Ocean boosters like to compare the kinetic energy stored in the sea to a ginormous oil reserve that’s never going to run dry.
It doesn’t matter if the sun shines or the wind blows. The tides turn. You can set your watch to them. The trick is how to generate cost-effective, renewable electricity from that limitless, ceaseless motion. They’re working on the problem here on Scotland’s Orkney Islands.
When you first look at the ideas for ocean-energy devices, it does look a little … sci-fi. Underwater corkscrews. Oscillating hydrofoils. Tidal kites? Seriously. And it gets more out there.
And maybe someday to heat homes and schools — and power passenger ferries and planes that hop between islands.
It’s all hopeful and ingenious — and the world needs some hope, as the COP26 climate summit continues this week in Glasgow, and we wait to see if there’s enough ambition to avoid potentially catastrophic warming.
It’s worth knowing, though, that the sea here is also a graveyard, with once pioneering ocean energy prototypes now turning into rust, after much hyped start-ups were liquidated in bankruptcies.
But after two decades of trial-and-error, the sector’s backers say marine energy is getting there. They say tidal machines could begin to work alongside the far more developed energy systems, based on solar and wind power, within the decade.
The basic concept? Imagine taking an offshore wind turbine, with its rotor blades spun by moving air, and turning the thing upside down, dunking it into the sea, and letting the tidal currents turn the blades.
Once in place, the turbine anchors itself to the channel bottom and lowers its wings.
The turbine’s blades turn in the tidal flow, powering the generators on the wings.
As the tide turns, the rotors simply reverse, drawing power from the flow constantly.
The wing generators produce electricity that charges the turbine’s large batteries.
The electricity also flows from the turbine to onshore power distribution centers through a large cable.
Neil Kermode, managing director of the European Marine Energy Center (EMEC), anticipates that tidal energy is poised to help Britain deliver on its promise to go net-zero on carbon emissions.
“The R&D has shown it works and industry has shown it can do this,” he wrote in an appeal to the electricity regulators to adapt to new technologies like ocean power.
“This opportunity is right here,” he said, “right now.”
Kermode lives in the Orkneys. About 20 of the more than 70 islands are inhabited. Total population: 22,000. It is not most people’s idea of a beach vacation. It’s gray stone houses and neolithic stone circles — and dreich weather. But for ocean technologists, it’s near perfect: fierce winds, wicked tidal races and endless sets of just-right waves.
Developers have been towing their ideas up to Orkney because the islands are home to the EMEC, dedicated to wave and tidal power, with a test site set up to trial blue-energy machines. The site also allows for some projects to be plugged into the national electricity grid or for their excess juice to be made into hydrogen.
Scotland is among a handful of such sites. Competitors are at work along the coasts of China, France, South Korea and Canada. In the United States, they’ve done demonstration projects in Maine and Washington state, and one in the East River in New York City.
Over the years, the sea passages between the islands have seen wave and tidal machines that bring to mind steel manta rays and undulating sea snakes. One early device looked like a giant propeller riding an elevator.
They had cool names, like the “Oyster 800” and “Penguin” and “OpenHydro.”
Some couldn’t keep water on the right side of the hull, and sunk. Other developers proved their concepts but ran out of money before they could make the leap from experimental to commercial.
There are three machines in the Orkneys today.
FROM TOP: The Magallanes Renovables ATIR installation. (Colin Keldie/Ocean 2G); Orbital O2. (Hoy Drone, courtesy of FloTEC); The Blue X by Mocean Energy. (Colin Keldie)
One is a prototype wave energy converter called “Blue X,” by Mocean Energy. The thing is a 65-foot hinged raft that resembles a floating double-ended kitchen spatula. As waves raise and lower the machine, the rocking motion of the hinge captures the energy of the ocean and the turbine converts it into electricity. The device can be operated wirelessly, with commands sent from shore.
Mocean Energy Managing Director Cameron McNatt said after sea trials, the company wants to connect the device to a subsea battery, which will power a remotely operated underwater vehicle. An underwater robot could be deployed to service offshore devices related to oil, gas, wind or tides.
The Blue X is dwarfed in size by two tidal machine operating in Orkney waters. “ATIR,” from Spanish developer Magallanes Renovables, is capable of producing 1.5 megawatts of power, while “Orbital O2,” from a British firm, is rated for 2 megawatts, enough to power 2,000 homes a year.
In 2019, Magallanes founder Alejandro Marques took a Washington Post reporter out to the ATIR to scramble up on the deck and down below, as the machine bucked in the waves.
“Basically, what you see is something that looks like a boat, yes?” Marques said. “But with a big windmill hanging off the bottom.”
“And this boat isn’t moving. It’s anchored to the sea floor. What is moving,” and here he paused, “is the ocean.”
Marques said the concept of generating power for the grid has already been proved. ATIR and other devices have sent a trickle of electrons to the shore. What needs to happen, he said, is for the price of producing that power to become more competitive, which he called “inevitable over time.”
The latest tidal machine to arrive in Orkney is Orbital O2 — 240 feet long, weighing 650 tons, as big as a floating jumbo jet. The thing looks like the Beatle’s yellow submarine.