Article pubs.acs.org/est
U.S. Refinery Efficiency: Impacts Analysis and Implications for Fuel Carbon Policy Implementation Grant S. Forman,*,† Vincent B. Divita,‡ Jeongwoo Han,§ Hao Cai,§ Amgad Elgowainy,§ and Michael Wang§ †
Sasol Synfuels International, 900 Threadneedle, Suite 100, Houston, Texas 77079-2990, United States Jacobs Consultancy Inc., 5995 Rogerdale Road, Houston, Texas 77072, United States § Systems Assessment Group, Energy Systems Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States ‡
S Supporting Information *
ABSTRACT: In the next two decades, the U.S. refining industry will face significant changes resulting from a rapidly evolving domestic petroleum energy landscape. The rapid influx of domestically sourced tight light oil and relative demand shifts for gasoline and diesel will impose challenges on the ability of the U.S. refining industry to satisfy both demand and quality requirements. This study uses results from Linear Programming (LP) modeling data to examine the potential impacts of these changes on refinery, process unit, and product-specific efficiencies, focusing on current baseline efficiency values across 43 existing large U.S. refineries that are operating today. These results suggest that refinery and product-specific efficiency values are sensitive to crude quality, seasonal and regional factors, and refinery configuration and complexity, which are determined by final fuel specification requirements. Additional processing of domestically sourced tight light oil could marginally increase refinery efficiency, but these benefits could be offset by crude rebalancing. The dynamic relationship between efficiency and key parameters such as crude API gravity, sulfur content, heavy products, residual upgrading, and complexity are key to understanding possible future changes in refinery efficiency. Relative to gasoline, the efficiency of diesel production is highly variable, and is influenced by the number and severity of units required to produce diesel. To respond to future demand requirements, refiners will need to reduce the gasoline/diesel (G/D) production ratio, which will likely result in greater volumes of diesel being produced through less efficient pathways resulting in reduced efficiency, particularly on the marginal barrel of diesel. This decline in diesel efficiency could be offset by blending of Gas to Liquids (GTL) diesel, which could allow refiners to uplift intermediate fuel streams into more efficient diesel production pathways, thereby allowing for the efficient production of incremental barrels of diesel without added capital investment for the refiner. Given the current wide range of refinery carbon intensity values of baseline transportation fuels in LCA models, this study has shown that the determination of refinery, unit, and product efficiency values requires careful consideration in the context of specific transportation fuel GHG policy objectives.
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Renewable Fuel Standard5 (RFS) set a carbon intensity standard for petroleum-derived gasoline and diesel, which form the baseline against which potential alternative fuels can be assessed for policy implementation.6 For example, to qualify under the RFS, a biofuel must meet a minimum reduction in lifecycle GHG emissions compared to baseline petroleum fuels. These specific lifecycle GHG reduction standards range from 20% for conventional biofuels to 60% for cellulosic biofuels.7 Carbon intensity is the measure of GHG emissions associated with
INTRODUCTION
In the first two decades of the 21st century important investment and policy decisions will need to be made to address global warming.1 Energy choices made today will likely have a substantial effect upon the composition of the future energy system due to the long lifetimes of technology and infrastructure development.2 Within this context, policy makers play a key role in influencing investment decisions by incentivizing various alternative technology options. Increased use of alternative fuels that possess life-cycle Greenhouse Gas (GHG) emissions values lower than crudeoil-derived fuels are being considered by policy makers as a way to decarbonize the average transportation fuel mix.3 Both the California Low Carbon Fuel Standard4 (LCFS) and the U.S. © 2014 American Chemical Society
Received: Revised: Accepted: Published: 7625
March 3, 2014 May 15, 2014 May 28, 2014 May 28, 2014 dx.doi.org/10.1021/es501035a | Environ. Sci. Technol. 2014, 48, 7625−7633
Environmental Science & Technology
Article
environment on refinery GHG emissions. On the supply side, fundamental questions are currently being asked about how the U.S. refining industry can adjust to the rapid influx of U.S domestic tight light oil from numerous shale plays, such as the Bakken and EagleFord. Many U.S. refineries are currently configured to run a blended medium (API < 33) to heavy (API
