New Oxford research assesses how much power tidal streams could deliver

Electricity demand is expected to triple by 2050. Wind and solar will supply most of this, but their variability means they cannot meet demand alone. As countries pursue net-zero, complementary clean energy is urgently needed. Tidal stream turbines – think underwater wind turbines – offer a new way to generate clean electricity. aIt is one of the few renewables that is both predictable and available daily.

For these reasons, it is attracting growing interest, and in the next 5 years, the UK and France are expected to install turbines to generate enough electricity to power 170,000 homes a year (similar to a city like Bristol). While more than 350,000 wind turbines operate globally, estimates of how many tidal stream turbines could be deployed – and where – are vague and untraceable. This raises key questions, such as: Can tidal stream energy meaningfully contribute to electricity supply in the future?

New research led by Dr Danny Coles, helps bring clarity, through the undertaking of a detailed review of tidal stream resources across the world. This research work published in the Proceedings of the Royal Society A, identifies suitable locations for tidal stream turbine projects, how much electricity it may deliver, and where evidence remains lacking. 426 sites are identified with current speeds and depths suitable for tidal stream turbines. Evidence suggests that tidal stream energy could supply over 10% of current electricity needs in the UK, Indonesia and New Zealand.

In countries such as France, the USA, Canada and China, the contribution appears smaller, at a regional rather than national scale. In others, including Norway, the Philippines and South Korea, whilst it is clear that there are highly energetic sites, data remains too limited to make conclusions regarding the electricity that could be generated. Findings broadly support the European Commission’s projected 8 gigawatts of installed capacity (enough to power 7 million homes, double that of London) in Europe, based on resource assessment of sites in the UK and France, and a further 26 sites in Norway and the Faroe Islands. Evidence is less conclusive when considering the validity of global installed capacity projections, which typically range between 100-120 GW (enough to power 100 million homes, equivalent to four UK’s).

By bringing together evidence of tidal stream energy resources around the world, this research aims to help improve decision-making by coastal nations regarding the level of support they provide for tidal stream energy alongside other electricity generation technologies in order to achieve their net-zero targets. In addition, the recommendations for improving resource assessment are intended to be adopted by the tidal stream energy community through enhancements to technical standards for resource assessment.

Dr Coles said: “Decision making regarding which electricity generation technologies to support in the transition to net-zero must be underpinned by reliable evidence. Tidal stream energy is an interesting proposition for many coastal nations, given its ability to compliment solar and wind energy. Nevertheless, the scale at which it may contribute to future electricity supply is uncertain. This research was motivated by the need to address this knowledge gap, and is the first to bring together the vast amount of tidal stream energy resource information in the literature at a global scale.

Our findings clearly highlight the significant energy resource that tidal streams exhibit around the world, with over 400 sites identified that exhibit the anticipated conditions needed for turbine deployment. At the same time, we highlight some of the key challenges to practical development, such as grid connection, given the remoteness of some high energy sites. Ultimately it is hoped that this research enhances certainty in the contribution tidal stream power can make to future electricity production, to help inform decision making by Governments and energy planners”.