Chemical Engineering Professor Andreas Heyden initially intended to pursue a career in industry when he began his Ph.D. studies at Hamburg (Germany) University of Technology. But that was where he found a passion for eliminating greenhouse gases and decarbonizing the chemical industry from fossil carbon sources. Heyden enjoyed the freedom to work on what he believed were important problems and pursue a topic with a bigger purpose.

For the last 16 years at the College of Engineering and Computing (CEC), Heyden has collaborated with colleagues and students on research to improve the sustainability of the energy and chemical industries.

The fundamental motivation for Heyden’s research group is the belief in global warming and its immediate consequences. This includes industrial and consumer markets, which he believes must have a massive transformation before achieving the federal government’s mandate for the United States to be carbon neutral by 2050.

“We have to largely move away from using fossil fuels to using carbon sources that are more renewable. But at the same time, I'm a big believer in the chemical industry,” Heyden says. “Carbon atoms are the basis for most things that engineers use. Three renewable carbon sources could, in principle, replace fossil carbon, and carbon from plastics recycling to biomass sources that should not be too expensive.

Plastics recycling consists of utilizing waste materials for future new products and is the most well-known renewable carbon source. Heyden is currently working on research projects, which include polyolefin and polyester recycling. Polyolefins are often used for single-use products before usually being incinerated, illegally dumped or disposed of in landfills. His research is working on developing sustainable and profitable methods of turning these problematic plastics into valuable raw materials by chemically recycling the plastics. In principle, polyester recycling is easier. But when mixed with other plastics, technologies must be developed to produce clean, higher-value products from these mixed waste streams since the processes cannot generate significant amounts of carbon dioxide.

“We’re trying to come up with energy efficient ways to give these carbon atoms a second life. The best thing to do before recycling is reusing the material, but you can only do that once or twice before the color of the material degrades,” Heyden says. “Some form of chemical recycling, which my research group is doing, makes sense by essentially chopping it into smaller building blocks and reassembling them.” 

Biomass, which is a renewable organic material from plants and animals, is another renewable carbon source. Since 2007, Heyden has completed multiple research projects on developing technologies or methods to transform biomass into useful fuels and chemicals. While this research initially focused on energy vectors, the research now focuses on higher-value materials that can replace petrochemicals, which release carbon dioxide during production.

“The idea of biomass is that a tree and the sunlight already did their job of extracting some of the carbon dioxide out of the atmosphere. We just need to process the material into a higher concentrated form,” Heyden says. 

Carbon dioxide from the air is the third renewable carbon source. Heyden is not currently working on any projects in this area since the concentration of carbon dioxide is less than 0.05%. 

“When you have something so dilute, you first have to concentrate it up, which is very energy intensive. We like to work on recycling and biomass because nature has already done its job to concentrate the carbon while using energy from the sun. But even for carbon dioxide from the air, there are opportunities in the future, such as jet fuel,” Heyden says.

Heyden’s additional research involves working on longtime energy storage of renewable electrons from solar or wind energy to eliminate the need for fossil fuels, which he refers to as an important step for electrification of the chemical industry.

“The problem with renewable electricity is that it's intermittent. But chemical plants usually work 360 days a year, and they need a constant amount of energy. There will be some processes that we will be able to electrify, but we need large-scale and long-term energy storage solutions, both for industry and the transportation sector,” Heyden says.

Heyden is currently attempting to use hydrogen as an energy storage material. Collaborating with Donna Chen from the Department of Chemistry and Biochemistry, they are storing the hydrogen energy in the form of liquid chemicals that can be stored without losses and converted to a hydrogen stream in the presence of a catalyst whenever needed.

“While water can be split to produce hydrogen, it's not energy efficient and convenient to store or transport hydrogen since it’s a light gas,” Heyden says. “Storing hydrogen in the form of chemicals that are liquids at ambient conditions is much more practical.”

Heyden’s two other smaller projects focus on shale gas utilization from fracking. The process produces large amounts of inexpensive natural gas that has dramatically helped the chemical industry in the U.S., which includes replacing coal-fired power plants. But shale oils that are the main target of the industry also come with shale gas that cannot always be utilized but needs to be flared to avoid the release of methane, a worse greenhouse gas than carbon dioxide.

“In principle, shale gas is used as a valuable raw material, but there’s often no pipeline where shale oils are drilled. Since gases are also produced but can’t be transported, the next best thing is to burn it,” Heyden says. “We’re interested in developing technology to transform methane gas into a liquid form [methanol]. Once it’s transformed into a liquid, it can easily be transported it in trucks or trains, so you don't have all these flare sites.”

All of Heyden’s research projects have the same idea: transforming the chemical industry and using more renewable carbon sources. Since different biomass and recycling processes are currently envisioned, the question for Heyden is how can his research group help improve the sustainability of the chemical industry, while creating valuable products at economical prices? 

“There are huge transformations in chemical engineering. It's a great time to be in this field because change means a need for people with skills and good ideas,” Heyden says. ”That's great for our students because in the next 30 years they will have an opportunity to have a real impact. It will be hard to achieve, but it is necessary and good for the world.”