More super-sustainable shipping! These from the Philippines, Tokyo and Norway are powered by the very waves they sail on
The Phillipines wave-powered hybrid trimaran
Now that we’ve seen low-carbon sustainable boats once, we’re beginning to see them everywhere… and here’s another concept: the wave-powered boat.
BBC Future Planet reports on this model based on the Filipino bangka (or trimaran), which is a boat that sports two outrigged rods (one on either side) that extend into the water:
“The outrigger’s job is to provide stability so the bangka doesn’t tip sideways,” Salvador says. “But I also noticed that each time a wave hits the outrigger, the outrigger constantly reacts to the upward and downward movement of the wave. What if we can convert this reaction – this kinetic energy – into electrical energy?”
The way wave energy works will be familiar to anyone who has waded in sea waters. At times, the waves are strong enough to push you back to shore or tall enough to push you over. “Waves have a lot of momentum, and it’s that momentum you feel when you’re out in the water,” says Bryony DuPont, professor of mechanical engineering at Oregon State University. “Wave energy uses that momentum, sometimes as-is and you just need the motion of the waves, and sometimes we capture that momentum and force it through machinery that generates electricity.”
The hybrid trimaran has this machinery – a wave energy converter – in the form of hydraulic pumps integrated into its outriggers. As the pumps move through the waves, they harvest the momentum of these waves, converting their kinetic energy into electrical energy, which will then be fed into a generator that will supply electricity to the ship. The electricity then provides propulsion via a motor. The more waves the trimaran encounters, the more power it can produce from those waves.
…waves are energy-dense; in other words, they can be ferociously powerful. At coastlines, waves can reach power densities of 60–70 kilowatts per metre in areas with deep waters. In the UK and the US, for example, the average wave power density is between 40 and 60 kW per metre. “If we can translate that energy into other useful forms, we can do a lot with very little,” DuPont says.
More here. The craft is powered by a standard combustion engine until it gets to the open, wave-ridden seas. Somewhat beset by COVID and other troubles, the Hybrid Trimaran seems to be back on course with its construction (report from Phillippines govt).
There are other attractive (and slightly odd) wave-powered boat designs around:
The Autonaut
“…packs solar-powered sensors for monitoring marine wildlife and ocean conditions and getting to where it needs to be using energy harvested from the waves it rides on” (New Atlas)
Dolphin-fin-based: The Wave Runner
“Two fins mounted side by side beneath the bow move up and down with the incoming waves, generating dolphin-like kicks that propel the boat forward” (Popular Science)
Whale-tail based: Norway
A group of researchers from the Norwegian University of Science and Technology (NTNU) are testing the biological process that propels the whale - its tail. The ‘tail’ looks like wings or fins that are attached to the front of the ship.
The waves that hit the 1:16.57 scale model ship cause it to move, which then make the fins go up and down just like a whale’s tail, while the shape of the fins harnesses the energy from the waves to help the ship move forward.
Eirik Bøckmann, a PhD fellow at the Department of Marine Technology at NTNU, said: “The foils reduced resistance on the ship by between nine and 17 per cent at wave heights of fewer than three metres.
“The resistance can probably be further reduced by optimizing the ship’s hull for the wave foils. The foils also reduced the ship’s heaving and pitching by about the same amount as for resistance.”
Although the long-term goal would be for small boats to use only wave power without relying on motors, the current goal is to cut fuel costs