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We propose an energy loop utilizing redox flow batteries.

Technology / Service Summary

Compactly designed redox flow battery that uses electrolyte and is safer than lithium-ion batteries and NAS batteries. Promotes the securing of distributed power sources.


Prime Star's vision of energy control innovation.
In recent years, the rising cost of electricity due to soaring raw material prices and energy supply shortages caused by wars have made it important to address issues related to energy shortages.
Small power plants using redox flow batteries are set up on surplus land, whether in urban or rural areas.
During normal times, the batteries are used to store electricity for daily use and to charge quick chargers for EVs, which are likely to become popular in the future. During disasters, the batteries are used to supply electricity to evacuation centers for the general public and as a BCP measure for companies.
The Redox Flow Battery is a safe and secure battery that uses water, and moreover, it is small and stand-alone, making it easy to install.
By spreading the use of these batteries throughout the world, we aim to resolve the pressing issue of energy shortages.


Power generation systems using solar, wind, and other energy sources are on the rise. There are areas around the world where the growing size of power generation facilities exceeds the transmission capacity, necessitating the construction of new large-scale power grids.

COP27 will propose new solutions to the challenges faced by municipalities and others regarding disaster preparedness and electricity supply stability.
Solar power generation systems gradually generate less power after noon, and by evening the amount of power generated declines to about 1/3 of its original level. During this time, offices and factories are still in operation, and households are using more electricity to prepare for dinner and other activities, which causes an imbalance between supply and demand. To solve this problem, it is necessary to store electricity generated by solar power during the daytime, and the introduction of large-capacity storage batteries, which are also effective as a measure to stabilize the power grid, has become an issue.
 In addition, the need for emergency power sources to secure power in the event of power outages is increasing due to the occurrence of natural disasters such as typhoons, torrential rains, and earthquakes, which are becoming larger due to climate change in recent years.

What are redox flow batteries?
The term "redox" is a combination of the words "reduction" and "oxidation.
The greatest advantage of redox flow batteries is safety. Since the electrolyte is nonflammable and the battery operates at room temperature, there is no risk of ignition or explosion if overcharging and overdischarging are controlled. Vanadium sulfate solution is used as the electrolyte for the positive and negative electrodes. Even if both solutions are mixed, they do not generate heat or harmful gases and are easily regenerated. Vanadium sulfate solution is a dilute sulfuric acid, so it is non-toxic and does not cause severe burns.

In addition to safety, the cell stacks are characterized by their "long life" and "ease of maintenance. The life of the cell stack is more than 20 years, and the electrolyte has unlimited charge/discharge cycles, enabling longer operation and superior overall performance compared to lithium-ion batteries. The only consumables are the ion exchange membrane (IEM) and some electrical components such as the power conditioner system (PCS), ventilation system (INV), and circulation pumps. Redox flow batteries can be installed with separate cells and electrolyte, and the charged electrolyte can be stored in a sealed container for low-cost, long-term power storage.

Thus, the redox flow battery has advantages in terms of safety and service life. The compact size and decentralized installation of the new system eliminates the need to build a new large-scale power grid.
It is ideal for public facilities such as airports and stations, condominiums, hospitals, and other safety-critical facilities.

In preparation for damage from prolonged power outages, we offer the Redox Flow Battery, a large storage battery that is more compatible with renewable energy and safer, in combination with a photovoltaic power generation system.

The greatest feature of this non-flammable large-capacity storage battery is the use of water for the positive and negative electrodes. The solar panels are affixed to the top of the container, and the complete system is contained inside, making a storage capacity of approximately 300kw/h standard.
In the future, we intend to go beyond 300kw/h and promote the use of this system as a local distributed power supply system using renewable energy.


Reduces the cost of building a large-scale power grid.
Can be used for BCP measures in the event of natural disasters such as typhoons due to climate change.

A large power source must be close at hand to be immediately available in the event of a disaster.

The Agency for Natural Resources and Energy has a policy of strengthening disaster resilience.
For example, in order to transmit electricity generated by solar power to various devices in the event of a power outage due to an earthquake or typhoon, it is necessary to build circuits and systems for private consumption.

In the event of an earthquake, typhoon, or other disaster, a large power system in one location would lead to a large-scale power outage. Small-scale commercial solar power systems are installed in a variety of locations, which will help in the early restoration of power during power outages.

Therefore, we will promote the disaster countermeasure of power source dispersion by including small-scale commercial solar power generation with an output of 10kW or more but less than 50kW, which is necessary for regional utilization requirements, with a basic base of huge power sources with a battery capacity of 300KWH or more.

A "safe storage" system is necessary for stable power supply, local production for local consumption, and disaster prevention measures.
Redox flow batteries have two major advantages over currently available energy storage systems in terms of safety performance and long life.

For municipalities with small budgets, we plan to strongly promote the "PPA model of storage batteries" (an installation model with as low an initial cost as possible). As for investors, funds, and other entities, we will help local companies and municipalities realize RE100 by purchasing electricity generated by solar power systems and wind power and stored in redox flow batteries, and in preparation for the future spread of EVs, we will sell electricity through EV quick chargers to reduce the costs associated with the introduction of these systems. We would like to build a win-win relationship by reducing the hurdles to the widespread use of EVs by selling electricity through EV quick chargers.

Controlled Substance

Applicable Regions / Countries

  • Japan
  • Southeast Asia
  • Central/South Asia
  • China/ East Asia
  • Middle East
  • Africa
  • Oceania
  • Europe
  • Central/South America
  • ASEAN countries

    Indonesia,Cambodia,Singapore,Thailand,Philippines,Brunei Darussalam,Viet Nam,Malaysia,Myanmar,Lao PDR

Locations for inspection


Related SDGs Goals

  • 2. Zero Hunger
  • 3. Good Health and Well-being
  • 7. Affordable and Clean Energy
  • 9. Industry, Innovation and Infrastructure
  • 11. Sustainable Cities and Communities
  • 12. Responsible Consumption and Production
  • 13. Climate Action
  • 16. Peace, Justice and Strong Institutions
  • 17. Partnerships to achieve the Goal

We propose an energy loop utilizing redox flow batteries.

Youtube Videos

COP28 Giant Battery for Safe Storage of Decarbonized and Renewable Energy Redox Flow Battery


Introducing "Sustainable Batteries: Redox Flow Batteries" introduced by Avatar

Compatct Size Redox Flow Battery