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Portland Business Journal: Grant-winning Portland State researcher looks to overcome skepticism — his own — on ocean energy
Author: Pete Danko, Portland Business Journal
Posted: June 22, 2017

Read the original story from the Portland Business Journal.

If Jonathan Bird succeeds, one of the most significant obstacles to marine energy development could be overcome — along with his own doubts about the viability of generating energy from waves and tides.

The U.S. Department of Energy thinks Bird’s work on cutting-edge gearing systems has possibilities. The department last week awarded the Portland State University professor a research grant of up $1 million, following on earlier grants he’d received from the DOE and other sources.

“I’m rather skeptical about ocean generation,” says Bird, a New Zealander who came to PSU two years ago from the University of North Carolina at Charlotte, where he began developing magnetic gearboxes for both marine and wind applications.

“The ocean is an immense resource, and that’s why it deserves attention,” he says. “But coming up with the right solution is really challenging.”

The trouble, Bird says, is the nature of waves. Waves are immensely powerful, thanks to the density of water, but they’re slow. Bird notes that the wind will commonly move around 10 times the speed of the ocean, while the ocean is about 1,000 times the density of air.

In engineering speak, ocean energy is high torque and low speed, so it requires significant stepping up to spin a rotor at a high speed to generate electricity.

Mechanical gearboxes are a common way to do that, but there are problems with such drive trains: As an Electric Power Research Institute paper put it, they're "typically large, complex, and costly, and historically they have been prone to premature failure."

Or as Bird puts it, “It’s not going to last 20 years — it’s going to break down.”

That's not good in any situation, but it's really bad in the ocean, where doing maintenance work can be especially expensive. Bird says one developer told him the cost of going out and replacing a mechanical gearbox can be as great as the cost of the wave energy converter itself.

Ocean energy devices, Bird says, "need to be like satellites," where you put them out in the ocean and don't have to worry about them for a very long time.

Hydraulic and direct-drive systems, a couple of other alternatives, have their own issues, Bird says, so he's betting on magnetic gearboxes. They hold out the promise of more reliable service because they don't have cogs that have to mesh with each other, eliminating the problems that friction inevitably brings. Instead, the systems work using rings of magnets, interacting through a metal segment, to transfer force from a low-speed shaft to a high-speed shaft.

"The magnetic gearbox, which creates speed change without physical contact, minimizes operations and maintenance costs and provides protection from overloading during extreme events," the DOE said in its funding announcement. At the same time, it also allows for a smaller generator, "which in turn reduces the structural support required, thereby lowering costs."

Bird says the magnetic gearbox technology is well understood, but needs to improve to move beyond small prototypes and become viable in actual devices. His goal with this grant is to push the tech forward, but he says getting all the pieces into place for wave and tidal energy won't happen quickly.

"Ocean technology will need consistent support from the state and federal government for a significant time," he says.