a new report by the National Energy System Operator (NESO) has concluded that adding tidal power to the system would raise prices for consumers. However, it said tidal may have a role to play in adding resilience to the system as thermal plant retires.
Locations with high generation potential are those with large tidal ranges, such as the North-West of England and the Severn Estuary. This study aims to establish the potential impact on Great Britain’s future energy system, and total cost to consumers, of using tidal range generation offshore. It considered three levels of ambition – low (1.5GW in the northwest and southwest by 2037-2040), medium (5GW in the northwest, southwest and east by 2035-2042) and high (8GW in the northwest, southwest and east by 2032-2045) – against a ‘no change’ counterfactual and with different support regimes.
It says that the cheapest scenario is the counterfactual when the total cost to the consumer is considered (wholesale market costs, subsidy requirement, impact on existing subsidies, cost of thermal constraint and energy balancing costs). The additional cost for the ‘low ambition’ scenario could be brought down to less than £500 million under a regulated asset base (RAB) financing mechanism, but NESO notes “this would shift additional development and construction risk on to consumers”.
Under RAB, the medium ambition scenario was £2billion more expensive and the high ambition another £2billion more expensive.
Under the more traditional LCOE style financing mechanism the medium ambition scenario was £19 billion more expensive than the counterfactual over the study period, and the high ambition another £12 billion more expensive than the medium.
The study shows that tidal range would not cause excessive constraint and balancing costs, and the scenarios all had similar levels of curtailment . That suggests “tidal range assets could help to address some of the challenges associated with the resilience of the GB power network as traditional thermal generation retires and is replaced by intermittent renewable generation”, said the report. The survey did not consider specific locations or proposed projects, but it found some locations offer better value, if a strategic approach was taken to issues like thermal constraints and battery storage considered alongside.
Tidal power would drive down wholesale market prices but this would be countered by the cost of a necessary subsidy, “as well as a knock-on increase in the required spending for existing CfD contracts, designed to protect generators against wholesale price volatility”.