Technical Classification
Definition
Quantification of gas release during thermal runaway of lithium-ion cells: identification, volume determination and toxicity assessment of released gases (HF, CO, H2, CH4, C2H4, electrolyte vapors). Basis for evacuation planning and safety distances.
Technical Background
During thermal runaway, 0.5-1.5 liters of gas per Ah cell capacity are released. Critical gases: hydrogen fluoride (HF) -- highly toxic, life-threatening above 30 ppm. CO -- lethal above 3,000 ppm. H2 -- explosive above 4 vol%. Gas release depends on: cell chemistry (NMC > NCA > LFP), SOC (higher = more gas), cell size and aging condition.
Risks
Acute health hazard for first responders and nearby residents from HF. Explosion risk from H2 accumulation in enclosed spaces. Environmental contamination from electrolyte vapors. Inadequate protective equipment at many fire departments.
Standards & Regulations
AGBF guideline (fire department recommendation), TRGS 900 (workplace exposure limits), TA Luft (immission control), GHS/CLP Regulation (hazardous substance labeling), BImSchG Section 5 (operator obligations), DIN EN 50632 (Gas Detection).
Testing Methods
Gas chromatography / mass spectrometry (GC-MS). FTIR spectroscopy. Real-time gas analysis with NDIR/electrochemical sensors. Calorimetry (DSC, ARC). Fire chamber tests with controlled ventilation. HF-specific ion chromatography.
Common Deficiencies
Laboratory results underestimate real gas concentrations in enclosed containers. Gas release models for aged cells insufficiently validated. HF measurement during fire events technically challenging. Lack of standardized emission factors for safety distance calculation.
Relevance for Investors, Insurers & Operators
Investors: permitting feasibility in populated areas depends on emission prognosis. Insurers: liability risk for personal injury from gas release. Operators: dimensioning of ventilation, gas detection and evacuation zones.
Assessment by PV-BESS-Assessor
The University of Sheffield quantifies gas release during thermal runaway. Identification of toxic gases (HF, CO, H2) is essential for fire protection planning and evacuation concepts.
Implications for Investors
Influences site planning and permitting feasibility: gas release scenarios determine required safety distances. Relevant for insurance conditions.
Implications for Assessments
Directly relevant for fire protection assessments: PV-BESS-Assessor quantifies expected gas release in worst-case scenarios and evaluates evacuation zones and ventilation concepts.
Technical Risks
Toxic gases (especially HF) pose a significant health risk. Released quantities depend on cell chemistry and state of charge -- LFP releases fewer toxic gases than NMC.
Regulatory Significance
Influences safety distances in AGBF guidelines and permitting procedures. Scientific basis for BImSchG-relevant emission prognosis.
Conclusion by PV-BESS-Assessor
PV-BESS-Assessor considers gas release as critical for permitting feasibility in populated areas. LFP chemistry has a clear advantage over NMC in this regard.
Last updated: 2026-06-16