A PMEC Insider Story, by Judy Twedt
Acronyms
WEC: Wave Energy Converter
TEAMER: Testing Expertise and Access for Marine Energy Research, a program run through the Department of Energy Water Power Technology Office
SEA Lab: Symbiotic Engineering and Analysis Lab
Olivia Vitale (left) and Alaa Ahmed (right) installing their WECs for testing in the Hinsdale Wave Basin.
Photo Credit: Kent St. Clair
Unlike the others, the WEC device fondly referred to as “Jo” took three days of troubleshooting to get her controllers in tune, she simply had more static friction in her powertrain. Immersed in a wave tank half the size of a football field, she and the other wave energy converters were part of a new experiment designed to test how different configurations of wave energy converters impact energy capture from ocean waves.
Olivia Vitale, a doctoral student from Cornell University, led these experiments at the O.H. Hinsdale Wave Research Laboratory at Oregon State University. This PMEC facility hosts the largest publicly funded wave basin in the United States. Designed for testing Tsunami hazards, the directional wave basin is also particularly useful for the study of wave energy capture. The basin, which looks like a giant swimming pool in a stadium, has a sloped steel ‘beach’, a maximum water depth of 1.5 meters (5 ft), and a unique and powerful snake-type wave machine that can generate a wide range of waves. A movable bridge extends across the middle of the basin for live monitoring and control from above.
Vitale was able to conduct this research through the Department of Energy’s TEAMER, which supports collaborations between marine energy technology developers, expert researchers, and state-of-the-art facilities, to advance marine energy toward commercialization. By getting access to external facilities and expertise, researchers like Vitale are able to advance their technology towards innovation in the industry.
PMEC facilities and expertise are utilized in a variety of ways through TEAMER collaborations. Vitale’s project, for example, is a collaboration between two academic labs. Projects also support marine energy developers, and many developers have applied, and received, TEAMER support to work with PMEC on projects including engineering support, environmental monitoring, and facilities access/testing support. This program also supports communities: PMEC researchers have contributed to multiple projects for the Alaska Native Igiugig Village Council, in partnership with ORPC, to harness local riverine energy generated by the Kvichak River. This is now the longest operating riverine power project in the Americas.
Vitale’s work seeks to answer an open and untested question in the wave energy community: since there are multiple types of motions in waves, could more energy be harnessed by wave farms that use multiple types of wave energy converters? While there have been many studies of WEC array optimization, Vitale’s is the first to test heterogeneous arrays. Her experiments combine an oscillating surge design that captures back-and-forth motion, and a point absorber design, which captures up and down motion.
“I was very excited when I saw this project – the heterogeneous aspect.” said Alaa Ahmed, a postdoctoral research scholar, is a collaborator on this project. She is an expert in hybrid wind and wave systems in the SEA lab at Cornell University, and paired up with Olivia to contribute to the project.
“When we talk about the ocean and getting permits to deploy WEC arrays, it’s not that easy...we are trying to limit the ocean space we use, so minimizing the space and maximizing the energy, this is the idea,” explains Ahmed.
This project grew out of exploratory student-led work to prototype WECs in the SEA lab. Vitale started mentoring engineering undergraduates Aisha Brundan and Kavya Mittha early in her graduate studies, “I jumped in as soon as I could. I started going to the meetings and getting involved. Then I applied for funding to mentor the undergraduate research to design and build the devices. That was a really fun summer.”
Building upon knowledge from wind farm research, Vitale wanted to know whether an array with two different types of WECs could capture more energy than a homogeneous array. The first prototypes were designed with in the summer of 2023 under Vitale’s mentorship. Brundan and Mitta named the first two point absorbers Meg and Laurie, for characters in Louisa May Alcott’s classic Little Women. The other two of that design are named Amy and Jo. The WECs in the second design are named Greta, Frances, Virginia, and Eloise – “all named after women I find inspiring,” said Vitale.
After initial testing in a smaller wave flume at their home institution, Vitale started looking for other basins for testing through the TEAMER program. She reached out to Pedro Lomonaco, director of the Hinsdale testing facility, to discuss her ideas. After several discussions about the best way to build the project, she applied in March and heard back in May – the project was funded.
Next, Vitale and her team began manufacturing the new designs, all by hand with machines and materials available in their lab’s makerspace. All of the floats on the WECs are made of repurposed marine foam leftover from another project. “Marine foam is really hard to shape. We tried a bigger band saw…the thing that worked the best was a kitchen bread knife! If you took a heat gun and heated the knife, it would melt through the foam nicer. For the final prototypes, it was me in the lab, 8 hours a day, carving foam, or drilling, or realizing ‘oh we need this part manufactured differently’.”
By the following March, the new prototypes – two designs with four converters each – were completed. Vitale and Ahmed packed them up for transport across the country to the Hinsdale Laboratory in Corvallis, to conduct their wave basin tests.
“Lots of people are doing array optimization,” Vitale says, “No one so far is combining different kinds of converters.” Her experiments will examine the effect of the different WEC’s on each other, and their effects on the wavefield downstream. “We want to see how different designs and mechanisms, in the same place, impact each other,” explained Ahmed.
The experiments required the basin to be completely drained in order to install the devices and fix them to the floor. Then the tank was filled, which took about 10 hours and was done overnight. While the experiments ran, Vitale and Ahmed worked from the bridge to monitor the measurements in real time. When a device needed adjustment, Vitale got in a kayak, paddled over to the device, and did whatever troubleshooting was needed.
Now Vitale is back in her home lab, crunching the numbers. She says preliminary results suggest that the point absorbers are more effective in the heterogeneous configuration, but more analysis is needed. Results will be available on the PRIMRE and the SEA Lab website, and all of the design and experimental data will be open source for accessibility and reproducibility on the GitHub repository.
“I want people to be very excited about wave energy. When you hear about numerical simulations, that’s not very exciting, but when you see these working in the water, you can see that this is a real thing.”
Thinking about applying for a TEAMER grant?
I asked the interviewees in this story for some tips on the application process. Here’s what they said…
What advice would you give to someone else interested in applying for a TEAMER grant?
Vitale: “Don’t be worried that your technology isn’t good enough or ready enough. When we applied, we had an iteration of our devices ready, but it wasn’t close to what we ended up with. We had some fear about applying, but it worked out for us. Don’t be afraid to apply. Just go for it! Maybe also reach out to a facility early, before you’ve completed your design and the experiments you want to do. Part of the thing about TEAMER is it’s also expertise, so the people can give you a lot of advice about what’s going to work. Reach out early.”
What advice do you have for prospective applicants who want to run experiments in Hinsdale?
Lomonaco: “We have observed that experienced applicants with the capabilities and physical dimensions of the facility get more during their time testing at Hinsdale. Also, applicants with a good background on waves, currents and their properties and effects on marine energy devices are better prepared for testing and the results of their experiments are more impactful.”
“Also, reach out early. The earlier, the better. If we have a good understanding of the needs of the applicant, we can certainly serve them better, and contribute to the success of the project.”