We have had the pleasure of interviewing many academics about their use of AIMMS. Often, they are working on innovative research projects that will shape the future of our economy for years to come. Edwin Zondervan is one of them. Edwin is a professor of process systems engineering at Twente University and has been using AIMMS for several years. His work focuses on the energy transition and topics surrounding the hydrogen economy, biobased production, carbon capture and utilization, and electrochemical energy storage. We were curious about how he applies AIMMS in these areas.
Can you tell us a little bit about yourself and your background? How did your interest in optimization and modeling develop?
I was born and raised in Leeuwarden, Friesland – in the north of the Netherlands. I got a bachelor’s degree in chemical engineering with a specialization in process automation. This is where my interest in mathematics and chemical engineering was born. I continued with a master's in chemical engineering and applied for a PhD in process control. The professor who advised me back then was working part-time at Groningen University, where I studied. He also worked at Twente University and had a vacancy for a PhD student there, in the field of control systems engineering. I applied and got the position. During my PhD, my research thesis focused on how to purify surface water with membranes. The project involved a good amount of optimization, as it required us to build models and use them to optimize the performance of the membranes. This is where I became really acquainted with optimization.
After completing my PhD in 2007, I got a job as an assistant professor at Eindhoven University. This job attracted me because it brought chemical engineering together with computing/mathematical optimization. During my time at Eindhoven, I visited all the major research groups that specialize in optimization and operations research. For example, I visited Professor Ignacio Grossmann’s group at Carnegie Mellon. He is the optimization guru in our field. I brought that knowledge back to Eindhoven and was able to apply it with students. In 2015, I moved to Bremen (Germany), where I developed my passion for optimizing process systems further. I started leading the Process Systems Engineering (PSE Laboratory) Group, and my research focus shifted here to applying optimization to solve problems in the energy transition. I spent 5 years in Germany and moved back to the Netherlands in 2020. I’ve been back at Twente University since then.
You’re part of the Sustainable Process Technology Group at Twente University (the Netherlands) and hold the new chair on Process Systems Engineering. Can you tell us more about process systems engineering and how the field is shifting towards sustainability?
PSE is a combination of mathematics, computer science and chemical engineering. We train computer science specialists who can optimize chemical engineering problems, and chemical engineers who understand how to translate a problem into an optimization model. Often, these disciplines are practiced in isolation. PSE gives you a winning formula.
In terms of the shift towards sustainability, there are global developments as we all know. We have to face up to climate change and population growth. The chemical industry provides a wide range of products to consumers, but we create environmental burdens. The PSE community can play a critical role in solving this challenge.
There are two topics that currently get a lot of attention in the field. One is how to deal with uncertainty. We have renewables entering the energy space, but these energy sources are not always available. Wind power supply, for instance, is unreliable. Biomass crops can also be used to address the energy needs of the chemical industry. However, harvests may not be the same year-on-year.
The other big topic is how we design our supply chains to deal with conflicting objectives, like lowering risk and environmental impact. Typically, we think of optimizing supply chains for cost minimization. The models look different if you weigh risks more heavily. Think for example of the hydrogen economy. Hydrogen has a large safety risk.
Both of these questions can be solved with the tools of the optimization community.
I'm curious that you mentioned biomass, what is your take on it? Is it a sustainable energy source?
The short answer is no. Biomass is not really sustainable and it will not be an important player in the energy transition. Converting biomass into fuels is expensive and you cannot grow biomass as fast as you consume it. It also entails considerable resource depletion. However, the biomass economy is broader than just making fuels. Biomass is also a feedstock for the process industry. We could extract or make value-added chemicals out of biomass. We need those. Think of pharmaceuticals, cosmetics, consumer products, construction materials, etc. Biomass can be this feedstock. For instance, grass has a lot of interesting molecules in it: antioxidants, sugars, etc. If you can extract these molecules, the economic value of grass increases orders of magnitude.
In the Netherlands, approximately 10% of the energy that we need comes from a renewable source (wind, solar, and biomass). Most of it comes from biomass resources. However, the wood (biomass) that we use is not used in an efficient way, it’s burned to make energy. Needless to say, that is not sustainable. Burning biomass gives us energy but it still generates CO2. On the other hand, of all the feedstock that the Dutch industry processes, about 20% is bio-based. So, biomass is a big player, but only 1% of the biomass used today is used to make smarter chemical products. This shows you that the industry is not adapting as quickly as we would like.
This brings me to one of your publications. You published a paper in 2020 which assessed the economic and environmental impacts of a biorefinery, and you used AIMMS to develop the supply chain network model. What is a biorefinery and what were the key findings in this case?
A biorefinery converts biomass intro products. In the paper, we look at optimizing production in the refinery itself, and optimizing production as part of the supply chain. For example, we looked at how much arable land would be required and whether we can have an economically feasible refinery while respecting certain restrictions. We modeled the production network (routes) required to convert cereal straw into products like ethanol, ethyl levulinate and electricity. The results of our AIMMS-based optimization model revealed that a wheat straw supply network with four biorefineries is economically feasible and can contribute to save about 4 Mt of CO2 per year.
We have also used AIMMS for carbon capture models and utilization, and to model the hydrogen supply chain.
Fascinating. Can you tell me more about your carbon capture models?
Think about algae, for instance. Algae captures CO2 and is full of interesting molecules you can use to make products. We have used AIMMS to model how you would set up a supply chain to benefit from algae for carbon capture and smart product manufacturing.
In this study, we looked at an integrated algae biorefinery in particular. Integration entails using the wastewater and CO2 emissions from a wheat straw biorefinery to feed the algae biorefinery; resulting algae waste is recycled back to the wheat straw biorefinery to produce value-added chemicals. We found that this integrated algae biorefinery performed economically better than a stand-alone algae biorefinery. To be precise, we found it can lead to an 80% reduction in biodiesel production costs.
Read the full publication: Superstructure optimization of an integrated algae biorefinery
When did you first discover AIMMS and how do you use the software in the classroom?
I discovered AIMMS in 2009, when I went to Carnegie Mellon. The tendency then was to use GAMS; AIMMS was starting to get into the picture at an international level. When I moved to Bremen, I started using AIMMS for a course on process system optimization. Since then, I have supervised many PhD students who used AIMMS in their research projects.
One of the first projects we worked on, using AIMMS, was for a large fast-moving consumer goods company. The PhD student looked at how this company’s ice cream production should be organized at a European level. They had an exceptionally large portfolio. We used AIMMS to optimize the supply chain network from production to distribution centers, to transport and retail. Producing and transporting ice cream requires a lot of energy, as you need cooling during processing and in the trucks. So, the project also entailed minimizing environmental impact. This type of large optimization model was ideal to do in AIMMS.
What do you and your students enjoy most about using AIMMS?
AIMMS is one of several tools you can use to solve optimization problems. The visualization capabilities in AIMMS are its strongest added value. The output files in GAMS, for instance, are created as text files. The output in AIMMS is presented in a UI that is friendlier and more appealing. It’s also free for academics, including a nice set of solvers.
You’re also active in CAPE, a Society for Computer Aided Process Engineering. Can you tell us more about this society and your role/work?
CAPE (Computer Aided Process Engineering) is a Working Party of the European Federation of Chemical Engineering (EFCE). Our purpose is to give visibility to the process engineering community and support engineers in Europe and around the world. We offer a networking platform so people can collaborate and meet, and we support curricula development in universities. The CAPE working party hosts two conferences per year. The larger one of them is ESCAPE, the European Symposium on Computer Aided Process Engineering. We held the 31st edition of ESCAPE in Istanbul this year. We also host CAPE Forum, a smaller meeting for students, where students can hear lectures and participate in workshops for professional development. Next year we will host CAPE Forum at Twente University, so stay tuned for that! We’re open to keynote opportunities at other events as well. Anyone interested in the field is welcome to check out our conferences and resources to learn more.