A new four-stroke gas power unit could lay the groundwork for future marine engines
Japan’s Mitsubishi Heavy Industries Engine & Turbocharger, Ltd (MHIET) is conducting tests on a pure hydrogen gas engine based on its four-stroke diesel and gas engine technology.
Part of the MHI Group, MHIET is conducting combustion tests of a hydrogen engine in a joint research project with Japan’s National Institute of Advanced Industrial Science and Technology (AIST). The modified single-cylinder gas engine, with a bore of 170 mm x stroke 220 mm, is based on MHIET’s four-stroke reciprocating gas engine GSR series, which is available in six- to 16-cylinder configurations. Installed at the AIST Fukushima Renewable Energy Institute, the engine was tested to identify the conditions to achieve stable combustion of 100% hydrogen without emitting CO2.
Initial applications for the engine will be in industrial power generation, but the research could yield benefits for the marine market. A spokesperson for MHI corporate communications told Marine Propulsion the engine "is currently aimed for power generation in industrial use, and the potential for marine engine usage will be examined further."
Joint research on combustion of the hydrogen engine between MHIET and AIST began in 2019. MHIET and MHI Research and Innovation Center designed and built the hydrogen engine using their knowledge of hydrogen combustion technology, industrial-use diesel engines and natural gas engines; they studied the conditions for optimum combustion and analysed the test data.
AIST constructed and operated the hydrogen supply equipment and the test bench, applying data utilising its experience in developing combustion technology for high-power, high thermal efficiency, and low NOx hydrogen engines for large-scale power generation.
Hydrogen has a wide flammability range and a high combustion wave propagation velocity, making the engine prone to abnormal combustion, such as backfiring and knocking. The test used MHIET’s existing lean-burn gas GSR series engine, modifying the methods of fuel supply, ignition, timing of intake air valve closing, and excess air ratio for optimum combustion to determine the conditions that ensure stable combustion with hydrogen-only firing and pre-mixed firing.
Results of the tests reveal the maximum output is 340 kW for a six-cylinder engine and 920 kW for 16-cylinder model.
MHIET intends to accumulate more test data that will lead to the realisation of multi-cylinder hydrogen engines, with the goal of producing engines for the ‘hydrogen economy’ in the 2030s.
Further into the future, MHIET will replace the gas engine generator set currently used with EBLOX in the Triple Hybrid, self-sustaining power supply system with a hydrogen engine generator set. The goal is to provide a distributed energy solution that achieves a self-sustaining power supply with no CO2 emissions using solar power, batteries, hydrogen engines, contributing to an energy-stable and carbon-free economy.
“Suiso Frontier will be used for a technology demonstration project aimed at establishing an international hydrogen energy supply chain”
Japan is betting heavily on creating the ‘Hydrogen Society’ as the government calls it. The country has 135 hydrogen filling stations – the most in the world – all backed by government subsidies, with more than 3,700 hydrogen-powered vehicles.
Hydrogen produced in Australia from coal is expected to be imported into Japan in 2021. Japan’s Kawasaki Heavy Industries (KHI) is building the world’s first liquefied hydrogen (LH2) carrier Suiso Frontier. Once complete, the 2,500-m3 Suiso Frontier will undergo operational testing, then it will be used for a technology demonstration project aimed at establishing an international hydrogen energy supply chain in which liquefied hydrogen produced in Australia will be shipped to Japan.
For transport, hydrogen must be cooled to -253°C in order to be liquefied, requiring special tanks, handling and loading systems.
Additional technologies being developed by KHI, in cooperation with other parties, are the world’s first marine loading arm for the transfer of liquefied hydrogen from an LH2 carrier to an onshore storage facility.