Student-built methane sensor aids mangrove restoration efforts

In fall of 2024, a team of students and faculty met to launch a project: creating a device that could measure methane from water bodies, a valuable tool in the fight against climate change.

The kind of methane sensor device they needed didn't yet exist. Their task - to help communities and researchers measure methane emissions accurately and protect their water bodies - required something low-cost, rugged and portable. It would need to be deployed anywhere in the world, robust to wind and rain, run off a light battery, and contain a chamber that can fill with gases and then efficiently clear those gases to enable new measurements.

"The real-world application of this was really motivating for me," said Grace Lo '24, M.Eng. '25, who is now a computer engineer for IBM. "Knowing that people are going to actually put this out in a lake or out in a real mangrove forest inspired me to make this the best device I could produce within the time limit and the supplies I had. That challenges you in a way you don't get just by doing projects isolated in a lab."

Sixteen months later, in partnership with the Cornell Atkinson Center for Sustainability and Environmental Defense Fund (EDF), these sensors were deployed in Colombia for the first time, informing global greenhouse gas assessments and reforestation of mangroves - ecosystems that can store up to four times more carbon per hectare than tropical rainforests. In the future, the student-built methane sensor devicecould be used to study emissions from lakes, wetlands, dairy farm manure lagoons, abandoned gas wells and many other sources.

"As we have growing wealth inequality, we're seeing more and more pressure on coasts from mining, lumber, tourism and development," said Todd Cowen, one of three faculty members in Duffield Engineering and the College of Agriculture and Life Sciences who worked with the students in a partnership facilitated by Cornell Atkinson.

"That puts mangroves in a very vulnerable position because mangroves are frontline coastal defense. They dissipate wave energy and offer wind breaks for inland indigenous communities. The wood from mangrove trees is used to make homes in those communities. And mangroves are incredible for carbon storage," Cowen said. "So as mangroves are destroyed, there is both carbon being released, and carbon not being sequestered."

Protecting Colombian mangroves

Mangroves thrive in the warm, brackish water along equatorial coastlines, where their spider-like exposed roots prevent erosion and protect against storm surges and rising sea levels. They also offer refuge for a wide diversity of sea creatures, anchoring ecosystems and creating a critical food source for Indigenous populations.

However, over the past 50 years, global coverage of mangrove forests has fallen 38-52%, primarily because of human activities like coastal development, agriculture, shrimp aquaculture and salt production.

Mangroves create such a supportive environment for fish and other aquatic species because roots grow closely together, overlapping and reducing wave forces. However, when people cut channels through the mangroves for transportation or to access natural resources, it "completely modifies the dynamics," said Johann Delgado, a doctoral candidate and research fellow in Cowen's lab.

"When you create an artificial channel in the mangroves, water velocities increase a lot, which erodes sediments. And the sediments are a very critical part of capturing the carbon in the ecosystem," said Delgado, who is also a Coastal Solutions Fellow in the Cornell Lab of Ornithology. "When you think about the small fish that rely on these mangrove ecosystems or the small mangrove propagules trying to establish, a channel like this is like having a highway in the middle of your house."

The ocean forces around Punta Soldado Island, where the research took place, were incredible, said Brooke Beers, a High Meadows Fellow with the ocean sciences team at EDF.

"The tidal environment between high and low tides was so extreme, which meant a lot of flux in methane and CO2," Beers said. "Our biggest task in Colombia was getting the flux chambers up and running and seeing how they would work in a pretty hostile environment, because this was their first real field trial."