Network stability from the boiler room

How can we ensure that heat is generated in buildings exactly when it is best for the stability of the electrical system? The Smart Energy Lab planned at the Institute of Energy Economics and the Rational Use of Energy (IER) at the University of Stuttgart intends to develop intelligent control systems for this purpose thereby providing an important building block for the energy transition.

The nuclear phase-out is currently ongoing, the coal phase-out is planned for 2038. This represents federal government policy reactions both to safety concerns expressed by many people and to the need to reduce carbon dioxide emissions. However, it is clear that even after 2038, when the last coalfired power plant in Germany is to be shut down, a sufficient, stable and both economically and environmentally compatible power supply will still be required. In 2018, more than 40 percent of the electricity generated in Germany already came from renewable sources. In all likelihood, this share will continue to rise signifi cantly over the next 20 years. Nevertheless, the energy transition poses certain challenges - in addition to other sectors - in terms of the supply of electricity, because neither wind power nor photovoltaic plants necessarily provide electricity when it is needed. So what can be done when the wind dies away and the sky is clouded over in the middle of a peak demand period?

This is the sort of question that Julia Kumm of the University of Stuttgart’s IER deals with. Kumm and her colleagues are setting up the Smart Energy Lab, a test facility for decentralized intelligent energy systems, on the former Telekom site on the University of Stuttgart’s Vaihingen campus. The Smart Energy Lab was designed by Prof. Kai Hufendiek, head of the IER. The complex will eventually accommodate seminar rooms, offi ces for researchers and staff as well as a guest house - usage types that will enable IER scientists to conduct research under real conditions in the future.

“The Smart Energy Lab will be an experimental space in which we will be able to investigate a wide variety of configurations as flexibly as possible,” Kumm explains. The experimental setups for the heating systems of the future are unlikely to be as spectacular as one might think at fi rst glance: “We use the latest standard equipment, of the sort that could be found in any building’s boiler room. The exciting thing happens behind the scenes, through the intelligent interaction of the components.”

The focus in the Smart Energy Lab is not on further technical development of the individual heating technologies themselves. “Our goal is for heating systems in the future not only to see their own supply function as such, but also to react intelligently to the prevailing situation throughout the entire energy system,” says Julia Kumm.

An example: Many contemporary boiler rooms house heat generators that produce hot water on demand. But what if there were an air heating pump and a large hot water tank? The heat pump could generate a lot of hot water on a windy night when there is a lot of electricity in the grid and buffer it in the storage tank. Conversely, this storage facility would also provide heat when less electricity was available. “In theory, any boiler room could take on the tasks required for the flexibility or stabilization of the entire system in this way,” says Julia Kumm. “You can use storage to run the generators exactly when it makes sense for the system, regardless of the current heat demand.” The most important condition, however, is that the heat supply is secured at all times. And these innovative control systems should not entail any additional expense or loss of comfort for the users. “Nobody would have to change their habits,” emphasizes Kumm, who also advocates fair compensation for “participation” in the supply system.

The Smart Energy Lab will serve as a test platform for testing the control algorithms for this complex task for many years. Including heat generators from different manufacturers, as well as different storage systems, building sizes and user habits as well as several control variants in the experimental setup will result in a huge number of possible configurations, which the researchers in Stuttgart want to investigate with regard to their benefit for the overall system under real conditions. The Smart Energy Lab on the Vaihingen campus will supply energy to an area of up to 5,000 square meters during the test periods, supported by a redundant heating system that will take over the supply outside the test time series. Among other things, a heat accumulator with a volume of about 70 cubic meters is planned. The end result should be the most robust, intelligent control systems possible.

The multitude of challenges that researchers have to face during this undertaking only become apparent at second glance. The first requirement for system control are load forecasts for the building. This means that the system needs to get an “idea” of what the heat consumption of the next hours and days will be. In addition, it must estimate how the electricity generation will develop, for example when using a photovoltaic system. And all of this should happen practically on a “building-focused” basis, i.e. not viewed across a region. Therefore, the control systems must be equipped in such a way that they can learn to reconcile individual user behavior and the weather conditions with the needs of the general power grid.

Julia Kumm uses a number of specific figures to counter those who doubt that decentralized heat storage systems can make a significant contribution to the energy transition and grid stabilization: one third of Germany's fi nal energy consumption takes place in the household, commercial, trade and heat generation service sectors. So far, around 80 percent of this demand has been met by conventional energy sources, whereas the German government is aiming for an “almost climate-neutral building stock” by 2050. So there is plenty of scope for AI-based intelligent control systems that can contribute to the energy transition.

“I find the interdisciplinary issues particularly exciting,” says Kumm, who has been researching at the IER for around four years, highlighting the appeal of her work. She sees this as a very practical application of AI: the control system “senses” what is happening in the connected house in real time and matches this knowledge with the distributed and highly complex supply grid. The exact launch date of the Smart Energy Lab has not yet been set. However, the first components are to be put into test operation before the end of 2019.

Jens Eber