Development of Community Energy Management System (CEMS) to Introduce Next Generation Secondary-Batteries into Market
Authors: Osaka Tetsuya , Sugiyama Atsushi , Yokoshima Tokihiko , Nara Hiroki , Mukoyama Daikichi , Mikuriya Hitoshi , Jeong Moongook , Momma Toshiyuki , Mori Yasurou 
Published: February 2020

Expectations for renewable energy are rising against the backdrop of energy resources on the brink of exhaustion, accelerating global warming, and apprehension of nuclear power plant accident. The Community Energy Management System (CEMS), which can provide a town with higher efficiency use of electric power, has been actively developed in major advanced countries. In Japan, there is an increasing need for the realization of CEMS system after the Great East Japan Earthquake on March, 2011, and some eco-town projects at national level have been carried out. To accomplish the CEMS main aim which is to plan a decrease in use of the fossil fuel, increase the electric power ratio of renewable energy such as photovoltaic and wind power, interchange of the surplus electric power between areas, development of power saving device, these are actively incorporated. In these development, the role of high-capacity secondary battery has been highlighted. By using electric power through storage battery, it becomes possible to give high efficiency use of electric power. In addition, the power transmission capability of the Tokyo and other large city areas are coming to the limit. Therefore, a new power line for electric power interchange is needed or electric power generated in a local area has to consume it in the local.
Beginning in 2012, Saitama Prefecture, which is adjacent to Tokyo, started a project called the "Saitama eco-town project". The project promotes the local supply and local consumption of energy, and the use of renewable energy that already exists in towns. In 2014, our CEMS project, which develops a community energy management system that uses technology to cooperatively control storage batteries in the community was started as one of "Saitama Leading Edge Project".
As mentioned above, the necessity of the utilization of secondary battery in CEMS is recognized. However, many batteries with high capacity are required to build a high efficiency CEMS. Unfortunately, the present high cost has barred use of the battery for CEMS.
The main feature of our CEMS is to use secondary batteries according to their deterioration status for reducing total cost. As for the recognition to a battery in other developments, the battery would be treated as a device which is not broken. On the other hand, battery does not seem to use all of battery ability. On the basis of results of an electrochemical impedance method to detect battery status that was developed by our group, we attempted to add a battery control function to CEMS, This addition makes it possible to use the secondary battery for twice as long by controlling the charging and discharging process suited for each storage battery based on the detection. This will lead to reduced battery costs, including running costs.
In tests, we have been able to achieve integrated control of batteries from different manufacturers and with differing specifications. CEMS has allowed for the creation of a battery-change schedule and the supply of new battery units. Moreover, CEMS also offers the function of Demand Response that communicates with big electric companies using a highly-versatile, globally-standard protocol.
The development of this system is expected to not only promote eco-towns, but also to promote the sustainable development of next generation secondary battery. The battery industry and battery-related businesses are expected to benefit through the spread of this battery-management system, CEMS. On the other hand, for promoting the use of batteries for CEMS, it is also thought that cooperation with other CEMS, reinforcement of the cooperation beyond the fence between companies are necessary.
Acknowledgments: This work was supported by Saitama Leading Edge Project “Development of community energy management system with secondary-batteries control for creating eco-towns”, Saitama Prefecture, Japan, and we thank the members in Mitsubishi Electric, Hitachi Chemical, Toshiba, Yoshino Denka Kogyo, and many companies in Saitama Prefecture for their cooperative work and support.

Figure 1