Tom Murphy of the UCSD Physics Department has an interesting post on his Do The Math blog on carbon capture and storage. One method is trapping carbon dioxide (CO2) with sodium hydroxide (NaOH) dissolved in water and absorbed into sheets. A diagram shows that the CO2 reacts with the NaOH to create carbonate solids and water. A natural gas flame then cooks the solids to liberate the carbon as CO2, which is then filtered out and pumped under appropriate pressure into a "safe place," such as an underground oil reservoir.
He has included the sketch shown below:
|Source: Carbon Engineering; Credit: Nelson Hsu, NPR - |
via Do The Math, "Putting the Genie back in the Toothpaste Tube"
Why Engineers Can’t Stop Los Angeles’ Enormous Methane Leak
“Our efforts to stop the flow of gas by pumping fluids directly down the well have not yet been successful, so we have shifted our focus to stopping the leak through a relief well,” Anne Silva, a spokesperson for the Southern California Gas Company, told Motherboard, adding that the company is still exploring other options to stop the leak. “The relief well process is on schedule to be completed by late February or late March.”Let's see... doing the math, 150 million pounds is 70,000 US tons or 68,000 metric tons, i.e., 68 kT. That's not much for a total atmospheric methane burden of about 5 GT (5 billion metric tons) but we should be aware that there may be escaping gas problems in the future with industrial carbon capture and storage, especially if we try to capture as much CO2 and stuff into the spent wells as would fit in there.
Part of the problem in stopping the leak lies in the base of the well, which sits 8,000 feet underground. Pumping fluids down into the will, usually the normal recourse, just isn’t working…
So far, over 150 million pounds of methane have been released by the leak, which connects to an enormous underground containment system. Silva says that the cause of the leak is still unknown, but research by EDF has also revealed that more than 38 percent of the pipes in Southern California Gas Company’s territory are more than 50 years old, and 16 percent are made of made from corrosion- and leak-prone materials.
Right now, relief efforts have drilled only 3,800 feet down—less than half of the way to the base of the well. At that rate, the torrent of methane pouring into California won’t be stopped any time soon.
http://motherboard.vice.com/read/why-we-cant-stop-the-enormous-methane-leak-flooding-la -- hat tip to dtlange at Robertscribbler.
Plus we must remember the Macondo Well (Deep Horizon) Blowout let 4.9 million barrels (210 million US gal; 780,000 m3) with approximate mass/weight of 1.5 billion pounds or 670 kT of crude oil, an unknown amount of methane into the Gulf of Mexico, chased by 1.84 million gallons of "Corexit." The Louisiana marshes and the Mississippi, Alabama and Florida Gulf Coasts were very much adversely affected and fouled by this, ecologically they are still not as healthy as they would be otherwise.
Then, of course, is the amount of CO2 created by the combustion of natural gas, the making of the sodium hydroxide, the operation of the carbon dioxide capture apparatus and the final storage of the CO2. Tom Murphy figured that the amount of CO2 created by power required for the capture and storage of carbon dioxide and related work is about 50 kg CO2 for every 350 kg captured and stored -- then he did a reality check and found he was off by 3.6 times on the optimistic side, which means the amount captured and stored would be about double the amount generated by the capture and storage machinery! Considering we have billions and billions of metric tons of Carbon that must be pulled out of the air to achieve the 2 degrees C (over 1880s values) goal of limited global warming, my gut feeling tells me that might not able to be done, given the limited amount of fossil fuel reserves left in the ground so far.