Turning Emissions into Fuel

Sam Zeitz

While smokestacks on power plants are bad for the environment and bad for our health, MIT researchers are working to put that pollution to good use.

MIT mechanical engineering experts have developed a membrane-based system that could convert power plant emissions of carbon dioxide into fuel and chemical feedstock. The fuel could be used to power cars, trucks and even airplanes.

Described in a paper in the journal ChemSusChem, the membrane is made of a compound of lanthanum calcium, and iron oxide. It works by allowing the oxygen from the carbon dioxide to seep through to the other side, leaving carbon monoxide behind. The carbon monoxide left behind can be used as fuel on its own or when hydrogen and/or water is added, it transforms the mixture into other liquid hydrocarbon fuels and chemicals such as methanol, syngas and more.

One researcher told MIT News the membrane is “100 percent selective for oxygen,” and no other atoms can pass through. On the other side of the membrane, oxygen can’t pass back through, stopping it from re-forming carbon dioxide. The part of the process that is still up in the air is how they will get the oxygen to flow to the other side of the membrane. A vacuum could be installed on the oxygen tank side to pull the particles through but that would require a lot of energy. Another option is to pump a material that is easily oxidized to push the oxygen through to the other side, or a combination of the vacuum and the fuel.

The process is powered by heat and the separation occurs at temperatures up to 990 degrees Celsius. To conserve energy, they plan to use either solar energy or waste heat provided from the power plant and other sources to keep the chamber heated. Researchers say they have demonstrated that the process works but still require more research to help increase oxygen flow.

So what does all of this really mean? Well right now, it is still part of a developing solution; however, chemical physics specialists from around the world are watching the MIT researchers work very closely. One Chinese chemical physics expert has said that the MIT process has indicated significant energy savings compared to traditional carbon dioxide decomposition processes and that the MIT work thus far is “…important to the field of sustainable energy.”