If a pair of University of Texas at Arlington scientists are right, people who prefer gas-guzzling SUVs or pickups could one day not contribute to harmful climate change by driving them.
The work of Frederick MacDonnell, a professor and chairman of the UTA chemistry department, and Brian Dennis, a professor of mechanical and aerospace engineering, has put them at the head of the global race for the holy grail of a green economy: an affordable and efficient process to make fuel out of the primary greenhouse gas, carbon dioxide.
MacDonnell and Dennis have developed what they say is the first one-step process to convert carbon dioxide and water from the atmosphere into liquid hydrocarbon fuels like gasoline, diesel and jet fuel.
It’s a long-range hope, to be sure, they said.
We make like a thimble-full of fuel over a week. But we’ve done enough to prove that the catalyst works, that the idea works.
Brian Dennis, UTA engineering professor
“What we’re doing in the laboratory is very small scale. We make like a thimbleful of fuel over a week,” Dennis said. “But we’ve done enough to prove that the catalyst works, that the idea works.”
The process ultimately would take carbon dioxide and water from the air and apply concentrated light, heat and high pressure to produce hydrocarbon fuel and oxygen as byproducts.
“You’re burning sunshine,” MacDonnell said.
The benefits to the environment, as well as to the economy and national security, are clear, according to a Princeton University study in 2012. It determined that synthetic fuels — made from a broad spectrum of sources, including coal, natural gas and nonfood crops — could reduce greenhouse gas emissions from motor vehicles by as much as half in the next several decades.
The synthesized gasoline burns like gas refined from petroleum, which means your car is still coughing carbon dioxide back into the atmosphere. But the fuel would be made by taking carbon dioxide from the atmosphere, so it’s a carbon-neutral process. It has the potential to reduce greenhouse gases naturally over time by not adding to the problem.
Another plus is that the entire refining and distribution infrastructure for synthetic hydrocarbon fuels is already in place, making and shipping today’s fossil fuels. Powering vehicles with batteries or hydrogen would require different refueling pumps and other infrastructure, MacDonnell said.
“We would produce a synthetic crude that we would submit to the refinery,” MacDonnell said. It would be cleaner than fossil crude, and 80 percent of it could be refined as transpiration fuel, while only about half of the fossil crude results in vehicle fuel, he said.
The refined fuel would require no adjustments to the combustion engines.
“I don’t think the cars would ever notice,” MacDonnell said.
The professors, who were assisted by Wilaiwan Chanmanee, a research scientist, and graduate student Mohammad Fakrul Islam, described their findings in an article published last month in the Proceedings of the National Academy of Sciences of the United States of America.
Duane Dimos, UTA vice president for research, commended the team.
“Discovering a one-step process to generate renewable hydrocarbon fuels from carbon dioxide and water is a huge achievement,“ Dimos said in a statement. “This work strengthens UTA’s reputation as a leading research institution in the area of global environmental impact, as laid out in our Strategic Plan 2020.”
The fuel-synthesis project was supported by grants from the National Science Foundation and the Robert A. Welch Foundation.
Over the past four years, MacDonnell and Dennis have received $2.6 million in grants and corporate funding for their projects exploring sustainable energy.
To take [carbon dioxide] out of the atmosphere is not an easy thing to do.
Tom Acker, North Arizona University professor of mechanical engineering
Other researchers are using different processes in their experiments to make hydrocarbon fuels. Many are converting CO2 into methanol, the simplest alcohol fuel, composed of molecules containing a single carbon atom — a process that can be conducted at room temperature and pressure, Dennis said.
The concentrated light and heat of the UTA team’s process have produced molecules with up to 13 carbon atoms, the more complex compounds found in hydrocarbon fuels, Dennis said.
But no carbon-dioxide-conversion fuel can be proclaimed a fully renewable energy source without an inexpensive and efficient means of capturing carbon dioxide from the atmosphere, where it does its harm. No such process exists now, says Tom Acker, a professor of mechanical engineering at Northern Arizona University, which has been developing processes to convert carbon dioxide into methanol for nearly 10 years.
“To take it out of the atmosphere is not an easy thing to do,” Acker said, adding research on that front is well underway. “It’s not very clear how to do that and how much it’s going to cost.”
He said methane can be produced for about $3.50 a gallon. But without an efficient CO2 capture process, that gallon “could shoot up to $5.50,” he estimated.
The UTA professors have been fueling their conversion process with CO2 from canisters. Looking forward to commercial production, they say their process wouldn’t be competitive at today’s depressed oil prices, which fluctuate around $30 to $40 per barrel. But they say their process is too new to estimate the oil price that would make it viable.
“It’s a 6-month-old baby and people are already asking if it will be good at sports,” MacDonnell said by way of illustration. “But the potential is there.”
Dennis said a small plant could operate with concentrated carbon dioxide supplied by pipeline, while waiting for those greater efficiencies to come about.
The next step for the UTA team is to develop a photocatalyst matched to the full spectrum of sunlight, which will move the process toward “the overall goal of a sustainable solar liquid fuel,” MacDonnell said. The current process uses only ultraviolet light, which makes up only about 5 percent of full sunlight, he said.
Acker said that he wasn’t familiar with the work going on at UTA but that it sounds intriguing.
“I think universities are supposed to work on things that are futuristic and transforming,” he said. “And that sounds like what the folks at UTA are up to.”