The power of underwater currents is vast and untapped. But harnessing that power is no easy feat.

The US Department of Energy (DoE) is set to explore the potential of underwater turbines with the hopes of making them more efficient and cost-effective. If successful, the endeavour could lead to a significant shift in how we generate electricity and help move the world closer to a clean energy future. However, some challenges must be overcome before underwater turbines become a reality.

SHARKS: Underwater turbine technology

The design and deployment of most underwater turbines are still in their infancy and there is much to learn about how they interact with the underwater environment. The high cost of hydrokinetic turbines is another barrier to their widespread commercial adoption.

Yet DoE's Advanced Research Projects Agency-Energy (ARPA-E) is funding 11 projects with a $38 million bundle of grants made in November 2020 to develop cost-effective underwater turbine technologies. These projects are collectively called Submarine Hydrokinetic And Riverine Kilo-megawatt Systems—or SHARKS.

The SHARKS projects aim to develop marine technologies that can generate electricity at an end cost below $0.05 per kilowatt-hour. That's about one-sixth of the current cost of electricity from underwater turbines. Two examples of underwater turbines developed under SHARKS are Tidal Power Tug and Manta.