STOFF2

STOFF2 GmbH has developed a new form of electrolysis technology for industrial applications of green hydrogen: Zinc Intermediate Electrolysis (Zink-Zwischenschritt-Elektrolyseur in German, ZZE). ZZE’s inherent energy storage function, hybrid hydrogen and electricity output, and high efficiency make it the ideal technology to decarbonize industrial processes. A single ZZE device can replace a traditional system consisting of an electrolyzer, compressor, storage tank, and battery. We combine hydrogen production and energy storage function in one system, and thus offer the perfect solution for the efficient grid-serving use of renewable energies.

The ZZE accomplishes this because it is not technically an electrolyzer. It is an electrochemical energy storage device. Put simply, it is a battery that discharges hydrogen gas. As such, ZZE operation occurs in three steps. In the first step, electricity is drawn at high power and the energy it contains is stored in the ZZE system. Oxygen is released during this process and zinc is deposited onto one of the electrodes in each cell. This energy is safely stored in the solid zinc; this is what we call the intermediate step or in german “Zwischenschritt”. Our system does not store the energy in gaseous form, which contributes to higher levels of safety. The final step is discharging. The energy stored in the zinc layer is released as hydrogen: the zinc dissolves back into the electrolyte and hydrogen is produced at the electrode opposite the zinc. In addition to the hydrogen, electricity and heat are also generated. 

The charge-storage-discharge cycle is asynchronous. The power at which the system charges is significantly higher than the power at which it discharges. This can be flexibly adapted to meet special requirements but means that the system charges fast and discharges relatively slow. This makes our “electrolyzers” the perfect technology to produce reliable green hydrogen from fluctuating renewable energy. Hydrogen costs are reduced because we use power during the cheapest hours of the day for market/grid connected systems, or power that could otherwise be curtailed from direct connected island systems. However the power is sourced, the asynchronicity of our system uses renewable energy in phases of high energy production and ultimately reduces the cost of the hydrogen produced. 

This brings innovative hydrogen projects ideas closer to reality because our system is already RED II-compliant, less technically complex, and can be integrated more easily into the existing electricity and gas supply. ZZE technology does not use complex membranes, PFAS, platinum, iridium, cobalt, or lithium. Instead, we use zinc. Which is widely available and can be produced cheaply. 

We are currently realizing our first demonstration projects and are looking for continued commercial project development. Participation in the “Hydrogen Terminal Braunschweig” project is an important milestone for STOFF2, as its ZZE is to be installed in an industrial environment for the first time worldwide. STOFF2 will be responsible for the technical design of the research project. In particular, this will involve the interaction of the ZZE electrolyzer with the existing power and hydrogen infrastructure on site. In a second step, the project partners will commission the designed STOFF2 electrolyzer. The produced hydrogen will be used in test benches for research work as well as injected into the local hydrogen gas network to supply other external consumers such as the Fraunhofer Project Centre for Energy Storage and Systems (Fraunhofer ZESS) and the Lower Saxony Research Centre for Automotive Engineering (NFF). At the “Hydrogen Terminal Braunschweig” site, the hydrogen produced is also used to operate a hydrogen refueling station for heavy duty vehicles with the support of a compressor from Maximator.

The REFORMERS project focuses on the development, realization, and rollout of Renewable Energy Valleys in Europe. In these renewable energy valleys, there is a place for several renewable energy carriers – such as electricity, heat, hydrogen, and biomethane – that are optimally integrated into the energy system. REFORMERS focuses on the entire chain from production – through storage, conversion, and distribution – to optimal end-use of these energy carriers. STOFF2 is contributing to this project by setting up and operating two container ZZE systems in Alkmaar. Our system will interact with other producers and consumers from the project via a data interface. This will showcase the value of our flexibility to both the electricity and hydrogen grids. Along the way, we will develop and streamline our internal capabilities develop projects for our future commercial customers.