Feature: E-mobility
Relying on thermal
conductivity sensors for detecting hydrogen leaks
By Rolf Horn, Applications Engineer, DigiKey
Figure 1: Honeywell’s HLD-111-111-001 sensor uses thermal conductivity detection to accurately and reliably monitor hydrogen leaks
F
rom heavy duty trucks to buses and automobiles, as well as aircraſt and ships, hydrogen-generated power is gaining popularity in transportation for several reasons: zero emissions, high effi ciency, long range and fast refuelling. When compared to the greenhouse gases emitted by conventional
fossil fuel based internal combustion engines, hydrogen fuel cells produce only water vapour as an exhaust emission. Although cost and infrastructure remain hurdles in adoption, technological advancements are further improving effi ciencies, with the aim for decarbonisation continuing to attract interest and investment in hydrogen as a clean alternative to fossil fuels. However, with the widespread adoption of hydrogen-powered
transportation, there is a tremendous need for detecting hydrogen leaks in these systems. Leaks are common in hydrogen power systems primarily because hydrogen molecules are extremely small and have high diff usivity, allowing them to escape through materials and seals. Additionally, hydrogen can cause hydrogen embrittlement, a process where it infi ltrates and thus weakens materials, including steel, creating more opportunities for leaks. Hydrogen is also highly fl ammable, colourless and odourless,
that can quickly lead to a dangerous situation. T erefore, it must be detected instantly, whenever and wherever a leak occurs. While there are many methods to detect hydrogen leaks,
including electrochemical and catalytic bead sensors, the most eff ective and accurate method is with thermal conductivity detection (TCD) sensors. T ese work by precisely measuring the thermal properties of hydrogen as it passes through the sensor, comparing it to the thermal properties of air.
Key benefi ts of TCD sensors T ere are several benefi ts in using TCD sensors for monitoring hydrogen leaks. Besides ensuring a high degree of accuracy, they off er a long operational life. HLD sensors are developed to operate for to ten years without intervention and calibration, reducing
34 June 2026
www.electronicsworld.co.uk
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