A group of scientists from NREL, Yale University, Argonne National Laboratory, and Oak Ridge National Laboratory are part of the Department of Energy’s Co-Optimization of Fuels & Engines (Co-Optima) initiative, which focuses on increasing fuel economy, reducing emissions, and increasing vehicle performance. These scientists published a paper, “Performance-Advantaged Ether Diesel Bioblendstock Production by a priori Design” in the journal Proceedings of the National Academy of Sciences.
Derek Vardon, a senior research engineer at NREL commented, “If you look at biomass, 30% of it is oxygen. If we can figure out clever ways to keep it around and tailor how it's incorporated in the fuel, you can get a lot more out of biomass and improve the performance of diesel fuel.” Biomass is 4-butoxyheptane and contains oxygen; petroleum-based fuels are comprised of hydrocarbons, not oxygen. Oxygen is what helps to reduce the “sooting” that comes from burning conventional fuels.
"With the goal of developing drop-in biofuels that work with our existing infrastructure," Vardon said, "there are a lot of rules and regulations out there that a fuel has to meet. That eliminates a lot of promising molecules because they may be great in certain properties but fail in others. As we're doing this process, it started to become clear which molecules could be successful fuels."
The scientists used a starting point of corn-derived molecules and then relied on predictive research to determine which molecules would blend the best and improve traditional diesel. They wanted to blend the 4-butoxyheptane molecule into diesel fuel at a mixture of 20%-30%. Initial results are promising, but further research is needed.
"That first step was just seeing what could rise to the top as far as fuel properties go," co-author Nabila Huq said. "Then it was asking, can we make any of these? The molecule that looked most promising was 4-butoxyheptane, and we were able to successfully produce and characterize it." The molecule wasn’t a perfect match, but it did make some of the desired improvements.