In June, in the remote, tribal community of Igiugig, Alaska, a marine microgrid replaced diesel generators for an hour, and with diesel and marine energy together, charged batteries for another hour during a test.
The microgrid consists of two 35-kW RivGen marine generators from Ocean Renewable Power Co., (ORPC), a marine energy technology provider that produces clean electricity from river and tidal currents, plus Schneider Electric’s energy storage and microgrid controllers, according to Pratap Revuru, senior director, microgrid solutions and strategic partnerships at Schneider Electric.
Along with other tests of marine generators coupled with diesel-powered microgrids, marine generators are now wading into the microgrid space, deployed to supply clean power to replace diesel.
Canada, as well as the U.S., has its eye on marine energy. About 250 coastal and island communities in Canada now use diesel for their main power source, but the global marine design firm BMT hopes to get them off diesel with a project using microgrids powered by tidal energy and other renewable resources.
In the Alaska case involving Schneider Electric and ORPC, the hope is to move diesel—which can cost 15 times more than grid power—to a backup position while marine microgrids provide a quieter, cleaner and less expensive alternative to diesel for 60% to 90 % of the time, said Revuru.
U.S. DOE invests $20M in marine energy technologies
Interest in marine-powered microgrids is growing, and the federal Department of Energy (DOE) gave the marine energy industry a boost in late July by announcing it will invest $20 million for seven projects that aim to accelerate marine energy technologies— including those that harness electricity from wave, tidal and ocean and river currents.
One of those DOE-funded projects is taking place in a remote, diesel-dependent community: the island of Cuttyhunk, Massachusetts. The Marine Renewable Energy Collaborative of New England—a nonprofit agency that promotes the use of marine energy in New England (MRECo)—is testing a marine system that could replace diesel energy in an existing off-grid microgrid, said John Miller, executive director of the collaborative.
The project received $1.78 million from the DOE to utilize Sea Potential’s Duo-Ds wave-powered desalination system., according the the DOE press release about its investments.The project aims to test the unit’s potential for desalinating seawater, and eventually for replacing diesel in the community’s microgrid.
“For over a decade surveys of developers have found prototype testing to be the number one challenge so we focus on that with our tidal test site and wave testing at Cuttyhunk, with the people of Cuttyhunk and potentially with the broader island communities globally,” said Miller. If the test provides any marine power, Cuttyhunk will receive it for free during testing, he said. If the device is effective, it’s expected the island will add it to the microgrid permanently.
Studying the social side of new technologies
As part of the project, MRECo is working with Station1, a nonprofit higher education institution founded by researchers from the Massachusetts Institute of Technology that focuses on the social impacts of science and technology. Two students are looking at how the wave generators might affect the community’s environment and socioeconomic status.
Right now, the island is powered by two 100-kW diesel generators plus two 275-kW diesel generators. The existing microgrid includes 350 kW of DC solar and 250 kW of AC solar that feeds back into the power house, said Giada Brandes, a student at Boise State University and one of the two Station1 participants involved in the project. Electricity demand during the summer peak of 2022 was about 323 kW, she added. During summer peaks, the system experiences voltage drops, which undermines optimization of the microgrid, she said. It’s expected that wave energy converters may fill the electrical gap that prompts the voltage drops, she said.
The diesel generators are aging and diesel prices are rising, plus getting diesel to the island is too expensive, said William Blakey, the second Station1 participant, a student at the University of Washington. The island is trying to avoid connecting to the mainland power grid because that’s too expensive, he said.
In addition to studying the potential for wave energy to be added to the microgrid, the students are looking at how wave energy would impact the island residents socially and economically.
“I feel personally this is overlooked in these scientific research programs,” said Blakey.
Studying maintenance & disposal for wave energy technologies
The students plan to look at the environmental impacts of using wave energy converters, asking whether the wave energy unit can be used over and over, and whether it can be disposed of in an environmentally safe manner, Blakey said. In addition, they’re researching whether island residents can provide the maintenance and servicing of the unit, or whether they’ll need workers from outside the island to provide maintenance and service.
The marine environment is harsh, and it’s unclear whether the wave energy converters can withstand the environment or will break down every five to 10 years and require high maintenance costs, he added.
“Are we thinking ahead enough when installing these new renewable devices and making sure all stakeholders are involved and are aware of any drawbacks related to financial issues or tourism?” he asked.
Cuttyhunk doesn’t have Martha's Vineyard's resources
The island is a fishing and boating community that relies on tourism in the summer. Its neighbor, Martha’s Vineyard, a wealthy tourist destination, doesn’t grapple with energy challenges and doesn’t use diesel, said Blakey.
Wave energy can help bridge the wealth gap between the two islands.
“If wave energy technology can benefit Cuttyhunk, it’s a cool idea,” he said.
