Earth has devised many efficient ways of maintaining carbon dioxide (CO2) levels in the atmosphere — from sequestration by forests and oceans to the formation of limestone and fossil fuels by long-dead organisms.
But the release of that gas through activities both natural and manmade is contributing more CO2 to the atmosphere than the earth’s natural processes can handle.
Acting to alleviate that stressor, researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory are looking to the concept of a circular carbon economy.
In its most simple form, the circular carbon economy is about changing mindsets, whether corporate or individual, from an attitude of “make it, break it, throw it away” to one of “reuse and recycle.”
“The ability to achieve that goal is what makes Argonne a key factor for companies looking to develop this approach. We have a highly diverse workforce with the resources to help them assess economic feasibility, model their processes and identify whether those processes are resilient.” — Meltem Urgun-Demirtas, Argonne Applied Materials division.
“It’s an alternative economy that takes into consideration the reuse, recovery and recycling of carbon-containing materials to keep carbon out of the atmosphere, creating a loop that incorporates the same carbon over and over into different products,” says Cristina Negri, director of Argonne’s Environmental Sciences division.
While adoption of this concept is further along throughout Europe, Japan and other countries, it is a relatively new concept in the United States — but is starting to gain traction among corporations that recognize its positive economic and environmental impact, notes Meltem Urgun-Demirtas, a group leader of process development research in Argonne’s Applied Materials division.
Negri and Urgun-Demirtas help companies develop strategies that will account for byproducts and waste and repurpose them for use as new products or energy. But it is no small feat and requires the wherewithal to track, recover and process those dissipated materials.
“We have found that many companies don’t have the resources that Argonne has to achieve some of these goals. So our aim is to help a company examine its processes and suggest a specific circular economy approach,” says Urgun-Demirtas, who is also Argonne’s laboratory relationship manager for DOE’s Bioenergy Technologies Office (BETO), which resides within the Office of Energy Efficiency and Renewable Energy.
For example, Negri and Urgun-Demirtas are working with the global chemistry and materials company, Koppers, Inc., to create such an approach and develop studies that can determine whether the company’s choices will make an impact on carbon reduction.
In its way, Koppers has been enabling some form of a circular carbon economy before the term was conceived. The largest railroad tie manufacturer in North America, Koppers was for many years focused on finding new uses for coal tar, a carbon-rich byproduct of the steel industry’s coking processes.
One of those products is creosote, which the company continues to use as a preservative for the rail ties. Another division makes additional wood preservation chemicals, many of them made predominantly of recycled copper.
In fact, the majority of Koppers’ raw materials are either waste products or scrap materials that they convert into productive materials, notes Joe Dowd, vice president for Koppers’ Global Safety, Health, Environmental and Process Excellence. To a certain extent, the same can be said of the wood the company uses in the production of railroad ties and utility poles.
The rationale goes that, while cutting down a tree to make a rail tie removes resources that sequester carbon, the carbon is immobilized in the creosote-preserved product that might last 50 years.
Koppers is also looking at afforestation — growing trees where none had grown previously — as an additional means of carbon offset. Working with local partners, including Argonne, Koppers is remediating one of its sites to enable the growth of hardwood trees to replace some of what they harvest for production.
To complete the circle, the company is recovering the ties and employing them in energy production. By treating them and using them as fuel for a paper mill boiler, for example, they reduce the need and cost to burn fossil fuels, and reduce the need for disposal of the ties at their end of their useful life.
Promoting a broader use of wood might seem contrary to what we might think of in terms of sustainability, but Negri calls it “expanding the box.”
“From the perspective of the U.S. Forest Service and other agencies, making the same structures in concrete would create more CO2 because concrete requires more resources, and more energy to make it, transport it, pour it, etc.,” she says.
“There is no totally perfect solution, but the end of the story is that only an accurate lifecycle balance may tell you if wood products are gentler on the environment in terms of CO2 emissions.”
Michael Wang, a systems assessment manager in Argonne’s Energy Systems division, works on lifecycle analyses associated with a circular carbon economy. He is working on a National Petroleum Council study that explores opportunities for reuse of CO2, deciphering whether the capture and repurposing of CO2 is environmentally viable.
The majority of CO2 sources are fossil fuel plants, particularly coal-fired power plants, where CO2 concentrations in the flue gases average 20–25 percent. Wang’s group is looking at the cost and energy required to capture, purify and transport pure CO2 to a utilization site. To assess long-term CO2 mitigation affects, they also need to know its fate.
“If we produce a fuel, the embedded CO2 will eventually get burned and return to the atmosphere. But the CO2 in the fuel can come from fossil or biogenic sources. So we want to know under what circumstances we will get permanent mitigation and when will it be temporary,” says Wang.
Globally, there are many projects that examine different ways of utilizing waste stream CO2 — from creating liquid fuels using renewable energy to developing synthetic concrete.
Invariably, the key to the success of any circular carbon economy strategy is to ensure that the energy put into any system is less than the energy that comes out.
“The ability to achieve that goal is what makes Argonne a key factor for companies looking to develop this approach,” says Urgun-Demirtas. “We have a highly diverse workforce with the resources to help them assess economic feasibility, model their processes and identify whether those processes are resilient.”
The Office of Energy Efficiency and Renewable Energy supports early-stage research and development of energy efficiency and renewable energy technologies to strengthen U.S. economic growth, energy security, and environmental quality.
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.