Roadmap to Defossilize Economy via Carbon Reuse Unveiled

One prominent approach to achieving net-zero carbon emissions relies on converting various parts of the economy, such as personal vehicles and heating, to run via electricity generated from renewable sources. But carbon cannot be removed from all parts of society. For example, plastics, ubiquitous in the modern world, cannot be decarbonized because they are made of carbon-based molecules.

Led by chemist Wendy Shaw of the Department of Energy's (DOE) Pacific Northwest National Laboratory (PNNL), a multi-institutional effort including the DOE's SLAC National Accelerator Laboratory has produced a new roadmap to reducing emissions in hard-to-electrify segments of the economy. The roadmap presents a future without waste, where carbon is reused and treated as a precious commodity rather than a disposable resource. Bringing sustainable sources of carbon into the carbon-circle economy is essential to this future.

A core idea of the roadmap is centered on defossilization, or removing fossil fuels while still using carbon in our economy, specifically for difficult-to-electrify sectors. To do this, the researchers outlined ways of developing non-carbon fuels, finding non-fossil sources of carbon, and keeping carbon in play once it enters the economy, ideally resulting in multiple uses of each carbon atom. Single-use carbon can no longer be widespread, the roadmap authors assert.

Carbon can play a role in a circular economy by reusing each carbon atom numerous times. For instance, developing polymer upcycling processes and efficiently reusing carbon-based materials will be central to a net-zero carbon emissions future. Additionally, carbon can be reused within the same industrial sector or act as a feedstock for a new industrial sector.

"We need novel and creative solutions to realize our decarbonization goals," said Steven Ashby, director of PNNL. "And collaboration is key to accelerating the use-inspired scientific research in catalysis and separations science that will underpin these solutions. I eagerly await these results and their deployment in aviation, heavy duty trucking, and marine transportation."

The ideas emerged from "Closing the Carbon Cycle: Opportunities in Energy Science," a workshop jointly hosted by PNNL, Ames National Laboratory, Argonne National Laboratory, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory, Oak Ridge National Laboratory and SLAC. Leads from each laboratory included Shaw, James Morris, Max Delferro, Sanjaya Senanayake, Francesca Toma, Michelle Kidder and Simon R. Bare, respectively. Their roadmap appears in the XX issue of Nature Reviews Chemistry.

"While achieving carbon neutrality is a huge global challenge, it also creates new opportunities for breakthrough research," said Bare, a Distinguished Scientist at the Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC. "This roadmap delineates some of these opportunities and lays the foundation for future collaborative research."

At SLAC, researchers will continue on the next phase of the project, which is coordinating with science and research communities to discuss how to defossilize carbon quickly.

A roadmap to defossilization

Hydrogen and ammonia both have potential as carbon-free fuels. However, both have clear challenges for implementation. In particular, the cost to store and transport hydrogen makes it impractical with current technologies. Work to develop carrier molecules and materials to enable safe and affordable hydrogen transportation will complement the DOE's Hydrogen Earthshot goal of renewably produced hydrogen for 1 $/kilogram or less. This cost reduction could help create viable hydrogen-based systems.

Using carbon from diverse sources, such as biomass, food waste and plastic waste, is central to the proposed approach. Carbon will continue to be essential for many critical economic sectors. These sectors are candidates for circular carbon cycling through recycling and incorporating multiple carbon sources. Making this process a reality requires effective and efficient separations and conversions because complex mixtures make up most non-fossil carbon streams.

"Advancing carbon recycling and conversion technologies is key to a clean energy future, and Argonne is committed to supporting its development," said Argonne Director Paul Kearns. "I commend the researchers who are collaborating across the DOE's National Lab complex to drive these transformative innovations to achieve net-zero by 2050."

"Carbon should be seen as a valuable commodity that must be conserved and reused," said Shaw, chief science and technology officer of PNNL's Physical and Computational Sciences Directorate. "Our vision is to transform the role of carbon in our economy by reusing each carbon atom multiple times in a circular economy."

Effectively transforming "traditional" waste materials into reusable materials remains critical. Combining the separation and conversion steps through reactive separations may provide a practical approach. Reactive separations combine chemical reactions with purifying separations and can provide process intensification, converting the non-fossil carbon more efficiently.

"We need new fundamental science developments to produce integrated industrial approaches," said Morris. "The resulting technologies will create new economic opportunities, educational development, and additional job growth."

SSRL is a DOE Office of Science user facility.

Citation: https://rdcu.be/dGoFk

This article has been adapted from a release written by Pacific Northwest National Laboratory.