Exploring the Untapped Power of Marine Current Turbines
Felicity Bradstock

Energy companies worldwide are pursuing innovative renewable energy solutions in support of a green transition as more and more governments are introducing strict decarbonisation policies and offering tax breaks and other financial incentives for developing green energy projects. One nascent technology that is gaining traction is underwater turbines, also known as tidal or marine current turbines, with new projects popping up in various countries. 

Scientists have long been optimistic about the potential for underwater turbines to produce vast amounts of clean energy, however, to date, the technology has been little used, compared to conventional renewable energy operations such as wind and solar farms. The power of underwater currents is vast and untapped but harnessing it can be complicated. 

Underwater turbines are designed to harness the kinetic energy produced by currents or tidal flows and convert it into electricity. The water passes through the turbine blades making them rotate, which drives a generator to produce electricity throughout the day and night. They work similarly to traditional wind turbines, only underwater. There are two main types of tidal turbines, tidal stream systems that require a fast flow of water and tidal range systems, which capture the potential energy difference between high and low tides.

In 2022, the U.S. Department of Energy (DoE) announced plans to explore the potential of underwater turbines, aiming to make them more efficient and cost-effective. The DoE highlighted the lack of understanding about how the technology would interact with the underwater environment. Further, the high cost of hydrokinetic turbines had long deterred developers from rolling out the technology at the commercial level. 

The DoE’s Advanced Research Projects Agency-Energy (ARPA-E) previously provided funding for 11 projects with $38 million in grants in 2020, to develop cost-effective underwater turbine technologies. The technology was known as Submarine Hydrokinetic and Riverine Kilo-megawatt Systems – or SHARKS. The projects were targeted at producing marine technologies capable of generating electricity at an end cost of under $0.05 per kilowatt-hour, which was around one-sixth of the cost of existing underwater turbines.

The SHARKS projects developed two types of underwater turbines – Tidal Power Tug and Manta. The Tidal Power Tug, created by Aquantis, is a second-generation floating tidal energy converter. It was deemed ideal for gulf stream currents along the U.S. East Coast, which create multiple circular flows called gyres. Manta was developed by the California-based SRI International Research Institute. It used a lightweight foam and fibreglass kite with a small generator moored to the seabed. It is equipped with a motor to redirect and deflate the machine to avoid a collision with ships and storms. It is better suited for powering small and isolated communities.

Over the last five years, there has been a larger rollout of underwater turbines in several locations around the globe. In January, U.K.-based tidal energy company Proteus Marine Renewables (PMR) launched a tidal turbine project in the Naru Strait, Japan, which made it “the first to operate such devices in two countries”, according to the company. PMR’s AR1100 turbine is expected to produce 1.1 MW of power, helping to decarbonise the electricity supply on the Goto Islands. 

Philip Archer, the Managing Director of PMR Operations Japan, stated, “Deploying the AR1100 in Japan is a testament to the dedication and expertise of our team working in collaboration with local professionals.” Archer added, “The result reinforces tidal energy’s potential as a dependable renewable source in Japan. Our next immediate focus is the commissioning of the turbine, Japan’s first-ever MW-scale grid-connected tidal system, and the subsequent testing and accreditation phase.”

In March, Normandie Hydroliennes (NH) began developing a commercial-scale tidal energy pilot project called NH1, off the coast of Normandy, which is expected to supply thousands of households with clean electricity if successful. The project will use four turbines to turn the Raz Blanchard tidal flow, the strongest tidal stream in Europe. The company was awarded funding from the EU’s Innovation Fund, which provides financing for research and development into innovative clean technologies. The company hopes to begin producing clean electricity from the project starting in 2028.

There is significant potential to develop more projects within the Raz Blanchard tidal flow, and NH1 may be the first of many. The Channel Sea current is one of the world’s most powerful, with a development potential of around 5 GW to 6 GW, meaning it could produce between 15 and 18 terawatt hours and supply electricity to 8 million people, according to NH. Katia Gautier, the director of the company, stated, “Being selected by the Innovation Fund is a major recognition of our work and the impact that our technological system, the innovative Proteus AR3000 horizontal axis turbine, can have on decarbonisation and the energy mix.” 

While underwater tidal turbine technology is in its infancy, the influx of investment seen in the industry in recent years has given hope to many energy companies looking to roll out the technology on a commercial scale. If various pilot projects show promise, it could encourage greater investment in the sector, which could lead to a widescale deployment of the turbines in tidal streams worldwide, to produce vast amounts of clean electricity. 

By Felicity Bradstock for Oilprice.com

 

 

Felicity Bradstock is a freelance writer specialising in Energy and Finance. She has a Master’s in International Development from the University of Birmingham, UK.

 

 

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