Energy Storage News

Deeya Energy L-Cell Iron Chromium Flow Battery

Deeya Energy is a company planning to manufacture flow batteries for electrical energy storage. As I have written before the promise of flow batteries is very long cycle life because the electrodes are inert and are not degraded by the chemical interactions which are taking place in the liquid electrolytes which flow past the electrodes and past the ion exchange membrane which separates the half cells of the battery.

Deeya's initial target market is backup power for cell phone towers in place of diesel generators in rural India. It is not clear to to me that they have any significant sales volumes as of this date. Their web site gives very little technical information about their battery design other than to say that it is based on Lawrence Thaller's flow battery design invented for NASA in the 1970's. However, I found an online article published by NASA which makes it clear that the battery employs the same iron/chromium chemistry used in Dr. Thaller's original invention.

Below are some selections from information posted on Deeya's web site

Founded in 2004 in the heart of Silicon Valley, Deeya Energy is a cleantech company dedicated to developing and manufacturing electrical energy storage systems.

Deeya Energy's innovation, the L-Cell, is based on a novel battery technology originally developed by NASA in the early 70's as a potential energy storage method for long term space flights.

Deeya Energy has productized its L-Cell Energy Storage Platform Deeya technology into an Energy Storage Platform (ESPTM) and the first product in this family is the ESP 24KTM. The ESP 24K achieves a new level of reduced cost and increased performance in providing critical infrastructure support for low availability service areas, and optimizing bulk renewable energy penetration within the energy industry.

The ESP 24K is an economically and technologically superior alternative to conventional and environmentally hazardous lead-acid batteries, enabling significant operational savings with diesel engine generators in applications ranging from a few kilowatts to megawatts. One of the design features of the technology is the decoupling of power and energy. This allows high-volume production to be easily tailored to site-specific backup requirements.

The design life of the ESP 24K product is 20 years, with 5-year service intervals and minimal maintenance. The technology is also insensitive to ambient temperature, enabling outdoor operation and eliminating costly and unreliable cooling equipment. Most importantly, ESP 24K can be charged quickly: a four-hour back-up system takes only three hours to recharge, dramatically improving system availability. Deeya's systems contain no heavy metals and release no poisonous or hazardous fumes, making them an excellent clean energy technology.

Benefits Summary

Affordable and reliable clean energy has been a tantalizing, but elusive, quarry. Featured in Spinoff 1985 and pioneered by Lawrence Thaller at Lewis (now Glenn) Research Center in the 1970s as a potential alternate energy source for long-term space flight, iron-chromium redox energy storage systems are a hybrid technology that offers the extended support of fuel cells with the flexibility of batteries. They act as “electron buckets” for existing clean energy sources, such as solar or wind, to store and deliver power predictably when needed.

FREMONT, CA (May 5, 2009) - Deeya Energy, an industry leader in next generation energy storage platforms, announced that it has completed an oversubscribed $30M Series C financing. Deeya's innovative solution addresses the $46 billion energy storage market by offering a scalable, economical and renewable alternative to current technologies. Deeya's Series C was led by new investor Technology Partners and existing investors BlueRun Ventures, DFJ, Element Partners and New Enterprise Associates (NEA) all participated in the round. This series C financing brings Deeya's total venture capital investment to $53 million since its founding in 2004.

Ira Ehrenpreis, general partner at Technology Partners who runs the firm's Cleantech practice, explains that, "Deeya has changed the paradigm of energy storage technology from being a consumable to becoming an asset which benefits the customers by increasing the performance and reliability of storage and saving fuel costs with zero environmental impact. Deeya's first product, the ESP, can save over a billion dollars annually in diesel fuel costs in the first target market, the Indian wireless cell tower industry." He adds, "The company's future markets in renewable energy and grid power are even larger potential markets over time."

Below are some selection from a technical brief published by NASA which reveals some details of the chemistry of Deeya's flow battery design.

In iron-chromium redox systems, electricity is generated when pumps move the electrolytes into separate sections of a reaction chamber. Electrodes collect that charge, and the electrolytes can then be recharged from an outside power source. Thaller’s initial design was a 1-kilowatt system (2 kilowatts at its peak), which used acidified chromium and iron in its solution and relied on soluble redox couples and an ion exchange membrane to generate and store energy in a liquid electrolyte solution.

Headquartered in Fremont, California (with offices in Gurgaon, India), Deeya Energy Inc. is now bringing its iron-chromium hybrid flow batteries to commercial customers around the world. Thaller supported Deeya’s founder, Saroj Sahu, providing development assistance for the company’s proprietary liquid-cells (l-cells.) The l-cells have higher power capability (3 kilowatts) than Thaller’s original design, and in January 2008, the Space Foundation approved the l-cells as a Certified Space Technology, a designation for products made possible by space research and development.

According to Rick Winter, an engineer and vice president with the company, Deeya’s l-cells offer a few fundamental differences from the original redox system. “With the advent of modern plastics, we have been able to replace critical components, dramatically improving the system’s performance, cost, and life,” Winter explains. “We have improved the reliability and reduced the component count and cost so that it can be commercially competitive.” Deeya l-cells are effectively 3 times less expensive than lead-acid batteries and 10 to 20 times less expensive than nickel-metal hydride batteries, lithium-ion batteries, and fuel cell options. The system represents a clean energy technology with no poisonous or expensive metals or fumes release.

Like the original redox system, l-cells offer several advantages over traditional lead-acid batteries: lower cost, longer life, small space needs, and excellent performance at high ambient temperatures. Because l-cells, according to Winter, “actually enjoy sitting in the sun,” rural communities in India with power supply problems have expressed interest in the technology. Deeya has tested the l-cells in air temperatures up to 120 °F, and offer significantly better performance than lead-acid, which only perform reliably in moderately cool temperatures. L-cells also have the ability to operate for thousands of discharge cycles without boost charging, as opposed to the current generation of rechargeable batteries, which are only good for 200 to 500 deep discharge cycles.

Deeya’s customers include cell phone providers in India who need smaller backup systems for their cell towers. Because of the backup l-cell battery systems, customers see improved reliability of services, including fewer dropped calls and fewer power outages. Other uses for l-cells could include backup systems for cash machines and traffic lights.

I like the fact that Deeya is targeting a specific market like Indian cell phone towers, but the only indication I have seen of actual sales is from a greentechmedia article published in June 2009 which claims that a few units have been sold to cell phone service providers at a cost of US $4000/kW. In the promotional information on their web site Deeya mentions a four hour backup system. I do not know if that is the storage capacity of these units or not. NGK is selling large orders of NAS batteries for $2500/kW with six hours of storage. Of course these are initial units and costs may come down with scaled up manufacturing. Also 10,000 cycles will bring down long term costs if customers really trust the specs, and if they have long term investment horizons. As I have said before grid storage is a tough market to break into. Companies are gong to need a lot of staying power to be successful in this endeavor.

Deeya says nothing about the round trip efficiency of their batteries, but they do claim a cycle life of 10,000 which, if achieved, would significantly beat NAS batteries 4500 cycles. They say that the batteries would require service at five year intervals, which service would presumably involve replacing the liquid electrolytes which are subject to cross contamination through the ion exchange membrane.

Chromium is a fairly abundant element (atomic % in crustal rocks = 55,000 ppb), and the USGS in its 2010 chromium commodity report claims that "World resources are greater than 12 billion tons of shipping-grade chromite, sufficient to meet conceivable demand for centuries.".

February 20, 2010

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