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Energy Return on Investment (EROI) of Oil Shale

DOI:10.3390/su3112307
Authors:
Cutler J Cleveland at Boston University
Cutler J Cleveland
Pete O'Connor at Boston University
Pete O'Connor
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The two methods of processing synthetic crude from organic marlstone in demonstration or small-scale commercial status in the U.S. are in situ extraction and surface retorting. The considerable uncertainty surrounding the technological characterization, resource characterization, and choice of the system boundary for oil shale operations indicate that oil shale is only a minor net energy producer if one includes internal energy (energy in the shale that is used during the process) as an energy cost. The energy return on investment (EROI) for either of these methods is roughly 1.5:1 for the final fuel product. The inclusions or omission of internal energy is a critical question. If only external energy (energy diverted from the economy to produce the fuel) is considered, EROI appears to be much higher. In comparison, fuels produced from conventional petroleum show overall EROI of approximately 4.5:1. “At the wellhead” EROI is approximately 2:1 for shale oil (again, considering internal energy) and 20:1 for petroleum. The low EROI for oil shale leads to a significant release of greenhouse gases. The large quantities of energy needed to process oil shale, combined with the thermochemistry of the retorting process, produce carbon dioxide and other greenhouse gas emissions. Oil shale unambiguously emits more greenhouse gases than conventional liquid fuels from crude oil feedstocks by a factor of 1.2 to 1.75. Much of the discussion regarding the EROI for oil shale should be regarded as preliminary or speculative due to the very small number of operating facilities that can be assessed.
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... The EROI of crude oil was approximately 100 in the early stages of development, but now the EROI of oil has decreased drastically, to approximately 6.0 (Murphy 2014). Unconventional energy sources, such as tar sands and oil shale, are generally harder to extract than conventional oil and are expected to have a lower EROI, which means that the production process releases more carbon dioxide and other greenhouse gases than conventional liquid fuel (Cleveland and O'Connor 2011). The EROIs of tar sands and oil shale are 3~6 and 1~4, respectively (Gupta and Hall 2011). ...
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Energy quality and energy surplus in the extraction of fossil fuels in the US
Article
The goal of net energy analysis is to assess the amount of useful energy delivered by an energy system, net of the energy costs of delivery. The standard technique of aggregating energy inputs and outputs by their thermal equivalents diminishes the ability of energy analysis to achieve that goal because different types of energy have different abilities to do work per heat equivalent. This paper describes physical and economic methods of calculating energy quality, and incorporates economic estimates of quality in the analysis of the energy return on investment (EROI) for the extraction of coal and petroleum resources in the U.S. from 1954 to 1987. EROI is the ratio of energy delivered to energy used in the delivery process. The quality-adjusted EROI is used to answer the following questions: (1) are coal and petroleum resources becoming more scarce in the U.S.?, (2) is society’s capability of doing useful economic work changing?, and (3) is society’s allocation of energy between the extraction of coal and petroleum optimal? The results indicate that petroleum and coal became more scarce in the 1970s although the degree of scarcity depends on the type of quality factor used. The quality-adjusted EROI shed light on the coal-petroleum paradox: when energy inputs and outputs are measured in thermal equivalents, coal extraction has a much larger EROI than petroleum. The adjustment for energy quality reduces substantially the difference between the two fuels. The results also suggest that when corrections are made for energy quality, society’s allocation of energy between coal and petroleum extraction meets the efficiency criteria described by neoclassical and biophysical economists.
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Oil Shale Development from the Perspective of NETL's Unconventional Oil Resource Repository
Article
The history of oil shale development was examined by gathering relevant research literature for an Unconventional Oil Resource Repository. This repository contains over 17,000 entries from over 1,000 different sources. The development of oil shale has been hindered by a number of factors. These technical, political, and economic factors have brought about R&D boom-bust cycles. It is not surprising that these cycles are strongly correlated to market crude oil prices. However, it may be possible to influence some of the other factors through a sustained, yet measured, approach to R&D in both the public and private sectors.
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Converting Oil Shale to Liquid Fuels with the Alberta Taciuk Processor: Energy Inputs and Greenhouse Gas Emissions
Article
  • Dec 2009
We calculate the greenhouse gas (GHG) emissions from producing liquid fuels from Green River oil shale with the Alberta Taciuk Processor (ATP). Kerogen contained in oil shale can be retorted to produce liquid and gaseous hydrocarbons. The ATP is an above-ground oil shale retort that combusts the coke or "char" deposited on the shale during retorting to fuel the retorting process. Using life cycle assessment (LCA), we calculate the energy inputs and outputs of each process stage. We then calculate the resulting full-fuel-cycle GHG emissions from producing reformulated gasoline using the ATP. Full-fuel-cycle GHG emissions are conservatively calculated at ≈130-150 g CO 2 equiv/MJ of gasoline produced. These emissions are 1.5 to 1.75 times larger than emissions from conventionally produced gasoline. The results depend most sensitively on the grade of shale used and the rate of carbonate mineral decomposition, which causes inorganic carbon dioxide (CO 2) release.
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