Carbon sequestration rears its ugly head again
Carbon sequestration is one of those things that might be a good thing, and on the other hand might not. Roger Jr, and Andrew Dessler are duking it out at Nature Geoscience. Issues include the energy cost of sequestering the carbon, the seal on the storage volume and more. However, IEHO, sequestration is a poor second choice. Better to find something useful to do with the CO2, a point that has escaped everyone except those actually working on the problem. There are a variety of clever ideas, whose principal virtue is that if you can extract value, especially energy, from the CO2, you don't have to have an absolutely perfect sequesterization to have a real effect.
Curtis Oldenburg at Lawrence Livermore has a potentially useful idea to combine carbon sequestration and enhanced gas recovery, using the CO2 to push methane out of old natural gas wells.
With their proven records of gas recovery, demonstrated integrity against gas leakage, existing infrastructure of wells and pipelines, and land use history of gas production and transportation, depleted natural gas fields are attractive targets for carbon sequestration by direct carbon dioxide (CO2) injection. The International Energy Agency (IEA) estimates that as much as 140 GtC could be sequestered in depleted natural gas reservoirs worldwide (IEA, 1997) and 10 to 25 GtC in the U.S. alone (Reichle et al., 1999). Although target gas reservoirs for carbon sequestration are depleted in methane (CH4) with pressures as low as 20–50 bars, they are not devoid of methane. Prior studies have suggested that additional methane can be recovered from depleted natural gas reservoirs by CO2 injection (van der Burgt et al., 1992; Blok et al., 1997; Oldenburg et al., 2001). The idea is to inject CO2 at some distance from producing wells and take advantage of the repressurization of the reservoir to produce additional CH4. The augmented methane production can be used to offset the cost of CO2 injection. We have termed this processFolk at the University of Kentucky have been looking at CO2 injection to push methane out of coal and black shale formations. A major part of the heating value of coal is in volatiles, but most of these are lost when the coal is pulverized for transport out of the mine. About 20 years ago, Eli tried to obtain a large block of coal to study this, only to find that in modern coal mines, the coal is broken into small pieces when cut deep in the mines or in the open pits.
CSEGR, or Carbon Sequestration with Enhanced Gas Recovery.