Fueling a sustainable future

Despite technological advances, we still live in a world that runs on oil, coal, and natural gas. In the United States, 80 percent of our energy—to heat our homes, drive our cars, and power manufacturing—comes from fossil fuel sources.

Not only are those sources finite, but they also are significant contributors to greenhouse gas emissions, which are among the causes of global climate change. Countries around the world have committed to going carbon neutral by 2050, but getting there will require adopting sustainable fuels across industries.

Sustainable fuels, including biofuels and renewable hydrogen, have the power to transform transportation, which accounts for 29 percent of total U.S. greenhouse gas emissions, according to the Environmental Protection Agency. But more work needs to be done in developing, capturing, and characterizing sustainable fuels before we can say goodbye to fossil fuels forever.

“It is a matter of engineering chemistry to convert fuel into an energy form that is useful,” said Vikas Berry, professor and department head of chemical engineering. “By understanding that process, we can do new kinds of conversions, and we have already seen tremendous work in this area.”

“There is a push to fund new research now, and we will see some new innovative technologies coming out in the near future,” he added.

UIC Engineering faculty and alumni are working toward that future by helping to create new sustainable fuels and by ensuring that our current technology can work with them.

What are sustainable fuels?

Sustainable fuels are created with renewable sources, including plant matter and waste, and emit less or zero greenhouse gases. Many of these fuels are used at least in part in the transportation industry, encouraged by policies in the early 2000s that began to require the blending of renewable fuels into transportation fuels.

Perhaps the most familiar sustainable fuel in use right now is ethanol. Made from plant materials called biomass, often from corn grain, ethanol is now a part of 98 percent of the gasoline sold in the United States. When ethanol burns in an engine, it produces fewer emissions. Some people even consider it carbon neutral because the plants needed to produce it absorb carbon dioxide as they grow.

For vehicles that use diesel fuel, biodiesel, which is made from oils, fats, and grease, can reduce carbon dioxide emissions by up to 74 percent through its lifecycle, according to the U.S. Department of Energy. Often blended with petroleum diesel, biodiesel is widely used in the United States. Consumption among large trucks, buses, and tractors has grown from about 10 million gallons in 2001 to about 1.8 billion gallons in 2019, according to the U.S. Energy Information Administration.

In the airline industry, many companies are looking to adopt sustainable aviation fuel, which is made from cooking oil, animal waste, solid waste, and forestry waste. The result is much lower carbon emissions than traditional jet fuel: up to 80 percent lower by some estimates.

But sustainable fuels do not need to use just waste material. Fuel cells, for example, use chemical energy to cleanly produce energy. Like batteries that don’t need charging, fuel cells use two electrodes and an electrolyte to separate electrons from the fuel source and create energy. Certain fuel-cell electric vehicles, for example, are powered by hydrogen and do not emit any greenhouse gases at all.

Industry gets on board

Many in the transportation industry are eager to adopt sustainable fuels in a bid to meet demand, take advantage of tax incentives, and meet new emissions standards.

United Airlines, for example, this year announced the purchase of 3.4 million gallons of sustainable aviation fuel and has said it is committed to becoming carbon-neutral by 2050. Car manufacturers express increasing interest in hydrogen fuel cell vehicles, current models of which include Toyota’s Mirai, Hyundai’s Nexo, and Honda’s Clarity Fuel Cell. Hydrogen-powered jets could be next: startup ZeroAvia is working toward a 10- to 20-person aircraft powered by hydrogen fuel cells and hopes to complete it by 2023.

These approaches are an alternative to the “plug-it-in” model that many passenger car companies tout as their path to sustainability. “The automotive fleet will likely go electric, but marine transport, heavy-duty truck transport, and aerospace will be hard to electrify,” said Sibendu Som (PhD ’09), manager of the computational multi-physics research section of the energy systems division at Argonne National Laboratory. “These are the industries that are looking closest at sustainable fuels.”

Finding fuels in places you never thought to look

UIC Engineering researchers are developing and optimizing new technologies to harness sustainable fuel sources. Berry has developed a microbial fuel cell that creates energy when bacteria consume acetate. Such a fuel cell could ultimately be used to power microdevices, or perhaps eventually a vehicle as large as a submarine.

Nanomembranes that derive energy from saltwater are another option for cleanly powering marine vehicles. Sangil Kim, an assistant professor of chemical engineering, has come up with a nanomembrane that takes advantage of the power source in salinity gradients that are found where salt water and fresh water mix, creating a difference in salt concentration that can result in electric potential. Kim’s device consists of vertically aligned boron-nitride-nanopore membranes that can efficiently exploit this power to generate voltage.

“There is a huge amount of potential energy available by using this salinity gradient,” he said.

Making it work in the real world

As with any solution to a problem, it’s important to be practical. New fuels may come on the scene, but companies may be unable or unwilling to immediately jettison their planes, trucks, and other costly items that were designed to run on the old stuff. That means scientists and engineers must find ways for engines built to run on gasoline and jet fuel to work with ethanol and bio-derived fuels.

Among those helping to close that gap are UIC mechanical and industrial engineering faculty members Patrick Lynch and Ken Brezinsky. The pair studies fuels for combustion engines and are experts in the process of ignition.

“We try to make fuels that have been identified as being sustainable to work as replacements in combustion engine configurations that were not designed for these kinds of fuels,” Lynch said. By analyzing blended fuels that contain ethanol and biomass, for example, Brezinsky and Lynch can determine the individual chemical species to understand how to better control ignition, and, consequentially, how well the fuel can run in traditional engines.

Meanwhile, Professor Suresh Aggarwal is conducting research into the aftereffects of sustainable fuel use, which is crucial given that not all sustainable fuels are zero-emissions. He develops simulations of how liquid fuels burn and turn into soot, with the goal of finding ways to reduce emissions.

“As we transition to more biofuels, and as companies face more stringent regulations, it’s going to be more important than ever to understand how sustainable fuels affect emissions,” he said.

At Argonne, Som and his group are working in a similar area, developing calculations and simulations that can accurately describe the combustion and emissions processes for fuels in automotive, maritime, and aerospace engines. They have studied bio-derived jet fuels and ethanol-gasoline blends, and they share their findings with industry to inform future designs.

“A small difference in fuel properties can have a big difference in combustion and emissions,” Som said. “It’s really exciting to be the bridge between those who develop new fuels and the industries that are trying to design engines that can use these fuels.”

Some estimates say fossil fuels will run out within the next 30 years. Under increasing pressure from governments worldwide to reduce carbon emissions, researchers and some companies are committed to making sustainable fuel sources work.