Freezing Carbon Into Snowflakes

Larry Baxter cleans up after power plants with cryogenics

There’s little debate that capturing carbon dioxide from coal-fired power plants is important. The problem is that it’s an energy-intensive process: The typical carbon-capture system can consume nearly 30 percent of a plant’s power output, mainly by heating solvents that scrub CO2 from chimneys only to cool them down again. Chemical engineer Larry Baxter of Brigham Young University is developing a more efficient way to remove the greenhouse gas: by freezing it into snowflakes. “It makes capture realistic and affordable,” he says.

Baxter’s start-up, Sustainable Energy Solutions, uses a cryogenic carbon-capture system to chill the emissions stream. When the carbon dioxide turns into an icy solid, it separates from other gases. “You get this blizzard of dry-ice flakes,” he says. The CO2 is then pressurized and melted into a liquid that can be safely stored in underground aquifers. In pilot studies, the system captured 99 percent of the carbon dioxide from emissions, while costing a quarter of what conventional methods do. It also scrubs other noxious chemicals from emissions, including mercury.

This article was originally published in the June 2015 issue of Popular Science as part of our “New Faces Of Energy” feature.