Oct
10
A Battery For The Grid
October 10, 2011 | 4 Comments
Aquion Energy in Pittsburgh uses the simple chemistry of water-based electrolyte and abundant materials such as sodium and manganese for a grid scale battery that is expected to cost $300 for a kilowatt-hour of storage capacity, less than a third of what it would cost to use lithium-ion batteries. Third-party tests have shown that Aquion’s sodium battery can last for over 5,000 charge-discharge cycles and has an efficiency of over 85%, closing on 90%.
The new technology could be the cheapest way to store large amounts of energy for the power grid using batteries and with $30 million in fresh venture capital to step up manufacturing of its sodium-ion batteries the chances are the battery will get to market.
Aquion Sodium Manganese Battery Set. Click image for more info.
The idea is to do what’s called peak shaving, using stored energy to meet the high electrical demand during peak usage periods, which helps keep the grid reliable, efficient and electricity prices low. It’s the kind of technology in a technique that may well cut the rates charged for periods of peak demand. If you’re in place where meters are time of day rated, this technology could save some money some day.
Trials at grid scale of the technology are coming up. Aquion has started shipping pre-production prototype batteries to off-grid solar power companies. Next month, a 1,000-volt module will go to KEMA, a Dutch energy consulting and testing outfit that has a facility outside Philadelphia Pennsylvania.
Jay Whitacre Aquion’s founder and chief technology officer says, “It’s very well-suited for off-grid solar and wind support, and also for peak shaving. It’s two very different applications, and our battery has been shown to be effective in both.”
Third party support is coming in. John Miller, an electrochemical capacitor expert and president of consulting firm JME in Shaker Heights, Ohio, says Aquion’s battery could be the cheapest of the various battery technologies vying to provide grid storage. Miller compares the Aquion sodium battery to today’s most common grid storage technology, re-pumped hydro that makes up to 95 percent of utility-scale energy storage. Re-pumped hydro returns water to a higher elevation when electricity demand is low, and releasing that water back down through turbines during peak periods. But re-pumped hydro is limited by topography and space, and pumped hydro systems take many years and millions of dollars to build, if the land can be purchased at all.
Aquion answers a demand, with quick delivery and a small footprint.
Miller says, “Lead-acid is even too expensive. Aquion’s technology is getting to the range of pumped hydro in cost, which is two cents per kilowatt-hour [over the system’s lifetime]. They’re unique. I would say it’s very promising for grid storage.”
The precedent is already in place, a few power companies use lead-acid batteries and sodium-sulfur batteries for grid storage. Lead-acid batteries are cheap but only last for 500 to 1,000 cycles, while sodium-sulfur batteries are costly at $1,000 a kilowatt-hour.
The flip side is the Aquion battery is heavy too, but the low cost and long cycle life compensate for that.
With capital in hand now Aquion, is making 35-watt-hour units that are modular and stackable at its research and development facility. Next year, the company wants to produce multiple megawatt-hours’ worth of batteries at this facility, launch its first commercial product, and break ground on a 500-megawatt-hour capacity factory.
The Aquion web site says the technology contains zero toxic or otherwise hazardous materials, which facilitates battery installation and manufacturing facilities by preventing delays associated with hazardous material zoning issues. The technology is designed so that harvesting and recycling both the packaging and the active materials is easy. The batteries are also much more efficient than traditional batteries at both a cell and systems level; the end result is an energy storage system that makes better use of the energy it stores.
Whitacre’s and in turn Aquion’s breakthrough is an electrochemical couple combining a high capacity carbon anode with a sodium intercalation cathode capable of thousands of complete discharge cycles over extended periods of time. The material couple can deliver over 30 watt-hours per liter. The device functions in a broad range of ambient temperatures and can be repeatedly cycled with little to no loss in delivered capacity. Rapid cycle testing indicates at least 5000 cycles with no fade in delivered capacity, while ongoing calendar life testing shows stable performance for over a year of continuous deep cycle use.
Whitacre has preplanned and thought this through to the end where only the cheapest raw materials were considered in the basic R&D phase. As a result, sodium interactive materials and water-based electrolytes are used instead of the traditional lithium-based materials and organic solvents.
If all the pre-production expectations get to market and commercial scale production drives to lower pricing a mass-market version will likely be available someday. If it’s low cost enough, and mass-market electrical electricity production costs keep coming down, personal or small-scale grid support could get widespread adoption.
For now let’s hope the government stays clear. The alarm that “incentives” or other manipulations could drive electrical utility costs even higher than peak demand does now could wreak the drive to lower energy costs.
For Whitacre and Aquion it’s a success with more to come. Whitacre and his group look smart enough to drive to commercial scale at better than competitive cost – the sure road to success – and well deserved, too.
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