Lithium batteries tapped for community storage

A smart-grid project in Ohio will test whether the electricity business will follow the history of computing, with storage moving from center to the edge of the network.

Start-up International Battery on Monday said that it has been chosen to supply lithium ion batteries for a community energy storage pilot project run by utility AEP set to go online by the middle of this year.

The storage units will be about the size of pad-mounted transformers, the roughly refrigerator-size boxes that step down high-voltage current from transmission lines for local service, said Ake Almgren, the CEO of International Battery.

The community energy storage will be part of a smart-grid project, where AEP is installing smart meters and other technologies in an effort to reduce power consumption in a 150 square-mile region in northeast Ohio. Installation of the storage units, one of several Department of Energy-sponsored grid storage projects, is scheduled to start in May and continue through the middle of next year, according to an AEP representative.

AEP is on the forefront of using energy storage on the electricity grid, which could help utilities use more intermittent wind and solar power and cut power demand during peak times. It has already installed sodium sulfur batteries from NGK Insulators of Japan at a handful of substations, which can provide 1 or 2 megawatts of power for a few hours.

With its community energy storage project, though, it will be using smaller batteries with different technology. In each location, the utility plans to install at least one 25-kilowatt storage unit, able to deliver one hour of electricity, or 25 kilowatt-hours of energy. AEP expects to try different configurations, but have close to 10 units which, in aggregate, will store 2 megawatts' worth of capacity, the AEP representative said.

The hope is that networks of these relatively small energy storage boxes can provide the same services as larger units, such as feeding power to the grid during peak times or providing backup in the case of an outage.

"You can aggregate these batteries, so you don't see them as standalone isolated units, but as a family that provides battery storage," said International Battery's Almgren. "These units will need to be smart, so that depending on the time of day and price, you can decide when you provide or store energy."

S&C Electric, which is the systems integrator on the project, said that distributed storage architecture will reduce power losses during transmission and make it easier to use community wind or solar power. A single 25-kilowatt battery could supply power for five homes or a shopping center for about an hour, Almgren said.

Other potential applications are using storage to ensure that networks of plug-in electric cars don't overload a local distribution grid, which is a serious concern for utilities if several people in a neighborhood charge at once.

The long-term vision of community energy storage is to have dozens or hundreds within an area which would allow a utility to also use the stored energy to maintain a steady frequency on the grid, Almgren said.

Large-format batteries
In grid storage trials, a number of different storage technologies are being tried out, including flywheels, giant batteries, and even ice-assisted air conditioners. Lithium ion battery company A123 Systems last November announced that utility AES put 12 megawatts' worth of batteries on the grid in Chile to regulate grid frequency.

But the energy needs for community energy storage are somewhat different than large centralized systems, said Almgren. Compared to incumbent lithium ion battery technologies, International Battery manufactures batteries that can store a lot of energy in a relatively small space. Instead of building a battery pack from hundreds or thousands of small cylindrical cells, the company makes packs using brick-size prismatic cells, he explained.

"Since you have these bigger building blocks, you can monitor and control each one individually...which lets us optimize the system," Almgren.

Although straightforward in concept, community energy storage systems still have a number of technical and business challenges before they become commonplace.

Storage, and specifically large-scale battery systems, are expensive and can be difficult for utilities to justify financially under traditional regulations, which are structured around power plant investments. Technically, there are a number of challenges for small-scale storage units, which need to operate reliably in a wide range of temperatures and communicate with other smart-grid hardware, such as smart meters.