For the introduction of unstable renewable energy such as solar and wind power, the use of a redox flow battery helps stable power supply, and thus, contributes to the alleviation of power shortages.
Meanwhile, Sumitomo Electric also plans to start the demonstration test of a factory energy management system (FEMS), which combines the existing gas engine power generators with the redox flow battery and CPV units to form an optimal management system that controls the entire energy flow in the Yokohama Works. The Company will cooperate with Meidensha Corporation for the demonstration, which will be the first attempt in the Yokohama Smart City Project, one of the Next Generation Energy and Social System Demonstration Projects 2012 led by the Ministry of Economy, Trade and Industry (METI).
Sumitomo Electric is planning to put these systems into practical use, particularly for major power consumers such as industrial plants and commercial facilities, with the aim of promoting the use of renewable energy sources and effective use of energy. With a plan for the commercialization during the fiscal year 2013 (ended March 2014), the Company continues to work on cost reduction and other improvements for the system.
* The system consists of 15 CPV units and produces the maximum power output of about 100 kW as of the date of the demonstration. The system will achieve the maximum power output of 200 kW when 28 units are connected at the end of this fiscal year.
1. Schematic Diagram of the Demonstration
2. System components
(1) Redox flow battery (1 MW x 5 hours)
A redox flow battery is a storage battery that comprises a charging/discharging cell section and a tank full of metal ion electrolyte. It charges/discharges through the oxidation-reduction reaction of vanadium or other ions.
The battery features a long service life with the electrodes and electrolyte that are not subject to deterioration even after repeated charge/discharge operations and is easily maintained because it uses the same electrolyte in both the cathode and the anode. It also provides increased safety as it does not require any combustible substances and operates at ambient temperatures. This battery is suitable for irregular, highly fluctuating charge/discharge operations due to the accurate monitoring and controlling abilities. These features make the redox flow battery an optimal storage battery for efficient use of renewable energy and surplus electricity supplied during the night.
(2) Concentrating photovoltaic (CPV) unit (maximum power generation of 28 units: 200 kW)
A CPV unit is a photovoltaic system that converts high-intensity sunlight directed by a lens into electricity with small photovoltaic cells. Thanks to these photovoltaic cells, which are made from a special compound semiconductor material, a CPV panel has twice the power generation efficiency of a silicon solar panel currently on the market. The concentrator panels can be installed at an elevated position, providing usable space below them.
(3) Energy management system (EMS)
An EMS monitors and manages the entire energy flow including electric power provided by 28 CPV units and commercial power networks, redox flow battery storage, and power consumption at an office or plant. Obtained data is sent to the central control server via optical communication networks and controlled collectively. The Company plans to use this system in the demonstration test of the FEMS, in which the existing gas engine power generators are connected with the redox flow battery and CPV units to obtain an optimal power supply-demand balance and power demand control within the Works.
3. The Megawatt-Class Power Generation/Storage System