Oceans absorb roughly 25 to 30 percent of the carbon dioxide (CO₂) that is released into the atmosphere. When this CO₂ dissolves in seawater, it forms carbonic acid, making the water more acidic and altering its chemistry. Elevated levels of acidity are harmful to marine life like corals, oysters, and certain plankton that rely on calcium carbonate to build shells and skeletons.

“As the oceans absorb more CO₂, the chemistry shifts — increasing bicarbonate while reducing carbonate ion availability — which means shellfish have less carbonate to form shells,” explains Kripa Varanasi, professor of mechanical engineering at MIT. “These changes can propagate through marine ecosystems, affecting organism health and, over time, broader food webs.”

Loss of shellfish can lead to water quality decline, coastal erosion, and other ecosystem disruptions, including significant economic consequences for coastal communities. “The U.S. has such an extensive coastline, and shellfish aquaculture is globally valued at roughly $60 billion,” says Varanasi. “With the right innovations, there is a substantial opportunity to expand domestic production.”

“One might think, ‘this [depletion] could happen in 100 years or something,’ but what we’re finding is that they are already affecting hatcheries and coastal systems today,” he adds. “Without intervention, these trends could significantly alter marine ecosystems and the coastal economies that rely on them over time.”

Varanasi and T. Alan Hatton, the Ralph Landau Professor of Chemical Engineering, Post-Tenure, at MIT, have been collaborating for years to develop methods for removing carbon dioxide from seawater and turn acidic water back to alkaline. In recent years, they’ve partnered with researchers at the University of Maine Darling Marine Center to deploy the method in hatcheries.

“The way we farm oysters, we spawn them in special tanks and rear them through about a two-week larval period … until they’re big enough so that they can be transferred out into the river as the water warms up,” explains Bill Mook, founder of Mook Sea Farm. Around 2009, he noticed problems with production of early-stage larvae. “It was a catastrophe. We lost several hundred thousand dollars’ worth of production,” he says.

Ultimately, the problem was identified as the low pH of the water that was being brought in: The water was too acidic. The farm’s initial strategy, a common practice in oyster farming, was to buffer the water by adding sodium bicarbonate. The new approach avoids the use of chemicals or minerals.

“A lot of researchers are studying direct air capture, but very few are working in the ocean-capture space,” explains Hatton. “Our approach is to use electricity, in an electrochemical manner, rather than add chemicals to manipulate the solution pH.”

The method uses reactive electrodes to release protons into seawater that is collected and fed into the cells, driving the release of the dissolved carbon dioxide from the water. The cyclic process acidifies the water to convert dissolved inorganic bicarbonates to molecular carbon dioxide, which is collected as a gas under vacuum. The water is then fed to a second set of cells with a reversed voltage to recover the protons and turn the acidic water back to alkaline before releasing it back to the sea.

Maine’s Damariscotta River Estuary, where Mook farms is located, provides about 70 percent of the state’s oyster crop. Damian Brady, a professor of oceanography based at the University of Maine and key collaborator on the project, says the Damariscotta community has “grown into an oyster-producing powerhouse … [that is] not only part of the economy, but part of the culture.” He adds, “there’s actually a huge amount that we could learn if we couple the engineering at MIT with the aquaculture science here at the University of Maine.”

“The scientific underpinning of our hypothesis was that these bivalve shellfish, including oysters, need calcium carbonate in order to form their shells,” says Simon Rufer PhD ’25, a former student in Varanasi’s lab and now CEO and co-founder of CoFlo Medical. “By alkalizing the water, we actually make it easier for the oysters to form and maintain their shells.”

In trials conducted by the team, results first showed that the approach is biocompatible and doesn’t kill the larvae, and later showed that the oysters treated by MIT’s buffer approach did better than mineral or chemical approaches. Importantly, Hatton also notes, the process creates no waste products. Ocean water goes in, CO₂ comes out. This captured CO₂ can potentially be used for other applications, including to grow algae to be used as food for shellfish.

Varanasi and Hatton first introduced their approach in 2023. Their most recent paper, “Thermodynamics of Electrochemical Marine Inorganic Carbon Removal,” which was published last year in journal Environmental Science & Technology, outlines the overall thermodynamics of the process and presents a design tool to compare different carbon removal processes. The team received a “plus-up award” from ARPA-E to collaborate with University of Maine and further develop and scale the technology for application in aquaculture environments.

Brady says the project represents another avenue for aquaculture to contribute to climate change mitigation and adaptation. “It pushes a new technology for removing carbon dioxide from ocean environments forward simultaneously,” says Brady. “If they can be coupled, aquaculture and carbon dioxide removal improve each other’s bottom line.”

Through the collaboration, the team is improving the robustness of the cells and learning about their function in real ocean environments. The project aims to scale up the technology, and to have significant impact on climate and the environment, but it includes another big focus.

“It’s also about jobs,” says Varanasi. “It’s about supporting the local economy and coastal communities who rely on aquaculture for their livelihood. We could usher in a whole new resilient blue economy. We think that this is only the beginning. What we have developed can really be scaled.”

Mook says the work is very much an applied science, “[and] because it’s applied science, it means that we benefit hugely from being connected and plugged into academic institutions that are doing research very relevant to our livelihoods. Without science, we don’t have a prayer of continuing this industry.”

A partially finished Quonset hut-style home in Maine is seeking out an industrious buyer who can put the finishing touches on the one-of-a-kind property—and help it to fulfill its impressive potential.

While the dwelling might not be for everyone, particularly those lacking in “tools and imagination,” its very affordable $270,000 asking price will undoubtedly make it a prime target for those with the ability to see beyond what is currently little more than an empty shell.

“This striking Quonset hut-style residence offers a one-of-a-kind ‘handyman special,’ perfect for those looking to create a custom vacation getaway or a high-potential Airbnb,” the listing notes.

Located in Shapleigh in the heart of the state’s lake region, the unfinished abode is situated on a lush 11.79-acre parcel that is within walking distance of Square Pond and Mousam Lake—as well as an array of more metropolitan amenities.

“Any owner will have multiple ponds and lakes at their fingertips in addition to countless hiking trails, all while being within an easy radius for shopping and convenience,” said listing agent Ezra Hodgson of The Zoeller Group at Keller Williams Coastal and Lakes & Mountains Realty.

While 75% of the construction is already complete, the remainder provides a “blank canvas” for the next buyer’s finishing touches, although they will first need to finish the installation of the electric, plumbing, and insulation before they can embark on creating their own aesthetic for the home.

“Septic and well are in, hooked up, and functional,” Hodgson notes. “Framing is almost completed. Custom white maple kitchen cabinets are already installed. A buyer will need to complete running electrical and plumbing, then insulation and drywall, and their finish work like fixtures, trim, decks, etc.”

The 1,792-square-foot “handyman special” boasts a distinctive exterior with arched metal design in keeping with the traditional quonset hut style, which was inspired by a military structure called the Nissen hut used by British forces during World War I.

After the war, the style was adopted by American troops stationed at the Quonset Point Naval Air Station in Rhode Island—from which the huts now take their name—who worked to advance the design, making it lighter, more flexible, and faster to build.

According to Innovation & Technology magazine, an estimated 170,000 quonset huts were built by the Americans during World War II, and when that conflict came to an end in 1945, the surplus structures were passed to civilians, who began using them as prefabricated vacation residences, storage units, and even guesthouses.

While they have since fallen out of style somewhat, the structures continue to be favored for their ease of construction—and their multifaceted design, which allows for all kinds of personalizations, much like the unfinished dwelling in Maine.

Inside, an open-concept floor plan features high ceilings, multiple sliding glass doors, and a loft area that could be transformed into a primary suite or additional living space.

The listing features several staged images that paint a stunning picture of what the home could look like, if someone is willing to invest in its completion.

Hodgson says its location and the “ability to finish it into exactly what a buyer wants” are some of the home’s most impressive features.

The 1,700-square-foot property is configured with four bedrooms and three bathrooms, although the construction process is not so far along that a future buyer couldn’t alter that layout.

“The interior framing is largely in place, showing a thoughtful layout that includes a kitchen area already equipped with quality solid wood cabinetry,” the listing notes.

“The bathroom is started with a vanity, toilet, and shower pan partially installed. A spacious loft area provides excellent potential for a primary suite or additional living space overlooking the main floor.”

Hodgson believes the next owner might be seeking “the perfect blueprint for their vacation home. They could be someone looking to get away from the hustle and bustle, and take advantage of the peace and quiet that the woods of Maine have to offer, or maybe it’s an investor who just found their perfect short-term rental opportunity.”

The spacious property also has a storage shed for tools and outdoor gear, and connects to a series of recreation trails at the end of the driveway.

The sale also includes shared rights to a private beach on Square Pond, however Hodgson notes that any additional plans should only be carried out with the necessary due diligence.

“We would encourage any buyer to do their due diligence with the town of Shapleigh when determining if the property could be subdivided and subsequently built on,” Hodgson added.