The U.S. Department of Energy (DOE) has announced the successful completion of the Long Duration Storage Shot program. Announced in 2021, the program was created for the Biden administration's goal of net-zero carbon emissions by 2035 from the electric grid and economy-wide in 2050 by reducing the storage costs of electricity by 90% when storing energy for at least 10 hours. Long-duration storage of electricity and energy has been a long-sought-after technological accomplishment due to both the massive benefits of the consistency and reliability of renewable energy, and thus also improving the United States' energy independence, as the demand for fossil fuel by power plants is expected to be greatly reduced. The newly completed storage system primarily utilizes sodium-ion batteries, but is supplemented by the previously ubiquitous lithium-ion batteries that many are familiar with.
Previously, the United States' grid energy storage was primarily based on Pumped-Storage hydroelectricity and lithium-ion batteries. Power plants often adjusted their production based on demand rather than attempting to store any reserves. To ensure a reliably supply of electricity regardless of demand, the United State's energy grid was designed to produce vastly more electricity than typically required, but the inefficient design of the infrastructure and the ramping up and lowering of energy production of coal, gas, and nuclear plants costs both time and money, with many stressed electrical systems still risking outages at peak usage.
Pumped-storage hydroelectricity has existed for decades and uses the simple principle of utilizing excess electricity to pump water from lower elevations to higher elevations, such as in a reservoir. Although this method is cost-effective and has had great success when implemented, it lacked the scalability required for the demand of US electricity usage due to only being cost-effective when built on favorable terrain, which has virtually all been already utilized.
Alternatively, Lithium-ion batteries have been renowned as the forefront of energy storage and are familiar to most households as the rechargeable batteries in phones, laptops, cars, vacuums, and other devices. The Lithium-Ion battery won the Nobel Prize in Chemistry in 2019 after its development had made life-changing changes to human lifestyle. This is largely due to their high power density, light weight, and high output, which makes them highly favored by both consumers and investors hoping to develop the technology further. However, the lithium used in the batteries has high reactivity, both making it prone to combustion, resulting in infamous exploding batteries, often from thermal runaway, and high rarity in the Earth's crust, in which Chile holds the greatest reserves at 8.6 million, and the United States only has the 5th highest reserve at 0.63 million. There has been fear and debate on potential shortages in lithium reserves, though many have argued that technological advancements in locating and obtaining lithium will likely ensure its continued supply.
Regardless, lithium is expensive and far more rare than sodium, most recognizable as making up 1/2 of table salt in sodium chloride, and is the 7th most abundant element on Earth and the 5th most abundant metal. Notably, it can be extracted from seawater, and in 2010, the cost of sodium's precursor, trona, was 135-165 dollars a ton compared to lithium carbonate, which costs 5000 dollars a ton.
Although sodium-ion batteries will make up most of the grid storage, lithium-ion batteries will not be going away anytime soon. Lithium-ion batteries have higher power density, allowing them to hold significantly more electricity while maintaining a small size. Sodium-ion batteries have greatly improved their power density over the years, but are unlikely to ever reach the level of lithium-ion batteries. Furthermore, lithium-ion batteries have had decades of a head start over sodium-ion batteries and thus have infrastructure and manufacturing far surpassing sodium-ion batteries, though this may change in the near future.
But, the low cost of sodium ion batteries makes them ideal for grid storage, as although their power density is lower, their weight is actually less compared to lithium ion, and high power density can be easily compensated by increasing the sheer size, number, and density of cheaper sodium ion batteries. Sodium ion batteries also experience less self-discharge compared to lithium ion, allowing for the longer duration of energy storage needed for renewable energy. Sodium ion batteries also lack the fatal flaw to the cold that lithium ion batteries have due to the slowdown of the chemical reaction required for energy storage, which reduces their effectiveness and can cause permanent damage when temperatures are below freezing. Several states experience this temperature, and thus, sodium-ion batteries have also entered the market for smaller devices locally as cold-tolerant alternatives despite lower performance than lithium-ion batteries at room temperature.
Long-duration grid storage is expected to quickly reduce electric bills in households as less fossil fuel will need to be used to compensate for the intermittent nature of solar and wind energy, allowing the energy industry to take advantage of the lower costs of expanding solar and wind farms compared to the construction of coal power plants.
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