Professor Frank Behrendt holds the Chair for Energy Process Engineering and Conversion Technologies for Renewable Energies at the Berlin Institute of Technology (TU Berlin), Germany, where he coordinates all energy-related research activities. He was also the Guest Editor of the Chemie Ingenieur Technik special issue “Energy” published in November last year. He talks to ChemViews magazine about the public perception of renewable energy, his research, and the sustainable cities of the future.
How is renewable energy viewed today?
I would say it depends strongly on what kind of renewable energy we are talking about. First, most of the discussion right now is focussed on the generation of electricity and to a far lesser amount on biofuels. Electricity results mainly from wind power, and also to a much lesser extent from photovoltaics. Second, the generation of fuels from renewable sources will play a role. Third, the energy supply system of an industrialized country consists not only of these two but of three main parts – supply of heat should not be forgotten. For Germany we look at roughly 620–630 TWh of electricity. With respect to heat generation, we talk about roughly double that number with 1350 TWh. Right now, roughly 9 % of this is generated from renewable sources and more than 90 % out of that number is from one kind of biomass or another.
How does this relate to the political situation in Germany?
The German decision to transform the energy supply of an industrialized country into one where at least 80 % of the electricity is generated from renewables and where roughly 60 % of the primary energy consumption is to be from renewable sources is a pretty unique approach on the worldwide scale. It does not necessarily mean that other countries will not adopt certain aspects of this, but right now we have a very specific and very unique situation in Germany. France, for example, is still generating roughly 80 % of its electricity from nuclear power plants.
We will see how far our current portfolio of technologies is sufficient to address this. One has to be very clear about one point. We are talking about changing the energy supply system of an industrialized country in a period of just four decades – 38 years left, to be more precise – and we have to be very clear that today´s technology will only carry us for the next ten or fifteen years. Consequently a significant research effort in a broad set of disciplines will be needed to generate solutions for 2050. To keep one thing in mind, we are right now extrapolating today´s technology in a pretty linear fashion. You never know what kind of disruptive technologies will show up in between. For example, 25 years ago, or let’s say 20 years ago, essentially no one talked about mobile phones. You never know what kind of technology may show up and may complement our current set. It´s an interesting game. 40 years seen only in a linear extrapolation of today´s technologies is prone for a number of interesting surprises.
So it is hard to say what the most promising technology will be then?
The most promising first step is to reduce the energy consumption and to improve efficiency of all processes involved. Second, it will be a mix of technologies. This mix will be even regionally different. You will have a different situation in more rural oriented landscapes where you can use biomass to much larger extent. You will have different situations if you talk about the energy supply situation, both in terms of heat and in terms of electricity for larger cities. So, there will not be a single solution for everything. We are talking about mixtures. These will evolve with time. The most dangerous thing which can be done by politicians, in part misguided by interest-driven advisors, is to hope for a single technology which solves all our problems. That is the old danger of having a hammer, everything looks like a nail. We will have a mix and not even this will be constant over time.
What do you mean with “not constant over time”?
For example, if we have strong sales in the photovoltaics sector, they may evolve more quickly than today’s technology. We will also have to see how offshore wind power evolves. Right now we are in a very early testing phase but we are already betting on having roughly 25 GW of installed power of wind power systems offshore in 2020. And honestly, we have no real clue of how to do this. For two reasons: First, we are still looking for materials which will resist the effects of salt and the power of the wind and the waves offshore. And second, we will have to find a way to get all the cables out there and to connect them to the cables onshore. The companies who are investing in offshore wind power right now are facing a lot of problems in getting the offshore wind parks under construction connected to the onshore grid. Companies are simply not able to supply the cables for the installation and the electronics, because there are too many orders coming in for them to fulfill.
Do you think the political and the public interest in this topic is a good or a bad thing for research?
I would say to optimize the energy supply system of an industrialized country is always an interesting, good, and positive development. On the other hand, the political decision in Germany in the summer of last year has caused a certain perception in the public that we simply need to take everything out of the box, install it, and everything will be done. That is a total misconception. We are talking about a lot of research efforts, starting with very basic research all the way up to applied research. And we will need to find some new business models. We have to define certain new technologies to implement this. The current hype with respect to renewables is only second to the hype of electromobility. Something which has a certain potential is viewed by the public as ‘we only have to do it, but there are bad people blocking it’. That is a wrong perception.
There are a lot of technological challenges to overcome. That is always a problem with public perception. There was the `Bürgerdialog Energietechnologie´ organized by the BMBF (German Federal Ministry of Education and Research) in the second half of last year, and I was privileged to chair the scientific advisory board for it. We had a number of interesting discussions with roughly 1000 participating citizens. One of the defining aspects was that when the discussion started there was always a trend to say everything could be done if the bad industry would not block us — the big bad industry. It took even pretty intelligent people quite a while to realize that there is no division between the personal well being and the well being of the industry, as most of them are working in the industry. And in case of energy intensive industries, it is a question of whether they can survive a 10 or 20 % general increase in energy prices without reducing the number of workers.
A significant part of the discussion of last year – right now the discussion is not so intense anymore, because we are talking mainly about the crisis in Europe – was focused on ‘who is blocking our way to the green future?’ There was less focus on the questions, ‘what are the consequences of what we have just decided with respect to private and public aspects?’ and ‘what are the challenges we have to overcome and what is currently missing?’ in open discussions about technological challenges, financial challenges and society challenges. Many people like renewables, but not in their own backyard.
Scientists have to do lobbing work in this area as well, so how important do you think is it to teach at universities or maybe also in school about renewable energies or energy change?
I would say starting in kindergarten, in schools at various levels, and at universities it is important to understand — at the appropriate level — that when we talk about energy, we normally have to deal with a system. We don’t have to deal with a single technology or with a single aspect of something, but with respect to the energy supply system of an industrialized nation you have to be somewhat careful about what to change in what timeframe. That is something you need to tell people.
Also, something many people don´t realize is that if you have a certain amount of energy at a higher temperature level, it is more useful than a larger amount of energy at lower temperature level. Energy at a very low temperature level cannot be reused again and again and again, because the efficiency goes down and down and down. This pretty trivial statement is something which you should start teaching early in physics.
I am not advocating, by the way, the introduction of Energy as a subject at school or as a study course. I am still a kind of old fashioned fan of a good education in the basic sciences – in chemistry, in physics, in mathematics – and to use this to gradually explain and introduce certain facts which you need to know about. People do need to be confronted with interesting examples from the field of energy, however.
How is your own research focused in that direction?
First, I am a chemist by education. I started my scientific work in physical chemistry in reaction kinetics, working in combustion processes, mainly with methane in gas phase combustion. Then I moved to heterogeneous systems, catalytic supported ignition, and combustion processes. When I moved to Berlin in 2001, I took over the chair of energy process engineering and conversion technologies to renewable energies.
A major part of my work is focused on the gasification of biomass in various reactor types, both in experiment and numerical simulation and on direct liquefaction of coal. A smaller part of my group is working on energy system analysis. We look, for example, at questions like ‘Is a state like Brandenburg able to supply enough biomass to generate all the biofuels needed for a city like Berlin?’ or other questions like ‘To what extent can renewable energies be used in seawater desalination processes?’. This is because an increasing amount of drinking water is generated worldwide from saline sources, simply because the ground water resources are depleted or contaminated by some means. In many cases desalination is based on either heat or electricity generated by diesel-generators. For example, we looked at island countries where desalination may be needed, and study to what extent renewable energies in an energy mix can be used to generate water. If you want to generate roughly 10 000 m3 of water per day — enough for approx. 20 000 island inhabitants — by using reversed osmosis you spent roughly enough energy to drive a personal passenger car four times around the globe — daily.
So, my research is both the physico-classical chemical approach to gasification of biomass, treatment of the product gases, removal of tar components, and the preparations for follow-up steps on the one hand, and also energy system aspects with a strong focus on the question to what extent renewable energy can be integrated in overall energy supply systems, on the other.
You were the Editor of the special issue “Energy” published in November by the journal Chemie Ingenieur Technik. Why do you think were you invited to do so?
I guess because I headed the topical network of energy and resources of acatech, The German Academy of Sciences and Technology, for two years. Also, at my university I am the speaker of “Innovationszentrum Energie” (innovation center of energy) which coordinates energy related research across six out of the seven faculties. This pluristic view of energy supply systems and the importance of chemistry, physics, and engineering in supplying both electricity and also heat and fuel, spans a much wider area than is covered in my own research group.
And what was it like to work on the special issue?
It was fun and very interesting. To edit such a kind of special issue is always a good way to understand the state of the art of a field and to learn something from it.
How did you decide who to include in the issue or which topics to concentrate on?
I did not decide to exclude topics, but they all had to have something to do with chemical engineering, because of the scope of the journal Chemie Ingenieur Technik. Then, due to my work in acatech and due to my own scientific work, I think I have a reasonable good understanding who is involved at what university in what field. So I looked around a little bit, talked to colleagues, and did seek some recommendations.
You are also in the science advisory council of the EUREF institute. Can you please tell us a bit about this please?
The EUREF area is essentially an operationally CO2-neutral urban area in Berlin. It is in the making around a former large gas storage tank (“Gasometer”) in Berlin Schöneberg known to the broader public as the location of a popular Sunday TV talkshow. The TU Berlin is establishing three Master classes urban energy concepts with focus on buildings, mobility and infrastructure. I happened to be the coordinator of this. Here we focus on how our cities — with respect to buildings, mobility, and infrastructure — will evolve in the upcoming years. How will we be able to be more energy efficient, less energy consuming and to what extent will we be able to introduce renewable energies at various stages?
So can you give us a short insight of how a city might look 50 years from now?
PPHHHH!!! Hopefully, we will be able to live in buildings that consume only a minimum of energy. I don´t think that in metropolises we will be able to supply all the energy we need within the metropolis itself. My assumption would be that the amount of energy needed for heating and for mobility aspects will be generated in large extent from renewable sources. But for that, we will need to introduce new materials, for example, strong and light-weight materials which allow us to build cars, or whatever will be used at that time. I still expect there will be individual traffic in that time. I don´t think that public transport will cover every aspect of life.
We hopefully will have a large amount of newly built, highly energy efficient buildings, but we will still have about half of the buildings that exist today and we will have to find ways to insulate and operate them in a way that the amount of energy used in their operation is minimized. With respect to infrastructure, essentially we will still have waste water and we will need fresh water, we will need heat and electricity. It´s always the question of to what extent.
And by answering your question I did something I condemned a few minutes ago: my assumption of the future city is pretty much a linear extrapolation of today’s situation. This is, in part, driven by the fact that the typical lifetime of a building is about a century. So, the older cities, which we have all over Europe and in parts of the US, will probably change only slowly. It´s slightly different if you look into green field situations, where you are able to build new cities where nothing has been before.
So this is good news for our old and historic houses, that they will survive.
By the way — when we talk about protection of historical monuments, this will also be an interesting challenge. Right now, we have a strong conflict between protection aspects and renewable energies, because you cannot do external insulation as needed. And internal insulation still holds lots of unsolved challenges. So if you want to make an older building more energy efficient, it´s an extreme challenge to the people who design the new materials to be used, to civil engineers who implement those materials, and maybe to architects who come up with interesting ideas on how to maintain the style of the old building while enhancing its overall energy efficiency. At the same time, a building must not loose its livability, because if you insulate a building nearly perfectly without any exchange of air you run into trouble with mildew and things like this. We all know these discussions. That is also a field where we will need to learn a lot of things. And because we have this large base of existing buildings, this change will be only gradually. Currently, we are modernizing roughly 0.6 % of our buildings in Germany on an annual basis, so it will take quite a long time to bring everything up to standard.
Are you interested in historic buildings in your spare time or what else do you enjoy doing?
I play golf but lack the intense training and time needed to become good at it and I like to travel a lot, which I also do for business reasons. I try to combine business travel with a few days of spare time, if possible. I like to see what the rest of the world looks like and meet people in foreign countries, learn about their perspectives of the world and their expectation of how the world will develop. To travel around a lot and meeting people with various cultural backgrounds is one of the privileges a scientist has.
Thank you very much for this interview.
Professor Frank Behrendt studied chemistry at the University of Heidelberg, Germany. He completed his Ph.D. at the same university in 1989 in the field of simulation of combustion processes using detailed chemical reaction mechanisms. He completed his habilitation on catalytic ignition and combustion processes in 1999 at the University of Stuttgart, Germany. Behrendt joined the faculty at the Berlin Institute of Technology (TU Berlin), Germany, in 2001, where he holds the Chair for Energy Process Engineering and Conversion Technologies for Renewable Energies and coordinates all energy-related research activities at that university.
His research interests include numerical and experimental investigations of gasification processes of biomass leading to synthetic fuels as well as numerical studies on heterogeneous catalytic reactions and reactors.
- Special Issue: Energy Editorial: Herausforderung Energiewende,
Chem. Ing. Tech. 2011, 83(11), 1755.
- Synthesis of Fluorescence-Labelled Glycosidic Prodrugs Based on the Cytotoxic Antibiotic Duocarmycin,
L. F. Tietze, F. Behrendt, F. Major, B. Krewer, J. M. von Hof,
Eur. J. Org. Chem. 2010, 36, 6909–6921.
- Direct Liquefaction of Biomass,
F. Behrendt, Y. Neubauer, M. Oevermann, B. Wilmes, N. Zobel,
Chem. Eng. Technol. 2008, 31(5), 667–677.