I understand that this is neither a typical research paper nor a collection of research papers summarising research findings in the usual manner of a review paper. Instead, this is my personal tribute to the memory of one of our esteemed colleagues, Professor Paul L. Younger, who held the Rankine Chair of Energy Engineering at the University of Glasgow from 2012 to 2017. He had a profound impact on the development of my academic career and that of others within the Energy group. The purpose of this piece is not to reiterate his world-leading contributions to energy research but rather to share my personal reflections as a colleague and friend. Looking back on those times, I still remember the friendly and insightful discussions I had with Paul —conversations that I continue to value and deeply appreciate.

In 2012, even before officially joining the University of Glasgow, Paul emailed me with a research proposal he was leading on “Subsurface Engineering for Underground Coal Gasification (UCG) and Subsequent Carbon Capture & Storage” in collaboration with Five-Quarter Energy Ltd. I found it fascinating to learn about his perspective on gasification – while I was exploring biomass gasification, he was focused on UCG. This alignment of interests led to the development of our first collaborative PhD project on the topic, which was later followed by another, supported by the Energy Technology Partnership (ETP) and Cluff Geothermal Ltd.

Paul, as a senior colleague, was always very approachable and easy to talk to. I still remember the day after he joined when he emailed me, saying, "Hi Manosh, can we have a cuppa at some point together? I have just joined the University ...".

One day, I was thinking about developing a Combustion and Gasification Engineering (CombGEN) network with funding support from the Carnegie Trust and the EPSRC Impact Acceleration Award, in collaboration with colleagues from Edinburgh and Robert Gordon Universities. When I first discussed the idea with Paul, his response – “This is an excellent idea, Manosh. Let's do it!” – filled me with energy and enthusiasm.

Our CombGEN proposal was shortlisted for an interview, and I asked Paul if he could join me. Without hesitation, he agreed to help. On the day of the interview, I planned to drive from the University campus to the Carnegie Trust, so I waited outside the James Watt School of Engineering Building for Paul to come from his office. When he saw me sitting in the car, he said, “Manosh, I can't wear a tie if you don’t because you’re the PI … ”. I laughed and said, “I didn’t bring a tie with me – I thought it was a research interview, so I didn’t think much about it!”. Without a second thought, Paul instantly removed his own tie and said, “Here, you wear this – I’m coming from my office, and I have a spare one”. It might seem like a small, everyday conversation, but whenever I recall this moment, I still get emotional. It reminds me of what a generous and friendly colleague Paul was. That day was also the first time I had the chance to sit and talk with him for a long period while I was driving. We discussed many things, and Paul even shared stories about his early research career, including his experiences with FORTRAN programming while working on a project in the USA!

We successfully secured the grant to officially launch the CombGEN project, which became a significant milestone in developing several other research projects and ideas in collaboration with industry partners. I continued to work closely with Paul on various joint projects, it is my pleasure to share below some photos of Paul taken at the CombGEN event we held in 2015, as shown in Figure 1-5. You are still greatly missed, Paul.

Figure 1 The CombGEN event banner.

Figure 2 Paul’s Keynote talk on the opening day of CombGEN.

Figure 3 Paul was giving a keynote in the opening event of CombGEN.

Figure 4 Paul was explaining the role and importance of future combustion technologies.

Figure 5 Paul joked on a picture he downloaded from online and someone photoshopped it.

Figure 1 The CombGEN event banner.

Figure 2 Paul’s Keynote talk on the opening day of CombGEN.

Figure 3 Paul was giving a keynote in the opening event of CombGEN.

Figure 4 Paul was explaining the role and importance of future combustion technologies.

Figure 5 Paul joked on a picture he downloaded from online and someone photoshopped it.