DENSO for years has pursued initiatives in the three areas of "Monozukuri (manufacturing)," "mobility products" and "energy use" to achieve carbon neutrality. The utilization of hydrogen energy is essential for realizing carbon neutrality as it does not emit CO2 when burned and can generate significant energy. To establish a hydrogen supply chain, DENSO engages in technology development related to producing, storing, transporting, and using hydrogen. As part of these efforts, the Hirose Plant, positioned as a green hydrogen utilization model factory in the semiconductor manufacturing field, will conduct a verification of green hydrogen production using SOEC technology and its application in manufacturing.
In terms of hydrogen production, DENSO will manufacture hydrogen within the factory using its SOEC. DENSO's SOEC is a device that efficiently produces green hydrogen through electrolysis by maintaining a consistent high temperature of around 700degC and incorporates various technologies derived from automotive components, such as thermal management techniques for controlling internal temperatures, ceramic technology for efficient electrolysis at high temperatures, and ejector technology(3) that recycles unreacted steam within the device.
Furthermore, in terms of hydrogen use, green hydrogen produced by the SOEC will be used in the prototype production line for power cards. Specifically, in the soldering process of assembling the components of the power cards, hydrogen traditionally used as a reducing agent to remove solder oxide and improve the joinability will be replaced with green hydrogen produced by SOEC. In addition to the existing line that uses externally purchased hydrogen, a new line utilizing green hydrogen produced by the SOEC will be established. Both lines will be used simultaneously to verify the stability of production and examine the impact of green hydrogen produced by the SOEC on the quality of power cards.
Initially, the SOEC will utilize externally purchased green electricity as its power source. However, starting from 2025, DENSO plans to replace this with green electricity generated by solar power generation facilities installed within the Hirose Plant. DENSO also aims to address the cost challenges associated with transporting hydrogen by establishing a model of local production and consumption. This involves producing green hydrogen using SOEC within the factory and consuming it internally. Additionally, DENSO aims to integrate the expertise and technology accumulated in semiconductor manufacturing at the Hirose Plant with the knowledge gained from this verification, eventually applying it to mass production in the future.
Based on the insights and achievements gained from the development of automotive products, DENSO aims to continue exploring the potential of green hydrogen in the manufacturing field and contribute to the creation of a carbon-neutral society.
(1) SOEC (Solid Oxide Electrolysis Cell): A device that operates at high temperatures using a ceramic membrane as an electrolyte to electrolyze water vapor and produce hydrogen. While there are other methods for hydrogen production such as alkaline water electrolysis, which uses an alkaline liquid as the electrolyte, and PEM (Proton Exchange Membrane) water electrolysis, which uses a polymer membrane as the electrolyte, the SOEC used in this verification has the advantage of requiring less electrical energy for electrolysis compared to these methods. Since March of this year, DENSO Fukushima Corporation and Toyota Motor Corporation have been conducting a joint verification using PEM water electrolysis devices.
(2) Power Card: A component of an inverter that drives the motor in hybrid or electric vehicles. This product controls the inverter by rapidly switching the power on and off, leading to enhanced fuel efficiency and energy conservation.
(3) Ejector Technology: A technology that recirculates discharged water vapor within the equipment.