Aquion's electrolyte, based on salt water rather than on a flammable organic solvent, makes its batteries environmentally friendly and keeps costs down, Whitacre said. The up-front cost of a lithium ion battery used in consumer electrical devices, for instance, is between $300 and $1,000 per kilowatt hour. Aquion's battery will cost between $150 and $500 per kilowatt hour, or about the same as a conventional lead-acid battery in most cars.
Technology Review - Third-party tests have shown that Aquion's battery can last for over 5,000 charge-discharge cycles and has an efficiency of over 85 percent.
Aquion's battery uses an activated carbon anode and a sodium- and manganese-based cathode. A water-based electrolyte carries sodium ions between the two electrodes while charging and discharging. The principle is similar to lithium-ion, but sodium ions are more abundant and hence cheaper to use. Compared to solvent-based electrolytes, the aqueous electrolyte is also easier to work with and cheaper. Even better, the materials are nontoxic and the battery is 100 percent recyclable
Grid-scale trials of the technology are next. Aquion has started shipping pre-production battery prototypes to off-grid solar power companies. Next month, a 1,000-volt module will go to KEMA, a Dutch energy consulting and testing outfit, which has a facility outside Philadelphia.
Aquion's battery could be the cheapest of the various battery technologies vying to provide grid storage. He compares it to today's most common grid storage technology, pumped hydro, which accounts for 95 percent of utility-scale energy storage. Pumped hydro involves moving water to an elevation when electricity demand is low, and releasing that water through turbines during peak periods. It is, however, limited by geology and space, and pumped hydro systems take many years and millions of dollars to build. Utilities are now starting to look at batteries because they can be delivered in months and, in principle, can be sited anywhere.
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.
Alternative Storage Energy Air bags
Testing of scale-model prototype Energy Bags has already commenced. Professor Garvey’s research has proven that by taking offshore wind turbines to a scale never before imagined — 230 meter diameter is the baby of the family — and considering some radical redesigns, the total amount of structural material per kW of rated power can be slashed, effectively cutting costs by a factor of four or more. He believes it is possible to store energy at costs well below £10,000/MWh — less than 20 per cent of pumped hydro energy, the cheapest competing technology. This would be $15/kilowatt hour.
E.On UK is still working with Garvey on energy bag storage
In July, 2011 results being discussed at a conference included expanding wind power by storing the energy it produces as compressed air in caverns or in giant energy bags anchored to the seabed.
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