Primus Power, a manufacturer of grid-level energy storage solutions, has received a contract to develop an energy storage system that will be used with a microgrid at the United States Marine Corps Air Station (MCAS) in Miramar, California. A microgrid is a small-scale grid that includes energy generation, distribution, and loads. A microgrid might be connected to the larger grid but it also needs the ability to operate independently.
If its primary method of generating energy comes from renewables like solar and wind, then a microgrid must include storage as well. Its immunity to major grid malfunctions - whether caused by nature, human error, or sabotage - makes a microgrid an ideal solution for a military base. Here's an early model of a microgrid, courtesy of Sandia National Laboratories:
The MCAS microgrid includes a 230kW photovoltaic array coupled with a Primus EnergyPodTM that holds up to 1MWh of electricity. The EnergyPod uses zinc-flow batteries, which offer certain advantages over other battery technologies. Zinc-flow batteries have a higher energy density than lead-acid batteries and they allow 100% depth of discharge without damaging the batteries. (With many other types of batteries, deep discharge shortens their lifespans.) Primus says that their batteries have a 20-year life, regardless of depth of discharge.
A 1MWh EnergyPod (Image courtesy of Primus Power)
In addition to high-security applications such as the military, microgrids may also be incorporated into communities that have distributed power generation capabilities using solar, wind, and other renewable sources. Natural disasters like hurricanes Katrina and Sandy have exposed the vulnerabilities of the standard grid. As the grid becomes smarter, we could see a "meta grid" made up of a network of microgrids, much like the Internet is made up of smaller computer networks. When a disaster causes widespread damage, community microgrids could run independently, decreasing the number of people without power in the aftermath.