By Kennedy Maize
Li-ion, LFP, Na-ion, graphene, lead acid, solid state, flow. Welcome to the Advanced Battery Warehouse.
What started 200 years ago, using primitive electric batteries to power wooden-wheeled vehicles, now appears to be a far more mature technology that can transform how the worldwide energy system works, from cars to household electric service.
Batteries, far advanced from the 19th century, are now used to store electricity to supplant internal combustion engines in vehicles and to store energy from falsely termed âintermittentâ generating sources â primarily wind and sun â and may overcome a serious limitation in nuclear power. A key feature is that the batteries are easily recharged.
The story of the rise of the electric vehicle is familiar and does not need retelling here. What is less understood is the important roles that batteries can play at the utility level.
Solar energy company EnergySage makes the case succinctly: âUtilities and grid operators often say that utility-scale battery storage is âa new tool in the toolbox,â referring to the many ways battery storage can support the grid.
âStorage can act like a load (charging from the grid when electricity prices and demand are both low) or like a generator (pushing electricity back onto the grid when demand and prices are both high). Moreover, when power plants take minutes or even hours to turn on, battery storage can inject electricity onto the grid in milliseconds. This level of flexibility from a resource is unprecedented, and the possibilities for harnessing this capability are endless.â
Three advanced battery technologies are the leaders in the race to capture the momentum from the EV market and turn it to electric utility markets: Lithium ion, lithium iron phosphate, and sodium ion.
Li-ion
The dominant battery technology for utility-scale battery energy storage systems (commonly referred to as âBESSâ) is lithium-ion. Researchers in the 1970s, during the periodâs âenergy crisis,â began exploring lithiumâs ability to store electric energy.
In 1991, Sony researchers altered the earlier work, coming up with what is todayâs Li-ion workhorse. Their work and that of their predecessors ultimately resulted in a Nobel Prize in chemistry in 2019.
In the years since 1991, the technology has been refined and improved. Todayâs Li-ion batteries are characterized by high specific energy, energy density, energy efficiency, and a longer cycle life. The downside is that the batteries can, and have, caught fire that are difficult to extinguish, recycling involves toxic wastes, and lithium is rare and expensive, as well as creating environmental issues in mining.
Tesla established the worth of the Li-ion batteries beyond cell phones and laptops. The batteries made electric vehicles practical and affordable.
Tesla also gets major credit for utility scale battery energy storage systems, based on its EV battery experience. In 2015, Tesla announced it would sell stand-alone battery storage for industry and utilities, with a 200 kilowatt-hour product. In 2019, Tesla unveiled its âMegapack,â featuring storage capacity of 3.9 MWh, fitting inside of a standard intermodal shipping container.
In September, Tesla announced a new product to be available late next year: the âMegablock,â 4 Megapacks connected with a transformer and switchgear.
LFP
Li-ion technology is getting challenged, including by Tesla itself, by lithium iron phosphate (LFP) batteries. They are a Li-ion derivative that has been around for a while but has had recent improvements. The key is a different composition of the LFP cathode (positive electrode).
The advantages of LFP batteries are resource availability, safety, cost, and a longer life cycle. LFP batteries use no nickel or cobalt, both of which are in short supply. They are less prone to catch on fire and suffer from thermal runaway. A 2020 Department of Energy report found that the cost of the LFP batteries was $356/kWh versus $366/kWh for the conventional Li-ion technology. The LFP batteries were also estimated to last about 67% longer.
Teslaâs Models 3 and Y, the most popular of its offerings, now use LFP batteries, as do Chinaâs BYD electric cars.
Na-ion
Last September, Denver-based Peak Energy announced it had powered up the nationâs first grid scale sodium-ion battery, a 3.5 mWh demonstration. China has also been pursuing the technology, for its major advantage of not needing rare and expensive lithium. Sodium is abundant and inexpensive.
Sodium-ion batteries have a higher operating temperature range and can be used in more extreme temperatures without the risk of thermal runaway. They can also be charged faster and have a longer lifetime.
Utility scale battery storage is conventionally seen as a way to expand the time renewables can be dispatched, since solar doesnât generate at night and wind depends on the wind blowing. Contrary to the ill-informed views of Energy Secretary Chris Wright, wind and solar, often the lowest-cost power available, are part of economic dispatch.
When they are available, which is much of the time, wind and solar can and do follow load. A recent Utility Dive article reported that âautomated markets are consistently choosing renewables over other resources because they are cheaper at the time the grid needs them.â
Less well understood is that batteries can remedy a serious shortcoming in nuclear generation, which Wright mistakenly calls dispatchable. Nuclear units must run 100% of the time, except for refueling and unscheduled outages. They cannot follow load, which means they are on the grid even when they are the most expensive power, displacing less costly generation. They are rigid when other resources are flexible.
The only nuclear unit in the U.S. that purposely varies its output is the 1,170-MW Columbia station in Richland, Wash., which can adjust its power during seasons of high or low water level in the Columbia River.
A 2021 Stanford University paper on nuclear load following notes that reducing power levels in the Columbia plant ârequire at least 12 hoursâ notice to reduce power output to 85% of full power, and at least 48 hoursâ notice to reduce power to 65% of capacity. These abilities are termed âload-shapingââŠ.â
Thatâs far too slow to be useful in the hour-by-hour and minute-by-minute requirements of economic dispatch. Battery energy storage systems tied to nuclear plants could remedy that problem, adding considerable flexibility and profit to nuclear plant operations without jeopardizing safety. BESS could be a welcome feature of small modular nuclear reactors.