Underground storage - Risk assessment

For 2020 a 30% share of renewable energy on electricity generation is demanded by the Integrated Energy and Climate Program (IEKP) of the federal government adopted in 2007. An electrolytic production of hydrogen and proportional feed-in to natural gas grid (Power to Gas) is one way of storing excess energy from renewable sources. According to DVGW-guideline G 262, a fraction of up to five percent of pure hydrogen can already be injected directly into the natural gas grid. Currently, higher limits are being debated.

Several studies have already pointed out microbial induced technical risks associated with a proportionate hydrogen injection into underground gas storage. The microbiological risk assessment of hydrogen storage developed by MicroPro GmbH takes account of this problematic. This risk assessment includes meaningful chemical, microbiological and molecular-biological analyzes, compiled under strict economic and practical considerations.

Microbiological risk assessment:

  • Current microbial colonization of the underground storage
  • Risk potential by hydrogenotrophic microorganisms
  • Evaluation of technical and economic risks
  • Preventing and treatment strategies


Additional information

For a comprehensive microbiological characterization of underground gas storages the advantages of several analyses are combined. In addition to a molecular identification of relevant groups of microorganisms, the detection of living microorganisms in enrichment cultures has proven to be very meaningful. In order to estimate the risk potential these enrichment cultures can be used in model tests under real storage conditions.

The risk assessment includes the following tests of memory samples:

  • Microscopic evaluation
  • Physical / chemical analyzes
  • Molecular-biological detection of relevant groups of microorganisms
  • Enrichment and characterization of living microorganisms
  • Model experiments under high pressure conditions
  • Testing of treatment strategies to control bacterial development

In order to evaluate the current risk potential an extensive knowledge of the history and the operation of storage facility is required apart from the actual laboratory analyzes.