Article Jan 3014 on Aquino, 35 million from Bill Gates
January 29.2014 | Sascha Rentzing
Aquion M100 Battery Module (© Aquion Energy, Inc.)
Lithium ion batteries have a high output and are durable, yet they simply remain too expensive to be widely used for storing excess solar and wind energy. Novel sodium-ion batteries could help solve this problem. Aquion Energy, a US-based company, has resolved the safety issues formerly associated with the technology and is now seeking to mass-produce sodium batteries at low cost.
When it comes to the energy transition, one question remains insufficiently answered: where will this eco-friendly power come from when the wind doesn’t blow and the sun doesn’t shine? Storage devices such as batteries, or processes to convert electricity into storable gas offer possible solutions, however these technologies are still too expensive for commercial application. That is precisely what U.S. start-up Aquion Energy, a Carnegie Mellon University-spin-off from Pittsburgh, hopes to change.
The company is planning to manufacture sodium-ion batteries, which are cheaper than other storage technologies currently available in the market. According to Jay Whitacre, Professor of Materials Science at Carnegie Mellon University, founder of Aquion and inventor of the underlying technology, the price per kilowatt hour of storage capacity will have to drop to 200 dollars for storage systems become competitive in the US power grid, where natural gas is used for peak applications. The costs associated with lithium-ion batteries, which are already employed in private households for the intermediate storage of solar energy, are still more than double that amount. Whitacre believes that Aquion’s so-called Aqueous Hybrid Ion (AHI) technology could be made available for considerably less than 200 dollars per kilowatt hour. On its quest for suitable electrode materials, Aquion focused on low-cost, readily available elements such as sodium and carbon, instead of the comparatively rare and expensive lithium.
Investors are impressed with AHI’s technology. Along with other financial backers, Microsoft’s founder, Bill Gates, promised a total of 35 million dollars in spring 2013 to fund the construction of a manufacturing facility. Prior to this, Aquion had been able to raise 25 million dollars worth of funds, including 5 million dollars from the U.S. Department of Energy. Aquion aims to use this capital to build a factory capable of manufacturing batteries with a yearly capacity of 200 megawatt hours on a commercial scale by 2015. This yearly output could supply around 20,000 households on days without wind or sunshine, or throughout a long winter’s night.
In addition to the low costs associated with sodium-ion batteries, the scale of Aquion’s plans is owed to several other benefits this technology brings: The batteries’ storage capacity remains constant during extreme fluctuations in temperature, making them suitable without limitations for use in the desert. This makes them ideal partners for the large solar power stations, which are mushrooming all along the Sunbelt. Sodium-ion batteries can be used equally as well for storing wind power. If they prove to be a success, they may also be attractive for those private households already producing their own solar or wind power which are seeking to maximize their self-efficiency.
Additionally developers at Aquion have considerably improved the output capacity and life span of sodium ion technology. The cathode, i.e. the negative pole, consists of a sodium alloy, while a carbon compound is used for the anode. A liquid electrolyte, allowing only positively charged sodium ions, i.e. atoms lacking one of their electrons, to pass, is located between the poles. When the battery is charged, the ions flow from the cathode to the anode, with the entire process being reversed as the battery is discharged. Just a few years ago, the energy storage capacity of sodium-ion batteries dropped to 50% after just 50 charge/discharge cycles. According to Whitacre, however, Aquion now has this problem under control, thanks to a better understanding of the chemical processes involved. The American batteries have managed 5,000 full cycles and achieved a life span of at least ten years when charged once daily. This means that the sodium batteries have drawn closer to lithium-ion technology, which currently achieves an average of 7,000 full cycles.