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Renewable Energy Carriers and Storage

Working Group 3.55


Working Group 3.55 is concerned with hydrogen technologies and lithium-ion batteries in the context of explosion protection.  With regard to hydrogen, it accompanies the expected upscaling of infrastructure and utilization from the safety point of view and investigates special phenomena such as the ignition of hydrogen/air mixtures by hot free jets. Lithium-ion batteries are a fundamental component of electromobility and are also expected to be used increasingly as stationary energy storage devices in the future. They are highly efficient, but pose a considerable hazard in the event of a fault. The Working Group's activities aim to support the safe use of hydrogen and lithium-ion storage in large-scale applications.

The Working Group 3.55 collaborates via the Opens external link in new windowEnergy Research Centre of Lower Saxony, with the Opens external link in new windowTU Braunschweig and Opens external link in new windowLeibniz University Hannover.

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Renewable Energy Carriers

Experimental investigation of ignition processes via optical techniques

Due to its high ignitability and flame velocity, hydrogen bears a considerable hazardous potential. Working group 3.55 investigates the ignition of hydrogen/air mixtures experimentally with the aim of describing the individual processes in detail.


Ignition processes

  • Electrical discharges
  • Hot free jets


Experimental techniques

  • Schlieren imaging: used to visualize changes in the refractive index (temperature and pressure)
  • Background-oriented schlieren (BOS): the change in refractive index causes distortions in a structured background pattern. The displacements can be analyzed to determine the local gas density.
  • Laser-induced fluorescence (LIF): selective excitation of gas molecules in a UV laser light sheet. The fluorescence is imaged and yields 2D concentration maps. 

    • OH-LIF: reaction zones
    • NO-LIF or tracer-LIF (e.g. acetone): mixing

  • Rayleigh scattering: scattering of laser light by gas molecules as a function of gas density and thus temperature.


Innovation laboratory "Sustainable Hydrogen Combustion Concepts"

In a Opens external link in new windowjoint project funded by the state of Lower Saxony, research is being conducted on low-emission and efficient hydrogen engines. For larger commercial vehicles, clean hydrogen use can be made possible without the shock-sensitive and expensive fuel cells. WG 3.55 is investigating the ignition of lean hydrogen/air mixtures by hot free jets (so-called pre-chamber ignition) using experimental methods.

Electrochemical storage

Electrical-thermal assessment of electrochemical storage systems  

Efficient and safe batteries are crucial for e-mobility and the integration of renewable energies into the power grid. Working group 3.55 investigates the widely used lithium-ion batteries with the aim of identifying unsafe operating stated, detecting them in time during use, and characterizing and mitigating the consequences of battery runaway.


Research topics

  • Characterization of Li-ion battery modules for second-life applications
  • Influence of temperature distribution on the lifetime of automotive battery cells in a whole-vehicle context
  • BaSS - BatterySafetyStandardisation
  • Lithium-Ion-accumulators in flameproof enclosures


Experimental techniques

  • Calorimetry for determining the amount of heat released
  • Accelerating Rate Calorimeter (ARC)
  • Current and voltage measurement
  • Measurement of internal resistance
  • Electrochemical impedance spectroscopy
  • Climate cabinets
  • Cell and module testers for cyclization
  • Pressure-resistant vessels for destructive testing



In the NetFlexum project (next generation of consumer-oriented PV combined systems for households and businesses for greater grid serviceability, flexibility and cost-effectiveness), new possibilities for providing grid services, in particular the provision of instantaneous reserve through innovative grid-serving prosumer systems, are being researched. Our group is focussing on the effects of this mode of operation on the safety and service life of the battery storage system.



The LIdEX project (lithium-ion accumulators in flameproof enclosures) deals with the effects of the thermal runaway of lithium-ion batteries in flameproof enclosures. The load on the enclosure is determined on the basis of numerous measurements in order to develop information for the design and certification of such enclosures

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