CO₂ to Fuel: Start-ups Advance Carbon Capture & Conversion Tech

The quest to turn carbon dioxide from environmental liability into industrial feedstock is gaining momentum, with two startups – Air Company and Prometheus Fuels – reporting advances in their respective approaches to creating fuel from CO₂. Both companies are pursuing modular systems designed for scalability and, in AirCo’s case, even deployment in remote military locations.

Air Company and the US Air Force Partnership

Air Company, previously highlighted as one of C&amp. EN’s 10 Start-Ups to Watch in 2022, has secured a $15 million funding commitment from the US Air Force to deploy its thermochemical process for producing transportation fuels directly from CO₂ and hydrogen. C&EN’s profile of AirCo details the company’s early work in this space. The plan centers around building fuel production reactors within shipping containers, enabling the military to generate fuel on-site, reducing reliance on vulnerable and costly supply chains. According to CEO Gregory Constantine, the full cost of delivering fuel to military operations can reach hundreds of dollars per liter due to logistical challenges.

AirCo’s system aims to leverage small modular nuclear reactors to provide both the process heat and the electricity needed for hydrogen production via water splitting. While direct air capture (DAC) and nuclear-powered hydrogen are currently expensive, Constantine argues that the overall cost proposition remains competitive given the alternatives. The company utilizes fixed-bed reactors, flowing hydrogen and CO₂ over solid catalyst pellets at elevated temperatures and pressures. Initially, research suggested a novel reaction mechanism, but Constantine now characterizes the process as a variation of the well-established Fischer-Tropsch process, yielding a mix of methanol, ethanol, jet-fuel alkanes and aromatic hydrocarbons.

Air Company is transitioning from a pilot plant in Brooklyn, Recent York, to a manufacturing facility in Pennsylvania, with the first modular units slated for operation in 2027. This initiative aligns with broader US government technology programs, including the Janus Program, which aims to have a small modular nuclear reactor operational at a military base by the end of 2028, potentially powering mobile water purification and fuel synthesis plants.

Prometheus Fuels’ Electrochemical Pathway to Kerosene

Meanwhile, Prometheus Fuels has unveiled an electrochemical method for producing synthetic kerosene, aiming to achieve cost parity with petroleum-derived fuel. The company’s process begins with direct air capture using an aqueous carbonate solvent to absorb CO₂. Inside the electrochemical cell, carbonate ions combine directly with water on the electrode surface to yield hydrocarbons and oxygen, bypassing the require for intermediate hydrogen production or CO₂ extraction – steps that typically drive up costs in other CO₂-to-fuel processes. Business Wire’s coverage of Prometheus’ announcement details the technical aspects of this breakthrough.

Prometheus founder Rob McGinnis claims the technology could render the Fischer-Tropsch process obsolete. The company has been piloting its DAC system alongside a methanol-producing reactor for four years, achieving a CO₂ capture cost of approximately $50 per metric ton – significantly lower than systems relying on heat or vacuum stripping. A 50-cell module, capable of producing 2,300 liters of kerosene annually, is projected to cost around $2,500. Factoring in infrastructure, cell lifespan, and renewable electricity costs, Prometheus estimates a kerosene production cost of around $0.66 per liter, competitive with current petroleum kerosene prices, which have fluctuated between $0.50 and $0.70 per liter over the past two years, according to the US Energy Information Administration.

Prometheus is currently seeking $150 million in Series C funding to support the deployment of its kerosene system.

Expert Scrutiny and the Path Forward

The claim of direct electroreduction of CO₂ to kerosene-range alkanes has drawn some skepticism from experts. Anthony Shoji Hall, a professor at the University of Pennsylvania specializing in electrocatalysis, expressed caution, stating that while recent literature supports some of the mechanistic steps described by Prometheus, further investigation is needed to understand the mass flow and reactive species near the electrode surface. “I’m not completely sure they are seeing what they suppose they witness,” Hall noted, while acknowledging the novelty of the approach and the difficulty of producing C₄₊ hydrocarbons.

Both Prometheus and AirCo are initially focusing on modular, smaller-scale systems, a strategy that IDTechEx senior technology analyst Eve Pope deems sensible for accelerating deployment and facilitating production expansion. Pope emphasizes the importance of efficiency, compactness, modularity, and the ability to integrate with renewable energy sources in the design of these systems.

Constantine views the success of other sustainable chemical technology firms as a positive sign, believing that increased traction in the sector will drive efficiency and scalability for all involved. The development of these technologies represents a significant step towards a more sustainable fuel future, though challenges remain in scaling production and achieving widespread adoption.