Saving the Planet By Producing Gasoline Out of Thin Air — Literally

Scientists and engineers have been underscoring for some time the need for carbon-capture technologies to help reverse the course of climate change. A solution of last resort, it relies on technology to strip the atmosphere of the most prevalent greenhouse gas —  a process referred to as “direct air capture.”

From National Geographic:

Keeping global warming to less than 2 degrees C (the international target to avoid the most dangerous impacts) will likely require “negative emissions”—some way of taking lots of CO2 out of the atmosphere and storing it permanently, according to the Intergovernmental Panel on Climate Change (IPCC).

Until now, the concept has remained elusive due to the exorbitant costs involved and few takers. But one Canadian company, Carbon Engineering, has been running a pilot facility since 2015 and says it has successfully developed a cost-effective technology for DAC.

National Geographic called it an “engineering breakthrough.” The founders recently published a paper detailing the costs of the ambitious project in the journal Joule.

“Our paper shows the costs and engineering for a full-scale plant that could capture one million tons of CO2 a year,” David Keith, a  physicist at Harvard University and founder of Carbon Engineering, told National Geographic.

The quest for direct capture has been frought with failure. Last year, a Swiss company called Climeworks launched a DAC pilot facility. The plant contains massive fans that blow air into a solution that contains a carbon-capturing chemical.

But the American Physical Society found that the procedure would likely cost about $600 per metric ton of captured CO₂. With our addiction to fossil fuel contributing close to 40 billion metric tons of CO2 a year, which doesn’t “pencil.”

Similarly, the technology developed by Carbon Engineering works by capturing the CO₂ in a solution that reacts with the carbon and converts it into a solid — and at lower cost. From the journal Nature:

Carbon Engineering’s design blows air through towers that contain a solution of potassium hydroxide, which reacts with CO2 to form potassium carbonate. The result, after further processing, is a calcium carbonate pellet that can be heated to release the CO2. That CO2 could then be pressurized, put into a pipeline and disposed of underground, but the company is planning instead to use the gas to make synthetic, low-carbon fuels. Keith says that the company can produce these at a cost of about $1 per litre. When Carbon Engineering configured the air-capture plant for this purpose, they were able to bring costs down to as low as $94 per tonne of CO2.

Keith and his team used their findings to project the costs of an actual commercial plant with the same technology.  They claim their technology can capture CO₂ for between $94 and $232 per metric ton.

“This isn’t going to save the world from the impacts of climate change, but it’s going to be a big step on the path to a low-carbon economy,” Keith told National Geographic.

The company uses a separate pilot project to convert the captured carbon into liquid fuels, including gasoline.  From Science Magazine:

[B]ecause the process recycles carbon from the air, it would constitute a low-carbon fuel, something that places such as California are increasingly requiring in their fuel mixes, and which command a premium price.

The eventual demand could further drive down costs. But for the technology to truly succeed in making a dent in international climate recovery goals, it will require widespread adoption, according to Klaus Lackner, director at the Center for Negative Carbon Emissions at Arizona State University.