Interview with Professor Alexander Sauer

Prof. Alexander Sauer of the University of Stuttgart, jointly with Prof. Abele of the TU Darmstadt, heads the management board of the SynErgie Kopernikus project.  An interview about production bottlenecks, the question of how individual solutions can be transferred to entire sectors, and about the enormous potential of flexibilisation for the success of the Energiewende.

Energy efficiency is one of the three key goals for the Energiewende - together with the expansion of renewable energies and climate protection. What role does energy efficiency play in SynErgie?

The focus of SynErgie is how we can make industrial processes flexible so that machines in factories can better adapt to fluctuating renewable electricity supply. Energy efficiency here is just one aspect among many - but the project does of course contribute to making the system as a whole more efficient.

What is your task within SynErgie?

The Institute for Energy Efficiency in Production (EEP) at the University of Stuttgart shares responsibility for the overall coordination of the project with the Institute of Production Management, Technology and Machine Tools at the TU Darmstadt. Specifically we at the EEP are responsible for two sub-projects in the car industry as well as coordination of the Potential Analysis Cluster. On the technological side for example we’re undertaking research in a supplier’s foundry that consumes a lot of energy, and so has high energy costs without exemption from the levy under Germany’s Renewable Energies Act (Erneuerbare-Energien-Gesetz - EEG).

Why have you chosen a foundry for your investigation?

A foundry allows us to get into some real technological development. During the casting process metal is first liquefied then pressed into shape under high pressure. Electricity, gas or oil can be used to melt the metal in the casting cell. Many of these cells are currently electrically-operated, the advantage being that electricity can be more precisely controlled than gas. Electricity consumption in this process is very high, due to the high temperatures.

How could this be made flexible?

To be able to melt magnesium, for example, you need temperatures of over 650 degrees. The question here is how can we make the electrical power consumption for the melting flexible. However, the bottleneck in the casting process is cooling of the metal, where little can be changed. What could however be changed for example could be the size of the melting vessel - this process step is very energy-intensive, so we could for example melt more metal at times of low electricity prices. This has almost no impact on the other logistics and value chain.

Are there any other possibilities for flexibilisation?

The second option would be to change the energy carrier: Here we want to operate a casting cell with both electricity and gas so that the machine can switch to the energy carrier that at the time is available on the best and most favourable terms. The decisive factor is that the final quality of the components remains the same. A technology that can be used to decide when to use electricity or gas would contribute decisively toward the flexibility of the industry. The next question then is where and how the signal comes to use electricity or gas. This must be automated.

Are you also working on automated control?

We are working on this in Cluster III, which is being headed by the Fraunhofer Institute for Production Technology and Automation (IPA). A key question here is: How does the electricity price signal get to the machine without an employee having to stand by the machine all day monitoring the electricity price and taking decisions? Moreover, we must also include the whole production infrastructure in our research. That applies to the compressed air system as much as it does to the lighting. We’ll look at anything that can be made flexible.

Why is the car industry a good area for research?

There are a very large number of manufacturing steps that are always aligned precisely. Because of this, the challenge is not to delve deeply into the production technology process itself, but rather into the systems not directly dependent on this process: Cooling and heating systems, pumps, all the ancillary processes that together account for about half the energy consumption. Gas is again used as an alternative to renewable electricity when this is too expensive. In the long term however we want to try to move away from fossil fuels. Gas produced from renewable electricity, for example in a Power-to-X process, could help replace fossil fuel gas.

You are first performing a potential analysis to establish how many steps in the industrial processes can actually be made flexible. How are you doing this?

We’re looking at the individual key production processes through to the network connection. Generally speaking, there is always a bottleneck in production processes and you need to know where these are if you want to make the individual components of the system flexible. If you ignore this bottleneck you cannot achieve the potential flexibility - it wouldn’t be achievable due to the system structure. So we firstly need to identify the bottlenecks, and secondly we need to work out how solutions from individual companies can be transferred into the sector as a whole. Factors such as the age of the plant and machinery, and machine utilisation, are important here.

What challenges do you see in making industrial processes flexible?

Spontaneously moving production shifts around simply because electricity is available on favourable terms, at the weekend for example, won’t be readily achievable in Germany. However a few process steps do offer potential for flexibility: Cement mills, where stone is ground, and the paper and aluminium industries, require huge amounts of energy. If we look at a cement mill, which is grinding down stone for producing cement - that is the bottleneck. If this mill stops, there is a 1:1 drop in overall cement production. Slowing the plant at the bottleneck operation is not an economic alternative if this leads to reduced turnover.

To what extent can flexibilisation of industrial process contribute to the success of the Energiewende?

There’s huge potential. Industry will have to convert many of their processes from fossil fuels, turning to electricity. But if we cannot at the same time make a significant leap in energy efficiency, the Energiewende will not be a success. Because if energy consumption in industry continues to rise we cannot produce the quantities of electricity from sun and wind that would be needed. However, energy efficiency is neither an equally-valued second pillar in the Energiewende, nor is it a first priority compared to the expansion of renewables.