The understanding of the earth's subsurface and availability of data to document what is there and how it all works has never been greater. Yet, conflicts and acrimonious debate about how we utilize this zone are also greater than ever. Is this because there is more money at stake than before? Is it because of a fear of the unknown or the "unseen" parts of nature that lie below the ground? Is it because multiple uses of the subsurface always represent a " you win, I loose" scenario - the modern equivalent of the historic conflicts between cattlemen and farmers?

The answer is probably " all of the above". The conflict is most vividly captured in the often acrimonious debate about the oil and gas industry both in its conventional and unconventional incarnations. The physics of combustion of hydrocarbons makes it impossible for fossil energy to attain a carbon footprint anywhere nearly as low as that of renewables. However, there are many offsetting benefits, not the least that fossil energy is still plentiful, it has a global and highly advanced distribution system in place, and the footprint that the fossil energy infrastructure occupies is orders of magnitude smaller than renewable energy facilities with equivalent energy capacity (Fig. 1). That factor alone argues for renewed efforts to find technology solutions to reduce the carbon footprint (carbon dioxide as well as methane and trace gases) of conventional and unconventional oil and gas.

Technology, policy, economics and personal values all can and do contribute to the reduction in greenhouse gas emissions from fossil energy currently underway here in the United States. This is mostly due to rapid growth in unconventional natural gas, and the existence of an already developed, but underutilized, power plant capacity that has been able to quickly accommodate this added supply. As documented in Figure 2, annual CO2 emissions from the U.S. energy sector have decreased from an all-time high of 6 billion tons/year during 200–07 to 5.3 billion tons in 2012.

This shift from coal to natural gas, however, is not automatically an unmitigated good. Offsetting the benefits of reduced emissions of CO2 is the fact that the infrastructure, related to production, transport, storage and consumption of methane, is a pretty leaky system, potentially offsetting many of the gains on the combustion side. This issue is now emerging as a major topic of investigation throughout industry and R&D organizations and numbers with smaller error bars are expected to emerge over the next few years.

There are many policy and economic issues, one of which is that decreasing demand for coal in the domestic market drives U.S. exports of that fuel, shifting some emissions offshore. Also, there are more „insidious? policy and political issues in some parts of the world including, for example, managed campaigns where some overseas governments cleverly use U.S. public opposition to shale fracturing as an argument to try to undermine development of unconventional natural gas, such that „client states? remain dependent on much more expensive conventional gas being delivered via existing pipeline systems.

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