Battery storage technology has moved in fits and starts, but today experts note that rapid advances make it difficult for safety standards to keep pace. Developers of storage systems are designing projects to enhance reliability and resiliency, and help integrate renewable resources into the grid, while ensuring rewards outweigh the risks.

Battery storage is considered a complex technology, but its implications for power generation are clear. As storage costs come down, it presents a challenge for utilities behind the meter, with small-scale installations in homes and businesses disrupting rate design and the traditional utility business model.

Larger-scale installations, though, present opportunities for power providers, as storage becomes available for on-grid applications. Utilities are moving to procure storage assets to address long-term regulatory requirements and more short-term needs, such as enhancing reliability or substituting for other generation construction projects.

Researchers at the Massachusetts Institute of Technology and Argonne National Lab in a 2016 study wrote, “Electrical energy storage could play an important role in decarbonizing the electricity sector by offering a new, carbon-free source of operational flexibility, improving the utilization of generation assets, and facilitating the integration of variable renewable energy sources.” The researchers wrote that storage installations could replace gas-fired peaker plants, immediately supplying power during periods of high demand for electricity. The key was bringing down the cost of batteries while increasing their energy density and lifecycle.

That’s the task for battery manufacturers, as they work to create products that can store more energy, operate longer between charging cycles, and do it with less risk, as technology advancements are moving faster than safety codes can keep up.

1. Saft’s Intensium Max lithium-ion containerized battery energy storage system has been used as a pilot project at the Grandview Substation in Glendale, California, operated by Glendale Water and Power. Courtesy: Saft

“We’re seeing codes desperately trying to catch up with energy storage deployment,” Jim McDowall, senior technical advisor with Saft, a century-old company founded and headquartered in France that develops battery technology (Figure 1), told POWER. “There have been a number of UL standards [established] over the past few years. The aim is always to develop a technology that is reasonably safe and not expensive.”

Waiting on a Legal Framework

Melding safety standards with advancing battery technology brings challenges. Morten Lund, a partner with Stoel Rives in San Diego, California, and part of the firm’s Energy Development group—he is chair of the Energy Storage Initiative and former chair of the Solar Energy Initiative—told POWER, “There still isn’t a good legal framework for battery storage anywhere. We don’t have a legal framework in which to reliably operate. There still isn’t a market anywhere in the world that is big and permanent, not propped up on precarious financial and regulatory stilts.”

Said Lund: “It’s the ongoing battleground between utilities and solar that is creating the market for storage. At the central level, there is some regulatory change, with the 100% RPS [renewable portfolio standards] coming in, that will function as a mandate for storage. Once there’s a true open market for ancillary services at the utility level, then we’ll see real storage in real-time. There’s a paradigm shift to the utility model coming on, but that’s not the same as no utilities.”

“A lot of people are forecasting that the price of storage is beginning to drop, and I think that sense is shared by the corporate investment side,” said Kelly Echols, an intellectual property lawyer with Stoel Rives in Salt Lake City, Utah. “Is the technology developed far enough along to where it makes sense to begin investing? Most of the innovation follows where the investment dollars are coming from, and [innovation] has been on the control side.”

Lund agreed, noting that much of the investment in storage “is in the control and management software.”

Balancing Load, Responding to Demand

Control systems are part of the evolving landscape for battery storage, as power generators look for ways to utilize more of their excess power, particularly at wind and solar farms. Storage also is being used to help balance grid loads and as part of demand-response initiatives.

“Battery storage solutions now vastly increase the capacity and accessibility of demand-side control by introducing flexible assets that can help grid reliability and power quality,” Rolf Bienert, technical director of the OpenADR (Automated Demand Response) Alliance, told POWER. “It makes sense that grid-scale battery storage arrays need to be controlled by the utility operator. Just like a fossil fuel or nuclear power plant, the capability of these large-scale batteries is and will be vital for the grid stability.”

An example of a control system is Eaton’s Power Xpert Energy Optimizer. John Vernacchia, who manages alternative energy solutions for the Pittsburgh-based company that serves utility, and commercial and industrial customers, told POWER that the system creates “software algorithms that can be used for controlling distributed energy resources, at the [facility] site in a microgrid, or on a utility feeder.”

2. Kevin Whitener, Portland General Electric’s (PGE’s) Smart Grid Project Engineer, stands next to the inverter switchboard in the Salem Smart Power Center in Salem, Oregon. Eaton helped PGE develop the 5-MW energy storage system, which integrates renewable energy resources and demand-response technology. Courtesy: PGE

One of Eaton’s projects is with Portland General Electric (PGE) in Oregon. Eaton helped PGE develop an energy storage system for the Salem (Ore.) Smart Power Center, a 5-MW energy storage facility (Figure 2). The site demonstrates how the integration of renewable energy resources, including wind and solar, and demand-response technology can increase the reliability and efficiency of energy for business and residential customers.

“For Eaton, we don’t manufacture batteries, so we’re not investing in that,” Vernacchia said. “But we are making grid control and management systems, and we recognize that controlling batteries is important today and will become more important in the future.”

Storage increasingly is being used in microgrid configurations, often at locations far off the grid such as in Alaska, and at commercial and industrial sites.

“Microgrids are split into two submarkets,” said Lund. “The EV-play (electric vehicle) related microgrids with a storage network, universities, airports, military bases. UCSD [University of California, San Diego] down the street has lithium-ion but also has some thermal storage. If your microgrid has a thermal component to it, which most of the larger ones will, a little thermal storage goes a long way. Thermal control storage elements are easy to include, as part of a biomass system with trash, [or a heating, ventilation, and air conditioning] system.”

Lithium-ion Leads the Way

Advances in battery technology continue as manufacturers look to increase storage capacity and power output, while also improving charge lifecycles and making batteries lighter.

“Battery storage technology has really been limited to the amount of energy density [the battery] can store, as well as the charge rate at which it could recharge,” said Rod Dayrit, director of business development for North America at Delta-Q Technologies, a manufacturer of industrial battery chargers, in an interview with POWER. “For current technologies, users need to understand what the limitations of the battery are, both for charging and discharging.”

The U.S. Energy Information Administration (EIA) in a 2018 report said lithium-ion batteries represented more than 80% of the installed power and energy capacity of large-scale energy storage applications. Nickel- and sodium-based batteries represented about 10%; lead-acid and other chemistries made up the rest.

The EIA said 90% of small-scale battery installations were at commercial and industrial sites. It said that while lead-acid batteries have been a popular choice for off-grid applications for years, lithium-ion’s lighter weight, longer lifecycle, and less need for maintenance have made it the frontrunner in most of today’s large-scale and residential applications, and in EVs.

McDowall said that Saft, “from an energy storage standpoint, is primarily involved with lithium-ion batteries, a range of lithium-ion chemistries.” McDowall said that “lithium-ion encompasses a very broad range of technologies,” and it’s considered an advanced battery technology, with the ability to use different materials as electrodes. A key for lithium-ion batteries is that they are capable of having a very high voltage, and charge storage per unit mass. Because lithium is the lightest of all metals, it has the greatest electrochemical potential and will provide the largest energy density for weight, according to the Clean Energy Institute.

Common combinations in lithium-ion batteries include lithium cobalt oxide, or LCO, usually found in batteries used in laptops and cellphones. Other combinations include lithium manganese oxide (LMO, found in some EVs); lithium nickel manganese cobalt oxide (NMC); lithium nickel cobalt aluminum oxide (NCA, used in Tesla vehicles); and lithium iron phosphate (LFP). LFP batteries do not generate much heat and thus do not require ventilation or cooling, enabling installation in indoor locations. Said McDowall: “Lithium iron phosphate is a much-safer positive material, with much lower cell voltage, but you have to use more cells to make up a given voltage, so those batteries tend to cost more per kilowatt hour.”

Safety Standards

NFPA 855, the “Standard for the Installation of Stationary Energy Storage Systems” from the National Fire Protection Association, establishes the criteria for minimizing the hazards associated with energy storage systems.

“NFPA 855 is going to be one that governs the energy storage world,” said McDowall. “UL [long known as Underwriters Laboratories] is working on large-scale testing, and fire testing. The top level of the fire codes, and the international fire code, and NFPA 1 [known as the Fire Code], those have been harmonized, and they’re basically the same document now. The latest versions of those have quite strict requirements for deployment of lithium-ion and non-lead acid technologies.”

“We’ve done a lot of safety work on our systems,” Arcady Sosinov, CEO and founder of California-based FreeWire Technologies, told POWER. FreeWire provides mobile battery systems for on-site power, as well as EV charging. “It’s important to have people understand that batteries are safe,” said Sosinov. “We spend a good majority of our money on safety testing. I think the industry builds much further than what UL prescribes,” he added.

“I have five or six utility customers, they audit our processes internally [to ensure safety],” Sosinov said. “I feel more comfortable sleeping next to a large battery than I do sleeping next to a big tank of fossil fuels. There’s a lot of talk about energy density. People need to realize that energy storage technology is evolutionary, not revolutionary. You’re not going to see Moore’s Law in the battery world, because it’s chemistry, not physics. It’s like with any technology that got to operational scale.

“The same thing is happening to the typical lithium-ion technology today. How does a new technology reach that scale?” Sosinov asked. It’s when manufacturers are “certain that technologies are safe.”

Said McDowall: “It’s a bit of a difficult time for storage from a [safety] codes point of view. There [are] a proliferation of standards, and codes are under active development. It’s expensive and it’s affecting people’s designs, and that’s a bit of a headache from a manufacturing standpoint.”

Hybrid Systems and NaS Batteries

Southern California Edison (SCE) in 2017 unveiled a hybrid storage technology at two of its gas-fired peaker plants, in Norwalk and Rancho Cucamonga, California (a POWER Top Plant award winner, see “Two SCE Gas-Battery Hybrid Projects Revolutionize Peaker Performance” in the September 2017 issue). The installed 10-MW lithium-ion battery system (Figure 3) can provide power to the grid immediately at times of peak demand, providing time for the GE LM6000 peaker gas turbines to ramp up and provide power as needed. The battery system is then recharged for its next cycle.

3. Southern California Edison (SCE) utilizes 10-MW lithium-ion battery systems at two of its gas-fired peaker plants to provide immediate power while combustion turbines ramp up to supply load. Courtesy: SCE

This Hybrid Enhanced Gas Turbine system, or Hybrid EGT, is a partnership among SCE, General Electric (GE), and Wellhead Power Solutions. SCE President Ron Nichols, at a ceremony celebrating the plant in April 2017, said, “This is the world’s first for a plant of this type. We are marrying battery storage with peaking generation. This plant provides stellar environmental benefits… and enables a greater integration of renewables.”

The battery storage system can provide spinning reserves when the gas turbine is offline, which improves the ability to integrate renewables onto the grid. SCE said the system cuts in half the number of times the peaker plant needs to be restarted, and helps the plant meet California’s strict environmental requirements on emissions and water consumption.

A different technology—sodium sulfur (NaS) batteries—is being deployed on a large scale in Abu Dhabi, capital of the United Arab Emirates (UAE). The batteries from Japan’s NGK Insulators are being used in 15 storage systems, in 10 locations in Abu Dhabi, with a total generation capacity of 108 MW. Each system has a six-hour lifecycle.

The Emirates News Agency called the project “the world’s largest Virtual Battery Plant” when it came online in January. An NGK spokesperson said all locations “can be controlled as a single plant,” and also “can still be controlled individually when local support to the grid is needed.”

NaS battery technology was developed by the Ford Motor Co. in the 1960s, and Ford sold the technology to NGK, which has deployed NaS battery systems across Japan and around the world. In Abu Dhabi, NGK is using what it calls a Centralized Integrated System Controller (CISC), located at a control room in Mussafah, an industrial district, to manage the system. Some of the batteries are in Mussafah, with the others in the Sila district in the city.

The project is designed to help Abu Dhabi balance its power load in the daytime, primarily during periods of peak demand, and provide up to six hours of backup power in the event of an outage. NGK said the project was planned as “thermal generation investment deferral,” and implemented to ensure “that diesel will not be used anymore for peak load.”

NGK said the use of NaS technology works in the UAE because the systems are not as sensitive to external temperatures as other battery types, and also are designed for frequent charging and discharging.

A Look Ahead

The future for battery storage is, like any generation source, dependent on legal, regulatory, and financial frameworks. Some areas, such as Australia, Hawaii, and California, have been at the forefront of adding storage, and New York state in 2018 released an Energy Storage Roadmap with a target of 1,500 MW by 2025. Getting utilities to embrace the technology, which may require government intervention, is key for larger projects.

Rob Allerman, senior director of power analytics at PRT/Drillinginfo, told POWER that utility-scale storage is “definitely something that they’re working on. The state of California is really pushing for a lot of research to be done, especially on utility-scale batteries. It’s hard to say when those [large-scale battery storage units] will come on. The ones building them say five to 10 years, others say it will take longer. But when it comes, you’ll just have a giant battery next to your wind farm or solar farm, and that would replace gas-fired peaker plants. That will completely change the wholesale market and be a real game-changer.”

Allerman noted that some areas are better-suited for utility-scale battery storage than others. “It’s going to work better in California and Texas, the sunnier and windier regions, maybe parts of MISO would work, where they have lots of wind generation. That’s going to have a huge impact on wholesale prices for sure.”

McDowall said there are “different types of players in the energy storage market now. Saft does a lot of customization, a lot of our business is in more-remote locations, with microgrids and islanded systems, in the far north of Canada and Alaska. There’s this dichotomy in the market now, between the smaller, more-customized systems, and the big tens of megawatts, maybe even hundreds, that are being deployed on a very standardized basis.”

The commercial and industrial side of storage, meanwhile, is growing as customers want more control of their power reliability, resiliency, and cost behind the meter.

“Using battery storage to self-sustain power for businesses, that’s a big area that a lot of businesses are moving toward,” said Dayrit of Delta-Q. “It’s something a lot of them could utilize. Illinois rolled out huge incentives for users who are not using the amount of energy that they have generated in backup storage.”

As with other products, advancements in battery technology should drive down costs, helping both small-scale and utility-scale storage projects.

“There’s still a fair amount of technology improvement going on,” said Lund of Stoel Rives. “It’s my sense there’s still a lot of improvement to come in the batteries. I don’t think we’re at the end of the road in technology.” ■

—Darrell Proctor is a POWER associate editor (@DarrellProctor1, @POWERmagazine).