Tuesday, September 20, 2011

Marcellus Shale reserves "only" 43 TCF ...

On August 23, 2011, the United States Geologic Survey (USGS) submitted 84 trillion cubic feet (84 TCF) as their estimate for undiscovered, recoverable natural gas in the Marcellus Shale, located primarily in Pennsylvania, New York and West Virginia.  Additionally, they believe 3.4 billion barrels of natural gas liquids will accompany that 84 TCF. (for reference, the great East Texas Field - discovered in 1930, and which helped the Allies win World War II - will produce about 5.2 billion barrels.)

The USGS pointed out that in this new analysis, they were increasing their estimates of recovery from the Marcellus, since their last report.  They actually publish range of estimated recoveries, ranked by the probability or confidence in a given estimate. So, a 50 % confidence level, or N50, is similar to the mean value, or the likelyhood that half the estimates would produce more than that amount, and half less.  Such is the 84 TCF number which the USGS quoted in their first paragraph.

USGS Marcellus Press Release

Curiously, there seem to be many opponents to natural gas, these days.  Some of them would likely tell you they are just opposed to shale gas, not natural gas in general.  But a more in-depth analysis of their positions would show that they just don't like anything except renewables.  So, some of these folks were quick to spin what the USGS termed an increase in estimated recoveries for the Marcellus, into a dramatic decrease!  One opponent of natural gas was quick to focus only on the very highest probability, and lowest reserve number, that being 43 TCF.  Another writer smugly commented, "There may not be as much natural gas in our future as some claim."

Additionally, neither of the two articles linked above happened to mention the associated 1.6 billion to 3.4 billion barrels of natural gas liquids (N95 to N50 estimates)!  That's enough liquid hydrocarbons to qualify the Marcellus as what's known as a "giant" oilfield.  How could they leave out that detail if they were trying to be objective, whatsoever?  The answer can only be that they were not making any attempt to be objective; rather, they were trying manipulate public opinion.  One of the articles also forgot to mention that there was a N5, or 5 % probability of having 144 TCF and 6.2 billion barrels recoverable from the Marcellus. Clearly, these folks want to suggest to the casual observer that "there just isn't very much natural gas in shale plays."  After all, how much could only 43 of something be???

Well, let's look at that.  Some of the folks writing these articles like to use the entire domestic natural gas consumption as the dividend, in doing their comparisons. And they fail to include that multi-billion barrel NGL production that comes along with the gas.  Is that a fair way to look at it?  After all, this Marcellus is a relatively new discovery (2004), and as such it is incremental or additive to the reserves prior to that point.

But let's look at "only" 43 TCF:  using 1 mcf = 1 mmbtu of heat energy (approximation for methane, the primary component of natural gas), 293 kwh/mcf, a combined-cycle gas turbine generation plant efficiency of 57 %, and 570 MW/coal power plant (594 coal plants in 2009, with 338,000 MW of total capacity), we find that 43 TCF could replace the average coal power plant for ... 1430 years.  Or, that 43 TCF could replace ALL 594 coal power plants for ... 2.4 years.  Oh, and then you still have the 1.6 BILLION barrels of natural gas liquids (ethane, propane, butane, etc.) to heat homes, make plastic, even run in vehicles - essentially to use in every application where natural gas can be used, plus a few more.  (Total production from the giant Prudhoe Bay Field in Alaska, has been about 11 billion barrels to date, for reference.)

So, even 43 TCF and 1.6 billion barrels of NGL comprise an awful lot of lower carbon, comparatively clean energy.  Further, those are the low estimates, not the mean, and the mean is about twice those amounts.  It makes one wonder,  "What is going on with all these anti-natural gas efforts?".  We'll attempt to take that up in a future article.

In closing, one might wonder, "Does the Marcellus or the Eagleford or the Bakken - or all the shale gas and shale oil plays taken together - eliminate the paradigm shift of Peak Oil?"  Unfortunately not.  However, these plays will mitigate, to some degree, the effects of Peak Oil.  They are very important in that regard; namely, they will somewhat reduce the "severe consequences" mentioned by Hirsch, the Bundeswehr and others.  But they will only do so if we can quickly integrate natural gas and NGL into the transportation sector, while we simultaneously work on conservation, efficiencies, mass transit retrofits, renewables and every other partial solution.

Note:  Our calculations on the original posting were incorrect - we omitted a "24 hours in a day" factor, yielding an incorrect 34,000 years, versus a more correct 1430 years, for running a single coal plant with 43 TCF (43 TCF being the USGS' N95 estimate of reserves from the Marcellus).  Dividing that number by the 594 coal plants in existence in 2009 indicates that the Marcellus alone could run all of the nation's coal power plants for 2.4 years, not 57 years.   We did have a third party do a quick check on the calculations before the original posting, but evidently they missed the error, as well.  Many thanks to commenter Nate for correcting our miscalculation.  (Nate was gracious, btw, and came up with 3 - 4 years, arriving at that answer in a slightly different, and probably more accurate method.)

We shouldn't have been off by an order of magnitude plus, but of course these calculations are not realistic, anyway.  The Marcellus would never be expected to replace all the coal fired power plants, nor would that be physically or economically possible.  The point is, the Marcellus has huge natural gas reserves, along with giant-class natural gas liquids (NGL) reserves.  Taken together, the natural gas and NGL from the Marcellus and other developing shale gas and shale oil (not be confused with oil shale) plays cannot solve Peak Oil;  however, if we use the resources from these unconventional plays wisely, these plays can help mitigate the serious transportation problems which will impact every facet of our lives, as Peak Oil becomes manifest in the United States. 

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