The ocean is one of the planet’s biggest untapped sources of renewable energy, and for decades people have been trying their best to harness its power. The amount of energy available is huge: Theoretically, the waves off the West and East Coasts of the United States could provide more than 60 percent of U.S. grid electricity generation. Australia’s wave energy has the potential to generate more than 1,300 terawatt-hours per year, nearly five times the nation’s energy requirements.
But the challenges are as big as the opportunities. Ocean waters can corrode electrical components and rust mechanical parts, and they are often destructively violent. In November, for example, a “bomb cyclone” battered a marine energy testing site in Oregon with 19-foot-high waves coming from two different directions, according to Burke Hales, an oceanographer at Oregon State University. “There’s lots of power in those kinds of waves,” he says, “but also lots of risk.”
Recently, though, the accelerating push for net zero emissions, along with slow but steady technological improvements and new investments, have sparked fresh optimism in the marine energy field. In September, the Biden Administration announced $112.5 million in funding for prototypes from the Department of Energy’s Water Power Technologies Office — the largest-yet U.S. investment in wave energy. In November, that office also issued cash prizes of $10,000 to each of 20 startup companies. Key to these investments is a new testing site in Oregon, developed by the Department of Energy, Oregon State University, and local stakeholders, with four “parking stalls” for wave energy prototypes. PacWave South, with Hales as its scientific director, plans to host its first companies in the summer of 2026, joining a handful of other testing sites globally.
“People often ask, why wave energy instead of solar? It’s really wave energy and solar,” says an offshore engineer.
Hales and others think the field is at an inflection point that will finally spawn commercial successes, with a handful of designs eventually emerging that can survive the brunt of both the ocean and fiscal reality. “It’s expensive and it’s challenging, but I think the opportunity is just so great,” says Lindsay Bennett, executive director of the Fundy Ocean Research Centre for Energy (FORCE) in Nova Scotia, Canada, which researches tidal energy. She sees the marine-energy field “making really significant headway in the next three to five years.”
About half of the planet’s renewable energy today comes from hydropower; wind turbines and solar panels together make up most of the other half. According to the International Energy Agency, the ocean’s tides and waves in 2020 generated a mere 0.2 percent of the world’s renewable electricity. While the IEA predicts that marine energy’s contribution will stay small, it is one of the fastest growing renewable energy sectors. In the agency’s 2021 Net Zero by 2050 Roadmap, marine energy electricity generation grows more than sixtyfold by 2050. Ocean Energy Systems, the IEA’s technology collaboration program for ocean energy, has charted an ambitious course where the world could, by 2050, ramp up from today’s roughly 1 gigawatt of ocean energy to an impressive 300 gigawatts — an effort that they reckon will involve 200 projects with a total price tag of $1.5 billion.
Three types of wave energy devices, from left to right: a point absorber, a gyroscope, and an attenuator.
Aqua-RET
“People often ask, why wave energy instead of solar? It’s really wave energy and solar,” says University of Western Australia offshore engineer Hugh Wolgamot. “It is presently more expensive than other renewables. But the key thing is the value of its persistence.”
“It will definitely be a small piece of the pie,” says Wolgamot. But to get to net zero emissions, “we need to pull all the levers, and we need to move extremely quickly.”
History suggests it will be a rough road. The European Marine Energy Centre in Orkney, Scotland, which opened in 2004, is perhaps the longest-running testing site for modern marine energy projects, offering to hook prototypes up to the grid and ease permitting paperwork. EMEC hosted the earliest wave project to transmit energy to a grid: the Pelamis Wave Energy Converter, trialed from 2004 to 2007. The device looked like the sea snake it is named after, with long, floating metal tubes that flexed against each other to drive hydraulics. It produced power and was followed up by several more versions of the machine at several sites, but the company buckled under financial strain in 2014.
Devices might be installed between the towers of offshore wind farms, so as to capture power from both wind and waves.
One particularly long-running device at EMEC was the Penguin, built by the Finnish company Wello Oy. This round floating barge was unevenly weighted, so it spun as it crested waves like a fairground ride; an internal generator converted this motion into electricity. “That’s an interesting machine and a clever idea, because there’s nothing much moving that’s in contact with seawater,” says civil engineer Neil Kermode, managing director for EMEC. One version started tests at EMEC in 2011 and ran successfully for years, then sunk in 2019. Wello Oy filed for bankruptcy in 2023.
EMEC alone has tested about 35 devices over 20 years, with various levels of success. The problem is that these systems need to be tested at scale and at sea, not in a wave tank, and thus typically cost millions to develop and build, says Kermode. Yet the companies building them tend to be small start-ups. “All these people are doing it absolutely on a shoestring,” he says.
Plenty of trials continue, though, and several are lined up to use the PacWave South test site. One, developed by the California-based CalWave, is a floating disk tethered to the seabed that rides the circular motions of the waves; it can be winched downward to keep working in gentler conditions underwater when things get too rough on the surface. Another company, C-Power, by contrast, will be testing a floating raft with a hanging pendulum.
A wave energy system installed on a breakwater in Mutriku, Spain.
dpa Picture-Alliance Archive / Alamy Stock Photo
Stockholm-based CorPower, meanwhile, has significant funding to back its bobbing wave-energy buoys, which it aims to install in “wave farms” in the near future. Such wave farms, hosting a large array of devices, are thought to be the best way to ramp up wave power to utility-scale generation. They might even be installed between the towers of offshore wind farms, so as to capture power from both wind and waves.
Single wave-power units might also come in handy for bespoke locations, such as remote spots in Alaska that lack great wind or solar resources. Waves could also be used to power localized energy needs, such as refrigeration for fisheries or dredgers to clear navigation channels. Some companies, such as Boston-based Resolute Marine, are interested in harnessing waves to power energy-hungry desalination plants. Many experts, including Hales, are enthusiastic about installing wave power systems inside breakwaters, which protect the shore from damaging waves. A few such projects already exist: the Mutriku breakwater wave power system in Basque Country, Spain, for example, has been running for 10 years.
Some tidal projects also have reasonably long histories of successful operation. These systems can be simpler than wave energy projects, in large part because they deal with waters that move mainly along a single axis as tides come in and out. Most tidal devices feature either propellers or water wheels and are placed in areas like narrow channels, where the current is particularly strong.
“There’s a lot of energy out there, so we’re going to go and get it,” says the director of a wave energy facility in Scotland.
The MeyGen project in Scotland, for example, has been running continuously since 2018 with four 1.5-megawatt tidal turbines. Each looks like a stumpy wind turbine, with rotors that span a diameter of nearly 60 feet. That project has plans to expand to a larger array of dozens of turbines, with hopes of eventually hitting nearly 400 megawatts. A 2024 report from an advisory body to the European Commission forecasts that ambitious action could ramp Europe up to 700 megawatts for tidal power by 2028. France, for example, recently announced plans for a relatively large (seven 2.5-megawatt turbines) tidal farm, due to open in 2026.
But tidal power faces challenges too. Developers have long been interested in exploiting the tidal energy in the Bay of Fundy’s Minas Passage, in Nova Scotia, for example, through which more water flows than in all the planet’s rivers combined, at speeds of up to 5 meters per second. But perhaps precisely because the flows are so strong, only three devices have been tested here. Overall, says FORCE’s Bennett, Nova Scotia is far behind its goal of getting 300 megawatts of tidal energy into its grid by 2030.
A tidal turbine installed at the MeyGen tidal energy project in northern Scotland.
MeyGen
An additional concern facing both tidal and wave energy projects is possible environmental issues. A 2024 report from the IEA’s Ocean Energy Systems concluded that some theoretical risks from marine power were so small they could be “retired,” meaning regulators can reasonably rely on what’s already known rather than fully investigating risks for each new project. That includes possible harms to marine life from electromagnetic fields, underwater noise, or changes to conditions like food supply — at least for clumps of six or fewer devices (the report says the risks might need to be reassessed for larger farms). But, the report adds, more information is needed to understand the possible risks of marine life displacement, collisions, or entanglements with mooring lines.
Researchers have raised concerns, for example, that fish might get hit by the propellors of a tidal energy project, but assessing those potential hazards, says Kermode, has proved difficult. FORCE is now planning a tagless fish tracking program, which uses cameras, sonar, and artificial intelligence to evaluate these risks.
It’s “a long slog,” says Kermode, to develop the technology to a place where wave and tidal energy can live up to their potential. But the recent U.S. investments, he says, are a positive signal of accelerating action.
“When [movers in the U.S.] wake up and decide to do something, it tends to happen,” says Kermode. “There’s a lot of energy out there, so we’re going to go and get it. It’s just a case of when, and that’s taking longer than planned.”
