Energy at the Crossroads: Global Perspectives and Uncertainties (MIT Press) by Smil Vaclav

Author:Smil, Vaclav [Smil, Vaclav]
Language: eng
Format: azw3
Publisher: The MIT Press
Published: 2005-02-10T16:00:00+00:00

Figure 4.18

Laherrère’s forecast of global natural gas extraction, based on his technical estimates of remaining reserves, is lower than all of the scenarios used by the latest IPCC assessment in modeling future CO2 emissions. By the year 2050 it is less than half of the IPCC’s median. Based on Laherère (2000) and SRES (2001).

Again, as with crude oil, the latest U.S.G.S. (2000) assessment of global resources of natural gas is much more optimistic, putting the total at just over 430 Gm3, or an equivalent of almost 2,600 Gb (345 Gt) of crude oil and about 53% above Campbell and Laherrère’s figure. Breakdown of the U.S.G.S. estimates shows that only about 11% of ultimately recoverable gas has been produced, that remaining reserves account for some 31%, their eventual growth should amount to nearly 24%, and that the undiscovered potential is almost exactly 33% of the total. Other recent estimates of ultimately recoverable natural gas, seen by their authors as rather conservative, range between 382-488 Gt of oil equivalent (Rogner 1997). Consequently, Odell (1999) forecasts global natural gas extraction peaking at about 5.5 Gtoe by the year 2050 and declining to the year 2000 level only at the very beginning of the twenty-first century (fig. 4.19).

All of these figures refer to conventional natural gas, that is fuel that escaped from its parental rocks and accumulated in unpermeable reservoirs, either with oil (associated gas, the dominant form of the fuel until the 1980s) or alone. Nonconventional gas embraces resources that are already being recovered, above all methane in coalbeds, as well as much larger deposits in tight reservoirs, high pressure aquifers, and in methane hydrates, whose eventual recovery still awaits needed technical advances (Rogner 2000). Gas in coalbeds is absorbed into coal’s structure while the gas in tight reservoirs is held in impermeable rocks whose leakage rate is slower than their filling rate and that would have to be fractured inexpensively in order to allow economic extraction. Gas in high pressure aquifers is dissolved in subsurface brines under high temperature and pressure, with the total resource estimate for the Gulf of Mexico alone being larger than Campbell and Laherrère’s total of the world’s remaining conventional gas reserves. Global resources of geopressured gas were estimated to be about 110 times the current proven reserves of the fuel (Rogner 2000).

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.