Exploration of open ocean seaweed cultivation selected for inaugural Dean for Research fund for the Sustainability of Our Planet award

Written by
Catherine Zandonella, Office of the Dean for Research
Sept. 30, 2022

An exploratory project to investigate the benefits of farming seaweed in the open ocean has been selected for funding from Princeton’s Dean for Research Innovation Fund for the Sustainability of Our Planet.

The Sustainability of Our Planet fund is the newest member of the Dean for Research Innovation Funds, which provide Princeton researchers with starting funds to explore bold new ideas across the disciplines.

Established this year, the Sustainability of Our Planet fund focuses on discovering, developing and adopting sustainable solutions to environmental challenges. The fund is made possible by the extraordinary vision and generosity of John McDonnell ’60.  

The fund will award $300,000 to the project led by Daniel Sigman, Dusenbury Professor of Geological and Geophysical Sciences and an oceanographer and geochemist, in collaboration with Curtis Deutsch, professor of geosciences and the High Meadows Environmental Institute, and Laure Resplandy, assistant professor of geosciences and the High Meadows Environmental Institute.

“This fund prioritizes high-impact solutions that have the potential to make a tangible difference in the near- and medium-term,” said Dean for Research Pablo Debenedetti, the Class of 1950 Professor of Engineering and Applied Science, and a professor of chemical and biological engineering. “This inaugural project exemplifies both the exploratory spirit of the Dean for Research Innovation Fund program, and the solutions-oriented emphasis of this new program.”

Three scientists headshots

Daniel Sigman, Laure Resplandy and Curtis Deutsch

As seaweed grows, it absorbs carbon dioxide from the air and converts it into plant material, which can be harvested for use as food, animal feed, fertilizer, and potentially for bioplastics and biofuels. Nearshore seaweed farms are common globally, and are expanding rapidly in the western hemisphere.

The new project explores the possibility of situating farms out in the open ocean, far from land and over deep water. The seaweed farms would be located in low-nutrient, low-productivity “subtropical gyres” that occupy most of the global ocean’s area. To support the seaweed growth in these nutrient-poor settings, nutrients would be brought up from underlying deep water.

Open-ocean seaweed farming has the potential to sequester large amounts of carbon dioxide. When seaweed debris from the farms sinks, it carries its carbon down into the deep ocean. Most of this carbon will be converted back to carbon dioxide as bacteria and other organisms break it down. However, deep waters are isolated from the atmosphere for hundreds of years or longer, sequestering the seaweed-derived carbon dioxide from the atmosphere.

“This is an area that I am really excited about and where my Princeton colleagues and I can make an important contribution,” said Sigman, a leading expert in the ocean’s chemistry.

Through a variety of natural processes, the world’s oceans currently absorb about a quarter of the carbon dioxide produced by human activities. When carbon dioxide dissolves into surface waters, it travels very slowly down into the deep ocean. This slow migration limits the rate at which the oceans remove carbon dioxide from the atmosphere.

By sequestering seaweed-derived carbon dioxide in the deep ocean, researchers hope to increase the absorption rate. “The faster you can get the carbon dioxide out of the surface ocean and into the deep ocean, the better,” Sigman said.

Sigman cautions that many questions need to be answered about open seaweed cultivation. “It appears sensible to turn to the open ocean to reduce current and future pressures on land and its ecosystems,” he said. “From what we know so far, the vastness and ecological workings of the open ocean make it well-suited for a significant level of seaweed cultivation. However, there are many dimensions to this possible activity, which involve science, engineering, economics, public policy, and even the question of where humans fit in the global biosphere.”

In the planned research project, the team will use computer models to simulate the performance and environmental effects of open ocean seaweed platforms.

The project was selected from among many qualified proposals, said Debenedetti, because it “has the right balance of an idea that was quite novel with a good mix of fundamental science with strong practical applications.”

McDonnell said that supporting research on the sustainability of our planet is one of the most important priorities to him.

“Climate change is an existential issue that we must as a society address,” McDonnell said. “I’m enthusiastic about helping to find a technology that can be a piece of the solution to the challenges facing the planet. This is a fascinating project and I look forward to seeing what comes of it.”