How Shrimp Shells Are Being Turned Into ‘Carbon Negative’ Fuel, Food and Construction Materials

Engineers in Singapore have developed a new, multistep chemical process that transforms organic waste into useful, sustainable products

Ashley Braun, bioGraphic

July 6, 2026 8:00 a.m.

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In low-lying Singapore, electrochemical engineer Li Hong has found a creative way to displace some of the city-state’s dependence on planet-warming natural gas. Using a new, multistep process, Li and his colleagues have figured out how to perform a surprising bit of climate-helping alchemy by transforming carbon-rich organic trash like shrimp shells into products the island nation needs, including hydrogen gas, food and biogenic calcium carbonate—a white salt used in products ranging from cement to antacids.

Li and his team at Singapore’s Nanyang Technological University report that by diverting waste from the landfill, and by processing it in just the right way, their laboratory proof-of-concept system can produce carbon-negative hydrogen gas. “Carbon negative” means that, overall, the process removes more heat-trapping carbon dioxide from the atmosphere than it produces.

To help reach that carbon-negative status, the chemical process also makes cultured protein—the sort of grown-by-microbes product that fake-meat companies are experimenting with—which can be fed back to farmed seafood, including farmed shrimp. The process “closes the loop from the waste to the food,” says Li, and it employs a waste-to-wealth mind-set.

The third output—calcium carbonate—could help displace some quarried limestone rock in the production of cement, 4.2 billion metric tons of which are produced every year. Juan Carlos Serrano Ruiz, a chemist and an engineer at the Universidad Loyola in Spain who wasn’t involved in the research, says the system is a “very clever” way of using biomass to solve a vexing problem in hydrogen production. “I was really amazed by the degree of integration,” he says.

Today, most hydrogen gas is produced by reacting natural gas with steam. This is known as “gray hydrogen.” There’s also a growing supply of “green hydrogen,” which is made using renewable energy like solar or wind.

Currently, most hydrogen gas serves as a starting ingredient for fertilizer and industrial chemical production. However, there’s growing interest in its potential energy uses, particularly in hard-to-decarbonize sectors like aviation and shipping. Hydrogen gas is not generally used as a fuel; however, it can function as a way to store energy, which can then be unleashed in a turbine or an engine without emitting carbon. Whether hydrogen gas can be considered environmentally friendly or not depends on a multitude of factors, including where and how the hydrogen is manufactured and how far the production facility is from the point of use.

“Everybody’s trying to find the right combination of technology that works and [has] low enough costs,” says Alex Pearse, a materials scientist at Modern Hydrogen in Washington State, a company that sells hydrogen derived from natural gas.

Li’s team found the key to making such low-carbon hydrogen gas by tweaking an existing technology called water electrolysis and adapting it to use organic waste that would otherwise be destined for the landfill.

Typically, electrolysis involves using an electrical current to split water into hydrogen and oxygen gases. This reaction requires lots of energy, and the abundance of oxygen gas makes the setup prone to exploding. Instead, Li’s approach uses organics materials—such as scrap shrimp shells—as raw material that readily reacts in the presence of a catalyst, skipping the issues with explosive oxygen and drastically lowering the energy required. (Keeping waste from decomposing in landfills further drops the process’s net carbon emissions.)

To turn shrimp shells into a feedstock for hydrogen gas production, the process begins with mashing the shells into a rust-colored shrimp slurry. The scientists have learned to separate the calcium carbonate from the mix by using ball milling equipment to grind the shells. The rest—organic acids and ammonia—is pumped into an electrolyzer the team erected on their university’s roof.

With a setup similar to a battery, the electrolyzer has a negative anode on one side of the tank, a positive cathode on the other and a membrane in between. Five nearby solar panels power the system, driving an electrical current through the shrimpy organic acids, while sampling bags hooked to the contraption capture the hydrogen gas that escapes.

Post-electrolysis, the final step in this multiphase process takes place in a bioreactor. There, the scientists mix in phototropic purple bacteria that make a real stink fermenting the biomass leftovers into a high-protein supplement suitable for aquaculture feed. Harvesting wild fish to feed farmed fish and other aquaculture products is a serious sustainability concern that alternatives like this cultured protein could help alleviate if the economics and technology pencil out.

As Li and his colleagues report in a study published last year, their small laboratory setup can produce 14 liters (4 gallons) of hydrogen gas per hour. The process is about half as efficient as existing commercial green-hydrogen techniques, and improving the rate of production is essential for making the technology economically competitive, Serrano Ruiz suggests.

Right now, green hydrogen costs more than natural gas-derived gray hydrogen, and the former’s price depends heavily on government incentives and local energy costs. According to projections by Li’s team, the biggest expense of running a pilot-scale version of their process—a plant capable of processing 200 metric tons of shrimp shells—would be electricity, which would amount to more than half the production cost. A potential upside for Li and his team, however, is that hydrogen gas isn’t the only thing they envision producing.

Selling hydrogen alongside their process’s other products—whether calcium carbonate or protein—can balance the economics, Pearse says. “That’s both powerful, because you get the revenue from it, but it’s also a little bit more complicated, because you’re coupling two markets together.” His own company, Modern Hydrogen, sells solid carbon for road asphalt alongside its methane-based hydrogen.

Although Li’s project used discarded crustacean shells, he emphasizes that the technology isn’t limited to seafood scraps. “It’s a very versatile technology, suitable for a range of wastes,” he says, including cardboard boxes, vegetables, grass, corn, and residues from industries ranging from palm oil and forestry to sugar and brewing.

To Serrano Ruiz, this is the main appeal. “I would sell this technology as a way of recycling biomass,” he says, “to convert biomass into something useful.”

In fact, two companies are already licensing the new technology for commercial ventures. London-based Ki Hydrogen, incorporated in 2022, sources biomass waste from forestry, agriculture and breweries. The company is using a tweaked version of the process, Li says, to produce hydrogen gas and pure carbon dioxide, which it sells to an industry partner to create sustainable fuels. Meanwhile, another company is looking to harness the process to recycle carbon from sewage sludge.

If companies can efficiently and profitably scale up this biomass conversion technology, Serrano Ruiz says, it might make a positive environmental impact, because the proposed feedstocks are food scraps and organic waste rather than edible products like corn, which is what’s used to make corn ethanol for fuel. But reaching that level of impact would require obtaining a stable biomass supply, launching a test plant and establishing a market with the right policy incentives for their products. And, Pearse adds, proving that the process produces carbon-negative hydrogen gas even in an industrial setting—something the commercial ventures don’t claim to do—means bringing in third-party experts to carry out a full analysis.

With the rate of climate change accelerating over the past decade, scientists are under ever more pressure to find creative, viable new approaches to supplying the world’s food and energy needs—especially as older, more polluting ways run their course.

The real test comes when moving technologies like Li’s from the lab to real-world conditions, says Serrano Ruiz. That’s where most companies fail to scale up.

“With biomass, you always have the barrier of making this thing big and profitable at the same time,” he says.

This story originally appeared in bioGraphic, an independent magazine about nature and regeneration.