Hydrogen

One obstacle on the road to a hydro­gen-based society is producing suffi­cient quantities of hydrogen. This will take adequate levels of green electricity, large electrolyzers and various means of transporting the hydrogen − issues that the lighthouse projects, among others, are working on. However, despite all these ef­forts, Germany will not be able to produce enough hydrogen to meet the high levels of demand that are expected. There is sim­ply no way around hydrogen imports. But realistically, will it be possible to establish this kind of importing infrastructure by 2030? The Fraunhofer Institute for Environmental, Safety and Energy Tech­nology UMSICHT has joined forces with the German Economic Institute and the Wuppertal Institute to answer this ques­tion. The results: “At a technological level, it would actually be possible to reach the target quantities that the National Hydro­gen Strategy has set for hydrogen imports in 2030, namely 76–96 TWh/a, but only with (occasionally significant) cutbacks in the areas of sustainability and economic viability. The time frames involved − for engineering issues like converting old pipelines or building new ones, or the availability of ships, and especially the time frames required under planning and approval processes − are also standing in the way of large-scale implementation,” says Dr. Christoph Glasner, a scientist at Fraunhofer UMSICHT.

While the Wuppertal Institute studied the selected target countries, namely Chile, Morocco, Spain and the Netherlands, the Fraunhofer researchers primarily con­centrated on transporting hydrogen to Germany via pipelines, trucks and ships. How feasible is it on a technical level? Could restrictions stemming from approv­al processes hinder hydrogen imports? The necessary quantities could be transported by truck, but it would take approximately 1.5 million truckloads a year − not exactly a climate-friendly option. Shipping is also not a viable alternative at least until 2030, since there are still simply no qualified ves­sels that could transport liquid hydrogen. “Japan is indeed working on a small pilot craft. But, by the time the tests are complet­ed, the approach has been transferred to larger ships and these ships have been con­structed, the 2030 deadline could well have elapsed,” affirms Dr. Bärbel Egenolf-Jonk­manns, a scientist at Fraunhofer UMSICHT. There’s no short-term large-scale solution to be found in converting hydrogen into ammonia or storing it in the form of liquid organic hydrogen carriers (LOHC) either. It is unlikely that the necessary plant tech­nology and harbor infrastructure could be developed by 2030. “In the long term, however, the technological potential for re­newable energy in the four countries in the study is high enough to supply Germany with large quantities of green hydrogen,” says Dr. Egenolf-Jonkmanns. Until then, the hydrogen will just have to be produced closer to the consumption sites − i.e. in Germany.

The PtX Atlas developed by the Fraunhofer Institute for Energy Economics and Energy System Technology IEE is a valuable source of information on future import possibilities: For the first time, the whole world’s power-to-liquid potential is on display. PtL is the term used for synthetic fuels that are produced from hydrogen using electricity. Due to the losses incurred during conversion, PtL fuels call for extremely cheap, renewable electricity.

That means Germany and Europe cannot really compete in this area. “This open, interactive tool allows users to view all the countries in the world, and see what potential they offer in terms of using electricity to produce synthetic fuels. And the map shows the conditions and costs involved too,” explains Maximilian Pfennig, a scientist at Fraunhofer IEE. When developing the atlas, the researchers took into account available space, weath­er conditions, local availability of water, environmental conservation and security of investment. The atlas shows that there are many places in the world where large quantities of the various power-to-X en­ergy carriers could be produced renew­ably – although that’s in the long term.

Ammonia is one of the most promising power-to-X energy carriers. It’s a good option for long-distance hydrogen trans­port and long-term hydrogen storage. “If we assume that in 20 to 30 years, around one third of our energy will be imported as hydrogen, then ammonia is going to be a very important material,” says Dr. An­dreas Menne, head of department at Fraunhofer UMSICHT. However, at present, the process of converting ammonia back into hydrogen and nitrogen still presents quite a challenge – it takes a lot of energy. Rather than heating the complete reactor to the temperature required for the reaction from the outside, as conventional process­es have done so far, Dr. Menne’s research team are raising the temperature right inside the catalyst. This makes the con­version far more energy-efficient, while the construction is also simplified. “We believe this will allow us to improve the overall efficiency by at least 20 percent – and in process engineering, that would be a quantum leap forward,” Dr. Menne re­ports. The first prototype, which is set to be completed in early 2022, will be able to produce around 1 kilogram of hydrogen per hour. Ultimately, the researchers’ goal is to use this process to provide the im­ported hydrogen on a decentralized basis, with lower costs than running electrolyz­ers locally.

Thermochemical storing

This winter is an ample demonstration of the value of a warm home. Solar collec­tors could be a solution for sustainable heating. But there is a drawback: They mostly generate heat in summer. In the ZeoMet project, a team at the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has improved one possible means of storing energy for the chilly season, by optimizing thermochemical storage systems. It’s a rapidly developing research field. The key to the systems is zeolite, a highly porous substance that can store heat for long periods with virtually no loss. It could allow us to harness the heat of summer even in winter. However, the problem is that so far, scientists have only been able to warm zeolite pellets that are in direct contact with the energy source.

“We coated the zeolite pellets with aluminum – this doubled thermal con­ductivity after just the first attempt, wit­hout negatively impacting water adsorp­tion and desorption. We are currently aiming to increase this by a factor of five to ten by adjusting the coatings,” says Dr. Heidrun Klostermann, project manager at Fraunhofer FEP. The institute has deve­loped a special facility for evenly coating hundreds of thousands of pellets with aluminum.

Cooling buildings down can guzzle just as much energy as heating them up. In the year 2016, for example, around 2000 ter­awatt-hours of energy were required for cooling commercial and residential prem­ises – according to estimates, that amounts to around 10 percent of worldwide power consumption. This amount could triple by 2050. “In existing buildings, if the heat pump – i.e. the heat generator – that is already installed can be operated in reverse to cool the place down, then it would be possible to use the existing heating system for cooling as well,” says Sabine Giglmeier, a scientist at the Fraunhofer Institute for Building Physics IBP. This approach would not only eliminate the need to buy new air conditioning systems but might also save on energy.

The team analyzed the solution’s po­tential for two different heating systems, in order to find out whether radiators and underfloor heating could replace air con­ditioning units. “In the end, we demon­strated that both systems could achieve sufficient cooling capacity depending on some parameters like heating area, type of construction and window surface area,” recounts Giglmeier. That means heat pumps with cooling functions could be an alter­native to expensive air conditioning sys­tems for existing buildings.