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While the ocean is already a destination for offshore wind turbines, engineers and researchers are channeling their inner Little Mermaid and looking into turbines that live under the sea.
The tech, a form of hydrokinetic power, is in its early stages, but experts say it’s worth pursuing at scale because it would be predictable in a way other renewables aren’t. Countries from the US to Japan are funding the tech—the latter recently kicked off a project one organization estimates could eventually produce 60% of the country’s current generating capacity. But subsea turbines face a long path to broader deployment.
“I see here that we can be in a similar situation as what we saw about 20 years ago at the end of the ’90s in Europe and then here in the US with wind energy,” said Mario Garcia-Sanz, program director of the DOE’s Advanced Research Projects Agency-Energy, whose SHARKS project is focused on developing hydrokinetic energy. “The systems are expensive, and that was the problem in the ’90s with wind.”
One of the leading companies in the space is Aquantis, which is working to develop a product called the Tidal Power Tug, “a floating machine that’s accessible from the surface,” per the company’s chief commercial officer, Peter Stricker. Aquantis is the largest recipient of funding from the SHARKS project, which in 2020 dished out a total of $35 million to 11 hydrokinetic projects that will run through 2024.
The target goal for each SHARKS project, Garcia-Sanz said, is to reduce its tech’s levelized cost of energy by 60%. That would help bring the hydrokinetic power sources’ cost under 10 cents per kilowatt hour (kWH), which is more competitive with other energy forms, according to Jing Sun, a professor of naval architecture and marine engineering at the University of Michigan, who is working on the school’s SHARKS-funded project.
For Aquantis, in particular, the project goal means bringing the price from 10 cents per kWh to 4 cents per kWh, according to Stricker.
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Stricker told us that the company—which was created via a renewable-energy incubator called EcoMerit Technologies—aims to raise a private-equity round over the next year and a half, before seeking an IPO further down the road. Right now, its focus is on demonstration projects, he added, like testing at the European Marine Energy Center in Scotland.
“An important part of the outcome of all this work is the ability to raise financing for Aquantis, based on the fact that we have clear ownership of technology,” Stricker said. “We’ll be coming out into the limelight to some extent upon the success of those tests.”
In practice, real-world hydrokinetic systems will likely need to contend with other obstacles beyond cost, like maintenance or interactions with other marine industries (e.g., commercial fishing), Roger Wang, an assistant professor of civil and environmental engineering at Rutgers University, told us.
Wang also said that the environmental impact of hydrokinetic turbines should be paid close attention to, adding that “the environmental permitting process actually could be the critical bottleneck for commercialization of the technology.”
He’s currently researching the effects of hydrokinetic power on aquatic life and flooding risk, and said things like cultural or historical heritage should also be protected when considering where to deploy the tech.
Ultimately, Garcia-Sanz said, the main reason this investment and effort are worth it—and what differentiates hydrokinetic power from solar and wind power—is the energy source’s predictability.
Because the energy is generated based on tides and aquatic flow, Garcia-Sanz said, “you can say this is the amount of energy that I am going to be generating in two years, two hours, in one hour, in two days, in a week.”
Even if hydrokinetic energy is able to scale up, experts told us it’d likely be a complement to other forms of renewable energy—not a replacement.