For the past four years, the US Department of Energy’s (DOE’s) Co-Optimization of Fuels & Engines (Co-Optima) initiative has focused research efforts on turbocharged spark-ignition (SI) engines, which are found in most of today’s light-duty passenger cars and light trucks. An article by Co-Optima team members shares scientific details to help the research community and industry identify viable candidates for biofuels that can maximize performance and efficiency when used in these engines.
The Co-Optima effort is designed to provide the American industry with the scientific underpinnings needed to identify fuel properties and engine parameters that can maximize vehicle performance and efficiency, leverage domestic fuel resources, and reduce engine knock and lifecycle emissions.
The collaboration combines the expertise of DOE’s Bioenergy Technologies (BETO) and Vehicle Technologies Offices (VTO), nine National Laboratories, multiple universities, and industry partners.
The article “What fuel properties enable higher thermal efficiency in spark-ignited engines?” published in the journal Progress in Energy and Combustion Science by Co-Optima team members from Oak Ridge National Laboratory (ORNL), the National Renewable Energy Laboratory (NREL), Sandia National Laboratory and Argonne National Laboratory, shares, for the first time, scientific details to help the research community and industry identify viable candidates for biofuels that can maximize performance and efficiency when used in these engines.
Merit function tool
Researchers developed a new computational merit function tool to quantify the fuel efficiency potential associated with six different fuel properties. The Co-Optima initiative has used the merit function tool to identify blendstocks with properties that can increase knock resistance when blended with petroleum refinery gasoline at up to 30 volume percent.
These high knock resistance blends allow engine designs and calibrations that are more efficient, resulting in reduced gasoline consumption and consequently reduced life-cycle greenhouse gas (GHG) emissions.
Making these Co-Optima blendstocks from biomass or other waste feedstocks would result in additional life-cycle greenhouse gas emissions reductions. In the journal article, the Co-Optima team explains how it has identified three fuel properties—research octane number, octane sensitivity, and heat of vaporization—as having the most significant impact on turbocharged SI engine efficiency.