By one account, ocean energy could fuel the United States’ total electricity needs. Credit: Courtesy of the U.S. Department of Energy

Most people walking or biking next to the Cape Cod Canal in the vicinity of the Bourne railroad bridge probably are at a loss to explain the three steel pilings sticking out of the water close to the canal’s mainland side. A dock in progress? A small weir?  

It happens that the structure — the Bourne Tidal Test Site — is this country’s only commercial open-water site available to any company wanting to analyze an underwater turbine made for generating tidal energy. Place a turbine midstream, where a pinch in the land causes the canal to flow extra fast, and a four-knot water speed will spin the turbine’s blades with the equivalent wind force of a hurricane. Given that water is 800 times denser than air, its movement creates phenomenal energy — energy we should be tapping, as some see it. By one account, energy from the tides could satisfy 10% of the world’s energy. By another, energy from waves could fuel the United States’ total electricity needs. 

Generally speaking, ocean energy refers to harnessing the movement of waves, tides, river and ocean currents, as well as thermal energy, and converting this energy into electricity. Offshore wind is included in this category. After all, wind blowing over the ocean’s surface is what creates wave energy.

Around the world, test sites for devices that harvest tidal and wave energy have proliferated. Found at every latitude, they are a sure sign that ocean energy is headed toward a bright future, the chairman of worldwide Ocean Energy Systems, Yann-Hervé De Roeck, recently stated. “The boom can only be spectacular, let’s bet on it!” he said. 

If that’s the case, why does the U.S. have only one commercial open-water tidal test site — the platform at Bourne — and why does it often sit idle? And, if harvesting energy from the ocean’s movements carries so much potential, why has the Marine Renewable Energy Collaborative [MRECo], the nonprofit that oversees the site, failed to gain the state’s assistance connecting to the grid? 

Some backstory is necessary. 

“Because tidal energy is driven by the moon, it’s very predictable,” said John Miller, an engineer who’s been studying ocean energy “longer than anyone,” noted John Bullard, president of the New Bedford Ocean Cluster.

John Miller stands beside the Cape Cod Canal Railroad Bridge with test-site pilings to his right. Credit: Ann Parson / The New Bedford Light

Miller, MRECo’s founder and director, is the primary mover and shaker behind the Cape Cod Canal test site, and he wears his passion for ocean energy on his sleeve.

“Importantly, you can predict tides 100 years ahead with 100% certainty, whereas you’re lucky if you can accurately predict wind or solar days ahead,” he said.  “Reliability and consistency. That’s what tidal energy is all about.” 

Once the U.S. Army Corps of Engineers approved the project, MRECo saw to the installation of its test site in 2017. A mid-sized testing platform like theirs, explained Miller, costs far less to operate than a full-scale ocean test. And it can save time and money to analyze a turbine’s workings in slower water before submerging it in rougher conditions. “Testing them is the only way the technology will improve,” Miller said.

Miller’s push for ocean energy has been right in step with global trends. Dams, for so long the main producers of waterpower, are coming under scrutiny for their harmful effects to a river’s natural elements — especially older dams that are no longer relied upon for making electricity yet continue to block fish migration and create river stagnation. But meanwhile, many countries are accelerating their investigations and innovations into other forms of water energy, notably hydrokinetic energy generated by the movement of river currents, ocean tides, waves and swells. 

According to Ocean Energy Systems, tidal and wave energy systems in its two-dozen member countries generated 20 megawatts of electricity in 2021, only enough to power a couple of thousand homes. Its year-end report concluded, however, that with more than 50 megawatts of projects under development and another 30 authorized, the industry was on the brink of a boom. 

Orbital O2, a tidal turbine launched last summer in the rough seas off Orkney Island, Scotland, speaks to that future. Resembling a floating 242-foot yellow submarine, O2 has the capacity to power 2,000 homes and eventually satisfy 7% of Orkney’s electrical needs. Rotors on its retractable underwater legs, pushed by tidal waters, harvest the power, which then gets transferred through an underwater cable to an onshore electricity network. 

While ocean-energy initiatives are making news in the UK, Canada, Denmark, Germany, France, Japan and elsewhere, it’s no secret — at least not in the industry — that here at home the technology has advanced more slowly. “The European side got started sooner,” observed John Ferland, president of Ocean Renewable Power Company [ORPC], a marine-energy technology developer based in Portland, Maine. “They’ve had early success with offshore wind and were willing to take the same interest in current and wave energy. But I think this decade is an important time for us. There’s a huge opportunity for American companies to work with (the Department of Energy).”

“I have a hard time understanding why more isn’t being done to develop both tidal and wave, given climate change and the urgency to end our reliance on fossil fuels,” said  Miller, who noted that the only sensible thing to do is to ramp up power from multiple clean energy sources, not just wind and solar. How else, he asked, do we achieve President Biden’s goal of 100% clean energy by 2035?

The Bourne Tidal Test Site was constructed in the Cape Cod Canal in the vicinity of the Bourne railroad bridge by the Marine Renewable Energy Collaborative in 2017. Credit: Courtesy of MRECo

As Miller will tell you, testing on the Cape Cod Canal has been frustratingly slow. He blames the time-consuming, costly challenge of applying for permits, as well as bureaucratic red tape. COVID-19 also has hobbled a few planned tests and faster progress. 

Since the Bourne test site opened for business, only one device, a two-bladed axial turbine developed by the New Bedford company Littoral Power Systems, has been tested there — but without grid access, which Miller said really frustrates him. For the test in August 2021, the power to operate the lifting arm that holds the turbine midstream had to be supplied by solar panels and batteries, and the power generated by the turbine could only be measured, not transferred to shore. That’s because, according to Miller, despite MRECo’s many requests, the state’s Department of Transportation, MassDOT, and OpenCape, a fiber-optics provider, have gone round and round about who is responsible for replacing rotted poles and electrical line, repairs that are necessary if an underwater cable from the test site is to be connected to the electricity grid on shore. MassDOT oversees the poles and lines that run along the railroad tracks. 

“How can we beat climate change when we can’t get permission to string 600 feet of wire?” asks Miller. “Our test site has support, but not enough visibility to really get action.”

This September, the federal Department of Energy is funding a trial for another Littoral turbine, and Miller said he has his fingers crossed that the Bourne site will be hooked up to the grid by then. “It’s tough to run the lifting arm off the generator,” he explained. The issue, he said, has been elevated to Sen. Ed Markey’s office. (Both Markey’s office and MassDOT were contacted for this article, but there’s been no word about whether the gridwork will get done.)

Because of seawater’s volatility and tendency to deposit algae, microorganisms, barnacles and other sea life on wet surfaces, tidal turbines are more difficult to make and maintain than wind turbines. “There’s the old saying, the sea will eventually exploit every weakness.” noted David Duquette, CEO of Littoral Power Systems. For his company’s turbine designs, “We’re experimenting with running everything fully flooded, no seals.” 

“If water velocity is 6, 8, or 10 knots, it’s the same as sandblasting the blades all the time,” said Miller. Turbine blades, once steel, are now made of less expensive composite materials. 

“Almost every single project I can think of has had problems with its blades,” said Miller. After Canada spent $80 million on a test site in the Bay of Fundy in 2018, where the tides are famously powerful, tidal force shredded the device during its very first test run. “The company went bankrupt and the device is still lying on the bottom,” recounted Miller.  A new project in the Bay, which just this June hooked up to Nova Scotia’s power grid, is testing a floating platform and its six turbines’ ability to capture 420 kilowatts.

As Sustainable Marine, the UK company behind the project, all but shouts from the rooftop, dozens of these platforms could help Nova Scotians kick their coal habit.

A sign of tidal energy’s early hour in this country is that there’s only one commercial tidal turbine in full-time use. It’s a noteworthy example, however. ORPC’s RivGen device just entered its fourth year of operation on the Kvichak River in Alaska and produces a steady stream of 40 to 80 kilowatts per hour, depending on the speed of the water, for a village of 70 residents. “We’re about to install a second device, and that combination, with energy storage, will allow the community to reduce its dependence on more expensive fuel (diesel) by 60 to 90 percent,” said ORPC’s John Ferland.  

Littoral Power is planning a tidal pilot installation in a fast-flowing tidal strait in SE Alaska, and, similarly, if deployed full-time, it would help another Alaskan community move from costly diesel to less costly water-supplied energy. Outside of greater Anchorage, Alaska generally has no formal electricity network, and Duquette believes that ocean and river current energy might allow villagers to be less dependent on diesel-fed generators.  

According to John Ferland, 700 million people worldwide get their electricity from diesel. “They pay 10 to 15 times more on a kilowatt basis than conventional utility rates in the U.S.”  Marine energy, he said he believes, could be a solution for remote populations scattered “throughout the northern latitudes of North America.”

New Bedford-based Littoral Power has plans two years from now to work with PacWave, a Department of Energy-funded test facility at Newport, Oregon. Credit: Courtesy of PacWave Energy

While the U.S. has no wave devices in full-time use, PacWave, a DOE-funded test facility at Newport, Oregon, will be testing equipment that converts wave energy into electricity. Littoral Power, one of the participating developers, has plans two years from now to position a wave energy converter 7 miles off the Oregon coast, at a depth of 200 feet, and measure how effectively it can harvest energy from a big swell coming off the Pacific. 

Not surprisingly, a question often asked is, do underwater turbines pose a threat to fish and other marine life? “The whole promise of the river setting is, you don’t have an impoundment as you do with a dam that gives rise to many environmental issues,” said Duquette.  “To put one of these tidal devices in a naturally-flowing waterway is far less of a problem. Most of them spin very slowly.”  A few closely-monitored sites in Alaska “have passed millions of fish without incident.”

Apart from the river setting, ocean turbines and their effects on marine life will likely be studied for years to come. A study of SeaGen, a 140-foot turbine that operated in a loch in Ireland for several years, reported a 1.1% “hit rate” for migrating silver eels, but a later report cited a much smaller threat of 0.3%. Some turbines are as big as a plane, with multiple rotors, and though water density slows the blades’ rotation, developers are aware that as they put more and more devices into the ocean, they will need to prove environmental compatibility. 

Along with the exorbitant costs of tidal projects, the United States also has been slow out of the ocean-energy gate due to one basic reality, which, as Duquette noted, is that “our coastlines are largely characterized by slow-moving, less energetic currents.”  It pays to put tidal turbines in faster water, since even a small increase in water speed can create exponentially more harvestable energy.

Miller said he feels that whatever limitations exist shouldn’t deter us from using our ingenuity to advance the technology to the best of our ability. 

“Tidal energy is admittedly a moderate resource here,” he said, in contrast to Canada, “where it’s estimated there’s enough tidal potential to power every home five times over.  But we have the intellectual capital to create these new technologies.” He noted that while the United States doesn’t have the best solar climate, “much of that technology was invented here.” 

There are plenty of rivers, streams and estuaries from which to capture and store energy for local use, said Miller. He also said he envisions attaching devices to the submerged platforms of offshore wind turbines, mid-channel markers, bridge piles and boat piers. Eventually, as the technology becomes more sophisticated, there’s also the strong current of the Gulf Stream to tie into.

Clunky designs at this early stage will evolve into state-of-the-art gleaners of ocean-produced energy, he predicts. “Now we’re building battleships. It would be nice to build sailboats.”

Ann Parson is a New Bedford-based freelance science writer. Email her at:

Thank you to our sponsors

Founding benefactors: Joan and Irwin Jacobs fund of the Jewish Community Foundation, Mary and Jim Ottaway