Assistant Professor AKIMOTO Yutaro, Institute of Systems and Information Engineering

Professor AKIMOTO looks forward to building a decarbonized society through his research and development. His diverse projects encompass everything from creating operational models for the large-scale implementation of renewable energy sources to pioneering advancements in battery technology and fuel cell systems that facilitate this energy transition.

His research focuses on developing an energy system that balances economic efficiency, environmental sustainability, and energy security. Among these aspects, he emphasizes resilience—the ability of energy systems to keep functioning and adapt during emergencies. He is currently working on methods to assess resilience in buildings equipped with solar power and batteries. Such systems are becoming increasingly prevalent, especially in public facilities. This is because they encourage the use of renewable energy and allow buildings to operate for some time if the external power supply is disrupted owing to a natural disaster or other emergencies. Until now, decisions regarding the installation of power generation and storage systems have mainly been based on cost and capacity. However, Professor AKIMOTO argues that resilience should also be a crucial factor in these decisions. Therefore, he proposed a framework that includes three key indicators: the duration for which electricity can be supplied during an outage (redundancy), the amount of extra capacity available under normal conditions (surplus capacity), and the extent to which demands are not met when supply is limited (supply shortage).

Earlier this year, Professor AKIMOTO's team published a study that applied these indicators to a real zero-emission building in Oita Prefecture. The building, equipped with solar panels and batteries, was capable of reducing its annual greenhouse gas emissions to almost zero. Looking forward, Professor AKIMOTO plans on developing a resilience index—which can be easily understood and is similar to energy star labels found on appliances—to assist local governments and households in making informed decisions about renewable energy sources and battery systems.

Along with this work, Professor AKIMOTO has been collaborating with Honda R&D to develop a method for verifying the authenticity of lithium-ion batteries (LIBs) without damaging them. As the adoption of renewable energy sources grows, pairing renewable sources with batteries becomes essential for maintaining a stable power supply, given the variability of solar and wind energy output owing to weather conditions. LIBs are a prevalent type of storage battery; however, the increasing use of nongenuine or "compatible" batteries has raised safety concerns, including the risk of fires. Because majority of batteries now resemble each other, distinguishing them based on appearance alone is challenging. Even identification chips and labels can be counterfeited.

They also use magnetic sensing technology in fuel cells to generate electricity through a chemical reaction between hydrogen and oxygen, yielding only water and no CO₂. Hydrogen generated using renewable energy is referred to as green hydrogen. Fuel cells are one of the main methods for its utilization. Fuel cells are a clean and promising power source for achieving a carbon-neutral future.

Fuel cells present with their own challenges. If an excessive amount of water accumulates inside, it can obstruct the reaction area and degrade performance. Conversely, if too much water is removed, the membrane that allows hydrogen to pass through can dry out, which also affects performance. Traditionally, internal sensors have been used to monitor and control water levels; however, they are expensive. Professor AKIMOTO and his team discovered a method to visualize the current distribution in real time using external magnetic sensors, enabling more efficient and cost-effective management of water levels.