Photo: Bluetti Power.
Using solar power for a fish farm is better for the environment than the usual diesel.
Who wouldn’t be encouraged to see all the clever ways innovators are working to reduce the harm that human activity can cause to the planet?
If it’s happening anywhere near Rhode Island, the nonprofit ecoRI News will find it and tell you about it. For example, Rowan Sharp covered the advent of a solar-powered, self-cleaning fish farm in Rochester, Massachusetts, back in 2012.
“Dale Leavitt told me to meet him at the 7-Eleven in this small town of about 5,000. I wouldn’t be able to find the fish farm on my own, he said. ‘It’s way out in the woods — it would be impossible.’
“He pulls up in a pickup — a cheerful, mustached man with slightly wild silvering hair. He wears a weather-beaten baseball cap and T-shirt, both advertising the marine biology program at Roger Williams University, where he teaches part time. He has blurry tattoos on his forearms, including one of a cartoonish, polka-dotted octopus. …
“I follow him down Route 28, until he veers into forest. Soon we’re rolling slowly down an unpaved track, just rutted wheel marks with grass tufting up between them. … Leavitt parks on a little scrap of solid ground amid the bogs, where a murky pond and a bank of solar panels are the only clues to the one-of-a-kind innovation hidden here. But this unassuming exterior packs a punch. Leavitt, cranberry farmer Brad Morse, Roger Williams University engineering professor Charles Thomas and a handful of undergraduate students from Roger Williams University have turned hard-won Environmental Protection Agency (EPA) grant money into a solar-powered, self-cleaning fish farm that may prove two to three times more efficient than conventional fish farms, at scant environmental cost. …
“Leavitt — his students call him Dale — is in his element here. He produces a plastic container of what looks like dog food pellets — Purina Fish Chow, actually — and happily leads me over to an unnervingly rickety plank onto a metal walkway over the pond. Weathered boards delineate the 15 6-by-8-foot mesh-sided fish pens.
The 15 6-by-8-foot fish pens are stocked with juvenile largemouth bass. … Soon the surface roils with activity: 6-inch juvenile largemouth bass, voracious eaters, which, by fall, will grow into 14-inch, one-and-a-quarter-pounders. Each pen is a module that can be lifted out with a backhoe. The mature fish will be sold at Boston’s live seafood markets or over-wintered for pond stocking this coming spring.
“Each pen can comfortably hold 100 bass, though some aren’t yet filled. Soon three of Leavitt’s assistants drive up with more fish in plastic tanks. Leavitt bought the bass as 2-inch hatchlings from a Delaware hatchery last winter; he and his students raised them to their current size in a Roger Williams University laboratory. …
“[Cranberry] farmer Morse is out today, but this enterprise owes its beginnings to a struggling late-1990s cranberry market that left Morse searching for other options. Morse is a fifth-generation grower who has farmed the 65-acre bog surrounding us since 1971.
“By 1999, cranberry prices were so depressed that many farmers feared selling their land for development was the only viable option. But Morse had another idea.
“ ‘I was looking for ways to diversify,’ he says in a telephone interview. He connected with the Massachusetts Department of Agriculture, where Leavitt then worked as an aquaculture extension agent. Leavitt found funding to help Morse launch a fish farm, and the two became good friends as they worked together on an elegant partitioned aquaculture system, kept clean by phytoplankton.
“It was a two-pond design: one pond for the fish, with water circulating by paddle wheel through a wider, shallower pond — a converted cranberry bog — where naturally occurring algae absorbed fish waste from the water. An aerator gave the needed oxygen boost.
“The farm was ‘a learning curve,’ Morse says, but it supplemented his income until the cranberry market recovered. The project’s Achilles’ heel, however, was its fuel consumption. The bog is too isolated for an electricity connection; a diesel generator powered the paddle wheel and aeration.
“In 1999, diesel had cost 76 cents a gallon. By 2006, it was well over $3. The fish were no longer profitable; Morse converted the filtration pond back to cranberries. Leavitt turned his attention to other things.
“But Leavitt’s passion has never strayed too far. He joined the Roger Williams University biology department and continued doing aquaculture outreach, advising new oyster farmers and even designing a solar-powered shellfish growing system. His lab also grows oysters for restoration of Narragansett Bay.
“In 2008, Leavitt called Morse to say, ‘Brad, I’m ready to start fish farming again.’
“This time, Leavitt had a different plan. He applied for an EPA grant to work with undergraduates in developing technology for sustainable living. Morse was more than willing to get involved. …
“Morse, Leavitt, and Thomas worked with a team of senior engineering students to “completely revamp the concept” of the fish farm. They modeled the new system on the flow dynamics of an automobile turbo-charger — a lucky stroke of inspiration from a student. They designed a single-pond system, with waist-deep fish pens on one side and a shallow, 18-inch algae filtration area on the other; algae need plenty of sunlight to photosynthesize fish waste, so depth matters. A single pump would aerate and circulate the water, and the whole pond would only be a quarter acre.
“Eighteen 200-watt, 24-volt solar panels power the fish farm’s water pump.Goodbye diesel. They were going solar.”
More at ecoRI News, here. No firewall.
Photo: Catherine Smart for The Boston Globe
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