Are underwater turbines the next big clean energy source?

Great ideas look very simple in hindsight, and you wonder why no one thought of it earlier. Perhaps this one might have been thought about but technology needed to mature to make it commercially feasible.

I wrote an article “Cheap, abundant sea wave power is around the corner” way back in September 2022; you can check it out here . In that article, we talked about the harnessing of surface waves of the ocean to generate power. Most attention in ocean power has been focused on tapping the energy from the ocean waves but this time we are talking about placing our turbines under sea to harness the sea currents which are present throughout the year.

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.

The biggest challenge for underwater turbines is demonstrating their technical and economic feasibility. But if they manage to do that, these turbines could become the next big renewable energy source.

The ebb and flow of the tide powers a turbine while the sun shines on solar panels. In May 2022, China’s first combined tidal and solar power station started feeding electricity to the grid, and the media waxed lyrical: “The sun and moon work together to generate power both above and below the waves.” This is a new model for power generation in China and marks an important step forward for integrated ocean energy. It is expected the electricity generated will power 30,000 homes.

The EU, US, Australia and China have all put policy frameworks in place to promote development of ocean energy. The EU has moved fastest. In terms of generating capacity, the bloc accounted for two-thirds of new tidal installations worldwide in 2021, and half of all wave energy.

According to estimates from the International Renewable Energy Agency (IRENA), generation capacity from ocean energy installations could reach 3 gigawatts (GW) in the next five years, then 70 GW in 2030 and 350 GW in 2050 – the equivalent of over 100 Three Gorges Dams.

Another very interesting company I came across is TidalWatt. TidalWatt, a Brazilian startup, has reimagined underwater turbines. Their technology is 60 times smaller than wind turbines but produces 3 times more energy. Here are the key points:

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Their technology claims to be harmless to marine life and is designed for the vast energy potential of ocean currents.

Unlike wind turbine-based tidal models, TidalWatt’s technology spans kilometers, tapping into gravitational disturbances caused by Earth-Moon-Sun interactions and planetary rotation.

TidalWatt has patented their technology which optimizes the turbine for working undersea with saline water. Further, their turbines are enclosed and are therefore marine life friendly. This is an important point unlike the undersea ocean power far I have depicted in my opening picture with this newsletter; and that looks far more promising to me.

Several other companies are actively involved in developing turbines for marine energy. Here are some notable ones:

Ocean Power Technologies (USA): They focus on capturing and converting wave energy into electricity using innovative power take-off systems.

AW-Energy (Finland): Their WaveRoller is a fully submerged wave energy converter that utilizes wave surge phenomenon.

Wavepiston (Denmark): They provide a low-tech modular system that harvests wave energy to produce electricity via standard hydropower turbines.

Mocean Energy (UK): They develop technologies to harness wave power and accelerate the transition to a zero-carbon world.

SINN Power (Germany): Their wave energy converter supplies remote coasts and islands with low-cost, renewable energy from ocean waves.

Oscilla Power (USA): Their Triton wave energy converter aims to deliver cost-competitive, utility-scale energy with reliability and survivability.

Carnegie Clean Energy (Australia): They offer a combination of wave, solar, battery storage, and desalination via microgrids.

Eco Wave Power (Israel): They design, manufacture, and operate wave energy converters.

INGINE (South Korea): INGINE develops technology to convert wave energy into electricity, starting with replacing conventional sources in remote areas.

Slow Mill (Netherlands): They harness wave energy to provide renewable energy and services sustainably.

Additionally, HydroQuest and Orbital Marine Power Ltd are notable companies in the tidal energy sector2.

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That’s all in this newsletter; more next week.

Please do subscribe to take full advantage of this newsletter. In case you wish to contribute or request an idea which you wish to be covered in the forthcoming issues do get back to me at [email protected] .Arun Bhatia

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