Microgrid: a solution to secure energy supply after natural disasters
Energy is a vital fluid for our modern society and its development. Electricity is a necessity in, for example, hospitals or security systems.
The U.S. Department of Energy defines the microgrid as a group of interconnected loads and distributed energy resources within clearly defined electrical boundaries that act as a single controllable entity with respect to the grid. A microgrid can connect and disconnect from the grid to enable its operation in both grid-connected or island-mode.
The microgrid is an innovation that can be used in different production systems such as windmills, photovoltaic panels and diesel generators. This microgrid usually operates at a low voltage and can be connected to the utility grid or can only supply batteries (island-mode). The microgrid supplies power to facilities like green neighborhoods, campus, islands…
For instance, after the earthquake in Japan in 2011, a city called Sendai used its microgrid to supply energy to some crucial infrastructures such as a hospital and nursing care facilities. The microgrid has a special technical feature: it is a multiple Power Quality Microgrid which means that it enables power supply with different levels of power quality for each customer within the area.
The new challenges
Energy grid is facing a huge evolution on both technological and economical sides.
It intends to mix green energy with fossil fuel energy as a safety net. This new system will produce less GHG and bring producer and consumer closer to achieve a new situation one day: a prosumer which produces and consumes energy at different times.
It raises the question of the overall economy of the system to obtain a stable business model. Indeed, the costumers connected to the microgrid will use the general grid only in case of emergency. The cost of the grid will be divided by a decreasing number of customers which implies that it will be more expensive. Moreover, this decentralized way of producing energy involves new ways of governing with many stakeholders such as citizens or local authorities.
This innovation is triggering many disruptions to the utility business model, and will eventually transform the historic dependency of electricity consumers on utilities into new prosumer relationships of interdependency.
“The Sendai Microgrid Operational Experience in the Aftermath of the Tohoku Earthquake; A Case Study”, Keiichi Hirose, Toyonari Shimakage, James T. Reilly,Hiroshi Irie, NEDO