I remember a crazy experiment discussed in the news a few years ago that proposed using cryonics to separate moisture and carbon dioxide from Earth’s atmosphere. The experiment concerned the fact that both water and carbon dioxide liquefy and solidify at much higher temperatures than oxygen and nitrogen, the main components of the air we breathe, so cooling the air enough both water and CO2 could be extracted and pure air sent. nitrogen and oxygen return to the world. Fresh water, of course, could be used for any of a number of useful purposes, especially in desert countries, and the CO2 could also be put to industrial uses in various existing businesses.
As it turns out, this experiment may not be so far-fetched after all, although the power requirements to cool large amounts of air would be prodigious. These and other technologies are discussed in detail in a new e-book, suck it, by Marc Gunther, who has previously written about the environment. The eBook takes a look at technologies, existing and developing, for extracting carbon dioxide from the air to, in effect, undo two centuries of carbon pollution from the Industrial Revolution. Some of these are called “direct air capture” of carbon dioxide, technologies that remove CO2 directly from the atmosphere by solidifying it or converting it to a non-gaseous compound.
Gunther begins his narrative by assessing how well governments have done in achieving reductions in carbon dioxide. As we know from reading the news reports, he has so far had little accomodation. Reducing carbon emissions requires relying on non-fossil fuel energy alternatives, and no serious effort has yet been made to artificially extract carbon dioxide from the air. This brings you to the big topic of “geoengineering,” which is the term used by scientists to describe the methods available on a colossal planetary scale to create significant atmospheric change around the world. The Industrial Revolution itself is an example of geoengineering, albeit a project that has had consequences that we must now try to reverse, namely the buildup of greenhouse gases at unseen concentrations in our atmosphere for tens of millions of years.
Taken as a matter of high school science, CO2 removal from breathable air is easily accomplished. Navies run it all the time on submarines with relatively simple chemical technology. The problem is one of scale and cost. One accepted way to achieve CO2 removal is to pass air through giant tanks filled with algae. Carbon dioxide dissolves in the water where it is taken up by algae to produce sugars and other carbohydrates that confine the CO2 into solid molecules. But this, too, cannot be done cheaply enough and on large enough scales to offset the tens of millions of tons of new CO2 we add to the air annually by burning coal and gasoline in our cars.
One surprising result of all these efforts for a non-scientist like myself is that while CO2 removal is not cheap, it is comparatively less expensive than the alternatives, which involve reducing CO2 emissions by switching to energy systems that do not they release carbon dioxide. absolutely. There are also smart technologies that would address global warming indirectly, not by reducing greenhouse gases, but by reflecting more solar energy back into space. If there is less heat from sunlight entering the atmosphere, Earth’s average temperature would tend to rise more slowly or not at all. This would save the poles and prevent the oceans from rising, two of the potentially catastrophic results of global warming most feared by environmentalists.
I also learned that there is a tradable market for carbon dioxide, beyond the folks at Omaha Steaks, who use it to keep their steaks frozen on the way home. Carbon dioxide can fetch prices of $50 or more per ton in the oil and gas industry, where oil companies inject it into oil reservoirs to displace fluids from permeable rock and toward the surface where these hydrocarbons can collected and sold. This use of carbon dioxide has the added benefit that, once injected into the soil, it tends to stay there, safely out of the atmosphere, for a long time.
Gunther then goes on to look at the small spectrum of startups, including at least one that has won the backing of Bill Gates, which is now building viable plants. There are no clear candidates, and all suffer from a possibly insurmountable problem, namely energy use. Clearly, it doesn’t make any sense to use dirty energy (and thus release more carbon) to remove existing carbon from the atmosphere. This is one of those fields where some kind of exogenous technology or new discoveries would be welcome.
Gunther’s book is the length of a long Atlantic Monthly article, and for the interested layman like myself, it is an excellent introduction to the subject.
