“It all comes down to the life cycle assessment.”

An interview with Prof. Dr.-Ing. Matthias Stripf, director of the Steinbeis Transfer Center for Thermo-fluid Dynamics and Efficient Energy Conversion.

Prof. Dr.-Ing. Matthias Stripf talked to TRANSFER about efficient energy conversion and the current infrastructure changes in the German energy grid. He also ponders the question of which challenges this process will create for everyone involved.

Professor Stripf, the laws of physics teach us that energy is neither created nor destroyed, but converted. Since the kick-off of Germany’s transition to renewable energies, we’ve been seeing an emphasis placed on efficient and environmentally friendly energy conversion. But how is that supposed to work?

The topic of efficient energy conversion has been shaping the engineering sciences for over 200 years. For example, as a result of this relationship, we were able to increase the efficiency of fossil fuel power stations by 6% over the last 20 years here in Germany. The resulting savings we were able to achieve could cover the entire power consumption of a country like Austria. We can achieve savings on a similar scale just by replacing all light bulbs with energy-saving alternatives or LEDs.

Although a lot has been done in terms of efficient electrical power generation and usage, we can’t really say the same for progress in other areas such as space and process heat or efficient travel. But these comprise 80% of our ultimate energy use, which is why we really ought to be focusing our development in these areas.

It doesn’t make sense to introduce many of the well-known technologies used for indoor heating (e.g., heat pumps and solar thermal systems) on a broad scale since this would require specific infrastructure: there isn’t enough roof area, not all buildings are equipped with modern under floor heating, or it wouldn’t be possible to install a downhole heat exchanger for an outside heat transfer system. New technologies such as gas heat pumps, fuel cells, and small cogeneration units are still in their infan-cy, and despite government funding, they aren’t yet as cost-efficient as standard gas-powered boilers.

Only those technologies that show large-scale cost reduction potential and greater production numbers will stand a chance on the market. Technologies that require rare or expensive materials or manufacturing processes, and that aren’t easily scalable to large batch numbers, won’t really play a part in world-wide energy conservation efforts. Overall, energy efficiency is only part of the picture when it comes to a technology’s or product’s life cycle assessment. But life cycle assessments are vital and this topic should feature much more prominently in political debate and legislation. It makes little sense to only look at the energy efficiency or CO2 emissions of products without considering all of the resources required to pro-duce and recycle them.

If we place greater emphasis on efficient technologies for heat supply and the transportation sector in future, and we start to take a closer look at life cycle assessments and cost-reduction potential, we will find a sensible way to achieve the transition to renewable energies here in Germany, and we will be able to export these new technologies worldwide.

Your Steinbeis Transfer Center offers its customers – among other things – services in the field of efficient energy conversion. Why did you decide to specialize in this area?

I’ve been fascinated by thermal and fluid dynamics since my college days. I also really enjoyed electrical engineering and computer science. All of these areas come together in efficient energy conversion. This has allowed me to make a career out of one of my hobbies. Add to this the fact that the Steinbeis Transfer Center works closely with the Institute of Refrigeration, Air-Conditioning, and Environmental Engineering (IKKU), which is based at Karlsruhe University of Applied Sciences. This gives us access to excellent know-how and outstanding infrastruc-ture including modern wind channels and measurement technologies. We can tap into the best setting imaginable.

Energy providers, network operators, and industry can expect new challenges on account of the current infrastructure changes in the German energy grid. What role will thermal energy conversion play here?

These days only 20% of the energy demanded is needed as electrical power, the rest comes from fossil fuels, for heat generation and mechanical energy for drives. But with the exception of biomass, renewables feed electrical energy directly into the electricity grid.

If we were to power all heating systems with electricity or heat pumps and make a switch across the board exclusively to electric vehicles, this would require drastic remodeling of not just the large power grids, but also the local distribution networks. But we’re already seeing the extensive costs involved in this kind of expansion, even though a rise in the number of electricity users hasn’t yet been accounted for. And then add the unresolved issue of how to store large amounts of electrical power. This is another reason why many consumers will still rely on fossil fuels in future. The natural gas grid, which offers large transfer and storage capabilities, could be used for renewable energies as well. This would involve using electrolysis, converting electrical energy into hydrogen and then converting it further into methane through car-bonation. Since so much gets lost in conversion, it’s all the more important that the conversion chain (e.g., from methane into heat using gas heat pumps, or from methane into mechanical energy using cogeneration units) becomes more and more efficient. It’s important to keep trying to improve thermal energy conversion processes.  An additional challenge lies in the many district heating grids, which are often supplied by coal-fed power stations. New solutions must be found for this as part of a sustainable transition to renewable energy sources. Such solutions could include connecting large manufacturers (which generate a lot of excess heat) to district heating grids or operating gas and steam power stations with renewable methane. At the same time, consumers have to become more efficient and come to terms with lower room temperatures. One option for this would be heat transformers, which use district heat to power motors to supply heat at higher temperatures or provide refrigeration.

What kinds of challenges do you foresee this process will bring on in future for the sciences, transfer, and edu-cation?

The required technologies for Germany’s transition to renewable energies dip deep into the engineer’s toolbox. Successful new products in this sector can only be achieved through interdisciplinary collaboration between the engineering sciences. Properly organized knowledge transfer between special-ized Steinbeis Enterprises, other research facilities, and industry can stimulate new approaches and help bring ideas and new products more quickly to fruition. But it’s even more important that more is done in schools and universities to lay the right foundations by introducing students to the basic principles. This is a prerequisite for finding new ways to collaborate seamlessly between the engineering disciplines. Shortening the time needed to earn a general qualification for university attendance and shortening the time needed to complete degree programs sends the completely wrong signal. As people are expected to enjoy longer lifespans, this time should be invested into more extensive education.


Prof. Dr.-Ing. Matthias Stripf is director of the Steinbeis Transfer Center for Thermo-fluid Dynamics and Efficient Energy Conversion at the University of Applied Sciences in Karlsruhe. The Steinbeis Enterprise has specialized in the design and optimization of cooled components and components subjected to through-flows. It also carries out applied research in the areas of waste heat utilization, efficient energy conversion, and component cooling.

Professor Dr.-Ing. Matthias Stripf
Steinbeis Transfer Center Thermo-fluid Dynamics and Efficient Energy Conversion (Karlsruhe)

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