Refi nery GHG emissions were predicted for 10% and 30% ethanol blends at refi nery blendstock octanes between 77 and 89 AKI at any gasoline pool energy content between parity and constant gasoline pool volume. Linear programming analyzed how separate E30 blending scenarios of 2017 PADD 2-based refi neries affect greenhouse gas (GHG) emissions relative to status quo gasoline (i.e., E10, 87 AKI and 93 AKI premium). The compliance synergy of higher ethanol blends illustrated here is pertinent to national policy goals and multiple environmental objectives. Study results have implications for CAFE Standards, US EPA Tier 3 fuel standards, and Clean Air Act regulations of stationary source CO2 emissions from refi nery operations. Results varied by amounts and types of crude oil processed, refi nery operations, refi nery gasoline blendstock produced (and fuel ethanol blended), and produced refi nery product composition and properties. Signifi cant differences exist in total refi nery GHG emissions (including emissions from purchased electricity and hydrogen) with the largest differences from coke burn in the fl uidized catalytic cracker and refi nery fuel gas combustion principally related to reformer operations. The concept of refi nery GHG emissions intensity was introduced to differentiate between differences in refi nery throughput (an extensive factor) and severity of refi nery operations (intensive factors). Refi nery GHG emissions decline 12% to 27% from a 2017 base case for the various 30% ethanol cases, highlighting a signifi cant gap in current life cycle analysis (LCA) and supporting incorporation of this improved approach into LCA related to higher ethanol blends. This methodology can be adapted to other PADDs and/or for the USA. 37Modeling and Analysis: Petroleum refinery greenhouse gas emission variations V Kwasniewski, J Blieszner, R Nelson effi ciencies, a higher minimum octane fuel (well above 88 AKI) is required. For these vehicles to be accepted by consumers, that higher octane number fuel needs to be widely-available and cost-eff ective which will mean high-CR vehicles will perform adequately. Ethanol has a higher octane rating than conventional gasoline. Consequently, higher blend levels could significantly increase a fi nished gasoline's octane rating. In addition, engine researchers have determined ethanol's high heat of vaporization provides a cylinder 'charge cooling' eff ect. Due to these two desirable properties, fuels with higher levels of ethanol could allow for design and use of direct-injection, spark-ignition engines with higher CRs and greater thermal effi ciency. 7Recent studies examined increased ethanol content in gasoline and its impacts on engine performance with favorable results. Jung et al.8 tested splash-blended E10, E20, and E30 fuels in a Ford 3.5L EcoBoost direct injection turbocharged engine at CRs of 10.0:1 and 11.9:1. Results showed E30 (101 RON) at a 11.9:1 CR reduced CO 2 emissions by 5% and 7.5% on the EPA M/H (Metro Highway) cycle and US06 Highway cycles, re...