An Emerging Technique for Captured Carbon Conversion
By Hamilton Waldron
A new method of carbon capture could help the nation’s coal plants reduce greenhouse gas emissions and take one step closer toward the industry’s long-term goal of converting captured carbon into a useable product, but economic obstacles currently impede full implementation of this promising technology.
Rethinking How Carbon is Reused
U.S. Department of Energy scientists at the Idaho National Laboratory (INL) established the process for converting captured carbon dioxide (CO2) into syngas, a combination of hydrogen (H2) and carbon monoxide (CO) that can be used to create fuels and chemicals. When the team of researchers recently published its findings, it noted that, “for the first time, it was demonstrated that syngas can be directly produced from captured CO2 — eliminating the requirement of downstream separations.”
The Art of Carbon Conversion
Typically, the method for capturing the carbon from CO2 involves a reduction step that requires high temperatures and pressures. This is because CO2 does not stay dissolved in water for a sufficient period to enable capture after its temperature has been lowered. The new process addresses this challenge by using specialized switchable polarity solvents (SPS) that help make the CO2 more soluble and allow the carbon capture medium to be added to a cell for electrochemical conversion to syngas.
Too Much Hydrogen, Not Enough Syngas
In 2017, the researchers at the INL were granted Laboratory Directed Research and Development funds to begin their study. Shortly after the first round of experiments, however, they found that too much hydrogen and not enough syngas were being produced. The team then added a supporting electrolyte (potassium sulfate) to increase ionic conductivity, which produced the expected amounts of syngas almost instantaneously.
Next Steps: Improved Industrial Application
Once syngas can be produced competently and consistently from captured CO2, options for using this new methodology in industrial applications will greatly expand. The SPS-based process proved optimal at ambient temperature (25oC) and 40 psi, after all, in sharp contrast with previous processes that required high temperatures and pressures.
Additionally, the INL has filed for a provisional patent and is discussing its methods with a Boston-based company that specializes in electrochemical technology development. “It integrates two areas that have been on parallel tracks: carbon capture and sequestration (CCS) and CO2 utilization,” said Diaz Aldana, a researcher at INL. “The problem with CCS has been its economic feasibility. If you can get some extra value out of the CO2 you are capturing, it's a different story.”
- Discuss why it’s important to reduce greenhouse gas emissions.
- Discuss how switchable polarity solvents work.
- Greenhouse Gas