Back in 2009, General Electric (GE) launched its foray into the grid-scale energy storage business, announcing it was investing $100 million into a plant to commercialize its sodium-nickel-chloride Durathon Battery technology.

A variant on the high-temperature sodium-metal battery chemistries from the likes of Japan’s NGK and Italy’s Fiamm now being used on the grid, GE’s Durathon batteries were aimed at storing lots of energy for longer lengths of time than competing lithium-ion technologies -- albeit without lithium-ion’s high power density, which makes that technology a preferred choice for electric vehicles and power-critical grid applications.

GE also promised longer lifespans, lower maintenance costs and fewer thermal management concerns (i.e., no catching on fire) -- and, critically, a price point that could put them in competition with their natural competitors on the grid, which are natural gas peaker plants at large scale, and diesel backup generators at small scale.

Durathon quickly landed customers wanting to use the batteries to augment backup generators for cellular towers in emerging markets like India and Africa. By September 2012, it had racked up $63 million in orders for cell tower backup, one of the earliest applications for energy storage systems ranging from lead-acid chemistries to flow batteries.

But sales for larger-scale grid storage applications didn’t come so quickly. The first came in May of this year, when GE announced it was backing up its three installations of its new 2.5-megawatt Brilliant wind turbines with 50 kilowatt-hour Durathon batteries, along with a software suite to manage their use for wind power firming and ramping control, as well as frequency regulation for the grid.

Last week, GE Energy Storage announced another grid-scale application, its largest yet: a 500-kilowatt-hour system, paired with inverter technology from Princeton Power, to back up the nonprofit Discovery Science Center in Santa Ana, Calif. As part of California’s Permanent Load Shift program, the array is meant to shift 10 percent to 20 percent of the building’s electrical load from expensive peak times to cheaper, off-peak use, while also providing backup power when the grid goes down.

It’s GE’s first move into a market that’s set to boom in the coming years, as California moves forward with a first-ever statewide mandate that calls for 1.3 gigawatts of grid energy storage to be deployed by 2020. It’s also one of the first deployments of battery technology aiming at such a large-scale shifting of power in a behind-the-meter setting, which will put to the test Durathon’s abilities to charge and discharge deeply over thousands of cycles.

Prescott Logan, general manager of GE Energy Storage, told me in a phone interview last week that Durathon batteries are also being deployed in transmission and distribution grid applications, as well as in microgrid settings. While he wouldn’t provide details on those projects, GE is working on military microgrids, including one at the U.S. Marine Corps base in Twentynine Palms, Calif.

“We’ve got projects that we’re executing in all those different applications,” he said, with the Discovery Science Center project, undertaken in partnership with utility Southern California Edison, being “one of the most recent ones that we’ve talked about.”

On the renewable integration front, GE recently moved its Energy Storage business unit to its renewable energy division, out of its transportation division, where the Durathon technology was originally developed for train locomotives. “The integration of those into one business is really making for an exciting platform in the renewables space,” he said.

Beyond the wind turbine projects announced earlier this year, “We have batteries that are part of solar farms,” he said, though once again he wouldn’t provide details. One potential partnership to watch is the one GE has formed with First Solar. The thin-film solar kingpin bought the intellectual property of GE’s PrimeStar Solar acquisition in August, and pledged to work with GE (which took a 2 percent stake in First Solar) on inverters and other solar-grid integration research.

While Logan wouldn’t provide exact details on how much Durathon-based energy storage has been deployed around the world to date, he did say it is in the multiple megawatts range. That’s not a lot, compared to competitors like NGK, A123 or Xtreme Power, which have each deployed close to 100 megawatts or more in announced projects. But then again, it’s not clear that getting lots of batteries into these early grid-scale storage projects has necessarily been a good thing for business.

Waltham, Mass.-based A123, for instance, went bankrupt last year and saw many of its lithium-ion grid battery projects derailed as a result, although its new owner, China’s Wanxiang Group, has promised to revive the business line. Japan’s NGK had to take many of its batteries offline since 2011, after reports of fires and explosions. And Texas-based startup Xtreme Power decided to sell off the factory where it makes its novel advanced lead-acid batteries earlier this year, to concentrate on the less capital-intensive business of energy storage management software.

GE, meanwhile, announced last year that it planned to use Xtreme Power’s battery management software in projects, as well as grid integration control systems from Arista Power, though neither partner has since announced any projects together. Logan declined to say whether GE Energy Storage was working on projects with either partner, beyond saying that the company has "a number of really valued partners” around the world.

When it comes to the all-important power electronics and software controls and management systems that allow batteries to serve multiple functions for the grid and buildings, “Our philosophy is, we work in the way our end customer wants us to work,” he said. “At GE, we have the capability to do full systems, and put in a lot of the AC equipment and power converters, and we have the control expertise and platforms to do the control systems -- and that’s certainly part of the way we offer our energy storage systems,” he said. Of course, that's also something that competitors like ABB, Siemens, S&C Electric and a host of other grid specialists do.

At the same time, “we also work with partners, and provide them a big DC battery box,” he said. That raises the question of how GE’s Durathon technology competes against all the other “big DC battery boxes” out there. GE hasn’t disclosed specifics on these matters, beyond broad statements about Durathon being “50% smaller and 25% lighter” than traditional large-format lead-acid batteries -- which doesn't provide much of a comparison to the advanced batteries being deployed on the grid today.

“We don’t talk about the cost of our product externally,” Logan said. “As you can imagine, that’s sensitive information. If you’re talking about pricing, what I can say is that Durathon technology is market-competitive.”

As we’ve been covering at Greentech Media, the cost of grid-scale energy storage systems is largely tied up with how they’re integrated and what services they’re capable of providing. Even so, raw battery system costs are still an important factor. It remains to be seen how the markets will decide on Durathon.