The newest report from the Intergovernmental Panel on Climate Change (IPCC) paints the bleakest picture yet with respect to climate change and man-made carbon emissions. The report states that even with large cuts in greenhouse gas emissions, the atmospheric carbon dioxide concentration is projected to reach 450 ppm (parts per million), which is a relative threshold to keep the Earth's temperature rise under 2°C by century's end.
Fearing that goals to reduce emissions may be too difficult to achieve (either politically or through technical challenges), IPCC members are considering other methods beyond conversion from fossil fuels.
One of the more interesting proposed methods is to take emissions form dirtier existing technologies, such as coal-burning power plants, and sending the carbonaceous emissions underground for storage.This technology goes by the name Beccs, for Bio-Energy Carbon Capture and Storage.
In the Beccs process, carbon dioxide is captured and converted into a supercritical liquid phase through massive compressors that raise the temperature and pressure above the critical points. The supercritical carbon dioxide is piped down more than one mile below the Earth's surface for permanent storage.
For proper storage, the proper set of geological conditions must be in place-primarily a deep permeable rock formation such as sandstone, with non-porous rock formations above it. Carbon dioxide saturates the sandstone by working its way through all the small pores, yet cannot escape beyond the sandstone because of the non-porous capping layer of rock.
Over many, many years, the entrapped carbon dioxide will eventually be formed into carbonate materials, becoming components of the rock formation.
While the technology is unproven on larger scale, pilot operations are underway-including one plant in Illinois that stores carbon dioxide effluent from ethanol production facilities. In this case, there is a convenient natural saline aquifer layer that is ready-made to accept carbon dioxide.
Aside from the potential for unintended consequences of underground storage, this technology faces some significant hurdles for the implementation level needed to have a worldwide impact.
For starters, the geology near carbon dioxide producers may not be suitable for storage nearby. The further the generation source is from the storage area, the more that traditional energy will be consumed in transport.
In terms of energy, one also has to consider the power consumed by the compressors and injection equipment. For worldwide operations, this would not be a trivial number, and the challenge would be to power these systems with the cleanest energy possible to maximize the reduction of carbon dioxide emissions.
Finally, there are enormous economic and political hurdles. There aren't any serious efforts to commit the land and the capital funds necessary to run this technology on an industrial scale. With no usable end product (since this is effectively a waste disposal process), the finances will almost certainly come from governments instead of private industry.
Even with all these hurdles, the IPCC is continuing to study these efforts-because projections indicate that without Beccs or a similar mitigation system we are unlikely to stay under the 2°C threshold for worldwide temperature rise. If these projections are right, we must hope that Beccs or another mitigation technology succeeds-and soon.