Emergy analysis of emerging methods of fossil fuel production

Abstract

The production of energy from unconventional sources of fossil fuels, (e.g., tar sands, shale or sandstone formations where oil or natural gas is tightly bound), is forming an increasingly large proportion of global energy use. This research evaluates three of the most prominent emerging methods of fossil fuel production—oil from oil/tar sands, shale oil and shale gas, both produced through hydraulic fracturing. In 2013, 42% of natural gas production and 41% of oil production in the United States was produced through hydraulic fracturing and ∼60% of new oil and gas wells use the method. In 2013, the Alberta region of Canada produced 1.7 million barrels per day of synthetic crude oil from oil sands, exporting 1.3 million barrels to the US every day, comprising ∼7% of daily US oil consumption. Results from this work show that natural gas obtained through hydraulic fracturing has an emergy yield ratio (EYR) between 4.23 and 9.18, depending on well productivity and whether the gas is “wet” (contains other hydrocarbons) or “dry” (pure or nearly pure methane). Synthetic crude oil from oil sands was found to have an EYR of 3.38–4.06 (in situ vs. mined production, respectively). The EYR of tight oil was found to be 3.43–4.73, dependent on the productivity of the well. Given the relatively high current market price of oil and relatively low market price of natural gas the observed results (i.e., similar or higher EYR for natural gas than past observations and a lower EYR for oil than past observations) are expected.