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Carderock, DOE Collaborate on Advanced Wave Energy Conversion Tests

By By Dustin Q. Diaz, NSWC Carderock Division Public Affairs | Aug. 7, 2017

WEST BETHESDA, Md. —

Naval Surface Warfare Center, Carderock Division engineers worked with partners from Sandia National Laboratories to test new control strategies for producing, converting and gathering wave energy in the command's Maneuvering and Seakeeping Basin in West Bethesda, Maryland, July 24 through Aug. 4.

The combined engineering team members are testing a 1-ton wave energy converter (WEC) in the MASK with a focus on control to increase energy generation, according to Ryan Coe, a research engineer with Sandia's Albuquerque, New Mexico, facility.

"The whole purpose of this project and this test is to try to increase the amount of electrical energy that these wave energy converters generate and collect," Coe said. "We're looking at how to control the dynamics of the device and the device itself in a way to increase energy capture and increase the efficiency of the device."

Coe and colleagues from Sandia, a multi-mission laboratory contracted to support the U.S. Department of Energy's (DOE) National Nuclear Security Administration, previously worked with Miguel Quintero and other ocean engineers at Carderock to test a WEC in winter 2016 in the MASK, Carderock's indoor ocean and ship-model testing facility. In the year since, Coe said they've analyzed the data collected, designed new testing models and improved the hardware to implement advanced new controls.

"This device can move in three degrees of freedom: it can move in heave, surge, and pitch; so it's basically all the motions in a single plane," Coe said. "It can move all over the place and we're able to collect energy in all those degrees of freedom.

"What that allows us to do is simulate a really wide range of different WECs and study those degrees of freedom separately and in conjunction with each other. We're now able to take the industry standard for WECs and apply a more complex, more optimal controller and as much as double the amount of power these devices produce in most sea states."

Quintero and Carderock colleagues like Dave Newborn have shared knowledge with DOE partners like Sandia and the National Renewable Energy Laboratory on large-scale wave energy conversion projects like this both during the previous test and during last year's Wave Energy Prize contest, which was a public prize competition that involved nine different WEC tests in the MASK over just 10 weeks. A self-described "waves guy," Quintero said this knowledge share has been a great opportunity for all parties to learn and benefit from the collaboration.

"We've built a large dedicated structure for these tests and mounted the WEC on it, which is different from the method we usually use," Quintero said. "We'll use controllers for rudders, props and wavemaking, but with the way they're implementing it, the methodology is a little different. It's beneficial for all of us to learn how to test a device like this in different situations. Sandia brings a lot of knowledge and expertise on how to do this, and we can share in it and have that knowledge to do similar tests in the future, even when they aren't here."

Giorgio Bacelli, another research engineer with Sandia, said he, Coe and Kevin Dullea, an engineer from Sandia's robotics department who built the new WEC, bring different techniques used in technologies like electronic systems, mobile phones and aerospace engineering to complement Carderock's background in ocean engineering and draw more energy from the converter. He compared these advanced power strategies to the process of swinging on a child's swing - putting energy in to gain more in return and managing that process.

"This is a substantially different problem than trying to control the route of a ship free-floating in the ocean's waves," Bacelli said. "We've developed a method of testing that runs in short periodic waves that repeat multiple times. This allows us to quickly sweep through the control system's parameters and see a response. So far, taking a different approach and bringing in tools that have been used for rockets, robots and radio tuners has been giving good results."

Coe said Sandia and DOE are looking at wave energy and other renewable energy sources to eventually power the continental U.S. electrical grid, and in the meantime, such development provides economic boosts in the form of new jobs required to install and develop technologies like WECs. But it also has applications that can directly benefit Navy and Marine Corps warfighters.

"The Navy and the Marines operate in the ocean and they need energy to do so, just like the U.S. power grid does," Coe said. "Further down the line, there's a possibility that a WEC might serve to power a naval off-shore base, an autonomous system or something else along those lines and provide greater operational capacity, similar to the flexibility a solar panel will give you today."

DOE officials including Alejandro Moreno, director for the Water Power Technologies Office in the Office of Energy Efficiency and Renewable Energy, visited the MASK Aug. 2 to see the test first-hand. This was the second of three rounds of testing Sandia plans to hold in the MASK, according to Coe, with the final and most technically advanced round set to take place later in the year.