Project meeting of STEP at the site of the company ATS - Agro Trading & Solutions in Hardegsen (Photo: DBFZ)

sector coupling | CHP Biogas Biomass technologies Validation market potential System integration Biofuels

Project ID 03EI5407

RhoTech - New strategy for hydrogen production by purple bacteria using fruit- and milk-wastes

Project RhoTech: Scheme hydrogen-production from fruit and dairy wastes with the help of purple bacteria (source: University Stuttgart, IBBS)


  • 01.01.2020 – 31.12.2022


University of Stuttgart
Institute of Biomaterials and Biomolecular Systems (IBBS), Department of Bioenergeticsg
Pfaffenwaldring 57
70569 Stuttgart

Prof. Dr. rer. nat. Robin Ghosh – project leader
Telephone: +49-(0)711-685-65040

Dr. rer. nat. Caroline Autenrieth – project coordinator
Telephone: +49-(0)711-685-65048


03EI5407B - University of Applied Sciences Biberach (HBC)
03EI407C - Fraunhofer Institute for Manufacturing Engineering and Automation IPA
03EI407D - KE-Technologie GmbH
  • Address:
  • KE-Technologie GmbH
    Pfaffenwaldring 31
    70569 Stuttgart
  • Contact:
  • Dr.-Ing. Schäfer, Patrick – project leader
    Telephone: +49-(0)711-685-69681

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Cooperation partners



Planned results: 

  • Plant: process, pilot plant, plant modules/system components
  • Concept: plant concept
  • Data: scenarios, methods
  • Publications: scientific paperaper (ISI, peer-reviewed), position paper
  • Market: market forecasts, marketable technologies
  • Strategy, evaluation


The project should demonstrate the potential of the purple bacterium Rhodospirillum rubrum for large-scale hydrogen production using fruit- and milk-wastes as substrates. This novel process ("dark photosynthesis") does not require light, is cheap to run, and readily up-scalable. Parallel to hydrogen production, the "dark photosynthetic" metabolic regime can be utilized for the simultaneous production of high-value industrial products, e.g. terpenoids. The "dark photosynthesis" process still allows the possible use of a low energy illumination for further enhancement of hydrogen production efficiency. It is intended that the project should be an important contributor to a future hydrogen economy and also circular bioeconomy in Germany. The future market potential of the "dark photosynthetic" process will be analyzed by a systematic study of the integration of the process into various energy sector scenarios.


The aim of the project is the development of an industrial-scale hydrogen production process with purple bacteria using fruit- and milk-wastes. The availability of raw materials will be evaluated and possible application scenarios will be systematically analyzed. The economic evaluation of this technology should facilitate a successful market entry.


University Stuttgart

The R. rubrum production strain will be genetically optimized for increased hydrogen production capacity, as well as a reduction in the excretion of wasteful fermentation products. The selection criteria will be adapted for stable large-scale fermentation. The genetic optimization will be performed by incremental improvement via high-throughput mutagenesis and robotic screening methods. 

Biberach University of Applied Sciences

The hydrogen production capacity and metabolic profiles of optimized strains will be characterized in an intermediate-scale bioreactor, and process-optimized by varying the environmental parameters. The optimized parameters will be used as starting values for a hydrogen-producing pilot-scale bioreactor process.

Fraunhofer-Institute IPA

The bioenergetics potential for hydrogen production obtainable from fruit and milk waste biomass via the “dark photosynthesis” process will be evaluated. Potential production topologies and various application scenarios will analyzed. The application with the highest economic and ecological potential will be selected, and the associated CAPEX and OPEX costs, as well as GHG emissions calculated. Strategies which are most likely to overcome barriers and inhibitory factors will be developed, and their economic and ecological potential re-evaluated. The results will be summarized as recommendations for a successful market entry.

KE-Technology GmbH

The possibility that the hydrogen production capacity can be increased by a weak “enhancement” light source will be examined. For this purpose, a wavelength- and pulse-programmable LED illumination source will be constructed, which can be embedded within the software of the process regulation. The illumination source will be optimized for the small laboratory scale hydrogen-producing process, and then these parameters used as starting values for the pilot-scale bioreactor process. The prototype will be modular in construction and adaptable to other photosynthetic systems, thereby facilitating a broad market entry.  


University Stuttgart

  • Development of R. rubrum production strains, genetically optimized for hydrogen production

Biberach University of Applied Sciences

  • Evaluation and process optimization of hydrogen production by R. rubrum "dark photosynthesis" in an intermediate scale bioreactor
  • Upscaling the process to pilot bioreactor scale

Fraunhofer-Institute IPA

  • Production topology, bioenergetic potential and application scenarios for the R. rubrum "dark photosynthesis" hydrogen production process
  • Bandwidth estimation of cost, efficiency and sustainability targets of the process

KE-Technology GmbH

  • Construction of a low-energy supporting illumination source for hydrogen production enhancement of the "dark photosynthesis" process
  • Measurement system development: soft- and hardware-development, initially at the small laboratory scale, later for the pilot scale


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