As the saying goes, we are creatures of habit. We operate best with routines, consistency and knowing what we’re going to get. The same goes for grid-connected power—the steadier and more predictable the flow, the better. This presents challenges for renewable energies like solar power; the sun, after all, doesn’t warn us before a stray cloud passes in front of it. So we must prepare for that unknowing, and that’s exactly what the Arizona Public Service Company (APS) is doing by testing a 1.5-megawatt (MW) energy storage system.
During a two-year pilot, the energy storage system, designed by Electrovaya, will first operate at an electrical distribution substation where it will capture energy at times when it is inexpensive, demand is low and the substation equipment is at low capacity. The stored energy will be released when energy is in higher demand, more expensive to purchase and equipment is at high capacity. At the size of a shipping container, the system can generate the power output of 1,200 hybrid cars or 300,000 mobile phone batteries.
For the second phase of the project, the system will move to the Doney Park Renewable Energy site, a nearby 500-kilowatt solar power plant. The storage system will capture energy that can be released to fill gaps in solar production in order to maintain a steady flow to the grid, as well as test releasing the energy after dark.
Beyond maintaining a smooth flow of power, APS believes the energy storage system can benefit equipment lifespan. “The steadier flow of electricity on peak days could keep our equipment healthy for longer periods, so we can improve reliability and keep maintenance costs down,” says APS Energy Storage Project Manager Joe Wilhelm. “In the future, if a piece of equipment fails and causes an outage, we could also dispatch energy from storage units temporarily until repairs were made.”