In 2019, Legena Henry, SM ’10, and her students at the University of the West Indies in Barbados sought to eliminate fossil fuel usage on their island by 2030. Initially, they looked to Brazil’s model of sugar-based ethanol. However, with local sugarcane production being minimal and distilleries relying on imported molasses, the approach seemed unfeasible.

The breakthrough came unexpectedly when student Brittney McKenzie suggested utilizing invasive sargassum seaweed, which was accumulating on local beaches. Henry decided to explore the idea, mixing wastewater from a rum distillery with the sargassum for lab experiments. The results were promising: the microbes in the mixture effectively digested the seaweed and utilized sugars in the wastewater. What began as a mere academic exercise transformed into a significant innovation, allowing the conversion of sargassum into renewable natural gas for vehicle fuel.

Barbados grapples with significant sargassum waste, sometimes filling over 800 dump trucks during peak times. Instead of discarding this waste, Henry’s findings present a dual solution to the island’s challenges, as both the sargassum and the rum distillery’s wastewater can be used to create sustainable fuel. “All the islands in this region of the Caribbean have a sargassum problem and a rum wastewater problem—and ultimately a climate-change problem,” Henry noted, underscoring the broader applicability of this solution.

Now, as the CEO of Rum & Sargassum, a startup she co-founded in 2021, Henry has been involved in practical demonstrations, showcasing vehicles powered by this biofuel in Barbados and Grenada. The project illustrates the necessity of collaborative efforts across various fields, a principle reinforced by her time at MIT.

Henry remains optimistic about the impact of her work: “Sargassum has now become part of the conversation that will turn the climate crisis around.”