This stealthy long-duration challenger to lithium-ion dispenses with batteries altogether. But simple tech does not guarantee success.
The energy storage industry is all about incremental improvements, so it’s rare to see a product come to market that does something radically different.
That happened last week when the stealthy Swiss/Southern Californian startup Energy Vault went public with an unusually creative grid storage concept. It devised a six-armed crane that stacks concrete blocks with cheap and abundant grid power, and drops them down to retrieve electricity when needed.
The company pitches this as a durable, trustworthy solution for the thorny problem of storing electricity for long periods of time.
The lithium-ion batteries that account for almost all of new grid storage deployments make economic sense for 4-hour duration, even 6-hour, but they get too expensive for super-long durations. Meanwhile, longer-term storage is getting more valuable as cheap but intermittent wind and solar power continue their rise on the grid.
That mismatch has inspired a cohort of lithium-ion challengers taking aim at the dominant technology’s safety concerns, degradation and duration limitations. So far, this wing of the industry has numerous bankruptcies to show for its labor, with a few survivors that could prove durable.
Energy Vault dispensed with the lengthy lab research required to commercialize new battery tech and drew inspiration instead from the granddaddy of grid storage, pumped hydro.
The shifting of water between higher and lower reservoirs still delivers the vast majority of global grid storage capacity. The problem, at least in the U.S., is that the Bureau of Reclamation and the Army Corps of Engineers have already dammed all the most auspicious sites, and modern regulations to prevent environmental devastation make new siting difficult, if not impossible.
Gravity has many uses, though. Energy Vault elevates giant bricks that eventually come down, releasing potential energy to the grid.
The concept is simple enough, although it depends on intellectual property in materials science, physics and software. The outcome, if it works as described, would be significant.
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