In the future, ammonia could play a decisive role in the transition from fossil fuels to climate-friendly alternatives, as long as it is produced from green hydrogen using renewable energy sources, for example. Ammonia is easy to store and transport. Researchers at the Fraunhofer Institute for Microengineering and Microsystems IMM are developing ammonia-based systems for mobile decentralized energy supply in the infrastructure, transport and industrial sectors.
Various research projects will be presented for the first time at the Hannover Messe Preview on February 15, 2023.
Implementing the energy transition is a major challenge for all industries that use large amounts of fossil fuels, such as transportation, logistics and manufacturing. Currently, the energy requirements of these sectors are mainly met by fossil fuels. This should be replaced with regenerative power or regenerative fuel.
Researchers at Fraunhofer IMM in Mainz are working on mobile decentralized supply and storage of electrical energy from sustainable sources. His Dr. Gunther Kolb, head of the energy department at Fraunhofer IMM and deputy director, explains: Today, the most important power-to-X fuel is hydrogen itself. However, there are still many hurdles to overcome in terms of transportation and storage for hydrogen to be widely used as an energy source. These include high space requirements for storage or other energetically unfavorable conditions. Ammonia (NH3) could be an alternative solution for easily storing and transporting the required hydrogen. ”
Advantages of Ammonia over Hydrogen
Until now, ammonia was mainly known as a raw material for agricultural fertilizers. However, it is also a high-quality energy carrier, especially as a storage medium for hydrogen. “Because ammonia can be liquefied at a moderate temperature of minus 33 °C, the volumetric hydrogen content is significantly higher than compressed hydrogen at 700 bar. Hydrogen produced from ammonia does not contain carbon oxides or methane, so it is also free of greenhouse gases,” Kolb explains.
Green cracking gas as fuel gas in brick production
Converting hydrogen to ammonia is a viable option for use as an energy source both on-site in large-scale industrial processes and on a distributed basis in the logistics sector. However, ammonia burns very little in air, making it less suitable for combustion to produce energy. “In cracking reactors, with the application of suitable catalysts, ammonia can be cracked into nitrogen and hydrogen. A mixture of ammonia, hydrogen and nitrogen is suitable for homogeneous combustion and can be used as an energy source known as ‘Spartgas’.” ‘ says Kolb. As part of the Spaltgas project, researchers from Fraunhofer IMM and his project partners are developing combustion technology for this gas mixture used in the brick firing process. In this way, ammonia from hydrogen produced by electrolysis can be used to make the entire brickmaking process chain carbon dioxide free. The Spaltgas project is funded by the German Federal Ministry of Education and Research (BMBF) as part of the “KlimPro-Industrie” programme.
Ammonia as a hydrogen source for fuel cell drive
Ammonia can also be used to supply hydrogen to land vehicles. It can be converted directly to hydrogen at petrol stations using decentralized plants. This eliminates the need to transport compressed and liquefied hydrogen. This is an expensive and complicated process. For this purpose, Fraunhofer IMM develops cracking reactors based on innovative catalyst technology and microstructured reactor technology. In this reactor, pure hydrogen is produced from ammonia by cracking and subsequent purification and injected into the PEM fuel cell. Hydrogen for use in fuel cell vehicles can therefore be produced sustainably from ammonia at petrol stations.
“By using pressure swing adsorption (PSA applied in hydrogen refining) off-gas as the energy source for the cracking process, efficiencies of 90% can be achieved compared to 70% using conventional technology. Additionally, our AMMONPAKTOR reactor is much more compact than traditional reactors, achieving a 90% size reduction, which is especially important for mobile and space-constrained applications. Compared to electrically heated reactor concepts, our technology has a lower carbon footprint, as we use the exhaust gases from the cracking process to generate sufficient energy and no other sources.” Kolb explains.
Fraunhofer IMM’s AMMONPAKTOR reactor, funded by the state of Rhineland-Palatinate using ERDF (European Regional Development Fund) funds, is also the most efficient reactor on a global scale. With Fraunhofer IMM’s proprietary technology, he achieved the second highest specific hydrogen production rate ever published, even in a first generation cracking reactor. A second generation cracking reactor currently in production has a throughput of 25 kg of ammonia per hour and produces 70 kg of purified hydrogen per day. We will exhibit at Hannover Messe 2023.
In addition to supplying hydrogen to land vehicles, ammonia is also of interest for marine propulsion systems. This is because there are many applications in this sector where CO2 reduction targets cannot be met using conventional fuels and compressed or liquefied hydrogen cannot be used. as an alternative. Partially decomposed ammonia can be burned in (ship) engines, similar to Spaltgas reactors. Additionally, as part of the ShipFC project, Fraunhofer IMM is working with 13 European consortium partners to develop the world’s first ammonia-based fuel cell system for marine applications.
Original: Highly efficient ammonia-based system for climate-friendly energy supply
Than: Fraunhofer Association
