Every harbor on a rough coast has a wall out front doing the unglamorous work, taking the punch so the fishing boats do not. Concrete, rock, a light on the end, and that is usually the whole job description.<\/p>\n
The wall at Mutriku, a town of about 5,000 people on Spain’s Basque coast, has 16 chambers buried inside it. Every wave that rolls in shoves air through them, and behind each one sits a turbine that has been feeding the Spanish grid since July 2011.<\/p>\n
This month it turned 15. BiMEP, the public company that runs the site, calls it the longest-lived wave power plant in the world and the one with the most operating hours on the clock. Nothing else in wave energy has stayed switched on this long.<\/p>\n
And in late June, an Australian company signed a contract to put its own turbine into that wall.<\/p>\n
The technology is called an oscillating water column, which is an elaborate name for a concrete box with the bottom open to the sea and a hole in the roof.<\/p>\n
A wave rolls in, the water inside the box rises, and the trapped air gets fired out through the hole. The wave retreats, the water drops, and air gets sucked back in through the same opening. Put a turbine in there and it spins on both strokes.<\/p>\n
Mutriku has 16 of those boxes. Each chamber is roughly 15 feet wide and 10 feet front to back, standing about 32 feet above low water, and each one necks down to a 30-inch opening with a Wells turbine and an 18.5-kilowatt generator sitting on top. Sixteen of those add up to the plant’s full rating of 296 kilowatts.<\/p>\n
The Wells turbine is the reason it works at all. Its blades are symmetrical, so it keeps rotating the same direction whether air is being blown out or sucked in, with no valves flipping and nothing clever happening underwater.<\/p>\n
The output numbers are small enough that nobody involved bothers dressing them up. Mutriku makes around 300,000 kilowatt-hours a year, which BiMEP puts at roughly 100 Spanish homes. Spanish households use far less electricity than American ones, so the equivalent figure over here would be smaller still.<\/p>\n
Run 296 kilowatts flat out for a full year and you would be looking at about 2,600 megawatt-hours. The plant delivers a bit over a tenth of that, because the Bay of Biscay does not send in useful swell on a schedule.<\/p>\n
Cumulative production passed 3 million kilowatt-hours in January 2024. By March 2025 the Basque Energy Agency<\/a> was reporting more than 3.2 gigawatt-hours. Spread that across the years the plant has been running and the average lands closer to 230,000 kilowatt-hours a year than to 300,000.<\/p>\n Then there is the part that actually explains why it exists. The Basque government has put the cost of the power plant itself at \u20ac2.3 million, comfortably under $3 million. The breakwater it lives inside was a separate public works job, approved because getting in and out of Mutriku harbor in a storm was dangerous. The generating equipment was an add-on to concrete that was getting poured anyway.<\/p>\n The 16 turbine-generator sets came from Voith Hydro Wavegen, an Inverness outfit founded in 1990 that had already done something nobody else had: put a commercial-scale wave device on a national grid. That was LIMPET, on the Scottish island of Islay, connected in November 2000.<\/p>\n LIMPET was decommissioned in 2011, the same year Mutriku opened. Two years after that, Voith shut Wavegen down<\/a> in a reorganization that cost 18 jobs in Inverness, pulling what was left of its marine work back to Germany and pointing it at tidal power instead. The public explanation was not that the machines had failed. It was that nobody was willing to fund any more of them.<\/p>\n Pico, the Portuguese oscillating water column in the Azores that started generating in 1999, was closed for good in 2018.<\/p>\n So the plant has now outlived its own manufacturer, the pioneer plant that came before it and the European contemporary that came after it, and it is still selling electricity into the grid. That is roughly the entire history of shoreline wave power, and one of the four is still running.<\/p>\n Fifteen years of salt air is hard on hardware. The Wells turbines are first-generation units, they need frequent attention, and their working life is finite, which is why the Basque agency set up a \u20ac3.2 million procurement program called TurboWave to design their replacement.<\/p>\n It runs in four stages: concept work, laboratory testing, a detailed design that gets built and tested at Mutriku itself, and finally a purchase order for somewhere between two and eight turbines. Four teams made it through to the funded stage, including IDOM and Arrecife in the Basque Country, Kymaner in Portugal, and a fourth based in Asturias.<\/p>\n When the tender opened, Offshore Energy reported<\/a> the process would culminate in 2026 with one winning technology chosen and supplied to the plant. Neither EVE nor BiMEP has announced that choice publicly, and there are five months of 2026 left to do it in.<\/p>\n On June 25, BiMEP announced<\/a> it had signed a contract with Wave Swell Energy, an Australian developer, to test a new turbine design at Mutriku ahead of commercial deployment in Europe.<\/p>\n Wave Swell’s version of the oscillating water column only works one way. The chamber vents outgoing air through a valve and takes its power from the vacuum that follows, which means the turbine can be a simpler unidirectional machine rather than a symmetrical one that has to cope with air going both ways.<\/p>\n The company has real operating evidence behind that claim. Its 200-kilowatt UniWave200 sat off Grassy Harbour on King Island, in the Bass Strait between Tasmania and the Australian mainland, and ran for about 18 months as the country’s first grid-connected device of its type before being pulled out, a step the Australian Renewable Energy Agency<\/a> had built into the funded project from the start.<\/p>\n The US Department of Energy went through the numbers afterward. Pacific Northwest National Laboratory<\/a> analyzed the King Island data and put the full wave-to-grid conversion efficiency on the order of 45% in seas with a significant wave height above one meter.<\/p>\n BiMEP also says the design has been through large-scale prototype testing at Oregon State University, where its performance held up when the technology was integrated into a breakwater. Which is convenient, because a breakwater is exactly what Mutriku is.<\/p>\n Oregon State also runs PacWave South, the grid-connected commercial wave test site off Newport that took the better part of a decade to permit and build. As of this spring, the berths were wired and waiting with nothing connected to them<\/a>, and the device first in line has not left the dock.<\/p>\n The rest of the field is offshore and expensive. A Basque-engineered spar buoy the height of a 14-story building is being tested further up the same coast<\/a> and tops out around 30 kilowatts. CorPower’s Swedish buoy has been feeding the Portuguese grid<\/a> by going limp in heavy seas instead of fighting them.<\/p>\n Every one of those machines has to survive the open ocean before it can earn a cent. Mutriku got the survival problem handed to it for free, because it is hiding inside a wall the port needed built regardless.<\/p>\n None of which makes it a model for powering a country. It makes about 300 megawatt-hours a year and its own operator publishes that number without spin. What it has that nothing else in wave energy has is 15 unbroken years of operating data from a real sea, a turbine hall you can walk into by booking through the town tourist office, and a reputation as the place where most of the significant air-turbine work of the last decade has ended up getting tested.<\/p>\n The next one arrives from Tasmania.<\/p>\n","protected":false},"excerpt":{"rendered":" Every harbor on a rough coast has a wall out front doing the unglamorous work, taking the punch so the … <\/p>\nThe company that built the turbines has been gone since 2013<\/h2>\n
Four teams are competing to replace those turbines<\/h2>\n
An Australian machine is booked into the Spanish wall<\/h2>\n
Oregon has the same idea and none of the mileage<\/h2>\n