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Companies use oceans and rivers to generate energy

As the world seeks to contain climate change and reduce fossil fuel emissions, some companies are focusing on a relatively untapped, vaster and more abundant energy source – giant waves.

On opposite sides of the Atlantic, two companies are working to harness ocean currents in different ways to try to generate clean, reliable energy.

Off the coast of Scotland, Orbital Marine Power operates the so-called “most powerful tidal turbine in the world”.

The turbine is about the size of a passenger plane and even similar, with its center platform floating on the water and two wings extending downward on each side.

At the ends of each wing, about 18 meters below the surface, are large rotors whose movement is dictated by the waves.

“Tidal energy itself is familiar to people, it’s kinetic energy, so it’s not very different from something like wind,” Andrew Scott, CEO of Orbital, told CNN Business. “The bits of technology that generate power don’t look very different from a wind turbine.”

But there are some important differences for wind power, mainly that waves are much more predictable than winds. The ebb and flow of tides rarely differ significantly and can be timed much more accurately.

“You can predict these moves years and decades in advance,” said Scott. “But also from a steering point of view, they only come from two directions and are almost 180 degrees,” he added, unlike wind turbines that must take into account wind from several different directions at the same time.

Giant waves are also capable of generating more energy than wind, says Scott.

“Sea water is 800 times the density of wind,” he said. “So the flow velocities are much slower, but they generate a lot more energy.”

The Orbital turbine, which is connected to the electrical grid in Scotland’s Orkneys, can produce up to two megawatts – enough to power 2,000 homes a year – according to the company.

Scott recognizes that the technology is not yet fully popular and some challenges remain, including the technology’s high cost, but the reliability and potential of tidal energy can make it a useful tool in the fight against climate change.

“It is becoming increasingly apparent that climate change will not be resolved with a silver bullet,” he said.

‘It could be energy 24 hours a day, 7 days a week’

About 3,000 miles away from Orbital’s turbines, Verdant Power is using similar technology to generate power near Roosevelt Island on New York’s East River. Although not yet on the market, Verdant turbines installed as part of a pilot project help provide electricity to the New York grid. But instead of floating close to the surface, they are mounted on a structure that is lowered to the bottom of the river.

“The best way to imagine what Verdant Power’s technology is is to think of underwater wind turbines,” company founder Trey Taylor told CNN Business. And river currents tend to provide the same power generation advantages as ocean currents, he explained (although the East River is also connected to the Atlantic).

“The good thing about our rivers and systems is that they can be powered 24 hours a day, 7 days a week,” he said. “Without wanting to harm the wind or solar sources, but the wind doesn’t always blow and the sun doesn’t always shine. But river currents, depending on the river, can be 24 hours a day, 7 days a week.”

Over the course of eight months, Verdant generated enough electricity to power about 60 homes — though Taylor says a complete power plant built with its technology could generate enough for 6,000 homes. And by your estimation, the global tidal energy capacity is enormous.

“The energy potential is somewhere around 250 gigawatts around the world,” he said, which is enough to power 250 million homes for a year. “There’s a lot of room and we really hope our competitors will succeed too, for the good of the industry.”

an expensive technology

The biggest obstacle to achieving that goal right now is how expensive it is to set up and grow tidal power systems.

“Generating electricity from ocean waves is not the challenge, the challenge is to do it in a way that people are willing to pay for and that competes with other energy sources,” said Jesse Roberts, lead environmental analytics at Sandia National Laboratories affiliated with the US government. “The additional cost of going to the ocean and deploying in the ocean is very expensive to do,” he added.

According to 2019 data from the US Department of Energy, the average commercial tidal power project costs as much as $280 per megawatt-hour.

Wind power, by comparison, currently costs about $20 per megawatt-hour and is “one of the cheapest sources of energy available today,” according to the agency.

Roberts estimates that tidal power lags two or three decades behind wind power in terms of adoption and scale.

The costs and challenges of operating underwater are something Scott and Taylor recognize.

“The sun and the wind are above the ground. It’s easy to work with things you can see,” Taylor said. “We’re underwater and it’s probably easier to get a rocket to the moon than it is to run them underwater.”

But the purpose of tidal energy is not so much to compete with these two energy sources as to grow the overall pie.

“The easiest fruits to achieve with solar and wind energy were pretty obvious,” said Scott. “But do they have to be the only solution? Is there room for other solutions? I think when the energy source is there and you can develop technologies that can take advantage of it, then for sure.”

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Reference: CNN Brasil

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