Rethinking the energy system


As part of the 11-14 March Water and Climate Festival in Louvain-la-Neuve, Science Today is highlighting UCLouvain ecological transition research and researchers. Gauthier Limpens, a PhD student at the Louvain School of Engineering (EPL), wants to offer decision-makers the best method of integrating energy storage.

We talk a lot about storing energy’, says Gauthier Limpens. ‘Yet there are very few studies on it.’ A mechanical engineer who graduated from UCLouvain in 2015, he studied aeronautics before starting his PhD three years ago, and is passionate about this innovative subject. ‘I wanted to better understand energy storage integration. Because to date studies focus only on storage technologies, such as electric batteries, and not on our society’s entire energy system.’

The energy system is Mr Limpens’s subject. It includes everything that allows for heating, electricity and mobility for both households and industries. With massive integration of renewables, storage needs will be enormous. ‘If we look at the power grid in isolation, for example, it will require a very large storage capacity just by itself’, he explains. ‘But if you extend the scope and look at the whole system, it's obvious that you can provide an equivalent service through other, cheaper and more easily integrated renewable technologies. In the end, the energy transition could involve an increase in spending on local infrastructure, but also, in return, savings on the purchase of fuels from abroad.’ How to integrate as much renewable energy as possible and address the future role of storage are two facets of his research.

Long-term investment

The only downside: by integrating renewables into the entire energy system, the question arises of immediate resource availability. ‘We all want to be able to turn the light on or off whenever we want. Renewable energy fluctuates too much for that. Considering other energy needs, however, such as heating or transportation, can help you see where to compensate.

For Mr Limpens, electric heating methods can increase energy efficiency: heat pumps, which are much more efficient than gas burners, fall into this category. ‘But the problem is economic: it's a higher investment cost and a lower operating cost. So it's profitable in the long term, but in the short term it requires more money.

It’s this thinking that has led him to focus on very flexible technologies at the level of consumption and to address the role of storage technologies in energy systems with high renewable content. The leading example is thermal storage, which is much less expensive than electrical storage. It’s an alternative to the intermittent nature of renewable electricity generation. He expects heat pumps, for example, to respond to this irregularity. Supervised by Hervé Jeanmart, an EPL professor deeply invested in the research, member of Louvain4Energy, Mr Limpens says the objective is clear: ‘To target policy! We’re working on how to answer very practical questions for decision-makers: how to reduce CO2, integrate more renewable energy, bring flexibility to the electricity grid or electrify heating, for example.

Another two years

He has two years to go. There’s already evidence of what the energy system will look like in high-renewable-rate societies: to integrate more renewable energy into the system, other sectors need to be electrified in order to integrate efficient technologies such as cogeneration that allows electricity and heat to be produced simultaneously. Also crucial: ‘We totally underestimate the role of thermal storage. In the appropriate legislative framework, it can provide a great deal of flexibility. It's obvious we'll need a storage mix in the future.

Mobilising policy

One of the goals of your research is to mobilise and deliver clear advice to policy-makers.
In Switzerland as part of my PhD, I worked at the Swiss Federal Institute of Technology in Lausanne (EPFL), in the ‘Industrial process and energy systems engineering’ group (IPESE). The researchers had developed a tool that I use today,, to evaluate a series of parameters related to the energy consumption of the federal state. It was developed in the canton of Vaud prior to a referendum on whether to integrate renewable energy; 58.2% of all Swiss voted in favour*, but in Vaud, where the tool had been used the most, 73.5% were in favour. I’m convinced that there’s a way to have an impact, not just on the population. We can also explain to politicians that technologies must be encouraged in parallel, such as heat pumps along with thermal storage, but then it’s up to them to see how to get there.

*More info

And businesses?
We’re clearly looking at the industrial level and showing what the future will look like: it’s a huge asset for them. Moreover, we have a lot of interactions with and requests from businesses. This will allow them to know what positions to take on the market but also increase their visibility in relation to future strategies and position themselves for a future that’s much closer than we think.


Energy system: at the country level, it includes everything that allows for heating, electricity and mobility for households and industries.

Marie Dumas

A glance at Gauthier Limpens's bio

Gauthier LIMPENS is a researcher at the University of Louvain (UCLouvain) where he has specialised in energy and aeronautics since beginning his master’s degree in 2015. After a residency as a computational engineer in the SAFRAN group (aeronautics), he transitioned to the energy sector, convinced of the challenges it faces in the 21st century. In 2016, he became an energy teaching assistant and began a PhD thesis on energy storage. His work entails addressing the energy system as a whole, a new subject at UCLouvain, which is why he is undertaking a research internship at EPFL, a leading school in the field. His research will continue for the next two years at the Institute of Mechanics, Materials and Civil Engineering and its Thermodynamics and Fluid Mechanics Division (iMMC-TFL) and in collaboration with EPFL.

Among his most recent publications: ‘Electricity storage needs for the energy transition: An EROI based analysis of the case of Belgium’ (2018) and ‘Quantification of electricity storage needs for energy transition Belgium: a sensitivity analysis based on EROI’ for the ‘International Conference on Efficiency, Costs, Optimization, Simulation’ (ECOS2018).

Published on May 02, 2019