Hydrogen with hydropower from the Ilm River

Project title:
Compact hydrogen supply system for decentralized mobility applications - h2well-compact

Funding body:
Federal Ministry of Education and Research (BMBF)

Project duration:
01.06.2021 - 31.05.2024

Principal investigator of the project:
Prof. Dr. Mark Jentsch

Project partners:
Involved in the project are partners of the WIR! alliance h2-well: Kyros Hydrogen Solutions GmbH, Energieversorgung Apolda GmbH, Fraunhofer IKTS Hermsdorf, Höschel & Baumann Elektro GmbH, Imaginata e.V., IMG Electronic & Power Systems GmbH, MAXIMATOR GmbH and Rießner-Gase GmbH. The project is lead by the Chair of Energy Systems at Bauhaus-Universität Weimar. Associated partners are the City of Apolda, eurocylinder systems AG and EnviroConsult Ingenieurbüro.

Team members involved in the project:
Saskia Wagner B.Sc., Nicole Meyer M.Sc.

Project outline

The h2well-compact project’s overall goal is to test a decentralized hydrogen production system and the application of green hydrogen in mobility. The Bauhaus-Universität Weimar is responsible for the overall coordination of the project, in which nine partners are working together on the development and realisation of a green H2 supply system for decentralized applications. The project receives funding from the BMBF within the framework of the WIR! Alliance h2-well Hydrogen Source and Value Added Region Main-Elbe-LINK (Wasserstoffquell- und Wertschöpfungsregion Main-Elbe-LINK) and is implemented in the Thuringian town of Apolda. The district town of Weimarer Land shall become a model for peri-urban and rural communities with similar conditions for local hydrogen production and use in mobility.

Fig. 1 - Diagram of the integrated overall system for decentralised hydrogen production at a small hydropower plant with transport logistics and hydrogen use by regional users.


Hydrogen production under the specific conditions of small renewable energy plants

One objective pursued by h2well-compact partners is to adapt a proton exchange membrane (PEM) high-pressure electrolyzer to the special conditions of small renewable energy plants. A small hydropower plant at the Ilm River in Apolda serves as a test field to scrutinize possible system dimensions of electrolysis plants adapted to fluctuating renewable energy sources. As there are no long-term data on the power feed-in of the small hydropower plant in Oberroßla on the Ilm, the Chair of Energy Systems developed a theoretical approach to derive a power profile of the average daily electrical turbine output in the years 2000 - 2020 on the basis of long-term flow data from the Mellingen gauging station located slightly upstream. The data thus obtained were also matched with further flow data from the downstream Niedertrebra gauging station. The basic applicability of the theoretical annual power profiles was demonstrated with the help of real power data from Energienetze Apolda on the grid feed-in of the small hydropower plant in the period from 01.05.2014 to 23.09.2021. Figure 2 shows that the theoretical feed-in capacity of the small hydropower plant varies between no feed-in during dry periods, i.e. 0 kW (dark blue areas) and a maximum of approx. 70 kW (dark red areas). In the summer months, the hydropower plant achieves a lower turbine output than in the rest of the year due to the lower water supply of the Ilm. Especially in the summer months of the comparatively dry years 2003, 2018 and 2019, the hydropower plant was unable to feed in any electricity at all for longer periods. Furthermore, as can be seen in Figure 2, in individual years there are power losses or even complete operational failures in the winter and spring months due to an excessive water supply.

Fig. 2 - Theoretical expected average daily turbine output of the small hydropower plant in Oberroßla near Apolda, sorted by calendar year

With the help of the theoretical annual performance profiles of the small hydropower plant, it was determined that the installed capacity of the electrolysis stack at the Oberroßla site should not exceed 25 kW in order to guarantee a sufficient number of operating hours (full load hours). This order of magnitude of the stack power corresponds to the electrolyser target size aimed at by the project partner Kyros Hydrogen Solutions in order to guarantee the H2 supply task envisaged in the overall project. Figure 3 shows the theoretical hydrogen production potential at the small hydropower plant per day and year at the recommended installed capacity of the electrolysis stack of 25 kW, assuming that 8 KW of power for peripheral devices are also added. If the electrolyser can be operated at full load, approx. 10 kg of hydrogen can be produced per day (dark green areas). However, based on the periods without electricity generation at the hydropower plant already shown in Figure 2, there are also longer periods in which no hydrogen generation is possible (dark red areas). The highest number of days without hydrogen generation is in 2018, with just under 100 days. (2018 was the driest year in the period under consideration.) However, for the trial operation scheduled in the autumn and winter months of the h2well-compact project period, as Figure 3 shows, it can generally be assumed that full-load operation of the electrolyser is possible.

Fig. 3 - Theoretical daily H2 generation potential at the small hydropower plant in the years 2000 to 2020 using a 25 kW electrolysis stack (periphery: 8 kW)

The Chair of Energy Systems at Bauhaus-Universität Weimar contributes with its expertise in system modelling to the development of a software tool for dimensioning the plant and its components.
While exploring possible system dimensions that work well together with small renewable energy production, another goal is to define different operating regimes for the electrolyser, which are adapted to and designed to serve both, fluctuating conditions for hydrogen production and changing hydrogen demands. 

The implementation work at the electrolysis site at the small hydropower plant has already started at the end of 2022. For the installation of the PEM pressure electrolyser and the associated H2 primary storage tank, a fence relocation, soil replacement and empty pipe laying were carried out, and the point foundations for the electrolysis container were constructed. Figure 2 shows the current status of the work on the site of the small hydropower plant.

Fig. 4 - Status of work at the electrolysis location on the site of the hydropower plant

Pure hydrogen for an innovative H2 service station

A new type of hydrogen refuelling station developed within h2well-compact will use a part of the “green” hydrogen produced on the shores of the Ilm River in Apolda. At this refuelling station, it will be possible to refill fuel cell vehicles based on the overflow principle, thanks to a high-pressure storage cascade. Hence, a compressor installed on site to compress the gas for the vehicles’ hydrogen pressure tanks - a significant cost factor of H2 refuelling stations - is not necessary. This type of hydrogen service station thus could make hydrogen refilling cheaper in the future.

Mobile storage and compression for flexible hydrogen delivery

For the delivery of the hydrogen, the project partners are designing a mobile storage solution that goes with an on-board compressor to fill the high-pressure storage tanks at the filling station. The mobile compressor is currently completing endurance tests and is expected to be integrated into the swap trailer in summer 2023.  With this flexible solution, different customers, for example industrial companies, can be supplied with hydrogen. For the project's overall vision is to design a green H2 supply concept with short and flexible logistics chains that benefit multiple infrastructure and economic sectors.

A public pop-up exhibition will reveal the technology behind the project

Hydrogen aficionados and newbies alike will be able to explore the hydrogen innovations developed in h2well-compact in an interactive pop-up exhibition designed within the project. The exhibition will feature interactive stations that reveal the principles of electrolysis and hydrogen fuel cell technology.  

Published work

Wagner S, Jentsch MF, Meyer N, Büttner S (2022)
Standortplanung von dezentralen H2-Erzeugungsanlagen an Erneuerbaren-Energie-Anlagen am Beispiel einer Kleinwasserkraftanlage29. REGWA Energiesymposium, Stralsund, 09-11 November 2022, 262-271. → view paper

Meyer N, Jentsch MF, Wagner S (2022)
Entwicklung eines Dimensionierungswerkzeugs für die überschlägige Auslegung dezentraler Wasserstofferzeugungs- und Verbrauchsinfrastrukturen für die H2-Mobilität, 29. REGWA Energiesymposium, Stralsund, 09-11 November 2022, 153-162. → view paper