US green energy storage hits headwinds
Metal Tech News - March 22, 2023
Last updated 3/21/2023 at 6:03pm
Supply constraints slow installations; WoodMac expects li-ion batteries to dominate energy storage in US over next five years.
The transition to clean electricity generated from intermittent sources such as solar and wind is energizing the energy storage sector in the United States. Supply chain constraints, however, are acting as an insulator to growth of battery installations that ensure the balance between energy supply and demand.
Go to for Wood Mackenzie Power & Renewables and the American Clean Power Association's quarterly energy storage report.
According to the fourth quarter 2022 U.S. Energy Storage Monitor report recently published by American Clean Power Association and Wood Mackenzie, 848 megawatts of grid-scale energy storage was installed in the U.S. during the fourth quarter of 2022. While this is nearly 50% more than all the storage capacity installed during 2019, it is down more than 25% from the more than 1,400 MW (1.4 gigawatts) installed in each of the previous two quarters.
The biggest contributors to this drop were supply chain and interconnection constraints that led to some projects scheduled to come online during the final three months of 2022 being delayed or canceled.
These restraints on large projects, however, did not hold back U.S. residential storage installations, which saw 11% growth to a record 171 MW during the fourth quarter.
Community, commercial, and industrial (CCI) installations accounted for another 48 MW of energy storage capacity installed in the U.S. during the final three months of 2022.
For the full year 2022, a record 4.8 GW of total energy storage capacity was installed in the U.S., a 34% increase over 2021 and a 235% increase over 2020.
"Grid-scale installations increased by 7% year-over-year, CCI by 3%, and residential experienced the strongest growth with installations up 36%," said Vanessa Witte, senior analyst with Wood Mackenzie's energy storage team.
The WoodMac energy storage team forecasts even larger gains over the coming five years.
"Looking ahead, we expect the U.S. storage market to install almost 75 GW between 2023 and 2027," Witte continued. "Grid-scale installations account for approximately 60 GW, 81% of the new capacity added."
Lithium-ion currently dominates the battery storage sector in the U.S., a situation that WoodMac forecasts will continue until at least 2027.
This means that over the next few years the stationary energy storage sector is dependent on the same battery materials that are already in short supply due to the global auto sector's swift transition to electric vehicles. This situation is driving up the costs for both of these facets of the envisioned low-carbon energy future.
If supply chain constraints are already holding back the installation of batteries to store renewable energy, what are the solutions for ensuring there are enough raw materials for the surge in capacity needed to meet America's clean energy goals over the coming years?
Gravity of the situation
Because stationary energy storage for utilities, businesses, and homes does not have the same space constrictions as EVs, stationary storage has more flexibility for change. This includes several battery options that are suitable, and potentially preferable, for ensuring Americans have plentiful electricity after sunset or winds die down.
In addition to the typical batteries that store ions to be discharged back into electrical grids, gravity storage systems offer another alternative to grid-scale battery storage.
Pumped hydropower, a gravity storage system that uses excess electricity to pump water uphill and generates electricity as the water flows back downhill, is an alternative that has long been a stabilizer of grid-scale electricity and currently stores 22.8 GW of electricity in the U.S., more than any other storage technology.
While pumped hydro capacity is expected to grow, this storage technology has topographical limitations – it requires elevation change and areas to install upper and lower reservoirs to hold the water.
Underground energy storage is a new concept that utilizes the same gravity model as pumped hydro but would lift and lower rock materials up and down an underground shaft to store and generate electricity.
The International Institute for Applied Systems Analysis (IIASA) recently published a paper that makes a compelling case for transforming old mines into underground gravity energy storage systems.
The basic idea behind the underground gravity energy storage system proposed by the IIASA research team is to store sand both on the surface and underground at a mine.
When there is excess electricity that needs to be stored, that energy is used to run motors that lift the sand to the surface or an upper reservoir. When power needs to be fed into the grid, the system converts the potential energy of the upper sand reservoirs into electricity via regenerative braking as the sand is lowered into the mine.
The deeper and broader the mineshaft, the more power can be generated, and the larger the mine, the higher the plant's energy storage capacity.
Since the storage mediums are sand and gravity, such a system can store energy for weeks or even years without any loss.
"To decarbonize the economy, we need to rethink the energy system based on innovative solutions using existing resources," said Behnam Zakeri, a coauthor of the study. "Turning abandoned mines into energy storage is one example of many solutions that exist around us, and we only need to change the way we deploy them."
Further details on the IIASA can be read at Storing renewable energy in old mines in the January 16, 2023 edition of Metal Tech News.
An Australian startup has taken this concept one step further with an underground energy storage system called Viper.
While Economical Energy sees the potential to utilize existing mines if they were available, the company believes that excavating underground shafts purpose-built for Viper may be the better solution for its energy storage system.
One of the reasons for this is Viper has a much more intricately engineered battery that automates the process for storing energy that matches the daily cycles of solar power generation.
The Viper battery involves a closed and automated system where buckets filled with roughly one-centimeter gravel pellets are lowered down an underground shaft when generating electricity. As these buckets reach near the bottom of the shaft, they dump onto a conveyor that then transports the pellets underground. When storing excess energy, the buckets are filled and lifted – storing potential energy that can be turned back into electricity after sunset.
With the pellets being roughly 2.5 times heavier than water and the ability to take advantage of a much larger vertical distance – up to 2,000 meters for Viper compared to 800 meters for pumped hydro – Viper has the potential to store much more energy. When you couple this with the fact that most of the infrastructure is underground, the footprint is much smaller.
"We distinctly describe it as pumped hydro but with pellets," said Matthew Forrest, founder and managing director of Economical Energy. "You take the best aspects of pumped hydro and negate the adverse side effects."
More information on Economical Energy and its Viper system can be read at An innovative take on battery mining in the March 2, 2023 edition of Metal Tech News.
Getting into the flow batteries
Redox flow batteries are one non-gravity option that some analysts predict will surpass lithium-ion batteries for stationary energy storage by 2030.
Vanadium redox flow batteries – variably called flow batteries, vanadium redox batteries, or simply VRFB – are the most common and technologically advanced of the flow batteries.
When it comes to cost, flexibility, quick response, reliability, and safety, vanadium flow batteries offer several advantages over lithium-ion and other batteries for keeping energy grids energized and stable.
The amount of energy a VRFB can store is only limited by the size of the storage tanks built to hold the vanadium electrolytes, which are separated by a membrane that allows vanadium electrons to flow back and forth during charging and discharging.
"The emerging need for large-scale electricity storage makes vanadium redox flow batteries a major potential future use of vanadium," according to the U.S. Geological Survey. "Because of their large-scale storage capacity, development of VRBs could prompt increases in the use of wind, solar, and other renewable, intermittent power sources."
Vanadium flow batteries, however, must overcome the economies-of-scale hurdle in order to compete with lithium-ion.
The rising costs of lithium battery materials is helping to level the playing field, as are investments by the Biden administration.
In 2021, the U.S. Department of Energy launched a $20 million initiative to address technical and manufacturing challenges that have prevented flow battery systems from achieving cost targets and commercial viability.
Pacific Northwest National Laboratory is leading the charge when it comes to vanadium flow battery research for DOE.
"This emerging grid-scale storage technology has great commercial and energy security potential," said Allan Tuan, a manager and researcher at PNNL.
An in-depth look at vanadium markets and uses, including redox flow batteries, can be read at Vanadium strengths go beyond alloys in the Critical Minerals Alliances 2022 magazine published by Data Mine North.
Zinc-air gets NY welcome
Zinc-air flow batteries are another promising clean energy storage option that is in the nascent stages of commercial development.
Electricity flowing into a zinc-air battery splits the oxygen off zinc oxide and stores the resultant charged zinc particles. This stored electricity is released back to the grid by reuniting the charged zinc particles with oxygen, regenerating the zinc oxide for reuse.
These batteries can hold a charge much longer, do not catch fire, and are up to five times less expensive to operate than their lithium-ion counterparts with the same capacity, according to Zinc8 Energy Solutions.
Through its commercialization and industrial-scale installations of this burgeoning battery technology, Zinc8 aims to bring balance between the intermittent supply of renewable energy and the cyclical power demands of homes and businesses.
"By decoupling the linkage between power and energy, and using low-cost, abundant materials, our system is capable of reducing its capital cost dramatically for longer-duration applications," according to Zinc8.
Zinc8's storage system won the New York Power Authority Innovation Challenge in 2020, resulting in a contract for a large installation of the system in New York State.
It also captured the attention of U.S. Senate Majority Leader Chuck Schumer, D-NY, who urged Zinc8 to set up a zinc-air battery manufacturing facility in the refurbished iPark 87 in the Hudson Valley region of his home state.
"I made it clear to Zinc8 CEO Ron MacDonald, that I stand ready to help their potential expansion in the Hudson Valley in any way, including fighting to secure the historic federal battery research & development incentives I passed in the Bipartisan Infrastructure & Jobs Law," said Sen. Schumer. "Zinc8's investment in the Hudson Valley would further power New York's leadership as a global battery manufacturing hub."
More information on Sen. Schumer's support of Zinc8 Energy Solutions can be read at NY Sen. Schumer calls Zinc8 with an offer in the July 11, 2022 edition of Metal Tech News.
Zinc8, which has also received tax incentives at the municipal and state levels, is currently working toward the commercialization of zinc-air batteries and plans to scale up production to 6,000 megawatt-hours per year by 2030, which could help fill much of the need for renewable energy storage in the U.S.
"The support that has been shown for Zinc8's energy storage technology and the clean energy sector from all three levels of the U.S. government ... is encouraging for the company," said MacDonald.
A liquid-metal option
Liquid-metal batteries developed by scientists at the Massachusetts Institute of Technology, is another emerging energy storage technology that touts multiple benefits over lithium-ion when it comes to storing electricity at grid scale.
Ambri Inc., a startup company born from research at MIT, is working to commercialize the antimony-calcium molten metal battery technology.
At room temperature, Ambri's cell is non-conductive, and its materials are solid. Once heated to 500 degrees Celsius (932 degrees Fahrenheit), however, the minerals and metals melt and become active. The passing of ions through the electrolyte as the battery charges and discharges keep the metals molten, eliminating the need for auxiliary heating or cooling.
Basically, these batteries are just one big stainless-steel tank without the need for dividers because, like oil and water, the liquid calcium alloy anode and molten salt electrolyte have different densities and do not mix.
Ambri says these batteries are less expensive to manufacture, work in a wider range of climatic conditions, last longer, need virtually no maintenance, and do not need the ancillary fire suppression equipment required for lithium-ion battery storage systems.
For these reasons, Ambri says its battery systems are a fraction of the cost of lithium-ion when comparing long-term energy storage systems over a 20-year span.
"Our technology will fundamentally change the way power-grids operate, increasing the contribution from renewable resources and reducing the need to build traditional power plants," Ambri penned on its website. "Customers will see lower electricity bills and more reliable service."
In September, Microsoft selected Ambri's liquid metal batteries as the storage technology of choice for moving away from diesel generators as the backup energy source for its datacenters and is part of the software giant's overall 100% renewable energy commitment.
"Enhancing energy storage capabilities – including implementing long duration battery solutions for datacenters – is critically important to our mission. With this partnership, we are strengthening our commitment to sustainability and taking another step in our work to support the grid with ancillary services and shifting," said Ehsan Nasr, senior design researcher at Microsoft.
Adam Briggs, chief commercial officer at Ambri, says the use of its technology as an uninterruptible power supply for Microsoft datacenters demonstrates "how advanced, sustainable, and versatile our technology truly is."
For now – lithium-ion
Despite the many battery options in the pipeline, WoodMac does not see any alternative that will dethrone lithium-ion as the go-to choice for renewable energy storage over the next five years.
"We barely see any non-lithium right now, and those we do see are often at the pilot stage, so the volume is negligible," WoodMac senior analyst Witte penned in a response to Metal Tech News.
This means that the 75 GW of new energy storage forecast by the research firm will likely be dominated by the same lithium-ion battery technology that is powering the EV revolution.
This means that the production of batteries for both renewable electricity and the EVs that hope to plug into it are dependent on the mining sector's ability to produce enough cobalt, graphite, lithium, manganese, and nickel for both segments of the transition to low-carbon energy.
Despite the high demand, WoodMac says price relief for lithium-ion batteries is on the horizon, as commodity prices have begun to decline after prices for materials, such as lithium carbonate, peaked at the end of 2022.
The global research firm, however, says other issues remain, such as supply delays and an increasingly tight labor market.