Mitsubishi Heavy Industries Engine & Turbocharger, Ltd. (MHIET), a part of Mitsubishi Heavy Industries, Ltd. (MHI) Group, has been working on commercialization of H₂ combustion engines as a key product to support MHI Group's MISSION NET ZERO declaration that aims to achieve net zero emissions by 2040.

In 2021, MHIET established technologies to achieve stable combustion of 100% H₂ in a single cylinder engine of 170 mm cylinder bore and 220 mm piston stroke developed from its GSR engine series through testing at Japan's National Institute of Advanced Industrial Science and Technology (AIST).

As the next step toward commercialization, construction of a 6-cylinder H₂ engine generator set of 500-kW-class output and of a H₂ supply facility for supplying high-pressure H₂ gas delivered on trailers to the generator set under reduced pressure has been completed. Starting with a trial run using Japan's city gas, MHIET aims to confirm stable combustion at 100% load while running on H₂ within this fiscal year.

As a part of this series of tests, a thorough evaluation of the newly-developed H₂ engine will take place, including combustion stability, performance, and reliability. Considering the characteristics of H₂, an evaluation of the safety and other performance required for a generator set will also be conducted. The use of green H₂ (produced using electricity derived from renewable energy with no CO₂ emissions) is planned for the tests.

By basing the entire development process, from design to evaluation, at a single premise, it is possible to quickly implement improvements that the evaluation discovers. MHIET aims to accelerate the process for commercialization and is targeting FY2026.

Reciprocating engines have a unique structure allowing them to burn a variety of fuels. H₂ engines are considered a promising technology for the energy transition that is targeting carbon neutrality. In particular, generator sets that use a H₂ engine can thereby contribute to the carbon neutrality of distributed power systems because they emit zero CO₂ while meeting power needs. Through demonstration tests, MHIET endeavors to help achieve a carbon neutral society by expanding the use of H₂.

A set of equipment required to generate electricity using a H₂ engine, including a generator mounted on the engine's output shaft, auxiliary equipment (piping systems for fuel gas, lubricating oil, cooling water, intake and exhaust gas, and a generator control panel) required to operate the generator set, and enclosures that house and protect the generator and auxiliary equipment.

Compared to natural gas, H₂ 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, H₂ engine generator sets require strict safety measures such as redundant leak prevention, leak detection, a safe stop of the integral system, and ventilation to avoid gas accumulation.

PREVIOUS RELEASES OF MHIET'S H₂ ENGINE DEVELOPMENT

1. Stable Combustion of 100% H₂ on a Single Cylinder Engine

MHIET Conducts Combustion Test for H₂ Engine with Pure H₂ -- Joint Project with AIST to Achieve Stable Combustion of 100% H₂ Fuel for a Carbon-free, H₂ Economy

https://www.mhi.com/jp/news/210121.html

Tested a single cylinder engine (cylinder bore 170 mm, piston stroke 220 mm) modified from a MHIET 4-stroke gas engine GSR series offered in 6-to-16 cylinders at Japan's National Institute of Advanced Industrial Science and Technology (AIST). In a joint research project with AIST, stable combustion of 100% H₂ fuel was achieved.

2. Test Operation of City Gas and H₂ Dual-fuel on Commercial Gas Engine for Cogeneration System

Successfully Conduct Test Operation of City Gas and H₂ Mixed-fuel Combustion in a Commercial Gas Engine for a Cogeneration System -- Rated operation at 35% H₂ mixed fuel burning ratio a first in Japan

https://www.mhi.com/jp/news/21082601.html

Toho Gas and MHIET succeeded in rated operation at 35 vol% H₂ mixed fuel in a test run, the first in Japan. The test was conducted at Toho Gas Technical Research Institute in Tokai, Aichi Prefecture, using one of MHIET's existing gas engines.

3. Achieves Stable Combustion of up to 50 vol% H₂ for 5.75-MW Gas Engine Cogeneration System

MHIET Achieves Stable Combustion of up to 50 vol% H₂ on Single Cylinder Test Engine

https://www.mhi.com/jp/news/23110101.html

Using a KU series gas engine (3.65~5.75MW), a model well-proven in a variety of industries, a single cylinder engine developed based on a 5.75-MW cogeneration system was tested. With the aim of lowering CO₂ emissions, stable combustion with up to 50 vol% H₂ admixtures at an output equivalent to its rating was verified.