Work headed by an Ohio waste-to-energy company to make plastic from biodigester byproducts is among seven projects recently selected for federal grants to develop new ways to use captured carbon dioxide.
The grants aim to advance the federal government’s goal of net-zero greenhouse gas emissions by 2050 in order to address ongoing climate change.
Quasar Energy Group, headquartered south of Cleveland in Independence, designs and builds anaerobic digesters, in which bacteria break down manure, food waste, or other organic materials. Methane is the systems’ main gas output and can be used to power generators or heat buildings, among other uses.
But anaerobic digesters also produce carbon dioxide, another greenhouse gas which has fewer commercial uses. Customers today include fertilizer manufacturers, oil and gas companies, and food and beverage makers. But those markets are tiny compared to the amount of CO₂ scientists think will need to be removed from industrial emissions, or even pulled from the atmosphere, to deal with climate change.
There’s a limit to how much carbon dioxide will be able to be stored in the ground, and community opposition to pipelines is another barrier to Midwest carbon capture plans. Using the carbon in products — such as cement or plastics — can be a useful alternative, especially if it displaces other fossil fuel inputs.
On Oct. 9, the U.S. Department of Energy’s Office of Fossil Energy and Carbon Management announced funding for seven projects aimed at commercializing new approaches to incorporating carbon dioxide into products. The selections are aimed at hard-to-decarbonize sectors, said Ian Rowe, division director for carbon dioxide conversion at DOE’s office of Fossil Energy and Carbon Management.
“There’s not going to be a non-carbon solution for those needs in the future, but we should make them from more sustainable forms of carbon,” Rowe said. “And carbon dioxide represents a feedstock that you can use.”
How the process works
Ohio is already a leader in plastics production that relies heavily on the fossil fuel industry. Hundreds of companies across the state play a role in manufacturing or the supply chain. And midstream processing provides a ready supply of natural gas feedstocks from the Utica shale play.
Quasar Energy’s team designed its process for making plastic so it will work well with biodigesters. Basically, the project will use lipids from algae as a feedstock for a type of polyurethane. Liquid effluent from the biodigester could help grow the algae and supply nutrients for it, such as nitrogen and phosphorus.
Carbon dioxide from the biogester’s gas would be another ingredient in the process. The project team estimates the process could cut carbon dioxide emissions at least 25%, compared to current technology for making the plastic.
The process already works on a bench-scale level in the lab, said Tao Dong, a chemical engineer with the National Renewable Energy Laboratory in Colorado, who is also working on the project. Other team members named in the group’s grant application to DOE include Caixia “Ellen” Wan at the University of Missouri, Xumeng Ge at Quasar, and Ashton Zeller, director of research at Algix.
Costs are an important factor for the Quasar team’s project or any other products aimed at displacing those made from fossil fuel sources. Those costs include expenses for “cleaning up” the biodigester gas to separate methane from carbon dioxide. But a chunk of that expense also can be allocated to the separated methane, which has its own value for energy, either for on-site use or for sale for use elsewhere.
In other words, using the gas for making the plastic and for energy helps the economics for both uses, versus just flaring the gas into the atmosphere.
“Our process can be cost-effective,” said Yebo Li, Quasar’s chief innovation and science officer.
The plastic made from the process also has an advantage from being a non-isocyanate polyurethane, said Mel Kurtz, president of Quasar. The Occupational Safety and Health Administration links isocyanates to various health problems, and some are potential carcinogens. So, a polyurethane plastic that doesn’t have them should reduce risks for workers at factories who would then use the material to manufacture products, such as shoes or other items.
“If [farms] can add another revenue stream, that can improve the economics” for biodigesters on farms, said Andy Olsen, a senior policy advocate for the Environmental Law & Policy Center, whose work focuses on energy issues relating to agriculture and is not part of the project team.
It’s also important to make sure staff are properly trained to use and maintain the equipment properly, Olsen added, noting potential problems with leaked gases. Others question whether emissions offsets from some biodigesters have been overstated.
Next steps
The Quasar project team still faces hurdles. Work under the grant will focus on identifying and addressing risks so the technology can be scaled up.
One challenge will be maintaining algae ponds over time to provide the lipids for the process. Another will be optimizing the process for making them into small chemical building blocks called monomers and then assembling them into polymers, which are the plastic. Maintaining the reduction in greenhouse gas emissions over time also will be important.
Other Midwest grant recipients include LanzaTech, an Illinois sustainable fuels company, and Washington University in St. Louis, which will develop a low-carbon process to convert carbon dioxide to high-quality carbon nanotubes. Those will be tested for use as anodes for lithium-ion batteries.
Whether these and other carbon management projects can scale up quickly enough for the United States to achieve net-zero emissions by 2050 is a big question, said Rowe at DOE.
The energy source for the production process will also make a big difference, Rowe said. Algae can make their own food with carbon dioxide and sunlight. But it takes energy to maintain the ponds throughout the year. The equipment to process the algae and then make the lipids and biodigesters’ carbon dioxide into polyurethane also needs energy.
“Carbon management strategies go hand in hand with an increased deployment of cheap clean electricity. So, a lot of these won’t work without the other,” Rowe said. On the flip side, “if that energy does not come from clean sources, you’ve just produced something that is worse for the environment than if you dug it up and just used fossil carbon.”
This article first appeared on Energy News Network on Oct. 31, 2024 and is republished here under a Creative Commons licence.
