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Founders & Leadership

Cameron Halliday, Danielle Colson, Sean Robertson, Professor T. Alan Hatton, Professor Takuya Harada


MIT, Harvard University

Investment Area

Reinventing carbon capture with novel materials.

Carbon capture may not be a panacea for climate change mitigation, but it is an essential wedge in reaching net-zero. But carbon capture has an efficiency problem. Existing methods require too much energy, making it challenging to scrub meaningful amounts of CO2 out of the free atmosphere (in “direct air capture” applications), and all-but-eliminating the economic margins needed to capture it on its way out of power, cement, steel, or chemical plants (in common “point source” applications). Carbon absorption technology has existed for a hundred years—but not cheaply enough to be broadly applicable for emissions reduction. “Carbon capture has failed to meet its promise—fundamentally, because it’s expensive,” says Cameron Halliday, co-founder and CEO of Mantel. “With our technology, we can drive the cost down by half, making carbon capture cost-effective for even the hardest-to-decarbonize sectors.”

Mantel, a startup out of MIT’s Department of Chemical Engineering, is pioneering the use of a fundamentally new material for carbon capture: molten salts that operate best at the high temperatures found inside boilers, kilns, and furnaces. While today’s point-source carbon capture systems require heavy parasitic loads on their host power and industrial plants, Mantel’s novel approach recaptures high-quality heat, dramatically reducing the net energy needed for the absorption of CO2 from exhaust, and its subsequent desorption to pure CO2. While still in early prototypes, Mantel’s fundamental material innovation promises a paradigm shift in the efficiency of point-source carbon capture—and, with it, the mitigation of industrial emissions most broadly. “If we can do carbon capture economically, added to every single power station and every single industrial process, we’ve solved a huge chunk of the problem,” says Halliday. As for the sequestration of the carbon itself, Mantel’s technology is agnostic—as long as it doesn’t go back into the atmosphere.

Mantel’s innovation emerged out of material research completed in MIT’s Hatton Research Group, with Professors T. Alan Hatton and Takuya Harada. In 2018, Harada, Halliday and Hatton began experimenting with a variety of high temperature solids known to hold promise for carbon capture. “We were basically exploring the periodic table,” recalls Halliday. Their challenge was finding materials that would reduce the amount of degradation that occurred over repeated cycles. When one sample—a sodium borate—showed unusual, if not unexplainable, reaction kinetics, it took them time to realize what was going on: the material was molten, giving it completely different properties from the solids typically used. Notably, it was uniquely stable. Scientists had been dogged by the unavoidable trade-off that high-temperatures came with rapid degradation. But this new material—a molten salt—eliminated that vexing imbalance. Which immediately presented a new challenge: “Can we actually build a system that uses these materials to capture CO2?”

Halliday, along with co-founders Danielle Colson (COO) and Sean Robertson (CTO), are focussed on developing systems that can be used for the full range of point-source applications—whether legacy fossil fuel plants, bioenergy facilities, or steel, cement and chemical factories. In all cases, conventional wisdom has it that higher temperature processes are less efficient, because of the energy required to reach those temperatures. But Mantel’s use of molten borates allows for a process in which the energy generated during the absorption of CO2 is high-quality, useful heat, which can then be used to generate more steam (for electricity) or recycled in the manufacturing processes. And since Mantel’s absorption materials are liquid, they avoid the rapid degradation that has plagued the solids previously developed for high-temperature separation processes. Mantel’s technology roadmap requires the engineering of successively larger prototypes, each designed to keep that extra heat inside the boiler, thereby increasing the efficiency of the overall system. ”Our underlying belief is if we can do this for one of these applications, we’re on our way to all of the others,” says Halliday.

The rapidly evolving economics of carbon capture, both in the United States and globally, expands the realm of commercial potential for the technology. At root, Mantel’s use of molten borates allows for a system that promises to reduce energy losses by more than 60%, and cut costs in half. With the material performance well understood—and patent-protected—new engineering approaches are now opening up. “What blows our minds is that this is really simple chemistry,” says Halliday. “There's no fancy rare earth metals or complicated compounds, it’s four really basic elements. But no one had actually explored this stuff before.”