A report released this week highlights the most significant breakthroughs of the last year in the US Department of Energy’s (DOE) Co-Optimization of Fuels & Engines (Co-Optima) initiative, with details on findings that could translate into significant greenhouse gas (GHG) and tailpipe emissions reductions.
Co-Optima researchers are focused on identifying and understanding fuel components known as blendstocks, which can be produced from a wide spectrum of common domestic resources. These include renewable domestic biomass, such as forestry and agricultural waste, which can be combined with petroleum-based fuels to improve vehicles’ carbon footprint and engine performance.
FY20 Co-Optima research focused on multimode combustion strategies for LD (light-duty) vehicles and mixing-controlled compression ignition (MCCI) and advanced compression ignition (ACI) strategies for medium-duty (MD) and heavy-duty (HD) vehicles. By concentrating on the relationship between fuel molecular structure and properties, as well as how fuel properties impact engine operation, researchers were able to devise strategies for further improving efciency, reducing emissions, and using blendstocks derived from renewable domestic feedstocks.
Signifcant progress was made in understanding blending efects on autoignition chemistry (needed to help alleviate harmful engine knock) and the connection between molecular structure and soot formation (essential to reducing particulate emissions). Researchers used this approach to defne critical properties for three LD multimode combustion approaches.
An improved understanding on both fronts was used to identify multimode and MCCI blendstocks that demonstrate the potential to meet economic and environmental targets. Engine combustion research on MCCI blendstocks was initiated, and structure-property relationships for phi-sensitivity—a new fuel property that refects how a fuel’s autoignition reactivity changes as a function of phi (the fuel-to-air equivalence ratio) and is critical for some ACI strategies—were investigated in detail.
In the last year, Co-Optima research has:
Revealed strong potential for many candidate blendstocks to reduce criteria pollutant emissions and cut life cycle GHG emissions by more than 60% compared to petroleum-derived diesel.
Identified bio-based blendstocks that show potential to increase efficiency and reduce GHG emissions when used in multimode engines.
Demonstrated that advanced combustion modes can boost efficiency and cut emissions for vehicles under typical driving conditions, while maintaining power density and efficiency gains.
Last year DOE selected seven industry-led projects through a competitive Directed Funding Opportunity (DFO) process to establish cooperative research and development agreements led by industry partners while leveraging the unique experimental and computational capabilities of the National Laboratories. The industry partners are contributing a market-facing perspective, specific complementary expertise, and cost sharing to address specific research barriers at the fuel-engine interface.
The selected Co-Optima DFO projects are:
ExxonMobil Research and Engineering Company and Argonne National Laboratory (ANL) are developing a life cycle analysis modeling framework to estimate the greenhouse gas emissions produced by refnery coprocessing of renewable fuels.
General Motors, Oak Ridge National Laboratory, and the National Renewable Energy Laboratory (NREL) are determining fuel property efects on abnormal combustion for biofuel-petroleum fuel blends.
LanzaTech and Pacifc Northwest National Laboratory (PNNL) are demonstrating the production of a gasoline-range fuel with advanced fuel properties.
CFR Engines and ANL are developing a fuel reactivity metric and test method for advanced compression ignition combustion engines.
Shell and NREL are applying metabolic engineering and process optimization to the biological production of the high-performance blendstock isopropanol.
Sylvatex and ANL are evaluating the injector performance of Sylvatex’s alternative diesel fuel and optimizing its formulation. u
Visolis and PNNL are converting Visolis’ bioderived intermediate into a high-energy-density blendstock for use in gasoline engines.
Sponsored by DOE’s Vehicle Technologies Office and Bioenergy Technologies Office, the Co-Optima initiative is designed to provide American industry with the scientific underpinnings needed to maximize vehicle performance and efficiency, leverage domestic fuel resources, and reduce life cycle emissions.