EROI projections for Marcellus Shale gas

June 25, 2013

A new article in an upcoming issue of the Journal of Industrial Ecology gives preliminary estimates on the Energy Return on Energy Invested (EROI) for horizontally drilled/hydraulically fractured wells in the Marcellus Shale formation.  EROI is the net value of an energy source – the surplus that remains after the energy used to acquire the energy is accounted for.  EROI is an important concept – it is not a measure of the financial viability of a project, but rather of the long term societal viability.  Modern economies depend on large energy surpluses in order to grow.  Fossil fuels have strong EROIs, although they decline over time (for example, a new oil strike can be a “gusher,” requiring little additional energy to produce the oil, but as the field ages it will require more and more effort to pump the remaining oil out).  EROI is a measure fo the quality of energy, and the quality of an economy is directly related to the quality and quantity of energy available to run it.  Here is a table of the EROI values of various sources in use today:

EROI table

The declining EROI of oil is a key factor in Peak Oil theory.  The argument is that, even as alternative sources of oil are found (shale oil, tar sands, ultra deep water fields), the quality of the energy as an economic factor inevitably declines as the EROI declines.

With all that as a preface, the new study in the Journal of Industrial Ecology looks at the huge Marcellus Shale formation in the Eastern United States and tries to make a preliminary estimate on the EROI of the natural gas that will come from well heads in the formation.  The study contains many assumptions that may turn out to be incorrect – but it is unknown at this time whether those assumptions are too liberal or too conservative.  So, the results are a best estimate at this time.  According to these estimates, we can expect and EROI of between 64:1 and 112:1, with a mean of 85:1.  This is a tremendous finding.  The authors’ put these values in context:

The range of EUR values in this study is not dissimilar to the 50:1 to 85:1 range that is reported for coal, and higher than the 20:1 to 40:1 range that has been estimated for natural gas in general. The range is higher than some estimated EROI values for wind (20:1), new nuclear (15:1), and photovoltaic electricity (10:1) and much higher than two other new sources of FF, tar sands, and oil shale, which a 2011 study asserts are in the range of 5:1 to 3:1 (Murphy 2011).

The following table puts this into perspective visually – the red X represents the estimated position of Marcellus Shale natural gas.

2000px-EROI_-_Ratio_of_Energy_Returned_on_Energy_Invested_-_USA modified

And, at the high end of the estimate (112), fracked gas could surpass even hydro.

This is a tremendous finding.  Shale gas is plentiful, cheap, efficient and clean.  We cannot say it often enough:  Welcome to the Shale Age.

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