Test & measurement
JTEC ENERGY BUILDS CONFIDENCE IN WASTE-HEAT-TO-POWER CONVERSION WITH VAISALA MOISTURE MEASUREMENT
As JTEC prepares its hydrogen-based waste-heat-to-power conversion technology for field deployment, Vaisala sensors provide the humidity and dew point measurements needed to protect critical components, simplify control and build customer trust.
TEC Energy has developed a novel technology that converts waste heat into electrical power at higher efficiency and at lower temperatures than many competing waste-heat recovery approaches. Its system uses hydrogen as the working fluid, pairing a heat-driven compression technology with electrochemical stacks that convert hydrogen pressure into electrical potential. Tight moisture control is essential to this process. The electrochemical stack needs humidified hydrogen to keep its membranes functioning optimally, while the metal hydride reactors used in the waste-heat conversion subsystem must be protected from excessive moisture exposure. To manage that balance, JTEC developed a closed- loop gas management system that removes and recirculates more than 99.99 per cent of the moisture introduced into the system. For this system to operate reliably, JTEC requires highly accurate moisture measurement across conditions ranging from high humidity at the electrochemical stack to the very low dew point levels required before hydrogen can be safely returned to the reactors. These critical measurements also need to be performed with industrial-ready sensors that can operate in hydrogen, support dynamic pressure and flow conditions, integrate with control systems and meet hazardous area requirements.
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PROTECTING A CRITICAL SYSTEM IN A DEMANDING HYDROGEN ENVIRONMENT
JTEC’s waste-heat-to-power conversion system brings together two subsystems with different moisture requirements: an electrochemical stack that requires moisture to operate efficiently and metal hydride reactors that must be protected from excess moisture.
In JTEC’s system, waste heat is delivered to one of the metal hydride reactors in the waste-heat conversion subsystem. Metal hydrides act much like a sponge for hydrogen. When cooled, they absorb hydrogen. When heated, they release hydrogen at a pressure linked to temperature. JTEC’s system uses that ability to generate hydrogen pressure as part of the process for converting waste heat into electrical power. From the metal hydride reactors, the high- pressure hydrogen is then sent to the stack
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module, where expansion across JTEC’s novel electrochemical stacks produces electrical power. After this expansion, the low-pressure hydrogen leaves the stack and can be absorbed back into a separate metal hydride reactor in the waste-heat conversion module, where it can later be heated, pressurised and used to generate power again. Through this process, JTEC has developed a waste- heat-to-power conversion technology that circulates a single charge of hydrogen in a fully closed loop: No hydrogen is consumed by the system, and waste heat is the only “fuel” JTEC needs to operate. During passage through the stacks, the hydrogen gas is humidified to keep the membranes in the stacks operating at peak performance. However, excess water exposure can damage metal hydrides by contributing to the development of oxide layers that limit hydrogen absorption and reduce reactor performance. As a result, JTEC must maintain enough moisture to support stack performance, then dry the hydrogen stream before it reaches the reactors.
“At its core, humidity measurement is so important to JTEC because we have two parts of our system
that work really well, but for them to work well together, we have to ensure that we can control humidity passing back and forth between them really tightly,” says Julian Bell, vice president of Engineering at JTEC Energy.
Before standardising on Vaisala, JTEC used conventional relative humidity and dew point sensors in lab and R&D work. These sensors were not always robust enough for the application, especially when exposed to condensation or saturation events. In R&D applications, a saturated humidity probe could force engineers to stop an experiment, dry down equipment, clean the system and begin again. In one case, an engineer spent three days trying to complete a six-hour experiment because the sensor saturated partway through the test and the system had to be reset.
The risks posed by inaccurate or unreliable moisture measurements are even greater in a production system, where the waste-heat conversion subsystem can represent more than a third of total system cost and is continuously in operation while the system is running. Moisture overexposures can degrade reactor system performance and require offline maintenance for
September 2026 Instrumentation Monthly
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