Dr. Liang-Shih Fan, Distinguished Professor of Chemical and Biomolecular Engineering at The Ohio State University, has been working with a group of engineers on chemical looping and the use of fossil fuels and biomass to produce useful end products without polluting the atmosphere with carbon dioxide (CO2).
Chemical looping is the process of using a metal oxide as an oxygen source under high pressure to ‘burn’ fossil fuels and biomass. Fan and his team pioneered a process, Coal-Direct Chemical Looping (CDCL), which chemically releases coal’s energy and contains the CO2 produced rather than releasing it into the atmosphere. The process can produce power, syngas, or hydrogen, as well as high-purity CO2 “In the simplest sense, combustion is a chemical reaction that consumes oxygen and produces heat,” Fan said. “Unfortunately, it also produces carbon dioxide, which is difficult to capture and bad for the environment. So we found a way to release the heat without burning. We carefully control the chemical reaction so that the coal never burns—it is consumed chemically, and the carbon dioxide is entirely contained inside the reactor.”
The key to this technology was the use of iron oxide particles which supplies the oxygen for the reaction, and then takes back the oxygen from the air to start the cycle again. The challenge was to keep the particles from wearing out after 100 cycles. The team was able to develop a new formulation that enables the particles to last for more than 3,000 cycles, or more than eight months of continuous use, and is being tested in pilot plants. The research was reported in the Energy and Environmental Science last year.
Fan’s group has also published a paper looking at the use of fossil and/or renewable fuels and CO2 to produce syngas and other commodity products such as methanol and hydrogen. There is no release of CO2 into the environment. Syngas, or synthesis gas, can provide the building blocks for other products such as ammonia, plastics or even carbon fibers. The use of CO2 as a raw material is exciting to decrease its release as a greenhouse gas and reduce carbon sequestration.
The university is collaborating with the Linde Group and Babcock and Wilcox Company for commercial use of the technology.