The small, subtle intermediate step

The famous ‘Gründer-Garage’, in which start-ups take their first steps, can sometimes also be a kitchen. This was certainly the case for STOFF2. In 2020, one of the two founders, electrical engineer Andrew Zwinkels, conducted his first experiments in a whisky glass. The young company has continued to grow ever since and now has around 30 employees. Located at the Berlin Zukunftsort site ‘Berlin TXL – Urban Tech Republic’, the team is developing a new technology for producing green hydrogen: STOFF2 wants to bring the ‘Zinc Intermediate-step Electrolyser’ (ZZE) to market maturity and is working closely with the Technische Universität Berlin (TU Berlin) to achieve this. In this Brain City interview, Christian Friebe, Head of Public Affairs, explains what ZZE is and why the high-tech product from STOFF2 could revolutionise the use of wind and solar energy.

Mr Friebe, what’s special about the STOFF2 product?

Standard electrolysers – devices which use electricity to split water into hydrogen and oxygen – produce green hydrogen whenever renewable power is available. This means that traditional electrolysers can only produce hydrogen if fluctuating renewable energies are also available at the same time. Our system combines electrolysis and an energy storage device in one. In other words, green electricity is initially charged for four hours in each cell of our Zinc Intermediate-step Electrolyser. The system safely stores the energy absorbed for hours – even days – in the form of solid zinc. In the third step, green hydrogen is then discharged as required for anywhere between 12 and 24 hours.

What specific benefits does this system offer customers?

There are many benefits: firstly, our ZZE systems use the ‘intermediate step’ of the energy storage device to charge the renewable wind and solar power only when it is being produced in excess – and therefore much cheaper. Electricity procurement is a major cost factor when it comes to green hydrogen. Secondly, they can also exclusively charge renewable power that would otherwise be ‘capped’ by the network operator, so which wouldn’t be generated at all. This renewable power would otherwise be lost due to a lack of network capacity. Additionally, our systems produce green hydrogen on a delayed basis, when the customer actually needs it. This could also involve a permanent supply 24/7. Such flexibility when it comes to hydrogen production is unique and particularly beneficial for industrial companies.

How did the business idea come about? 

Our founders, Andrew Zwinkels and Alexander Voigt, had already spent years working on the development and scaling of alternative energy technologies. The rise in renewable energies has also increased the demand for energy storage solutions. Both have many years of experience with battery storage devices, high-temperature storage units and can now collect zinc. In fact, Andrew Zwinkels performed one of the first experiments with a whisky glass in his kitchen. If you visit us in Tegel, you’ll see a whole range of prototypes from recent years. With around 30 employees, we are now working on the final steps to batch produce an electrolyser that will fit inside a six metre-long container and which can be used in an industrial setting.

What were and remain the biggest challenges when founding and developing STOFF2?

A technology company is usually more capital-intensive than other businesses and needs more time to develop its product to an industrially relevant scale. Developing technologies is expensive and therefore needs to happen as quickly as possible. At the same time, the product should be stable once finished, operate safely and also be cost-effective to produce. We’ve been navigating this terrain since the day the company was founded.

How have you financed the start-up so far?

Through the founders and various strategic investors. During the previous scaling phases, we also benefited greatly from public funding by the Federal Ministry of Education and Research (BMBF) and the Federal Ministry for Economic Affairs and Climate Action (BMWK). However, it’s not just the financial support that’s important to us but also the external validation of our work. The progression and feasibility of our system were continually reviewed and followed by external experts at the German Aerospace Centre (DLR) and Projektträger Jülich (PtJ) at the time of the grant application as well as during the funding period. 

Do you have any customers yet? 

We’re currently in talks with a number of potential customers. These include project developers, often from the field of wind and solar farms, energy providers who are also interested in electricity and gas infrastructures, and industrial companies that require a reliable supply of green hydrogen around the clock. There is a lot of interest in our product, particularly among those who have already implemented hydrogen projects in the past and have some experience in this area. At the same time, all of these customers want to see the technology in action. That’s why we are currently testing it intensively in collaboration with other players in the energy industry: We want to install our system in an industrial environment for the first time as part of the research project Hydrogen Terminal Braunschweig, which we are carrying out in partnership with Steinbeis-Innovationszentrum energieplus (SIZ). STOFF2 is also involved in the European REFORMERS project. A Renewable Energy Valley is being set up in the Dutch city of Alkmaar. The STOFF2 electrolyser will be installed there in 2026 and heavily tested along with other alternative energy innovations and infrastructures. 

Do you also have research links with Berlin’s universities and scientific institutes?

We are working closely with the TU Berlin at the Tegel site as part of the joint project ZZE-GREEN-H2 to implement the initial final scaling step. This will increase the technological maturity of our product and thus form the basis for series production.

Why is Berlin a good location for start-ups with a scientific background?

Berlin – particularly the .GUT Community (link in German only) in the Urban Tech Republic – is a great location for developing climate protection technologies. Start-ups convene here that also need workshops to build prototypes. There’s a community area on site that is heavily used by local companies like us as well as external organisations for events. There are now a good 20 start-ups here that cover all sorts of areas from sustainable building materials and high-temperature energy storage devices to solar roof tiles, algae and drones. This community has a presence far beyond Berlin and Germany.

What vision do you have for STOFF2 – and where do you want the company to be in five years?

In five years’ time we want our technology to make a significant contribution to the energy transition across all sectors. Until then, we will be focusing on industrial series production of our ZZE electrolyser at multiple sites and implementing a number of green hydrogen projects together with our partners and customers in Germany and Europe.

Interview: Ernestine von der Osten-Sacken

• stoff2.com
• zukunftsorte.berlin
• urbantechrepublic.de