Bu Wang has always been drawn to engineering. Whether it was building model planes as a child or roasting his own coffee beans after he moved from China to the United States for graduate school, he would spend hours tinkering with parts and pieces and figuring out the perfect conditions for a process of interest.
“I initially roasted coffee beans with a popcorn popper that I modified for better temperature control,” says Wang, who joined the University of Wisconsin-Madison in January 2018 as an assistant professor of civil and environmental engineering and a Grainger Institute for Engineering fellow. “But it didn’t end up working very well, so I eventually purchased a dedicated coffee roaster.”
Now, Wang is thrilled to have the resources for building something much bigger: a research program that revolves around materials, from glass and concrete to next-generation batteries and ceramics for fuel cells.
His longstanding interest in materials can perhaps be traced to his dad’s job as a construction company manager, while his mom—a college-level Chinese literature instructor—may have passed on the teaching skills he’ll put into practice in fall 2018. But he found his true calling at Alfred University in New York, where he completed his PhD in ceramic engineering in 2015.
“At Alfred University, I began to focus on researching materials that generate energy or make commonly used production processes more sustainable,” Wang says. “One example of that is concrete.”
Traditionally, concrete—the developed world’s primary building material—is made by gluing together various rocks and minerals with cement paste. Making the cement paste consumes a lot of energy, since it requires temperatures up to 1,500 degrees Celsius, and generates carbon emissions galore.
One way to make the process more environmentally friendly is to replace a fraction of the cement—the higher, the better—with already existing fly ash, a waste material generated by coal-fired power plants.
Most of this fine-particle material is stored in landfills as ash ponds, but the concrete industry is already replacing up to 20 percent of cement with fly ash. The catch? Only fly ash below a carbon content threshold may be used, according to current industry specs.
Wang’s research could help boost that percentage to at least 75, while also using ash that falls outside the specs. In a 2017 study, for example, he and his colleagues showed that a different type of reaction between fly ash and carbon dioxide yielded a product with the same strength as cement-based concrete, but without any cement at all.
While some of Wang’s concrete research is in its early stages, he has also helped develop a low-carbon, low-energy concrete production process that could be implemented in a pilot plant soon, thanks to Carbon XPRIZE: an ongoing industry-sponsored international competition for new carbon capture and utilization technology that Wang joined after he had moved from Alfred University to the University of California, Los Angeles, for a postdoctoral fellowship.
In the process developed for Carbon XPRIZE, fly ash and lime react with the carbon dioxide produced by a coal- or natural gas-fired power plant to replace most of the cement paste in concrete. The demonstration system that Wang and his team presented to the judges captured 200 kilograms (441 pounds) of carbon dioxide and produced 8 metric tons (8.8 U.S. tons) of concrete in 24 hours.
“Our team is now in the second round of the competition, whose winners will be announced in March 2018,” Wang says. “Advancing to the third round would give us some of the $20 million cash award, but even if we don’t win, we plan to move forward with the project, perhaps by starting a spinoff company.”
In another line of research Wang has brought from UCLA to UW-Madison, he studies the impact of radiation on a nuclear power plant’s outer shell.
That shell is typically made of the same concrete as other buildings, while a different material is used for the reactor shield itself. Using a recently published atomic-scale study of the damage that radiation inflicts upon concrete as a starting point, Wang would like to eventually develop models that better predict the structure’s lifetime and can become a part of regulatory monitoring plans.
For the time being, however, Wang is most excited about finding new collaborators, both within and beyond the College of Engineering, with whom he will continue to expand the range of materials he investigates. He’s also looking forward to working with his own group of students.
“In my new position, I hope to build a strong lab for researching more sustainable materials and processes, especially those used by the energy sector,” Wang says.