Grid-scale energy storage has—thus far—predominately relied on lithium-ion battery chemistry. While that’s been necessary to advance clean energy transformation as far as we’ve come, the near future looks markedly different. Alternative technologies have emerged that are expected to perform better across stationary storage use cases and, critically, also take the load off of lithium-ion. Lithium shortages, accelerated by the widespread use of li-ion batteries in EVs and consumer goods, have swelled demand for the resource to unsustainable levels. The subsequent rise in materials cost has also highlighted some of the weaknesses of li-ion when applied to stationary applications, including susceptibility to fire, long-term degradation, and environmental and recycling challenges.

Make no mistake about it: to meet long-term clean energy and sustainability goals, other chemistries and storage methods are needed. Three fast-maturing energy storage technologies are the front-running candidates for meeting the stationary energy storage market’s sustainability goals going forward.

Metal-hydrogen (Ni-H₂) batteries outlast lithium-ion while improving safety.

Metal-hydrogen batteries differentiate themselves through improved safety. Their chemistries are inherently safer, with none of the thermal runaway risks common to li-ion. That advantage is coupled with the cost efficiency of metal-hydrogen batteries, which have lower material costs, longer battery lifespans (exceeding 30 years), and a greatly reduced cost-per-cycle. As demonstrated by more than 200 million cell-hours in NASA orbital spacecraft use cases (before more recently coming to terrestrial energy storage applications), metal-hydrogen batteries can perform 30,000 charge/discharge cycles with minimal degradation.

This superior durability—even under ambient temps of -40° to 60°C and conditions as extreme

as deserts, tundra, and the aforementioned outer space—makes metal-hydrogen batteries more sustainable from an operational standpoint as well. There are no moving parts and maintenance is minimal. With no augmentation or gross oversizing required, and little maintenance, OPEX is greatly reduced, resulting in a lower levelized cost of storage. Metal-hydrogen batteries also stand apart from a sustainability perspective by utilizing mostly non-toxic components, mitigating several of the environmental issues associated with lithium-ion materials.

This versatile battery chemistry is beginning to enable an expansive array of use cases, from solar plants to wind farms to microgrids, and do so across remote locations where challenging conditions render lithium-ion-based strategies unworkable.

Gravity-assisted batteries offer a dead (weight) simple approach to sustainability.

Gravity-assisted battery technology stores energy by raising and lowering large bricks made of composite materials. These bricks are suspended from cranes, cables, and pulleys on towers that reach as high as 500 feet in the air. These battery systems can store energy by raising a brick up and then releasing energy to the grid by lowering a brick. These systems can also perform complex manipulations by moving multiple bricks simultaneously to achieve rapid and optimized energy management. As a result, gravity-assisted batteries can absorb and deliver energy to and from the grid at high speed, with response times measured in milliseconds.

Gravity-assisted batteries themselves use commodity equipment that’s affordable, safe, and fully sustainable. While the large footprint of gravity-assisted battery infrastructure may not be congruent with urban deployments, this approach is a strong fit for many locations that are otherwise difficult to utilize—such as Superfund sites, unused mining or extraction sites, and brownfield locations. Gravity-assisted battery systems are ideal for balancing grid energy from renewable sources, delivering backup energy, and rapidly restoring grid power to mitigate outages.

Sodium-ion batteries provide a sustainable drop-in lithium-ion alternative.

Sodium-ion battery technology provides another alternative for energy providers upgrading their existing stationary lithium-ion storage systems. Unlike lithium-ion batteries, sodium-ion uses more environmentally friendly (and readily-available) materials. Advances to the battery’s chemistry could outpace lithium-ion batteries in terms of energy density, which will only accelerate sodium-ion adoption as a li-ion replacement. Also, the manufacturing process of sodium-ion batteries is congruent with existing lithium-ion production facilities.

More alternatives mean more sustainability

While lithium-ion battery technology has driven the early stationary energy storage market, it will soon pass the baton to a range of technologies that are both more sustainable and better suited to the specific use cases at hand. Advances in these technologies—and healthy market competition among them—will shape more optimized and effective options for organizations to harness, especially as the sustainability of lithium-ion wanes.