Wave-Powered Robot Revolutionizes Ocean Exploration

By Michael D. Lemonick

Edward Lu isn’t the easiest guy in the world to impress. He’s not only an astrophysicist and an electrical engineer, but also an astronaut who’s flown on the Space Shuttle (twice) and the International Space Station — and on top of that, he ran Google’s Advanced Projects Group that gave Google Maps and Google Earth their imaging capabilities.

Then, last year, Lu heard about a technology so simple yet powerful that it could fundamentally change the way oceanographers, meteorologists, fisheries experts and climate scientists gather their data — so he signed on with a company called Liquid Robotics, which owns the technology, as Chief of Innovative Applications. “It seemed like chance to get in on something that can really change way we monitor the ocean,” he said.

The Wave Glider is an unmanned maritime vehicle (UMV) that floats on the surface and is connected to a flat wing-like structure that hangs 20 feet below. Credit: Liquid Robotics.

“It” is the Wave Glider, a surfboard-shaped apparatus, about 7 feet long, that can sail the open seas propelled by nothing more than wave power. Just last week, a flotilla of four Wave Gliders arrived in Hawaii after a months' long excursion that started in California last November, and they’ll soon be continuing on toward Australia and Japan. For people who keep track of such things, the little vessels have already shattered the Guinness Book World record for distance by an unmanned wave-powered vehicle. “It can go essentially forever,” Lu said, “until it’s covered with barnacles.” (That hasn’t happened yet.)

But for people who care about what human-caused global warming is doing to the oceans, in particular, and the climate more generally, the Wave Glider could turn out to be pretty important. The way it works is completely straightforward: the surfboard part of the device, made of carbon fiber and plastic foam, is connected by a tether about 20 feet long to an underwater “glider,” fitted out with hinged flaps. “It’s kind of like a Venetian blind that lies horizontally,” Lu said.

At 20 feet down, the water is pretty still, so when the surfboard is lifted by a wave, it yanks the glider upward. That makes the flaps angle forward, and propels the whole assembly forward at about 1.5 knots. When the surfboard drops into a trough between two waves, the weighted glider pulls the assembly downward, putting the flaps in a position that moves everything forward as well (it’s hard to describe in words, but there’s a video that helps).

The surfboard itself is covered with solar panels that power any scientific instruments on board, along with a transmitter that uses Iridium satellites to send data to, and receive commands from, a control room at company headquarters in Sunnyvale, Calif. What that data consists of depends on which customer has signed up as a client — oil companies, for example, which uses Wave Gliders to sniff for leaks around drilling rigs and undersea pipelines; or the Scripps Institution of Oceanography, which uses them to tow earthquake-monitoring sensors; or the National Oceanic and Atmospheric Administration (NOAA), which uses them to gather carbon dioxide data out at sea where sensing buoys are few and far between. “Over the world’s oceans as a whole,” Lu said, “there are maybe 5,000 or 6,000 buoys, which amounts to two, on average, for an area the size of California.”

Not only could a fleet of Wave Gliders add dramatically to that sparse coverage, Lu said, but it could also fill a crisis that faces climate science: a looming gap in satellite observations as budget problems allow older satellites to fail without new ones ready to go. “We have an uninterrupted 30-year record of climate observations,” Lu said, but if there’s no overlap between older satellites and new ones, there’s no way to calibrate the two to make sure they’re making measurements consistently. It’s kind of like trying to carry out a commando mission without everyone synchronizing their watches.

Credit: Liquid Robotics.

Originally, the company intended to sell Wave Gliders to their customers, but, Lu said, “we’re beginning to transition to simply selling data. Most of our customers don’t want to run a fleet of robots — they just want the measurements. We’re good at operating robots.” And as it turns out, getting those measurements through Liquid Robotics is turning out to save the customers money. “Wave Gliders are quickly becoming the future of ocean research. They require no expensive research ships and can be deployed off the back of a small fishing vessel,” said Christian Meinig, Director of Engineering at NOAA’s Pacific Marine Environmental Laboratory, in a company press document.