High Octane Fuels: Challenges and Opportunities

This fact sheet examines the potential for deploying mid-level ethanol blends (E25 to E40) in the United States passenger vehicle fleet to improve fuel efficiency and reduce greenhouse gas (GHG) emissions. It discusses the role of ethanol as a renewable octane provider, the compatibility of existing vehicle fleets and retail infrastructure, and the lifecycle GHG reductions associated with different ethanol sources.

• Research from Argonne National Laboratory (ANL), the National Renewable Energy Laboratory (NREL), and Oak Ridge National Lab (ORNL) indicates that blending 25 to 40 percent ethanol (E25 to E40) with gasoline can result in lower overall GHG emissions and greater fuel efficiencies for the existing passenger vehicle fleet.
• Ethanol serves as a renewable source of octane, which prevents engine 'knock' and allows for higher compression ratios, turbocharging, and downsizing/downspeeding to increase engine efficiency.
• A significant portion of the current U.S. vehicle fleet is compatible with higher ethanol blends: over 80 percent of cars on the road (model year 2001 and newer) are certified for E15, and there are 17.4 million FlexFuel Vehicles (FFVs) capable of using blends up to E85.
• While infrastructure upgrades are required for mid-level blends, the costs are generally lower than those for E85. NREL found that 56 percent of tested Underwriters Laboratory refueling equipment was compatible with E17, and the majority of underground storage tanks can store blends up to E85.
• Lifecycle GHG reductions vary by ethanol type: conventional corn ethanol reduces emissions by 19 to 48 percent relative to gasoline, while cellulosic ethanol from corn stover can reduce them by 90 to 103 percent.
• Using the GREET model, ANL estimates that a nationwide E25 blend with a 5 percent fuel economy gain could reduce transportation sector GHG intensity by 5 to 9 percent, while an E40 blend from cellulosic ethanol could achieve reductions of up to 30 percent.
• The DOE's Co-Optimization of Fuels and Engines (Optima) Initiative aims to reduce per-vehicle petroleum consumption by 30 percent by 2030, which could save consumers up to $50 billion and reduce petroleum consumption by 4.5 billion barrels.

APA

Stolark, J. (2015). High Octane Fuels: Challenges and Opportunities. Environmental and Energy Study Institute. https://www.eesi.org/papers/view/fact-sheet-high-octane-fuels-challenges-opportunities

Chicago

Stolark, Jessie. High Octane Fuels: Challenges and Opportunities. Environmental and Energy Study Institute, 2015. https://www.eesi.org/papers/view/fact-sheet-high-octane-fuels-challenges-opportunities.

Wikipedia

{{cite report |last1=Stolark |first1=Jessie |title=High Octane Fuels: Challenges and Opportunities |publisher=Environmental and Energy Study Institute |date=12 June 2015 |url=https://www.eesi.org/papers/view/fact-sheet-high-octane-fuels-challenges-opportunities |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{stolark2015high, author = {Stolark, Jessie}, title = {{High Octane Fuels: Challenges and Opportunities}}, institution = {Environmental and Energy Study Institute}, year = {2015}, month = jun, url = {https://www.eesi.org/papers/view/fact-sheet-high-octane-fuels-challenges-opportunities}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }