A review of the UK and British Channel Islands practical tidal stream energy resource

Abstract

This review provides a critical, multi-faceted assessment of the practical contribution tidal stream energy can make to the UK and British Channel Islands future energy mix. Evidence is presented that broadly supports the latest national-scale practical resource estimate, of 34 TWh/year, equivalent to 11% of the UK’s current annual electricity demand. The size of the practical resource depends in part on the economic competitiveness of projects. In the UK, 124 MW of prospective tidal stream capacity is currently eligible to bid for subsidy support (MeyGen 1C, 80 MW; PTEC, 30 MW; and Morlais, 14 MW). It is estimated that the installation of this 124 MW would serve to drive down the levelized cost of energy (LCoE), through learning, from its current level of around 240 £ / MWh to below 150 £ / MWh , based on a mid-range technology learning rate of 17%. Doing so would make tidal stream cost competitive with technologies such as combined cycle gas turbines, biomass and anaerobic digestion. Installing this 124 MW by 2031 would put tidal stream on a trajectory to install the estimated 11.5 GW needed to generate 34 TWh/year by 2050. The cyclic, predictable nature of tidal stream power shows potential to provide additional, whole-system cost benefits. These include reductions in balancing expenditure that are not considered in conventional LCoE estimates. The practical resource is also dependent on environmental constraints. To date, no collisions between animals and turbines have been detected, and only small changes in habitat have been measured. The impacts of large arrays on stratification and predator–prey interaction are projected to be an order of magnitude less than those from climate change, highlighting opportunities for risk retirement. Ongoing field measurements will be important as arrays scale up, given the uncertainty in some environmental and ecological impact models. Based on the findings presented in this review, we recommend that an updated national-scale practical resource study is undertaken that implements high-fidelity, site-specific modelling, with improved model validation from the wide range of field measurements that are now available from the major sites. Quantifying the sensitivity of the practical resource to constraints will be important to establish opportunities for constraint retirement. Quantification of whole-system benefits is necessary to fully understand the value of tidal stream in the energy system.

Marine Mammal HiCUP: A High Current Underwater Platform for the Long-Term Monitoring of Fine-Scale Marine Mammal Behavior Around Tidal Turbines

“…The global need for low-carbon energy is driving ambitious targets for wind, wave, and tidal energy in many countries. Tidal stream generators (hereafter termed "tidal turbines") have the potential to contribute 11% of the UK's current energy demand (Coles et al, 2021) and tidal energy has an important role to play in ensuring grid stability in a renewable energy future (Tróndheim et al, 2021). However, while wind energy is now making significant contributions to global energy supplies, tidal energy industries are currently at relatively early development stages (Ocean Energy Systems, 2020).…”

Combining shallow-water and analytical wake models for tidal array micro-siting

“…stream is set to remain at more than £150/MWh by 2025 (Smart and Noonan 2018;Topper et al 2021), whilst the LCOE for solar and both onshore and offshore wind will fall to approximately £25-£32/MWh (U.S. Energy Information Administation 2020). Reducing LCOE is paramount if tidalstream energy is to become a competitive, sustainable energy source (Coles et al 2021). This could be achieved through several measures (Coles and Walsh 2019;Goss et al 2020Goss et al , 2021a: (i) physical infrastructure improvements, which could involve optimisation of the turbine design and operation, (ii) economies of scale in turbine design, (iii) economies of volume in manufacturing, operation and maintenance, (iv) technology innovation, (v) learning, and (vi) financing mechanisms.…”

“…Array optimisation has already shown potential to increase array power by up to 33% relative to a regular aligned layout, albeit with power capping removed (Funke et al 2014). Hence, developing more robust, yet practical optimisation methods could be a key step to achieving further LCOE reductions (Coles et al 2021).…”

Tidal streams, fish, and seabirds: Understanding the linkages between mobile predators, prey, and hydrodynamics

“…For example, a renewable energy target of at least 32% by 2030 was previously set by the European Union (EU), which was recently proposed to be increased to 40% (Directive [EU] 2018/2001). Marine renewable energy (MRE) sources, which include offshore wind, wave, and tidal, are an abundant and geographically diverse resource with the potential to supply up to 10% of EU's (Ocean Energy Forum, 2016) and 11% of UK (Coles et al, 2021) annual energy demand by 2050. Tidal stream energy, extracted from tidal currents in areas characterized by extremely fast currents (>2 m s À1 ) and a range of turbulent features (e.g., shear, jets, eddies, and boils), is becoming one of the preferred sources due to the predictable regular periodicity of tidal currents (Lewis et al, 2015).…”