With support from Minnesota Corn, Professor Paul Dauenhauer is exploring the corn-to-methanol pathway for biofuels.
Modern corn ethanol is a marvel of clean fuel production, harnessing the energy of the sun to make a single seed into 600 or more kernels, and then rendering the glucose polymers in the grain into an alcohol fuel. Modern production efficiency renders nearly three gallons of fuel from every bushel.
Making alcohol is a biological catalytic process as old as civilization, but, even with the latest refinements, the biology in the process requires the sacrifice of about a third of the glucose molecules in the lifecycle of the yeast catalyst, producing CO2 along with the alcohol.
Paul Dauenhauer, a University of Minnesota Professor of Chemical Engineering, asks, what if there were a process that could utilize 100% of the corn glucose polymers to make fuel? He believes an inorganic catalyst could turn all those molecules into another form of alcohol, called methanol.
In a project funded by the Minnesota corn checkoff, Dauenhauer is testing a series of metal catalysts, to see which could produce the highest yield at the greatest economic efficiency.
“Methanol has a universality to it,” Dauenhauer said. “Using existing technology you can make methanol into jet fuel. You can also make clean burning diesel fuel, and you can make polyethylene polymers—plastics.”
The jet fuel made this way achieves a major reduction of carbon emissions, and so qualifies as sustainable aviation fuel (SAF)—corn-based methanol could potentially supply that entire American SAF market, he said.
He believes this new process will yield 50% more fuel, while still leaving the corn fiber, protein and oil for coproducts like distillers grains animal feed.
“In 2022, the USA produced about 14 billion bushels of corn (~360 million tonnes of corn, source: USDA),” Dauenhauer wrote in his research proposal. “(That same year), the USA consumed about 145 million tonnes of diesel fuel (source: EIA). Using about half of the annually produced corn would provide the renewable carbon required to manufacture all of the country’s current jet fuel consumption.”
The “universality” of the methanol molecule will allow biorefineries to respond to the various markets and direct production into different amounts of jet fuel, diesel, or plastic, depending on demand, Dauenhauer said.
Methanol-based diesel also offers a huge environmental benefit.
Dauenhauer said, “You manufacture a molecule called dimethyl ether…People have been talking about it for a long time. The benefit of using dimethyl ether in a diesel engine versus conventional diesel is it burns really cleanly. All the problems you have with exhaust with a conventional diesel engine, you would not have with methanol-based diesel.”
Between now and 2028, Dauenhauer’s team plan to refine the process of turning corn into methanol using inorganic catalysis.
The vision for this technology, according to Dauenhauer, is that existing ethanol plants could make the switch and reap all these benefits. The final year of the project will include an economic assessment to judge the feasibility of making that changeover, and in particular, it would focus on the economics of producing methanol for SAF jet fuel market.
Additional ethanol uses
Minnesota Corn is also supporting several other efforts to expand ethanol’s utility beyond the passenger vehicle. For example, the organization is supporting research out of Marquette University that aims to adapt diesel engines to run on higher ethanol blends, including E98. Backed by the U.S. Department of Energy, John Deere, and others, the researchers are testing an “actively fueled pre-chamber” that allows a standard diesel engine to run on high-ethanol blends without losing torque or performance.
Additionally, the organization is supporting research at the University of Minnesota, led by Will Northrop, that is modeling how to produce SAF by combining corn ethanol with captured CO2. Traditional ethanol-to-jet processes ignore CO2, but this project uses ethanol dry reforming to turn ethanol and CO2 into syngas, which can be converted to SAF and other fuels. The team is using Aspen Plus simulations and machine learning to analyze energy use, capital costs, and emissions. Early results suggest this pathway could lower costs, cut greenhouse gases, and strengthen ethanol’s role in future SAF production.
