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Cover story
Connected energy
Cover story
Connected energy
The man pulling all the strings: Dr. Stefan Kasselmann, scientific project manager of the Living Lab Energy Campus.
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In the future, we will use many distributed energy systems to meet our needs, and it will be essential to optimally link all sectors with each other. Experts from Jülich are testing how this works out most efficiently in practice. To do this, they transform their own campus into a living lab.
Even in times of energy being scarce and expensive, you don’t have to sit in a cold office in the morning in winter,” says physicist Stefan Kasselmann. “In the future, when you arrive at work at Jülich, the heating will already be on and the room will be comfortably warm – with less energy consumption.” This is already being tested in individual buildings, and it works because the energy is used according to demand. The key to efficiency: intelligent connectivity and largely automated control systems.
Picture above: The man pulling all the strings: Dr. Stefan Kasselmann, scientific project manager of the Living Lab Energy Campus.
“We’re currently testing that in real operation on the Jülich campus,” says Kasselmann, the scientific project manager of the Jülich Living Lab Energy Campus (LLEC). The aim of the LLEC is an intelligent energy system that combines sustainability, economic efficiency and user comfort.
The supply and consumption of individual offices is only one aspect, however. “With the LLLEC, we want to test how energy can be efficiently distributed and used within a city district or a small settlement in the future under real-world conditions. Around 7,000 people work at Jülich, so it’s fairly comparable to a small town. There are offices, laboratories and different kinds of energy demands. This allows us to simulate different scenarios in a real environment, from industrial areas to residential neighbourhoods.”
On the dashboard, which Eziama Ubachukwu helped to develop, users can view various data from the living lab and, for example, select settings for their office. Almost everywhere in Germany, the energy supply is currently still characterized by large power plants that burn fossil fuels such as coal, oil and natural gas to generate electricity and heat. In the future, however, wind and solar power will dominate the energy grid – which means that the energy will be produced in a far more decentralized way. The experts at LLEC want to find out how the energy flow between the individual grid nodes can be optimized and how electricity and heat generation can be better interconnected. “This is also referred to as sector coupling. A good example of this is the low-temperature district heating network that we are currently building on campus. It also shows how sources that have not been factored in so far can be integrated so that there's no energy waste,” Kasselmann explains.
The photovoltaic systems on the campus produce 1.5 megawatts of peak power (pictured from left: Susanne Hoffmann, Simon Rottland and Dr. Andreas Gerber). Reusing waste heat
In the future, the low-temperature district heating (LTDH) network will be used to supply the Jülich Supercomputing Centre (JSC) and eight surrounding buildings with thermal energy. The heating power comes from the cooling of the supercomputer JUWELS. When computationally intensive simulations run on its processors, the electronics emit a lot of waste heat to the cooling water. This pre-warmed liquid is fed into the LTDH network on campus afterwards and distributed.
“The water has a temperature of just around 40 degrees Celsius,” explains André Xhonneux from the Institute of Energy and Climate Research (IEK-10), who is responsible for the “Software and Simulation” team at LLEC. This water, only just lukewarm, is enough to keep energy-efficient buildings at a comfortable temperature. However, it is too cold for the heating systems of older buildings: “These require water of up to 85 degrees Celsius in order to heat all rooms sufficiently. That’s why we use heat pumps to bring the water to this temperature,” says the mechanical engineer. “This also allows us to continue using the buildings’ existing heating systems and building envelope for the time being.”
“If the power grid is under heavy load, we can turn down the heat pumps for a while without leaving the comfort zone in terms of temperature.”
André Xhonneux
This is particularly important in order to be able to transfer the knowledge gained at LLEC to urban neighbourhoods: one have to work with existing buildings there, too, that cannot be properly converted in a short time. In this case, the waste heat could come from companies and businesses. “In our region, for example, Jülich’s sugar factory would be worth considering. Beyond that, however, there are countless untapped sources that can be identified through the German heat cadastre.”
Another advantage: since the heat pumps link the electricity and heat sectors, the system can also stabilize the electricity grid. “A room doesn’t cool down straightaway if it isn’t heated around the clock. If the electricity grid is under heavy load, we can save electricity by turning down the heat pumps for a while without leaving the comfort zone in terms of temperature,” explains Xhonneux. There may be heavy load on the electricity grid when the supply of renewable energies is scarce, for example.
“We installed photovoltaic systems on campus. With these, we can generate a peak output of one and a half megawatts. This is only a small amount compared to the total consumption of the campus, but for our research purposes, it is close enough to reality,” says Stefan Kasselmann.
Some of the solar modules are located at an open area, the rest is spread across various buildings on the campus. “The systems are easy to integrate when it comes to new buildings,” explains Andreas Gerber from IEK-5, LLEC team manager for photovoltaics. “Either on the roof, as semi-transparent modules in the skylights or in the facade. But of course we would also like to continue equipping older buildings as well.”
At Forschungszentrum Jülich, this has turned out to be a challenge, as many roofs already support infrastructure for the laboratories below, such as air conditioning and air purification systems. This causes shading. Other roofs were not designed for bearing such high loads. In an urban area, however, the situation might be very different: “While there are usually no large open spaces there, you can, for example, perfectly use the roof of a car park or make increased use of the roofs of shopping centres and industrial plants. Novel lightweight photovoltaic systems are therefore also being tested for our campus.”
The low-temperature district heating network, which Dr.-Ing. André Xhonneux is helping to set up, supplies buildings with heat. The network uses the waste heat from the JUWELS supercomputer to do this. Schools Laboratory as a pioneer
One building that has already been converted at Jülich is the JuLab Schools Laboratory. Its roof terrace supports a photovoltaic pergola made of semi-transparent modules plus a photovoltaic roof system, and right next door, the rotor of a small wind turbine is turning. “We built an LLEC on a small scale here. With it, important components of the system are tested in advance before the technologies are used on a larger scale on campus,” Kasselmann explains.
For example, the conference rooms are equipped with special sensors: they recognize, among other things, how many people are in the room. “A room will heat up slowly through body heat alone,” says the physicist, “so the heating is then automatically turned down. This saves heating energy without anybody noticing it.”
Sensors measure not only the temperature of the rooms and the heating, but also data such as CO2 concentration, humidity, brightness and whether the doors and windows are open – not only at JuLab, but also in many other rooms of the LLEC. Information on the weather is incorporated as well.
The data is processed by the LLEC’s “brain”: the cloud-based information and communication platform (IKT) and its control software ensure the right balance of energy flows between the nodes of the grid. “To achieve optimal results, we work with a ‘digital twin’ of the entire system, with a mathematical model of the LLEC’s buildings and facilities”, says André Xhonneux. “Based on a target and certain framework conditions, operation is automatically optimized. User specifications are also taken into account. If the thermostat is turned up, the system will not lower the temperature.”
One user interface is the “energy dashboard”, which is accessible on the intranet. The start screen shows a map of Forschungszentrum Jülich with all the buildings: “We can display the consumption for each location here,” says Stefan Kasselmann. “We do this to raise awareness about how energy is used.”
The next step is to extend this system to individual rooms: “Then everyone will be able to look at the consumption profile and comfort parameters of their own office and also make adjustments.” At the same time, energy-saving behaviour is to be rewarded through an online simulation game: employees can design a virtual energy system for the campus – and even contribute their real-life usage behaviour. Significant efficiency gains can only be realized by actively involving users.
Surplus energy is to be used to produce hydrogen with the help of an electrolyzer. Dr. Holger Janßen and his colleagues are working on this. Various storage systems
Sun and wind do not always supply consistent amounts of energy. “If more electricity is generated than is needed, we have to store it – for a rainy day, so to speak. We are building up various storage facilities at the LLEC for this purpose,” explains Stefan Kasselmann. “For example, we can store electricity in two large batteries or, in the future, also chemically in the form of hydrogen. The hydrogen storage system can provide energy during renewable droughts, when no wind and no solar energy is available for days or even weeks.”
The hydrogen is produced from water with the help of electrolysis cells. It can then be stored chemically, bonded to an organic carrier liquid, known as Liquid Organic Hydrogen Carrier (LOHC). A globally unique demonstrator is being set up at Jülich. The hydrogen can be released again on demand from the LOHC.
The gas can be converted back into electricity using a fuel cell. “However, we could also burn it and thus replace some of the natural gas that the energy centre built on campus will use to generate electricity, heating and cooling. Therefore, hydrogen plays a very central role in sector coupling,” says Holger Janßen, group leader of Stacks and Systems (electrolysis) at IEK-14.
“The high-power battery is particularly suitable for so-called peak shaving, that is, to compensate for short-term fluctuations in the power grid of seconds to minutes.”
Dr. Luc Raijmakers
The other storage system – two stationary battery systems based on lithium-ion technology – is located in containers. “They have different characteristics,” says Luc Raijmakers (IEK-9), LLEC team manager for battery systems. “The high-performance battery is particularly suitable for so-called peak shaving, that is, to compensate for short-term fluctuations in the power grid of seconds to minutes. It also serves as an uninterruptible power supply. There is also a high-energy battery that serves as an energy buffer for a period of several hours.”
Dr. Luc Raijmakers focuses on energy storage: the LLEC has purchased two enormous batteries with a total capacity of 3,125 kilowatt hours. In the high-performance system, twelve individual battery cells are combined to form one module. These modules cover an entire wall in the container. The special challenge: “The cells all have to be charged and discharged evenly within a certain voltage range,” explains Luc Raijmakers.
“We already installed charging points for e-vehicles to test bidirectional charging”, adds Stefan Kasselmann. “During the day, when the vehicle is parked and the power demand is high, energy from the vehicle battery can thus be temporarily fed back into the grid for stabilization. With a large number of vehicles, this could make a significant contribution in the future. Although there are still regulatory hurdles, this is one of the advantages of a living lab: we identify new challenges in the interplay of science, technology and society that we would probably not have seen without direct reference to practice.”
Arndt Reuning
LLEC members report on the progress of the project in their blog (in German):
blogs.fz-juelich.de/llecPhotos: Forschungszentrum Jülich/Sascha Kreklau