Sustainably distributing green energy
We need flexible electrical networks to supply energy generated from renewable sources
© photos: thyssenkrupp Steel
Generating energy from renewable sources is not enough if the energy transition is to succeed; it also needs to be distributed sustainably. Although green energy generated from wind turbines and solar power systems is good for the environment, we can only be certain that this energy is distributed reliably if it can be fed into the transmission networks at a consistent frequency and voltage. A growing number of consumers now produce their own electricity, for example, using solar panels installed on their roofs. This leads to a steady increase in the number of decentralized, regenerative energy sources.
Grain-oriented electrical steel makes a new network structure possible
That’s why the Flexible Electrical Networks (FEN) research campus at RWTH Aachen University took it upon itself to research and develop a flexible, electrical power network. Among other things, the aim is to develop new technologies that allow this energy to be distributed efficiently, securely, and affordably in the future.
The consortium consists of representatives from the field of science and business. In the interview, Professor Rik De Doncker, Managing Director of the FEN research campus, and Dr. Jens Overrath, CEO of the Electrical Steel business unit at thyssenkrupp Steel, discuss the use of renewable energies and what role grain-oriented electrical steel has to play in it.
Prof. De Doncker, you are in charge of the research campus for Flexible Electrical Networks, or FEN for short. What is this project all about?
De Doncker: Our electrical supply system will continue to shift towards environmentally friendly, decentralized energy sources. However, this requires a new network infrastructure to transport, distribute, and store this energy in a more efficient and flexible way. But these types of electrical networks cannot be developed and implemented without a high degree of transdisciplinary research and interdisciplinary cooperation.
What does that mean in practice?
De Doncker: At RWTH Aachen University, we have set up a local medium-voltage and DC network for demonstration purposes. This 5,000-volt DC network is operated within the university’s infrastructure and couples the Center for Wind Drives with the E.ON Energy Research Center’s five-megawatt laboratory for medium-voltage converters. This enables us to develop new DC voltage components such as DC converters for modern substations, wind turbines, or fast-charging columns.
Science and industry researching together
Who is involved in the FEN project?
De Doncker: The research campus is funded by the German Ministry for Education and Research (Bundesministerium für Bildung und Forschung; BMBF). It is an association of institutes at RWTH Aachen University as well as a consortium of 21 partners from different specialist and company departments. One of those is thyssenkrupp Steel – specifically, its Electrical Steel business unit.
Mr. Overrath, why is the Electrical Steel business unit involved in the FEN project?
Overrath: We think it’s exciting and hugely important that alternative concepts for the transportation and distribution of electricity are not only being developed here, but are actually being implemented. This is because if we want to take the energy transition seriously, then we have to find new technical solutions to tackle it and produce evidence that these solutions work. It is important for us to know what electrical power networks will look like in the future when it comes to the issue of transporting energy. If the networks change, then the associated transportation equipment will also change.
Which is where Electrical Steel comes in…
Overrath: Exactly, because you need transformers to transport electricity, and grain-oriented electrical steel is at the heart of every transformer. For us, it is about optimizing our materials at an early stage so that they can fulfill any future requirements.
DC technology is the solution
What sort of requirements do you mean?
De Doncker: If we want to feed in more or even just renewable energies in the future, then we also need to create a storage system for it. And we need flexible networks that are capable of also distributing energy in the locale in which it was generated.
Why can’t we do that now?
If you have a photovoltaic system on your roof right now, you can’t transfer any excess energy directly to your neighbor. As it stands, this electricity is normally fed back into the high-voltage networks, meaning it is increased over the voltage level present following generation before then being transported via the overhead medium- and high-voltage network and redistributed.
What is your solution?
De Doncker: The key to this is DC technology, which enables distribution networks to be coupled with one another at the same voltage, creating a direct flow of energy between the generator and consumer. Multiple customers in the same network can be connected with one another via these decentralized solutions and exchange energy locally. This turns consumers into prosumers who do not just use energy, but also produce it.
Lower losses ensure the highest efficiency
What role does grain-oriented electrical steel play here?
Overrath: Electrical components and systems such as DC transformers are required to set up and operate this type of DC network. The core of a device like this consists of highly magnetic electrical steel, which is designed to perform with the utmost efficiency. For the FEN project, we are using the thinnest material available to us right now to first set up a three-phase, so-called solid-state transformer.
What is so important about the material?
Overrath: First and foremost, the magnetic power loss must be reduced to a minimum. But thermal stability and strength are also important. This type of transformer is constantly in operation. The transformer and its grain-oriented electrical steel core have to perform 24 hours a day, 365 days a year. Transformer downtime can lead to massive economic losses or create a safety hazard. For example, Hamburg Airport had to cease operations for one day last year due to a transformer going down.
There is no energy transition without electrical steel
Is the energy transition possible without grain-oriented electrical steel?
Overrath: No, without our powercore® trade mark electrical steel there is no energy transition. It doesn’t matter if we are talking about wind turbines or photovoltaic plants, they all require a transformer to store their energy in the networks. Electromobility also doesn’t work without grain-oriented electrical steels since a transformer plugs into every charging column.
The efficiency rate of electrical steel rose to 40 percent over the last year. Is there still even room to improve?
Overrath: I’m absolutely certain there is, and it is also an innovation driver for us. Sophisticated heat treatment processes are needed to manufacture electrical steel with the lowest amount of electrical power losses possible. We are always investing in the latest technologies in research, development, and production. That is precisely why we are also involved in the FEN project: so that we identify trends early and our materials are ready for the future.
De Doncker: Besides, all of our studies have shown that we achieve the highest degree of efficiency with the grain-oriented electrical steel from thyssenkrupp Steel. Given the current state of power electronics, both the thermal and electromagnetic properties achieve outstanding results.
Save the climate with electrical steel
What makes the transformer for a flexible network different from a transformer for our current electricity network?
Overrath: It’s a lot smaller and lighter and it’s fitted with a lot more electronics. This new type of transformer is currently being manufactured using our extremely thin and low-loss powercore®. The best thing about it is that the transformer isn’t an idea, it is actually being built here in Europe by one of our customers on the FEN research campus, meaning it can be reproduced and could go into series production immediately.
Proof that steel is an ultra-modern material and is not related to outdated iron at all…
Overrath: As a mechanical engineer and materials scientist, I always find steel fascinating as a material. It combines a range of properties that other materials are unable to provide in this form. Apart from that, no other material has such a high recycling rate and is as sustainable as steel. Can climate change be slowed down with the sustainability concepts you are developing together here at FEN?
De Doncker: As a power electrician, I’m convinced that will be the case. Power electronics are able to convert, manage, and store green energy flexibly – so that we can all generate electrical energy from regenerative resources. And we need both power semiconductors and magnetic components such as transformers and coils.
Overrath: As has already been said, if we expect the energy transition to be successful without limiting our standards of living, then we have to solve the technical issues. Concrete evidence is being produced here at the research campus that solutions exist and they are also feasible. If we as Electrical Steel can contribute to that, such as in the specific case of implementing intelligent, flexible electrical power networks, even better.