Mantel

Market position

Mantel positions itself as a lower-cost, energy-efficient alternative to conventional amine-based point-source carbon capture for heavy industry, in a field where prior projects have struggled with cost, scale and on-site integration complexity. It has been selected as carbon capture technology partner for the 1.6-gigawatt TerraSpark Energy Campus in West Virginia, a U.S. Department of Energy-supported project involving a large-scale coal-fired power plant.

Unlike conventional amine-based capture systems that impose heavy parasitic energy loads on host plants, Mantel's molten borate operates at high temperature and recovers the heat of absorption as usable process heat. The liquid medium resists the degradation that affects high-temperature solid sorbents. The company reports 97% lower energy losses, CO2 purity above 99.9%, and costs less than half the industry average per tonne, with a modular design intended to reduce capital intensity and integration complexity.

Technology

Mantel's system is a high-temperature, liquid-phase point-source capture process using proprietary molten borate salts. The salts absorb CO2 from exhaust gas at the elevated temperatures found in boilers, kilns and furnaces; the absorption releases high-quality heat that can be recovered to generate steam or be recycled into manufacturing processes, offsetting the energy needed for desorption and regeneration. The liquid medium avoids the degradation over repeated cycles that has limited high-temperature solid sorbents. The material chemistry is patent-protected and, per the company, uses four basic elements rather than rare earths or complex compounds. The technology is described as agnostic to the downstream sequestration route. Deployment uses a modular, systems-engineering design, including standardized molten salt tank systems developed with Aalborg CSP.

Go-to-market

The company advances customer projects through front-end engineering and design studies and demonstration installations at host industrial sites, and works with strategic corporate and energy-sector investors and suppliers. Its investor base includes venture arms of Shell, Eni, bp, Vale and Constellation, providing links to potential industrial customers.

Operators of point-source industrial emissions, including power generation (including legacy fossil fuel and bioenergy plants), oil and gas, pulp and paper, chemicals, cement and steel producers.

Geography

Headquartered in Cambridge, Massachusetts, with projects in the United States (TerraSpark Energy Campus, West Virginia) and Canada (Kruger's Wayagamack mill in Québec and a front-end engineering and design study for a steam-assisted oil recovery operation with a major Canadian oil and gas producer). The company states it is expanding deployment into Europe and other geographies.

History

Founded in 2022 out of MIT, Mantel initially operated at early prototype stage, demonstrating carbon capture at lab scale of half a tonne per day. In September 2024 it announced a $30 million Series A led by Shell Ventures and Eni Next to fund a demonstration project at an industrial site roughly ten times larger than its lab unit, rated at 1,800 tonnes of CO2 per year. In December 2025 it announced acceleration toward a commercial-scale project with a strategic industrial partner, and in July 2026 entered a strategic supply agreement with Aalborg CSP for standardized molten salt tank plant designs. In August 2026 it raised an additional $18 million from Constellation Technology Ventures and Azimut Investments, bringing total funding to $50 million.

Risks & controversies

Performance figures cited for the technology — 97% reduction in energy losses, CO2 purity above 99.9% and costs below $50 per metric ton at scale — are company-reported and, as noted in press coverage, still require validation through sustained commercial operations. The company is transitioning from lab and demonstration scale to first commercial installations.