MHIET to Install 100% Hydrogen Engine Generator Set for In-house Evaluation

TOKYO, Jul 6, 2023 – (JCN Newswire) – Mitsubishi Heavy Industries Engine & Turbocharger, Ltd. (MHIET), a part of Mitsubishi Heavy Industries (MHI) Group, has been developing hydrogen combustion engines referred to in its roadmap to carbon neutrality(1) and generator set for commercialization as one product that supports MHI Group’s MISSION NET ZERO declaration.

Installation site in Sagamihara Plant
Illustration of hydrogen engine generator set for technical evaluation

Earlier, MHIET has established technologies to stabilize combustion of 100% hydrogen in a single cylinder engine of 170mm cylinder bore and 220mm piston stroke modified from its GSR series, a gas engine offered in 6 to 16 cylinders at Japan’s National Institute of Advanced Industrial Science and Technology (AIST).

As the next step for commercialization, the knowledge gained from the testing has been utilized to develop a 6-cylinder 100% hydrogen engine with 500kW output and integrate it into a generator set. The hydrogen engine generator set as well as hydrogen supply facility will be installed within its Sagamihara Plant, and construction work for the supply facility has begun first. The facility depressurizes the high-pressure hydrogen gas brought in by hydrogen trailers and supplies the hydrogen gas to the generator set. The technical evaluation of the hydrogen engine generator set is planned to start in FY2024.

A thorough performance of the newly developed engine will be evaluated, including combustion, output and reliability. Safety system of the generator set will be closely monitored as hydrogen requires very strict care in handling(2).

Reciprocating engines have the unique structure that can burn a variety of fuels. Hydrogen engine generator sets are considered as a promising technology in energy transition that can bring about carbon neutrality of distributed power systems because they emit zero CO2 while responding to power needs. MHIET endeavors to help achieve carbon neutral society through the marketing of fully validated hydrogen-fueled engine products to the world.

Previous releases of MHIET’s hydrogen engine development
Stable combustion of 100% hydrogen on a single cylinder engine
MHIET Conducts Combustion Test for Hydrogen Engine with Pure Hydrogen — Joint Project with AIST to Achieve Stable Combustion of 100% Hydrogen Fuel for a Carbon-free, Hydrogen Economy –

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– Tested a single cylinder engine (cylinder bore 170mm, piston stroke 220mm) modified from a MHIET’s 4-stroke gas engine GSR series offered in 6 to 16 cylinders at Japan’s National Institute of Advanced Industrial Science and Technology (AIST)
– a joint research with AIST, stable combustion of 100% hydrogen fuel was achieved

Rated operation of hydrogen mixed fuel on commercial gas engine for cogeneration system
Toho Gas and MHIET Successfully Conduct Test Operation of City Gas and Hydrogen Mixed-fuel Combustion in a Commercial Gas Engine for a Cogeneration System — Rated operation at 35% hydrogen mixed fuel burning ratio a first in Japan –

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– Toho Gas Co., Ltd. and MHIET succeeded in achieving rated output using 35% hydrogen mixed with city gas (by volume) on a commercial engine
– The test was conducted at Toho Gas Technical Research Institute in Tokai, Aichi Prefecture using a commercial gas engine from MHIET

Future development
– Starting the evaluation from FY2024, MHIET plans to release the 100% hydrogen engine in FY2026.

(1) MHIET’s roadmap to carbon neutrality is available at
(2) Compared to natural gas, hydrogen is highly combustible and can ignite with an energy equivalent to static electricity and with a wider combustion range. Furthermore, because the molecules are small and leaky, hydrogen engine generator sets require strict safety measures such as redundant prevention of leak, detection of leak, safe stop of the integral system, and ventilation to avoid accumulation.

About MHI Group

Mitsubishi Heavy Industries (MHI) Group is one of the world’s leading industrial groups, spanning energy, smart infrastructure, industrial machinery, aerospace and defense. MHI Group combines cutting-edge technology with deep experience to deliver innovative, integrated solutions that help to realize a carbon neutral world, improve the quality of life and ensure a safer world. For more information, please visit or follow our insights and stories on

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