A couple of years ago Judith Curry came up with an interesting geo-engineering idea for capturing and storing CO2. Her idea essentially involves building various kinds of giant refrigerators powered by giant windmills, and is based on the fact that CO2 will "snow" out of the atmosphere at ca. 133° K, and forms a stable, solid compound known as "dry ice" at these low temperatures. Her geoengineering idea involves building a huge network of giant refrigerators in Antarctica to capture and store atmospheric CO2.
Dr. Curry describes the giant refrigerators in this way : A depositional plant constructed on Antarctica could conceivably pull air into a refrigerated chamber, where sufficient cooling could result in CO2 snow deposition......Demonstrated success of a prototype system in the Antarctic would be followed by a complete installation of .... 446 plants for CO2 snow deposition
Then, once the CO2 "snow" is produced, it would be moved into giant refrigerated pits dug into the surface of the ice sheet, i.e. ....solid CO2 can be stored in an insulated CO2 snow landfill that is 142 380m x 380m x 10m, which amounts to 0.00224B tons. The intake-exhaust fans will allow reversed air flow to permit the chamber to operate with the ambient wind direction . It is further noted that five insulated landfills (380m x 380m x 10m for each) will be constructed in a semicircle in close proximity to each deposition plant to accommodate for five years of CO2 sequestration (one landfill filled per year at each deposition plant). [The landfills] will be insulated with polyisocyanurate (effective down to 93°K). Snow cat excavators will operate in groups of five to move the dry ice rapidly into the insulated landfills.
The idea is intriguing, but I'm a little unclear as to why the giant refrigerators and the landfills have to be in Antartica to start with. Trying to maintain 446 refrigeration plants and hundreds of windmills and snow cat excavators, not to mention feeding and housing all the workers needed to support such a huge operation operation on top of the Antarctic Ice sheet, where the worst weather in the world prevails, would not be an easy operation. And either the refrigeration units and wind power units would have to be engineered to never fail, or total redundancy would have to be built into every system, because if the temperature in the giant refrigerated landfills rose above 133° K the CO2 "snow" would quickly start to sublimate and evaporate back to atmosphere. Even the coldest day in Antarcic is far far warmer then the temperature needed to quickly empty an entire CO2 snow landfill.
I've got a suggestion---why not put the whole operation somewhere more accessible and easy to deal with? How about trying this geoengineering idea in west Texas or at the Hanford National Laboratory in eastern Washington State. There is plenty of wind power there, and while the refrigeration units used to create CO2 snows and the insulated refrigerated pits would have to be better insulated, they would operate just as well somewhere in the continental US as they would in Antarctica, and it would be a heck of lot easier to make it all work if this operation was built somewhere accessible in the mainland USA. After all, refrigerators can break---and have you ever tried to get a refrigerator repairman to make a house call to Antarctica?
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