Researchers turn eggshells into fuel

The patented process uses eggshells to soak up carbon dioxide from a reaction that produces hydrogen fuel. It also includes a method for peeling the collagen-containing membrane from inside of the shells, so that the collagen can be used commercially.

L.S. Fan, professor of chemical and biomolecular engineering at Ohio State says that he and former doctoral student Mahesh Iyer hit upon the idea when they were trying to improve a method of hydrogen production called the water-gas-shift reaction. With this method, fossil fuels such as coal are gasified to produce carbon monoxide gas, which then combines with water to produce carbon dioxide and hydrogen.

“The key to making pure hydrogen is separating out the carbon dioxide,” Fan says. “In order to do it very economically, we needed a new way of thinking, a new process scheme.” That brought them to eggshells, which mostly consist of calcium carbonate—one of nature’s most absorbent materials. It is a common ingredient in calcium supplements and antacids. With heat processing, calcium carbonate becomes calcium oxide, which will then absorb any acidic gas, such as carbon dioxide.

According to USDA, the country produces about 455 tons of eggshells each year that could potentially be used to make hydrogen. But even if that shell were utilized, it would only provide a portion of what the United States would need to seriously pursue a hydrogen economy.

“Eggshell alone may not be adequate to produce hydrogen for the whole country, but at least we can use eggshell in a better way compared to dumping it as organic waste in landfills, where companies have to pay up to $40/ton disposal cost,” Fan says. He is currently working with a major egg company to produce large quantities of the eggshell granules for testing.