ENEOS Corporation has constructed a demonstration plant in Brisbane, Australia, to produce methylcyclohexane (MCH), a liquid organic hydrogen carrier (LOHC), using its proprietary low-cost electrochemical synthesis of organic hydride method Direct MCH. (Earlier post.) The plant will begin operation this month.
Methylcyclohexane (MCH) is a liquid hydrogen carrier made by the chemical reaction of hydrogen with toluene. MCH contains more than 500 times more hydrogen per unit volume than hydrogen gas. MCH is a liquid with petroleum-like characteristics that can be transported at ambient temperature and pressure, and can be used in existing petroleum infrastructure. After dehydrogenation, the toluene can be reused to create MCH again. Both toluene and MCH are toxic substances.
Eneos’ Direct MCH uses an electrolyzer to produce MCH directly from water. Water is oxidized on the anode catalyst to produce oxygen, protons, and electrons. The resulting protons flow to the cathode through the ion exchange membrane, where they react with toluene and electrons from the external circuit on the cathode catalyst to produce MCH.
The key performance indicators in this process are current density (reaction rate) and reaction selectivity (Faraday efficiency). If these performances are improved, a large amount of MCH can be produced in a small-sized electrolyzer, eventually leading to reduced equipment cost and lower hydrogen costs.
ENEOS has worked to scale up electrolyzers using Direct MCH technology in order to mass-produce MCH derived from renewable energy (Green MCH). The operation of this demonstration plant is a part of this effort.
The 150-kilowatt-scale medium-sized electrolyzer (approximately 200 times larger than the electrolyzer used in the 2021 demonstration), for which ENEOS recently succeeded in developing the technology, consists of stacked electrodes with a surface area of 3 m2>. The electrolyzer realizes increased efficiency in MCH production with electrodes which are nearly the largest by size that is used industrially.
The demonstration plant will produce green MCH by combining the medium-sized electrolyzer with a 250-kilowatt solar power system in Queensland, which is ideal for solar power generation.
With the aim of maximizing production efficiency, the plant will confirm the durability of the electrolyzer under subtropical conditions as well as develop optimal operation and control technologies for it when plant operation is adjusted to match fluctuations in solar power during the approximately eight-month-long demonstration period from February to September 2023.
Additionally, during the demonstration period, MCH equivalent to approximately 2 to 3 tons of hydrogen for 400 to 600 fuel cell vehicles (FCVs) will be produced and transported to Japan, where hydrogen will be extracted from MCH in ENEOS’ Central Technical Research Laboratory.
ENEOS will use the knowledge gained from this demonstration plant to develop a larger-sized 5 megawatt-scale electrolyzer (more than 30 times larger than the medium-sized electrolyzer used in this demonstration plant) for commercialization by FY2025.
ENEOS will work to develop production technology for stable and cost-competitive CO2-free hydrogen (green hydrogen) in Australia, a country with excellent potential for green hydrogen production due to its favorable climate conditions, including wind and sunlight, and expansive land.