Argonne Making Sodium-ion Batteries Worth Their Salt

Although lithium-ion technology dominates headlines in battery research and development, a new element is making its presence known as a potentially powerful alternative: sodium.

Sodium-ion technology possesses a number of benefits that lithium-based energy storage cannot capture, explained Argonne National Labs chemist Christopher Johnson, who is leading an effort to improve the performance of ambient-temperature sodium-based batteries.

Perhaps most importantly, sodium is far more naturally abundant than lithium, which makes sodium lower in cost and less susceptible to extreme price fluctuations as the battery market rapidly expands.

"Our research into sodium-ion technology came about because one of the things we wanted to do was to cover all of our bases in the battery world," Johnson said. "We knew going in that the energy density of sodium would be lower, but these other factors helped us decide that these systems could be worth pursuing."

Argonne chemist Christopher Johnson holds a sodium-ion cathode.

Sodium ions are roughly three times as heavy as their lithium cousins, however, and their added heft makes it more difficult for them to shuttle back and forth between a battery's electrodes. As a result, scientists have to be more particular about choosing proper battery chemistries that work well with sodium on the atomic level.
While some previous experiments have investigated the potential of high-temperature sodium-sulfur batteries, Johnson explained that room-temperature sodium-ion batteries have only begun to be explored. "It's technologically more difficult and more expensive to go down the road of sodium-sulfur; we wanted to leverage the knowledge in lithium-ion batteries that we've collected over more than 15 years," he said.

Because of their reduced energy density, sodium-ion batteries will not work as effectively for the transportation industry, as it would take a far heavier battery to provide the same amount of energy to power a car. However, in areas like stationary energy storage, weight is less of an issue, and sodium-ion batteries could find a wide range of applications.

"The big concerns for stationary energy storage are cost, performance and safety, and sodium-ion batteries would theoretically perform well on all of those measures," Johnson explained.

All batteries are composed of three distinct materials—a cathode, an anode and an electrolyte. Just as in lithium-ion batteries, each of these materials has to be tailored to accommodate the specific chemical reactions that will make the battery perform at its highest capacity. "You have to pick the right materials for each component to get the entire system to work the way it's designed," Johnson said.

To that end, Johnson has partnered with a group led by Argonne nanoscientist Tijana Rajh to investigate how sodium ions are taken up by anodes made from titanium dioxide nanotubes. "The way that those nanotubes are made is very scalable—if you had large sheets of titanium metal, you can form the tubes in a large array," Johnson said. "That would then enable you to create a larger battery."

The next stage of the research, according to Johnson, would involve the exploration of aqueous, or water-based, sodium-ion batteries, which would have the advantage of being even safer and less expensive.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.

Nearly 600 Energy Storage Projects Announced or Deployed

A new tracker report from Pike Research indicates that nearly 600 energy storage projects have been announced or deployed worldwide, with a surge of new project activity during the past decade.
"Energy storage offers the opportunity to significantly improve the efficiency of the grid at every level," says research analyst Anissa Dehamna.  "The energy storage market is dynamic, but still immature where most technologies are concerned.  The vast majority of active storage projects are utilizing decades-old pumped hydro storage technologies, but the industry has entered a new period of innovation as a number of market players invest considerable resources to prove emerging technologies such as advanced batteries, compressed air energy storage, flywheels, and thermal storage."

Dehamna adds that the wide variety of technologies, applications, and lead times for installations in this sector can make it difficult for many industry participants to analyze the overall market.  Pike Research's tracker aims to identify key market trends on a holistic basis by systematically compiling the available data on all projects around the world including analysis of site, region, size, status, duration, market segment, applications and funding profiles.

Pike Research's "Energy Storage Tracker" provides a comprehensive database of worldwide energy storage projects, including quantitative and qualitative analysis of key trends within the various application and technology segments.  The tracker provides key facts and figures for each project including capacity, location, primary and secondary applications, technologies utilized, and investment cost where available.

Energy Storage Industry Grows To Integrate Wind, Solar

By Robert Crowe, Contributor. Reprinted with permission from Renewable Energy World.

Grid-scale energy storage is gaining momentum as batteries, flywheels and compressed air systems begin proving they can regulate frequency and ancillary services with the same efficiency of "spinning reserves" from fossil fuel-fired power plants.

"We still hear people say storage isn't ready for primetime, but that isn't the case because we already have 20-MW storage plants being built all over the country," said Brad Roberts, executive director of the Electricity Storage Association (ESA).

As more renewable energy hits the grid, generators and independent system operators are looking to new storage systems to provide emissions-free backup and regulation when intermittency interrupts solar and wind power.


A rendering of how A123 Systems Nanophosphate battery sysetms can be used for energy storage at wind farms. Source: A123 Systems.


"We are interested in the potential of battery storage to be a game changer in our industry in both regulated utilities and commercial businesses," said Greg Efthimiou, spokesman for Duke Energy, which operates more than 1,000 MW of wind farms.

Duke Energy is installing the country's largest battery storage system, a 36-MW unit, near its 153-MW Notrees Windpower Project. The system will regulate frequency and store excess energy for use during peak demand. In Texas, where nearly 11,000 MW of generation comes from wind farms, grid operator Electric Reliability Council of Texas relies on standby gas turbines and steam coal generators to ramp frequency up or down as wind generation changes.

The Notrees battery system is funded by a $22 million grant from the U.S. Department of Energy (DOE) and matching funds from Duke Energy, which will use Austin-based Xtreme Power's proprietary dry cell technology.

Investment, Policy Gains
ESA's Roberts said the $158 million in stimulus earmarked by the DOE for storage research generated $780 million in investments for battery, compressed air, flywheels and other systems.

The storage industry has been calling for creation of an ITC to further stimulate growth. With passage of Assembly Bill No. 2514 in September, California began the process of developing a portfolio standard for energy storage.

Storage technology pulled in $150.3 million in venture capital during the second quarter, according to Ernst & Young. General Compression received the largest percentage, with $54.5 million. The company plans to use General Compression Advanced Energy Storage (GCAES), a unique heat transfer technology, to compress air in underground caverns. Investors include ConocoPhillips, US Renewables Group, Duke Energy and Serious Change L.P.

Compressing air underground has the potential for storage in excess of 100 MW but there are only two such projects in the world: A 290-MW facility built in Huntorf, Germany in 1978, and a 110-MW facility completed in 1991 in McIntosh, AL. And in July Iowa officials and the DOE scrapped the Iowa Stored Energy Park, a facility intended to store up to 270 MW of wind energy in a limestone cavern 3,000 feet underground. Studies showed limitations with air permeability in the site's geology.

CAES Winners, Losers
Compressed Air Energy Storage (CAES) utilizing man-made, above-ground storage tanks has also gained traction with DOE funding. Startup SustainX, Inc. is working with AES Energy Storage to demonstrate a one-hour, 4-MW storage system. SustainX was founded in 2007 by engineers at the Thayer School of Engineering at Dartmouth College. It received $5.39 million DOE grant.

The Arizona Research Institute for Solar Energy (azRISE) at the University of Arizona has been developing a CAES solution for three years. DOE funds will enable azRISE to scale up a 10-kW proof-of-concept prototype (image, below) that will be grid-tied to a 1.6-MW solar power plant.

SOLON Corp., the solar plant's developer, is working with azRISE and Tucson Electric Power (TEP) to demonstrate a variety of storage projects, including lithium ion batteries. "As we see more integration of solar, we want to control storage for our utility customers," said Bill Richardson, SOLON's director of research and development. "The ultimate goal is to make renewable energy plants look like traditional plants with dispatchable energy."

Joseph Simmons, azRISE director, said storage prices are high, particularly for battery systems, but he predicts a breakthrough will come with "intermediate size" compressed air systems that use off-the-shelf storage containers and have capacities of up to 100 kW. The institute's concept, he said, can be scaled up to 1 MW with a coiled natural gas pipeline buried underground.

"I like batteries but they are very expensive," Simmons said. "We expect to see more of a combination of batteries and compressed air storage."

Heat transfer is another issue associated with CAES since air cools when it expands and warms during compression. The azRISE system removes heat from a compressor then stores it in fluid. The system recovers electricity when heat returns to the compressed air before entering an expander. SustainX manages heat by uses an isothermal system to cycle air in hydraulic cylinders.

Price Points Still High
In just three years, the storage industry has grown rapidly from a handful of prototypes to revenue-generating corporations, Roberts said. Current battery technology has a long way to go before renewable energy can be stored and dispatched in meaningful amounts. Meanwhile, revenue is limited to ancillary services, critical observers say. And then there's the price: At $43.6 million, the 36-MW Notrees system costs $1,211 per kilowatt. Others are down to $400. "But the price is still way too high for this market," said Donald R. Sadoway, Professor of Materials Chemistry at MIT.

The leading battery systems are based on lithium ion or sulfur-sodium (NaS) power cells. A multiple-megawatt storage system using these technologies can require thousands of cells.

Sadoway co-founded Liquid Metal Battery Corp., a startup that uses pizza box-sized power cells made with liquid metal and molten salt. Sadoway is banking on his batteries to provide game-changing, cost-effective power storage capacity. "Storage will have to be below $200 per kilowatt if we're going to be major players in the long-term storage firming in renewables without government subsidy," he said.

Pumped-hydro, which accounts for 20 GW of the country's energy storage, can provide 1,000-MW storage systems for $100 per kilowatt-hour, according to The New York Times. It requires massive reservoirs that cost more than $1 billion and take years to construct with ideal geography and abundant water resources. That pretty much rules out the arid Southwest, so researchers like Simmons and Sadoway look to alternatives. (For a primer on Energy Storage Costs, see Sidebar: Understanding Energy Storage Costs, below.)

Sadoway's company received a $6.9 million grant from the Advanced Research Projects Agency-Energy (ARPA-E) as well as seed money from Total, an oil company, and Microsoft Co-Founder Bill Gates. Sadoway said the size of his batteries will broaden grid-scale storage capacity since more liquid will be present per cell than conventional cells.

Lithium Ion Still Popular
"We're starting to see prices come down as we scale up each project," said John Zahurancik, AES Energy Storage vice president. AES Energy Storage is installing a 32-MW lithium ion storage system to regulate the 100-MW Laurel Mountain Wind Farm in West Virginia. Since it was founded in 2007, AES Energy Storage has completed more than 32 MW of storage, and it claims to have 500 MW "in the pipeline."

"We are starting to demonstrate the real commercial competence of storage," Zahurancik said.
Storage is attractive to generators – parent company AES Corp. operates 132 power plants worldwide – because it provides "fuel-free" power during peak hours, Zahurancik said.

Large-scale battery storage is still years away, so revenue streams are limited to ancillary services, which represent a small piece of all sales on the electricity market. The ESA and American Wind Energy Association are lobbying utility regulators who oversee electricity sales to create markets that recognize a premium for emissions-free storage and regulation.

Some systems are growing outside of ancillary services. AES is installing an A123 Systems battery unit capable of providing 20 MW of spinning reserve for 15 minutes in Northern Chile.
"We're moving out of the lab and into large production facilities," said Chris Campbell, vice president of marketing for A123 Systems' Energy Solutions Group.

He said A123 Systems European customers are interested in 100-MWh to 500-MWh storage systems that will help them meet clean air goals. Zahurancik said battery storage devices in the next three years will offer two to four hours of storage for that can transfer nighttime wind energy for peak use. "We're already seeing our market grow like the solar and wind industries," he said.

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Sidebar: Understanding Energy Storage Costs
Energy storage systems are typically quantified in terms of capacity (kilowatts or kW) and generation (kilowatt-hours or kWh), but there are some exceptions. "In the case of energy storage costing, dollars per kilowatt-hour can be very misleading," said Brad Roberts, executive director of the Energy Storage Association.

Battery storage is growing rapidly, but costs remain high, so the industry is striving for average prices to dip below $500 per kWh within three years. "Technologies like lithium ion need to see huge price declines in the next few years which may be possible as electric transportation grows," Roberts said.

The approximate cost of a 1-MW, 6-hour sodium-sulfur (NaS) battery is $3,000 per kW. That translates to a cost of $500 per kWh ($3,000/ 6 hours = $500), Roberts said.

Xtreme Power Chief Development Officer Darrell Hayslip said battery costs are expressed in dollars per kWh when considered "stored energy." Xtreme Power often quotes prices in terms of dollars-per-kilowatt because it markets its dry cell products as a "generating or supply resource," Hayslip said.

Xtreme Power's 36-MW Notrees project is funded by about $22 million U.S. Department of Energy grant and $22 million in matching funds from Duke Energy, which Hayslip said brings the cost to $1,211 per kW ($43.6 million/36,000 kilowatts = $1,200).

Joseph Simmons, director of Arizona Research Institute for Solar Energy (azRISE), estimates a 10-kW compressed air storage system with a $50,000 price tag can generate 30 kilowatt-hours, or three hours of electricity at 33 cents per kilowatt-hour.

Calculations for the University of Arizona system call for use of a 1,000-gallon storage tank. He said the system could be scaled up to 10 MW using coiled pipeline to create 1 million gallons of storage space. Such a system would generate 30 MWh, but price is unknown at this point, he said.

Robert Crowe is a technical writer and reporter based in San Antonio, Texas. He has written for Bloomberg, the Houston Chronicle, Boston Herald, StreetAuthority.com, San Antonio Express-News, Dallas Business Journal, and other publications. He covers renewable energy and sustainability for various publications. As a consultant, he works closely with companies to develop technical materials for renewable energy and sustainability strategies.

Electric Vehicle Batteries: New Report

Over the past few years, the automotive industry has increased its focus on the electric vehicle (EV) market by successfully introducing several new plug-in hybrid and battery electric vehicles as the process of moving away from petroleum based fuels and toward battery power intensifies. These vehicles will rely almost exclusively on lithium ion (Li-ion) batteries, while hybrid vehicles will slowly switch from nickel-metal hydride (NiMH) technology. While the cost of Li-ion batteries is gradually declining, cost still represents a significant hurdle as it accounts for a large portion of total EV cost.

The government subsidies that gave the initial impetus to the electric vehicle market will continue to drive the market in the near term. However, significant reductions in battery cost are imperative for the industry to grow to the $14.6 billion and 28 million kWh market that Pike Research forecasts by 2017. Nearly half of the demand is likely to come from Asia (led primarily by China) while Europe and the United States are likely to constitute 25% and 21% shares respectively.

There are currently more than half a dozen battery chemistries with unique properties for power, energy density, and life cycle performance that are being commercialized. While there is no chemistry that emerges as the clear winner (owing to the tradeoffs in the various properties), initial indications point to a greater interest in the lithium iron phosphate chemistry in the years to come due to its superior performance characteristics coupled with increased safety.

A new report from Pike Research outlines the critical role that governments around the globe will play in establishing the electric vehicle market, and the challenges that manufacturers face in creating an industry that will be able to stand on its own as government influence diminishes. The study examines the key market drivers for the electrification of vehicles, the status of the R&D in batteries, the impact of declining battery production costs on vehicle sales, and the resale of batteries after their useful life in vehicles.