I remember a far-fetched experiment discussed in the news a few years ago that proposed the use of cryonics to separate moisture and carbon dioxide from Earth’s atmosphere. The experiment was based on the fact that both water and carbon dioxide liquefy and solidify at much higher temperatures than oxygen and nitrogen, the primary components of the air we breathe, so that by cooling the air sufficiently , it could extract both the water and the CO2 and send the pure air. nitrogen and oxygen return to the world. Fresh water, of course, could be used for any of multiple useful purposes, especially in desert countries, and CO2 could also be used for industrial uses in various existing companies.
It turns out that this experiment may not be so outlandish after all, although the energy requirements to cool large amounts of air would be prodigious. These and other technologies are discussed in depth in a new e-book, Suck it, by Marc Gunther, who has previously written about the environment. The e-book looks at technologies, existing and developing, to remove carbon dioxide from the air and, in fact, 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 turning it into a non-gaseous compound.
Gunther begins his narrative by evaluating how well governments have done in achieving reductions in carbon dioxide. As we know from reading news reports, little has been accomplished so far. Reducing carbon emissions requires relying on energy alternatives other than fossil fuels, and no serious efforts have yet been made to actually remove carbon dioxide artificially 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 attempt to reverse, namely the accumulation of greenhouse gases in concentrations not seen in our atmosphere for tens of millions of years.
Taken as a matter of high school science, removing CO2 from breathing air is easily accomplished. Navies run it all the time in submarines with relatively simple chemical technology. The problem is one of scale and cost. An accepted way to achieve CO2 removal is to blow air through giant tanks filled with algae. Carbon dioxide dissolves in water where it is absorbed by algae to produce sugars and other carbohydrates that confine CO2 into solid molecules. But this also cannot be done at a low enough price and on large enough scales to offset the tens of millions of tons of new CO2 that we add to the air annually by burning coal and gasoline in our cars.
A surprising result of all these efforts for a non-scientist like me is that while CO2 removal is not cheap, it is comparatively less expensive than alternatives, which involve reducing CO2 emissions by switching to energy systems that do not 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 into space. If less heat enters the atmosphere from sunlight, the earth’s average temperature will 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 negotiable market for carbon dioxide, beyond the folks at Omaha Steaks who use it to keep 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 move fluids from permeable rocks to the surface, where these hydrocarbons can collected and sold. This use of carbon dioxide has the added benefit that once injected into the ground, it tends to stay there, out of the atmosphere for a long time.
Gunther then looks at the small spectrum of startups, including at least one that has earned the backing of Bill Gates, who is now building feasibility plants. There are no clear candidates for the lead, and they 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 discovery would be most welcome.
Gunther’s book is the length of a long Monthly Atlantic This article, and for the interested layperson like myself, is an excellent introduction to the subject.