Mitsubishi Heavy Industries Engine & Turbocharger, Ltd. (MHIET), a part of Mitsubishi Heavy Industries (MHI) Group, previously achieved rated operation (435kW/1,500min-1) of a 500kW-class hydrogen engine generator set at its demonstration facility using 100% hydrogen fuel. Recently, the company has established operational capabilities and completed reliability verification for commercialization, indicating that the generator set has reached a level of technological maturity suitable to support practical applications. MHIET will further accumulate operating hours and conduct tests to accelerate the process toward full commercialization.

The demonstration tests were conducted at its Sagamihara Plant. Through more than 100 hours of operation, the following have been completed to support practical application:

• Year-round operation was conducted to evaluate performance under various atmospheric conditions, including electrical output, generation efficiency, and emissions performance.
• Operation strategies were established for abnormal combustion, a major challenge due to the characteristics of hydrogen.
• Using the prototype generator set representative of a near-commercial product, the ability to handle sudden fluctuations in power demand that may occur during actual operation was verified.
• Various measurements including engine vibration and combustion chamber temperature were taken to confirm that there are no issues with reliability.
• The process from receipt of green hydrogen produced in Yamanashi Prefecture at the Sagamihara Plant to using it for power generation was confirmed.

With these achievements, all evaluations have been completed except for a long-term durability assessment, which is difficult to conduct at present because of hydrogen supply constraints. This demonstrates that the generator set has reached commercially viable technology readiness.

Reciprocating engines, due to their ability to run on various fuels, are expected to play an important role in the energy transition towards a carbon-free society. Among these, 100% hydrogen engine generator sets, which use pure hydrogen as fuel and emit no CO2 during combustion, contribute substantially to the decarbonization of distributed power systems.

MHIET has established a development cycle at its Sagamihara Plant that integrates design, manufacturing, and demonstration testing for hydrogen engine generator sets, enabling immediate incorporation of findings from successive demonstration tests into final products. Going forward, MHIET will continue to pursue product development with the aim of realizing a decarbonized society through widespread use of hydrogen.