Geo-engineering—the idea that we can fix our carbon problem with a massively-scaled techno-intervention—might be amazing. But the projects—from seeding the ocean with iron to creating highly reflective artificial clouds—usually peter out when people realize that they’re unworkable. The Economist has just taken a critical look at one of the most intriguing prospects: Carbon capture, or using giant filters to suck carbon from the air. Turns out it might not be crazy after all:
This is not as mad as it sounds. After all, such machines already exist: They are used to “scrub” carbon dioxide from the air on board submarines and spacecrafts. “It has been around for decades, but the only people who cared were at NASA, because too much CO2 in a space shuttle means you die,” says Matthew Eisaman, a researcher at the Palo Alto Research Centre (PARC) in California. Proponents of air capture propose scaling up such machinery so that it can process the
atmosphere directly, extracting the CO2 so that it can be sold for industrial use or stored underground…
…But given that air-capture machines are electrically powered, and generating electricity usually produces carbon-dioxide emissions, do the sums add up? Dr Keith’s prototype captured a tonne of CO2 using 100 kilowatt-hours of electricity. To generate this much power, a coal-fired power station would add around 35kg of carbon dioxide to the atmosphere, or 3.5% of the amount removed by the air-capture machine. Using a cleaner source of power—and anything is cleaner than coal—would make the machine come out even further ahead. Similarly, GRT estimates that when its technology is scaled up, the emissions associated with
operating each machine will be less than 5% of the CO2 captured over its lifetime. So there seems little doubt that air capture would indeed be carbon-negative overall.
The big hurdle will be figuring out how to make carbon filters in massive quantities at low-enough prices—but some engineers are optimistic that scale might eventually be achieved by first marketing less efficient, early generation devices to places such as coal plants that really need them, then using the profits to scale up the technology. Read the whole story here.
[Image via Charlie Lawrence]