A module stores many individual batteries.
Energy storage is key to expanding the use of renewable energy. Combining variable wind and solar-energy production to the needs of the power grid is an ongoing issue for utilities and will become more important as renewable resources further penetrate the electric industry. Equipment from Xcel Energy, Minneapolis, has potential to reduce the impact caused by the variability and limited predictability of wind and solar generation.
A cutaway of a sodium sulphur battery shows a few internal details
The company is testing emerging energy-storage devices as part of its overall Smart Grid strategy, which aims to modernize and upgrade the grid to adapt more easily to renewable energy sources.
To this end, Xcel Energy will test a one-megawatt wind energy storage battery that is based on sodium-sulfur (NaS) cells. The test will demonstrate the system’s ability to store wind energy and release it to the electricity grid when needed.
NaS batteries are used for this project because of their high storage capacity, they handle many charge-recharge cycles as would be incurred with an intermittent renewable energy resource. What’s more, the large battery can be scaled up further, it has a good dynamic response to system changes, and it has demonstrates adequate commercial performance.
The battery was purchased from Japan-based NGK Insulators Ltd., a firm involved in manufacturing and sale of power-related equipment. Versions of this battery are in use in Japan and in a few U.S. applications, but this is the first application of the battery as a direct wind energy storage device.
The battery is made of twenty 50-kilowatt modules. It is roughly the size of two semi trailers and weighs about 80 tons. The battery stores about 7.2 megawatt-hours of electricity, with a charge-discharge capacity of one megawatt. When the wind blows, the batteries are charged. When the wind calms, the batteries supplement the power flow. Fully charged, the battery could power 500 homes for over 7 hours.
Battery installation began in Q1 2009 in Luverne, Minn. Modules are stacked five high in four stacks forming an array that stores some 7 MWh. Connection is to a nearby 11-MW wind farm owned by Minwind Energy LLC.
GridPoint Inc, Arlington, Va, a developer of smart-grid technology, provides communications and controls for system integration, remote control, and data access. This equipment will let the battery act like a power plant, including selling power and responding to controls.
Filed Under: Turbines
