Fraunhofer Institute for Physical Measurement Techniques IPM
The greenhouse gas methane (CH4) is increasingly being targeted by climate policies. In addition to agriculture, the energy sector also emits significant amounts of methane because CH4 is the main component of natural gas. The EU is tackling methane emissions in the energy sector with a new regulation requiring gas grid operators to closely monitor their infrastructure for leaks from 2025.
Leakage detection with photoacoustics: more efficient, precise and cost-effective
Fraunhofer IPM developed a measurement system for vehicle-based leak detection for Schütz GmbH Messtechnik. This mobile measurement technology is a more efficient, precise and cost-effective way of checking for leaks in natural gas pipelines. Schütz GmbH Messtechnik went on to develop the system into a marketable product. The Leak Detection and Emission Monitoring (LDEM 2000) product is hardly bigger than a shoebox and its compact size, low weight and low electrical power consumption allow it to be flexibly integrated into vehicles.
The measuring principle is based on resonant photoacoustics supported by interband cascade lasers in the mid-infrared wavelength range. This measurement technology stands out for its excellent robustness and low level of complexity. The measurement system draws ambient air into a measurement cell. The methane in the air absorbs some of the laser light. This absorption process indirectly creates a pressure wave that is amplified by the acoustic resonator (measurement cell) and measured using a microphone. The very small cell volume allows a response time of less than 0.4 seconds. The system can measure leaking gas also from a distance of several meters. This enables sections of the grid not located directly on the road, such as household connections, to be included in the measurements as the vehicle drives past. The system works at vehicle speeds of up to 50 km/h and has a sensitivity of 6 ppb or, in other words, 6 particles per billion particles.