It’s always sunny in Groningen: storing energy with water and sunlight

30 March 2023

Thomas Freese

The Joseph Breen Memorial Fellowship is not awarded to just anyone; a panel of experts in green chemistry critically analyzes the different candidates. It is not surprising that the jury selected ARC CBBC and RUG PhD candidate Thomas Freese from the applicants: he has green chemistry running through his veins, within as well as outside of his research. What does he work on, and how does he take his work as a chemist into society? We interviewed him to get answers to these questions.


Recipe for energy carriers. Ingredients: water and light. Even though matters are a bit more complicated, this recipe is closer to reality than you might expect. Thomas works on photochemistry, which means he uses light as a source of energy to power reactions. This can be applied in a variety of chemical processes, but his main focus is to create green hydrogen with it. “I’m aiming to split water molecules and get hydrogen from that, and my goal is to do that with photochemistry”, Thomas explains.

Another slightly more common way to create hydrogen from water molecules utilizes electricity, but there are certain advantages of using photochemistry instead: “I try to skip the solar panel, and use the light directly by shining it on the water. Without the cables and electrodes in between, there will be ideally less energy loss, as in comparison to the process of electricity to hydrogen around 30% of the energy is lost. That is also why electric cars are more energy efficient than hydrogen cars.”

Marie Brands, like Thomas also a bilateral ARC CBBC PhD candidate with Shell, is working on making hydrogen from water using electricity. Even though their projects and approaches are different, they can help each other out: “Already at the beginning of my PhD, we discussed how we can make use of each other’s expertise, because her knowledge about electrochemistry and mine about photochemistry are complimentary. I needed some additional information on the energy that was needed to make my reaction work, and for that I needed someone with insights in electrochemistry. I was at the University of Amsterdam for a few days, we did experiments until deep in the night, and we had some amazing discussions about photochemistry on the very same molecules that she uses in electrochemistry. Photochemistry and electrochemistry in fact are very similar.”

Two birds with one stone

Next to the hydrogen that Thomas produces in his reactions, he also produces hydrogen peroxide (H2O2) in the same process. Splitting water molecules results in the production of oxygen and hydrogen, which could be a dangerous explosive mixture if left untreated. Therefore, Thomas removes the oxygen by simultaneously making hydrogen peroxide, eliminating the explosion hazard.

The production of hydrogen peroxide not only makes the process safer; it also produces a valuable chemical. There was an enormous demand for hydrogen peroxide in the last years, as it can be used to produce hand disinfectants. “At the moment, the regular production process of hydrogen peroxide is based on compounds made of fossil fuels and is very energy intensive. But now, I’m also making that from water”, Thomas emphasizes. “It is safer and greener: I obtain two products in one run, allowing for facile separation without having any problems with explosive gas mixtures.”

There could even be another application for hydrogen peroxide; it shows promising results as an energy carrier by itself. “Just like hydrogen, hydrogen peroxide can be used for energy storage. So essentially, we obtain two energy carriers via water oxidation. Where the advantage of hydrogen peroxide as an energy carrier is that it is a liquid and not a gas. This makes it much easier and more efficient to transport”, Thomas elaborates. Since a few years hydrogen peroxide is recognized as an energy carrier, making it a rather novel development.


Even though his project is about green hydrogen, Thomas has also been involved in research on green coatings. In collaboration with his former MSc supervisor and later fellow ARC CBBC PhD candidate George Hermens (now ARC CBBC alumnus) he applied his expertise on photochemistry to make biobased coatings. “We used light to convert furfural, which can be obtained from wood waste, into valuable butenolide building blocks. Those can then be used to replace acrylates for coatings. We also designed some high scale photoreactors to increase our production per day. So, it is certainly related to photochemistry and oxygen as well!”, he explains.

Green chemistry in green labs

Next to his research as a PhD candidate, Thomas is active in other facets of working towards a more sustainable world. He believes that when you work on making chemistry more circular and sustainable, it is logical to also invest in making the research process in the lab itself greener. Therefore, he is the LEAF (Laboratory Efficiency Assessment Framework) coordinator of the Green Labs RUG initiative to make labs more sustainable. “We are all doing research in the field of green chemistry, but sometimes the process of conducting the research itself is not that green. Labs produce quite some plastic waste, chemical waste and have a considerable energy and water usage. Instead, we consider using reusable glass materials instead of plastics, and use greener, biobased solvents. But there are also easy adjustments you can make, like turning equipment off overnight or increasing the freezer temperature.”

These adjustments make the labs more sustainable, but it also saves money. “By switching to being a Green Lab, you can save up to €5000 per lab each year. By increasing the freezer temperatures of the participating labs in Groningen from -80°C to -70°C, you save the energy worth of up to 18 Dutch households per year, without harming the quality of the frozen goods. We also improve the teaching labs to being more sustainable, this way the students are educated with the right mindset, achieving a paradigm shift over the years.”

Green Politics

Not only does Thomas invest in making labs more sustainable, he is also politically active in his home country Germany for the Bündnis 90 / Die Grünen party, which is the German green party. Thomas thinks his work as a PhD candidate is actually not that different from his role within the party: “As a scientist for ARC CBBC that is always trying to find solutions for climate change at work, you become more and more aware of climate change in your private life as well. As every day you read about things, that can be improved, or about energy carriers in general.”

“People regularly approach me to talk about green chemistry, since I can often answer questions about hydrogen and sustainability more appropriately than politicians or the media, being a PhD candidate in the field. So, I decided to join the Green Party, and help around elections and educating people in my area about hydrogen and energy carriers. I essentially use my CBBC knowledge about green energy and green chemistry to tell people about the importance of the energy transition.”

So, is there any difference between Thomas’ work as a researcher and his role in the Green Party? “I think it is the same! Because my job is green chemistry within the CBBC, I also became more environmentally aware in my private life. And then all of this became more political, as I wanted to see change in Germany. I wanted to help and do something with my position as a scientist.”

His activities next to his PhD work might be the thing that convinced the jury of the Joseph Breen Memorial Fellowship to award him with the honor of receiving it. More than deserved, if you ask us. In June, Thomas will be joining the 27th Annual Green Chemistry & Engineering Conference in Long Beach, California with his Breen Fellowship. We had to wrap up our interview, as Thomas needed to leave: he had a next appointment, checking a lab that applied for the Green Labs initiative. We hope he still finds some time for his research within his busy schedule, and we are looking forward to see what he brings us in the future!