Community spotlight: Charlie Stephan, Doctor of Process Engineering

In this month’s community spotlight, we speak with Dr Charlie Stephan, who is an expert in process engineering and an involved fan of political ecology. How did he move from an engineering post in Cambodia to a Paris-based PhD and potential start-up? Charlie tells us about the moment he realised that innovation is not necessarily about using high levels of technology, as well as his work on biomass as a renewable resource and an alternative to oil.

Nia Cason: Great to meet you Charlie. Could you introduce yourself in a few words?

Charlie Stephan: My name is Charlie and I’m 28, I was born and raised in Paris. I’m a graduate in process engineering from the University of Technology of Compiegne, and recently finished a PhD in thermodynamics at Mines ParisTech. Processing engineering deals with fundamental principles – like chemistry, mass transfers, and thermal transfers – and applies that knowledge to design processes for various industries, including the food industry, cosmetic industry, oil industry, and renewable energy. Thermodynamics is concerned with physical and chemical equilibriums, so it’s a fundamental part of process engineering.

NC: What inspired you to choose this research topic?

CS: Right after my engineering diploma, I went to work in Cambodia as an engineer; when I came back to France I found a wonderful PhD opportunity at ParisTech – I loved it and now want to keep working in this field. My professional life also means I can combine three things that are close to my heart: renewable energy, scientific expertise, and helping developing countries.

I’ve been working on biorefineries, which are the answer to two problems: waste management and energy transition. This is just one part of the solution to climate issues, which needs to be much more global, but what I also love is the complexity of this problem. By definition, all waste is different, so it’s a complex task to valorise each and every kind of waste and biomass.

NC: Could you describe your research topic?

CS: Biomass is a renewable resource and an alternative to oil. I’m working on biorefineries, which are processes to convert biomass waste, like agricultural or forestry waste, into something more valuable. This could be for fuel, but also materials and chemicals that are used to make cosmetics, pharmaceuticals, plastics… Today, all these products are mainly made from oil, so the objective is to use biomass waste instead. I was working on pyrolysis, which is a process of heating wood at around 500°C without oxygen – pyrolysis cuts the huge molecules found in wood into small molecules to create a liquid: pyrolysis oil. There’s been a lot of research on how to use biomass to make fuel, but much less on how to valorise the chemical parts of the pyrolysis oil product, which is what I worked on during my PhD. I developed a new methodology to extract valuable chemicals from pyrolysis oil. The advantage of using biomass is that it’s accessible to everyone across the world rather than just in some countries, like we see with oil. More generally, the objective is to achieve carbon neutrality – so reducing carbon emissions and so on.

NC: Did you encounter any challenges during your PhD?

CS: Yes, a lot I guess! The main problem was that I had three supervisors, each of them with their own vision of my topic. I spent the first four months going between each of them and receiving completely different information and advice. But after that, it was quite easy; Mines ParisTech has lots of resources, so it was pretty easy if we needed to buy something. I know that students in other labs find it more difficult to do that, so I was lucky to be there.

NC: Could you describe an important project that you’ve been involved in?

CS: I’m really passionate about ecology and political ecology and have been involved in several NGOs. A few years ago I was in Cambodia for a year, where I was working as a lab engineer to design an improved cooking stove. In Cambodia, everyone cooks with a stove that uses charcoal or wood, so that’s a lot of pollution for the atmosphere and not good for people’s health. The aim was to reduce the emissions and improve the energy efficiency of the stove – the end product was very simple, but it was necessary to do simple things so that the stoves were affordable for people in Cambodia. They sold more than 2 million of these stoves in Cambodia. What I learnt during that project is that innovation is not necessarily about using high levels of technology. It has to be realistic and fit with the context, and should address a real problem.

NC: What’s Cambodian food like?

CS: We were working with cooks that taught us the traditional way to use the stove and to make a fire in it, so that we would do it the same way during our experiments. We were also working on another project in Cambodia, on the artisanal way to make palm sugar. We went to a region in Cambodia where they produce palm sugar, studied how they make it and how to improve the process and design new ovens. And yes of course the cooks made food for us in the lab – it was really good, typical Cambodian food. My favourite is fried rice and fish amock, which is cooked in banana leaves with coconut and is delicious.

NC: As a next step, are you more interested in academic or industry research?

CS: I finished my PhD a few months ago and I don’t have a new job – yet. I’m not sure yet, but most of all I want to work on a project that I love. In academic research, you have more freedom to study what you want, but there’s less resources. In industry, you’re less free to choose your research topic, but you have more resources. What I like about academic research is that everything is public and there’s free access to your findings, so you work for the common good. In industry, you work for the good of the company and everything you discover is protected. In that sense, I prefer academic research.

I’m also thinking of creating a start-up with my PhD directors. The goal of that will be to develop a software to help people to choose a solvent, which is one of the highlights of my thesis work, and to sell our expertise in this field. It would be a collaboration of different academic partners to make a start-up that would sell to industries, so kind of a mix between academic and industrial aspects.

NC: Do you recommend any scientific events?

CS: Pint of science is a good event for communicating science to the general public. Experts in their field make a quick presentation, and then there’s a short discussion. It’s informal, you can choose a topic that you like, and you don’t have to be an expert to understand the content. Also, it’s usually in a bar, which is a good start. I also quite like “Ma thèse en 180 secondes !”. PhD students have to explain their thesis in 3 minutes using only one slide. I didn’t do it myself but I like to watch their videos, they have a YouTube channel and some events.

NC: Do you follow any online personalities?

CS: I don’t just follow scientists, but also people that speak about ecology and political ecology, such as Pablo Servigne, who studies the science of how our society could fall because of ecology; he’s also a scientist, so he provides scientific way of thinking about ecology and transposes it to society. Another is Jean-Marc Jancovici, who studies renewable energy and ecological transition. I also like YouTube channels like Science étonnante and e-penser, which speak about many different topics and simplify science to make it accessible to everyone.