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And Then There Were Six…

Co-Optima Homes in on Promising Fuels for Passenger Vehicles, Revs Up Strategies for Commercial Trucks

June 25, 2019

Report cover

The Co-Optima FY18 Year in Review report spotlights the initiative’s advances in engine and fuel innovation.

Three years after embarking upon rigorous evaluation of a pool of more than 400 candidates, researchers with the Co-Optimization of Fuels & Engines (Co-Optima) initiative have identified the six blendstocks from two chemical families that exhibit the greatest potential to dramatically increase efficiency when combined with petroleum-based fuels in boosted (or turbocharged) spark-ignition engines for light-duty vehicles. A report released this week by the U.S. Department of Energy (DOE) describes this and other recent Co-Optima breakthroughs that hold promise to optimize the fuel economy and performance of light-duty passenger cars, as well as that of medium- and heavy-duty freight trucks.

The National Renewable Energy Laboratory (NREL) is helping to lead this landmark project in collaboration with eight other national labs and 13 universities.

While fuel economy ratings of today’s cars significantly outstrip those of just a decade ago, cost-effective efficiency improvements remain limited by existing engine designs and fuel formulas. The FY18 Year in Review  outlines how Co-Optima’s examination of fuels as dynamic design variables that can work with modern engines is providing industry with the scientific underpinnings needed to accelerate introduction of high-performance fuels and engines that reduce energy consumption, improve air quality, and lower drivers’ costs. 

"This objective scientific research is giving industry the knowledge and tools to more rapidly improve today’s combustion engines and petroleum-based fuels, while also blazing a trail for more revolutionary long-term changes in component design and fuel formulas," says NREL Vehicle Technologies Program Manager John Farrell. Farrell served as Co-Optima project leader from its early planning stages and 2015 launch through December 2018. Fellow leadership team member Robert Wagner of Oak Ridge National Laboratory recently assumed management responsibilities for the project.

At this June’s Vehicle Technologies Office Annual Merit Review Meeting, DOE honored the Co-Optima research team for its outstanding achievements. The award recognizes the team’s groundbreaking work to synergistically improve fuels and engines, which is described in detail in the recently published report.

Much of the Co-Optima research is focused on components known as blendstocks, which can be produced from a wide spectrum of domestic resources including renewable, non-food, domestic biomass such as forestry and agricultural waste, as well as petroleum or natural gas. They have the potential to deliver deep cuts in polluting emissions from transportation, create much-needed new jobs in rural areas, leverage a billion-ton annual biofeedstock resource, and keep energy dollars in the United States.

NREL researchers played a central role in the Co-Optima team’s identification of the six blendstocks—di-isobutylene, ethanol, fusel alcohol blend, isobutanol, isopropanol, and n-propanol—that exhibit the greatest potential to increase engine efficiency with the fewest barriers to implementation when combined with petroleum-based fuels in optimized engines. Co-Optima research is also addressing challenges specific to medium-duty and heavy-duty trucks, exploring strategies for mixing-controlled compression ignition and advanced compression ignition engines.

Other Co-Optima accomplishments from NREL researchers in the last year include:

  • Addressing soot formation issues by identifying chemistry impacting direct-injection spark-ignition engine emissions and examining autoignition and soot-precursor formation chemistry of high-octane blendstocks
  • Inventing a new tool to accelerate estimates of fuel blendstocks’ sooting tendencies
  • Coupling fermentation-derived mixed acids to form promising bioblendstocks for mixing-controlled compression ignition
  • Synthesizing oxymethylene ethers from methanol to potentially make more cost-effective diesel blendstocks
  • Establishing a new rapid low-volume octane estimation method to accelerate the characterization of fuels.

Potential benefits of Co-Optima research include significant improvements in vehicle fuel economy and increases in the use of domestically sourced fuel for transportation. This, in turn, has the potential to create new U.S. jobs while reducing emissions and costs for consumers and commercial operators at the pump.

Sponsored by DOE's Vehicle Technologies Office and Bioenergy Technologies Office, Co-Optima partners include NREL as well as Argonne, Idaho, Lawrence Berkeley, Lawrence Livermore, Los Alamos, Oak Ridge, Pacific Northwest, and Sandia National Laboratories.

Read the full report, get an overview of the Co-Optima initiative, find more information on Co-Optima activities, and learn about NREL's involvement in Co-Optima and other transportation research.