Researchers at the U.S. Department of Energy’s Argonne National Laboratory are tackling big problems facing the world. One of the biggest is climate change.
In the United States, as elsewhere around the globe, the symptoms of climate change have become plain to see: record-setting heat waves, unprecedented storms and flooding, historic droughts and wildfires. Scientists have linked these symptoms to greenhouse gases in the atmosphere, primarily carbon dioxide. Globally in 2021, total emissions of carbon dioxide reached about 36 gigatons, the highest level ever. These emissions are estimated to increase in the coming years unless bold actions are taken.
“The need to decarbonize is as urgent as it gets, and Argonne is in a good position to do something about it.” — Vyaas Gururajan, research scientist, Transportation and Power Systems division
In the face of the threat, the U.S. has made a pledge to achieve net-zero carbon emissions by 2050. Within the next decade, according to the National Academy of Sciences, the world should be removing about seven to 10 gigatons of carbon dioxide per year. Today, we’re nowhere near that; the current rate is about 0.04 gigatons.
One of several means to help meet the net-zero goal is removal of carbon dioxide from industrial plant emissions and directly from the air. Argonne researchers are thus aligning a variety of research programs toward the development of highly effective and energy efficient systems to capture carbon.
Though Argonne researchers have been doing important work related to decarbonization for decades, this new joint effort unites experts across the lab. “Essentially, we want a group of scientists dedicated to this pressing problem,” said Vyaas Gururajan, a research scientist in Argonne’s Transportation and Power Systems division who is working with Sibendu Som, director of the lab’s Center for Advanced Propulsion and Power.
In the near term, the researchers are focused on studying point-source capture technologies. In point-source capture, the unit trapping carbon dioxide is attached, or very close to, an exhaust stream such as a factory’s flue-gas stack. Point-source capture is far less energy intensive and, therefore, cheaper than another common method called direct-air capture. During direct-air capture, carbon dioxide is pulled right out of the atmosphere. In this research, Som can call upon his deep well of experience using high performance computing systems to model engines.
Currently, Argonne researchers are creating computational tools to numerically simulate and model a variety of complex elements of theoretical carbon-capture systems. “We are developing a software framework to solve this problem,” Som said, “because there are way too many parameters in the problem to investigate experimentally.” The ideal system achieves a high rate of carbon dioxide transfer while using a low amount of power.
One technology the researchers are looking into is called a hollow fiber membrane contactor module. Basically, a gas that contains carbon dioxide and a liquid solvent are fed into a container that has very thin fibers whose walls, or membranes, possess pores that are able to maintain liquid-gas contact, selectively removing carbon dioxide from the gas stream. The CO2-rich solvent is then heated, producing pure carbon dioxide gas and solvent that can be reused.
Scientists at Argonne and elsewhere are also investigating possible ways to reuse or store the captured carbon dioxide. For example, it could be stored underground or used in processes to create liquid fuels.
Another carbon capture method involves flow through a so-called packed bed reactor. Gas containing carbon dioxide is pushed through a matrix of sorbents — materials that adsorb a liquid or gas, such as zeolites or silica gel. The carbon dioxide accumulates on the sorbent material and can then be boiled off and captured, allowing the sorbent to be used again.
“If we are going to simulate these processes numerically using a computer, we need lots of parameters for the various solvents and sorbents we are using,” Gururajan said. “Therefore, we need a range of experts at Argonne on board.” The research dovetails, for example, with that of Di-Jia Liu, a senior chemist in Argonne’s Chemical Sciences and Engineering division. He recently discovered a new electrocatalyst (a substance that increases the rate of an electrochemical reaction) that converts captured carbon dioxide and water into ethanol. Solving the carbon-capture conundrum will require experts in this and many other highly specialized disciplines, including chemical kinetics, molecular transport, material characterization and synthesis and computational fluid dynamics.
This effort has been made possible, in part, by a grant from Argonne’s Launchpad Program, designed to provide motivated early- and mid-career researchers the opportunity and support to build a technology program that can scale to about $10 million in funding per year within five years.
“The need to decarbonize is as urgent as it gets, and Argonne is in a good position to do something about it,” Gururajan said. “We have all of these scientists doing research on so many different fronts. Why not channel some of that work toward this critical need to remove carbon dioxide?”
Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.
The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.