McMahan “Mac” Louis Gray


Created a game-changing technology that removes carbon dioxide from power plant emissions and absorbs heavy metals, such as lead, from municipal water supplies

Access to clean air and water are among the biggest challenges facing our country, if not the world, with carbon dioxide emissions contributing to climate change and many American cities reporting high levels of lead in their water supplies.

Through his research, National Energy Technology Laboratory chemist McMahan “Mac” Gray created a new technology to remove carbon dioxide from power plant emissions and heavy metals, such as lead, from water

In addition, Gray discovered a means to collect rare earth elements, or REEs, from water supplies. The discovery could lead to a potentially valuable domestic source of REEs, which could help the U.S. economy and lessen our reliance on China and other foreign sources.

“Gray’s work will have a profound national impact because it provides an economically feasible and environmentally sound way to clean air and water and secure a domestic supply of REEs that are essential for use in high-technology applications like consumer electronics and national security technologies,” said Randy Gemmen, an NETL supervisor for energy and water processes.

“His work as a federal government researcher is testament to innovation that can protect the environment and bolster the economy,” Gemmen said.

Gray’s research began with the development of a sorbent — a material that can separate and absorb carbon dioxide from power plant emissions.

The technology has wide-ranging impact because it is an easy to produce, reusable chemical compound that can be tweaked to separate different materials, depending on the need. The filtering technology is known as basic immobilized amine sorbent, or BIAS. Besides removing lead, Gray said it also has the potential to absorb toxins and other dangerous materials from water.

Sean Plasynski, NETL’s deputy director, said Gray’s discoveries are characteristic of his curiosity, his ethic of service and his desire to help society.

“He gets excited and wants to see his technology work — it’s the human health and safety aspect that really drives Mac,” Plasynski said.

Many researchers come up with great ideas that are never put to use, but Gray has shown an ability to attract companies interested in commercializing his inventions by “showing them the technology for what it is, the usefulness in their own area and enticing them to take it and run with it,” Plasynski said.

“Mac has done it multiple times. It’s a unique characteristic,” he added.

In the case of his sorbent, Gray is close to commercialization for all its current uses. For example, Dow Chemical is testing a waste-water cleanup application, PQ Corporation has licensed the water technology patent and is sharing in the manufacturing cost for materials to test the carbon dioxide technology, and a university is testing a reusable drinking water filtration system.

In addition, Brazil is testing carbon dioxide extraction from coal plant waste, and NASA is in the early stage of testing carbon dioxide extraction for use on spacecraft in long-term space travel.

Bryan Morreale, the NETL’s director of research and development, said Gray has always had “an entrepreneurial approach to his research that focuses on “providing real solutions to real problems that will touch every single person, not just in the U.S., but globally.”

Just as Gray strives to apply his research to improve society, he goes out of his way to mentor young scientists, giving individuals opportunities to present their work to the laboratory’s leadership and passing on his research skills. For nearly a decade, he provided service to America’s historically black colleges and universities by working as a program chairman and technical reviewer.

“Mac is dedicated to training future scientists to carry the work forward,” Gemmen said. “He is an active participant in the laboratory’s work to prepare the next generation of scientists, engineers and researchers to tackle emerging energy challenges.”

For Gray, it’s all about action and service.

“I’m from the school of ‘let’s help somebody,’” he said. “I’m someone who looks at a problem, prays about it and gets it solved. I think it’s a gift. The material that I’ve made, it’s not in a book anywhere. My motivation is to get people clean water and clean air. I just believe that we should be stewards of the earth.”