Balancing act
How can the energy transition succeed?
(Credit:Shutterstock/Renata Palinchak)
Leaving the fossil fuel era behind us is both a mammoth task and a balancing act. To ensure that the energy turnaround succeeds in time, experts at Helmholtz are working on solutions across a broad front.
Bernd Rech has been Scientific Director of HZB since June 2019 and is responsible for the "Energy and Information" division. (Credit: Phil Dera)
"All over the world, scientists are looking for ways to make the energy system of the future sustainable and reliable," says Bernd Rech. As scientific director of the Helmholtz-Zentrum Berlin (HZB), the physicist is not only familiar with research at his own facility. He also knows what his colleagues at the other centers, as well as at universities and major research institutions, are doing. The key to the global energy supply of the future, he is sure, shines down on the earth every day. "Of all energy sources, the sun has the greatest potential," says Bernd Rech. "There's ten thousand times more energy in the sunlight that reaches the earth than we need worldwide as primary energy. Of course, we can't use all of it. But even a tiny fraction of it is in principle enough to supply us."
Steve Albrecht is head of the Young Investigator Group Perowskite Tandem Solar Cells at HZB. (Credit: Michael Setzpfand)
Technology in a double pack
Steve Albrecht also sees the sun as the primary solution to the energy problem. He heads the perovskite tandem solar cell research group at HZB. "Today, solar cells made primarily of silicon have established themselves worldwide," Albrecht said. However, he says, manufacturing the wafers from the semiconductor material, also known as wafers, is not exactly trivial. For example, he said, it requires high-purity fabs like those used for microelectronics. "We have therefore turned to other materials," says Steve Albrecht "the metal halide perovskites." Behind the somewhat unwieldy name lies an entire group of materials. "Perovskite" describes a structure according to which a material is built. Various elements can be arranged in this very structure.
"We can tailor perovskites," explains the materials scientist. "With the type and ratio of elements we incorporate into the perovskite structure, we change the properties of the finished semiconductor material."
Perovskite solar cells are already achieving efficiencies around 25 percent in the lab, putting them nearly on par with cells made of silicon. This means that from 100 percent incident radiation energy, 25 percent is converted into electricity. However, Steve Albrecht does not want to enter into direct competition with established technology. While silicon cells have a lifespan of about 20 years, perovskites only last a few thousand hours, says Albrecht: "But we're working on making perovskites more stable and longer-lasting." The researchers therefore focused on combining new material with known material. "We're researching tandem solar cells," Albrecht explains, "for which we apply an ultrathin layer of our perovskite materials to tried-and-tested silicon solar cells." The trick is that the perovskite layer uses the entire wavelength range of visible light and converts it into electric current. Near-infrared light, on the other hand, penetrates the layer, hits the silicon cell underneath and is also converted into electrical energy there. This increases the duo's efficiency to about 30 percent. "We want to push this up further, of course," says the materials scientist, giving an outlook. "Theoretically, 40 percent is possible."
Steve Albrecht is convinced that he is in exactly the right place for his research here at HZB: "Tandem cells combine two different technologies, which in themselves are being researched in many places around the world. There are only a few facilities in the world that can successfully combine these two technologies at one location to create tandem solar cells. And HZB is definitely one of them."
Visions of the energy system of the future
The efficient solar cells Steve Albrecht is working on fit perfectly into Bernd Rech's vision of a clean future: "We will get our energy mainly from the sun," Rech says. "There will be a lot of photovoltaics and also solar thermal. Not only in solar parks. Solar cells will also be ubiquitous on the roofs and in the facades of homes, office buildings and industrial plants." Of course, he said, there will also be wind energy, and wherever conditions are particularly favorable for it.
"Where it makes sense, the electricity will be used directly," he continues. "And, of course, it has to be stored." Battery storage is one possibility here. At their heart is the electrolyte, and research is being conducted by, among others, the still young Helmholtz Institute in Münster. The Forschungszentrum Jülich, the University of Münster and the RWTH Aachen University have pooled their expertise in this institute. Developing efficient battery storage systems together with industry is, in turn, the declared goal of the Battery Technology Center at the Karlsruhe Institute of Technology (KIT). With its Battery Technology Center, it wants to help develop the next generation of efficient battery storage systems. The German Aerospace Center (DLR) is researching a completely different storage technology. In this, molten salt will store energy from solar farms or wind farms in the form of heat and release it via turbines during times of need.
"In the future, however, the renewably generated energy will also be used to produce green hydrogen," Bernd Rech elaborates. "This is because it can not only be reused directly, but together with CO2 from the air it becomes transportable and storable energy carriers in the form of green hydrocarbons."
Decoding the complexity of nature
At first glance, generating hydrogen seems quite simple. All that is needed is to split off the hydrogen atoms in water and combine them to form a molecule. "But in reality, this process is very complex," says Olga Kasian. "There are a lot of intermediate steps and many energy barriers that the atoms have to overcome."
Olga Kasian is head of the Young Investigator Group Dynamic Electrocatalytic Interfaces at HZB. (Credit: private)
The chemist heads the "Dynamic Electrocatalyst Interfaces" research group, combining the strengths of two Helmholtz sites. Olga Kasian and her team bridge the gap between HZB and the Helmholtz Institute Erlangen Nuremberg (HI ERN). "With large-scale research facilities like the synchrotron, we have an excellent infrastructure at HZB," she says. "And in Erlangen, we have excellent expertise in hydrogen production and storage."
She is certain that hydrogen plays a central role in the energy transition. "I don't think one technology alone can serve the entire energy sector," she says. "Of course, neither can hydrogen. But it is extremely versatile." Hydrogen can be converted back into electrical energy in fuel cells; it can be converted into kinetic energy in engines and into thermal energy in boilers.
The key is inexpensive production of the lightest of all elements. This is where the scientist's work comes in. "We are looking at why the catalyst materials become unstable over time during electrolysis," says Olga Kasian. "Understanding these processes should help us find better materials. That will then make electrolysis more efficient and thus more cost-effective." To do this, her team is taking a closer look at the processes involved in electrocatalysis. "We are researching how the catalyst materials behave. How they change. And why they do so," the scientist says. "Deciphering this complexity of nature and understanding how things work at the atomic level is something I personally find very exciting."
Energy transition process
More efficient technologies for energy generation and storage are only one pillar of the energy transition. Energy distribution and use are also up for grabs. "The entire energy system must be transformed," explains Bernd Rech. "What an enormous societal task that is, as expert colleagues from the Ariadne Initiative have recently shown."
Ariadne project
To address the challenges of the energy transition in a scientific way, the German government launched the four Copernicus projects in 2016. Each of them focuses on a different aspect of the energy transition. The focus of Ariadne is on the social sphere. The researchers from a wide range of institutions and disciplines want to find out how certain political decisions are suitable for the energy transition and what level of acceptance they meet with among the population. The aim is to develop an optimal strategy. In an initial report, the project group compared various ways in which Germany could become climate-neutral by 2045.
The Helmholtz Association is also conducting research on this complex, for example, with the Energy Lab 2.0, a cooperation between KIT, DLR, and Forschungszentrum Jülich. The latter also operates another real laboratory, the Living Lab Energy Campus, in which electricity, heat, mobility and chemical energy sources are combined to form an intelligent energy system.
Powerful solar cells, long-lasting batteries, efficient electrolysis, intelligent energy systems; even if the research results sound promising, the time factor is still important. "We have to get going and not wait until the new technologies are mature," Bernd Rech therefore warns. "We must be clear that the transition to clean energies is a process and that there will also be an energy transition 2.0, 3.0 and 4.0." It is also clear to him that we must all pull together to achieve this, but still be open to technology and solutions: "The energy transition must succeed globally – but it must also work locally."
In a nutshell
- Of all energy sources, the sun has the greatest potential, making it the key to the global energy supply of the future.
- The energy transition must succeed on a global level, and it must work on a local level.
- Hydrogen is a cornerstone of the energy transition because it is a storage medium, fuel and raw material all at once.
- The energy transition is a process in the course of which technologies will mature. Openness to technology is therefore important.
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Infographic
"We should recognize the opportunities of tomorrow"
Six at one stroke - The laws for the energy turnaround
EEG - Since 2000, the expansion of renewable energies has been controlled by the Act on the Reorganization of the Legal Framework for the Promotion of Electricity Generation from Renewable Energies, or Renewable Energy Sources Act (EEG). This is now in its eighth version and, as EEG 2021, sets the expansion target of 65 percent for 2030.
AtG - With the Thirteenth Act Amending the Atomic Energy Act, Germany said goodbye to nuclear energy in 2011.
EnWGÄndG - Since 2011, the Act on the Reorganization of Energy Industry Regulations has been intended to strengthen the neutrality of the energy network. It separates network operators from the areas of energy generation and energy sales.
NABEG - Since 2011, the Act on Measures to Accelerate the Expansion of Electricity Networks has been intended to shorten the duration of planning and approval procedures for line expansion and creates a simplified nationwide approval procedure.
The law amending the law establishing a special fund "Energy and Climate Fund" specifies where the money for the "Energy and Climate Fund" comes from. The fund's assets are to be used to finance measures for energy and climate change.
The law to strengthen climate-friendly development in cities and municipalities amends building law. For example, it regulates the modernization of wind power plants and neighborhood solutions for climate protection.
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