Grid-scale power storage: the limitations of lithium-ion
Lithium-ion batteries are everywhere. They’re in our phones, computers, power tools, drones, electric vehicles, hospital equipment, and more—pretty much anything that needs a battery.
These batteries can do it all thanks to the many inherent advantages of their design. They’re light, can be recharged many more times than other battery types, have a high capacity, can charge and discharge quickly, are maintenance-free throughout their long shelf-life, lose very little charge over time—and all of their properties can be tailored to the needs of the equipment using the battery.
In short, they’re well worth the pricy cost of lithium metal.
But when it comes to seriously large-scale storage—the kind that’s needed for power grids that rely on renewable energy—lithium-ion runs into trouble.
Let’s take a look at why battery storage is so important, why our current options don’t cut it, and what technologies we’re developing to solve these problems.
The need for grid-scale power storage
As we shift to renewable means of generating our power, we must also find ways of storing that power. Most renewable methods of power generation are intermittent—they only generate power for part of the day (like solar) or only under certain conditions (like wind), and the amount of power they produce varies from day to day.
Even with a source of low-carbon power that runs constantly, like nuclear, the grid can’t be supported without power storage. Fluctuations and spikes in power demand surrounding events like hot days, cold nights, and mealtimes need to be met with increased output from the grid. But unlike fossil fuels, the output of renewables and nuclear can’t be quickly increased as needed.
To meet these demands and work around intermittent generation, renewable power must be stored at the grid scale, to be released when demand is high and generation is low.
In the near future, using renewable energy to produce hydrogen gas could give us a clean fuel to combust when demand is high, although its safe storage and utilization is another issue. But in the present day, we use two main methods of grid-scale power storage.
Pumped-storage hydropower is the current leader, in which excess power is used to pump water from a lower reservoir to a higher one, where it can later be released to spin a turbine, acting as a giant battery. But while pumped-storage hydropower is currently the most common storage method, it’s held back by limitations like access to water and sites for reservoirs. Grid-scale batteries, which don’t have these limitations, are catching up fast.
The principle is simple. Large arrays of batteries store the excess power generated when demand is low, then release it when demand is high. But the batteries needed for this critical infrastructure aren’t easy to make.
Our grid-scale battery options today
Current large-scale battery storage uses one of two battery types—lead-acid batteries and a particular variant of lithium-ion batteries.
Lead-acid batteries have been used in energy storage for many years. Although they’re cheap, that’s the only benefit they offer. These heavy batteries are also the least energy-dense, meaning more of them are needed to equal the storage capacity of other battery types.
They also rely on lead and sulfuric acid to operate, in some cases needing regular refills of acid to continue to function. The need for heavy metals like lead is a serious strike against this technology. Additionally, lead-acid batteries have a maximum lifespan of just five years. That means replacing and disposing of heavy metals far more frequently than is practical or safe.
Due to the limitations of lead-acid batteries, it’s no surprise that lithium-ion batteries are increasingly used for grid-scale energy storage. Although they’re more expensive, lithium-ion batteries are lighter, safer, quicker-charging, and longer-lasting than lead-acid batteries.
But despite the clear advantages they hold over lead-acid alternatives, lithium-ion batteries also suffer from several obstacles to their use in grid-scale storage.
The limitations of lithium-ion batteries
One of the most significant obstacles to the use of lithium-ion batteries in grid-scale storage is safety. They are liable to overheat and inherently flammable, and the fires they produce are difficult to extinguish and can quickly spread to other batteries. This trait makes them expensive to ship, as companies require extra controls on lithium-ion cargo—some won’t even accept the batteries on aircraft.
But the main limitation of these batteries is their cost. At 40% more expensive than nickel-cadmium, they are by far the most expensive type of general-purpose battery to manufacture, mainly due to the high price of lithium metal.
Current events like the conflict in Ukraine have highlighted how supply chain instability can further spike the price of this already costly metal. The materials required for batteries are quickly becoming considered a matter of national security by countries like the United States, and lithium, as a difficult-to-refine and expensive metal, is only still included because it lacks a commercially viable alternative.
Additionally, applications like vehicles require lightweight batteries, making lithium-ion their only viable option. As demand for electric vehicles continues to rise, so will the need for lithium, increasing prices even more. And these rising demands are predicted to exceed global lithium reserves—we’ll need alternative battery technologies to meet them.
Beyond cheaper, more abundant materials and better safety, researchers are always on the hunt for batteries that might outperform lithium-ion in other ways. A longer lifespan is a particularly key metric—and some developing technologies promise to compete with lithium-ion batteries in this area and others.
Up-and-coming alternatives
Many alternatives to lithium-ion batteries have been proposed—zinc-ion, aluminum-ion, sodium-ion, magnesium-ion, lithium-silicon, sodium-glass, and more. But in terms of near-future viability for our grids, two options in particular stand out: iron-air batteries and flow batteries.
These alternatives use heavier elements than lithium and require larger battery sizes, but this is only a downside for shipping and construction. In grid-scale storage, batteries—especially longer-lasting ones like these—will rarely need to move, lowering the impact that weight and size have on their viability.
While lithium-ion may remain king in applications requiring light, small batteries, the future of alternative technologies like these in grid-scale storage looks bright.
Iron-air batteries
This technology, which relies on iron metal and oxygen to operate, is particularly promising. Already in field-testing at grid scale by Form Energy, these preliminary versions of this technology allow for up to 100 hours of energy storage, smoothing unreliable energy production from renewables.
They operate on the principle of “reversible rusting,” and while their need for on-board equipment that can produce pure oxygen makes them too large for use elsewhere (they’re the size of a “side-by-side washer-dryer set”, according to Form Energy), they’re a great candidate for the power grid.
Iron-air batteries have a few key advantages over lithium-ion and other batteries. In terms of safety, they present no risk of thermal runaway or heavy metal pollution and are easily recyclable. And in terms of cost, they’re a staggering one-tenth of the price of comparable lithium-ion installations—using much more widely available materials, too.
As the technology is improved and further tested at the grid scale, iron-air batteries promise to become even better candidates for power storage, freeing up more lithium for use in batteries that need to be lightweight and small, such as in electric vehicles.
Flow batteries
This newer technology takes the form of a variety of chemistries, but the basic principle is the same. Tanks of liquid electrolytes store and release energy by pumping them into opposite sides of a container separated by a membrane, through which they can react to produce electricity or absorb it. Although they have less energy density than lithium-ion batteries, these tanks can be easily scaled to compensate.
Flow batteries are also already in the early stages of commercial use. Companies like ESS have developed cheap, effective iron-based flow batteries. These powerful systems can be re-balanced as they age, allowing them to operate for up to 25 years without losing efficiency.
Like iron-air batteries, they’re also much safer than lithium-ion storage, as they pose no fire risk and their liquids are relatively safe. And the batteries ESS is currently developing can store power for up to 12 hours, enough to make them competitive with gas-fired compensation for spikes in power demand.
The impressive scalability of these inexpensive batteries built from widely available materials makes them an excellent contender for grid-scale storage.
The bottom line
Lithium-ion batteries will always be useful. Their low weight, solid lifespan, and good efficiency and power density will ensure they stay in use long into the future.
And in some ways, the technology is still developing—future advances in the chemistry within lithium-ion batteries could create a new variant that solves many of its problems in grid-scale applications.
But lithium will always be pricy, and our reserves of it are limited. In the near future, other developing fields like iron-air and flow batteries look more promising at the grid scale.
References
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1. Battery safety: Top 5 reasons why lithium-ion batteries catch fire. ION Energy. (2023, January 11). Retrieved March 3, 2023, from https://www.ionenergy.co/resources/blogs/battery-safety/
2. Battery Technology. Form Energy. (2022, October 5). Retrieved March 3, 2023, from https://formenergy.com/technology/battery-technology/
3. Battery University. (2022, October 18). BU-205: Types of lithium-ion. Battery University. Retrieved March 3, 2023, from https://batteryuniversity.com/article/bu-205-types-of-lithium-ion
4. Deng, D. (2015). Li‐Ion batteries: Basics, progress, and challenges. Energy Science & Engineering, 3(5), 385–418. https://doi.org/10.1002/ese3.95
5. Dragonfly Energy. (2022, April 7). Batteries: The Renewable Energy Storage Bottleneck (until now). Dragonfly Energy. Retrieved March 3, 2023, from https://dragonflyenergy.com/renewable-energy-storage-bottleneck/
6. ESS Iron Flow Chemistry. ESS, Inc. (2022, December 28). Retrieved March 3, 2023, from https://essinc.com/iron-flow-chemistry/
7. Flow batteries. Clean Energy Institute. (2021, August 13). Retrieved March 3, 2023, from https://www.cei.washington.edu/education/science-of-solar/flow-battery/
8. IEA. (2022, September). Grid-scale storage – analysis. IEA. Retrieved March 3, 2023, from https://www.iea.org/reports/grid-scale-storage
9. Lithium Ion Battery Advantages & Disadvantages. Electronics Notes. (n.d.). Retrieved March 3, 2023, from https://www.electronics-notes.com/articles/electronic_components/battery-technology/li-ion-lithium-ion-advantages-disadvantages.php
10. What is a lithium ion battery and how does it work?. Clean Energy Institute. (2020, September 25). Retrieved March 3, 2023, from https://www.cei.washington.edu/education/science-of-solar/battery-technology/
11. McCarthy, E. (2022, April 5). Lithium-ion roadblocks drive development of US-based alternatives for grid Battery Storage. Utility Dive. Retrieved March 3, 2023, from https://www.utilitydive.com/news/lithium-ion-roadblocks-drive-development-of-us-based-alternatives-for-grid/621565/
12. Pumped Storage Hydropower. Energy.gov. (n.d.). Retrieved March 3, 2023, from https://www.energy.gov/eere/water/pumped-storage-hydropower
13. Report, P. B. E. S. (2022, July 15). 12 alternatives to lithium-ion battery storage. Energy Storage Report. Retrieved March 3, 2023, from https://energystoragereport.info/12-alternatives-to-lithium-ion-battery-storage/
Thomas Praisner—Freelance Writer 