Joining other companies seeking to turn waste carbon dioxide into fuels, the start-up Dimensional Energy has begun production at a pilot-scale CO2 utilization plant in Tucson, Arizona.
The technologies on display at the facility are catalysts and reactors for the reverse water-gas shift reaction, CO2 + H2 → CO + H2O. With carbon monoxide in hand, Dimensional adds more hydrogen in standard Fischer-Tropsch reactors to create hydrocarbons.
The reverse water-gas shift reaction is one of several routes—including electrochemical reduction and direct catalytic conversion—being explored to turn waste CO2 into a hydrocarbon fuel or chemical feedstock. Air Company, one of C&EN’s 10 Start-Ups to Watch this year, recently opened a pilot plant using the latter route to produce ethanol, methanol, and jet fuel.
The Dimensional pilot plant puts out 19 L of synthetic crude per day and has been operating around the clock for about 4 months, the company says.
Chief Science Officer Brad Brennan says the firm has already secured funding for a 238-L-per-day plant in Canada set to open in 2024. There, CO2 waste from a LaFarge cement factory will be gathered by the carbon capture firm Svante and fed into Dimensional’s system. Local hydropower will provide the energy for both operations.
Next up, Brennan says, is another hydropower-fueled project that will produce about 32,000 L of renewable diesel per day when it opens in 2025 at a site owned by the Seneca Nation, a sovereign Native American nation based near Niagara Falls.
Brennan says Dimensional Energy mainly plans to own and operate its own plants, though it is working on a license with a sustainable aviation fuel maker in Greece that is planning a facility with a capacity of around 160,000 L per day.
David Dodds, a renewable chemistry and biotechnology consultant, calls CO2 utilization “a critical undertaking, essential to our future, that fits with the concept of circular use of resources.” He cautions, however, that the net greenhouse gas footprint of CO2-to-chemicals technology depends heavily on the sources of H2 and energy.
In addition, “taking CO2 effluent from a fossil-carbon-fueled process and turning it into a hydrocarbon fuel . . . simply delays the emission of the fossil CO2.” A truly circular CO2 feedstock would need to come from the ambient air or from biogenic carbon, Dodds says.