Can Gravity Batteries Help Save Energy

I’ve been seeing more articles about this topic. I even discovered one company specializing in this idea last week ($NRGV) while surfing chart setups I like. And now we have the name of another company (obvioulsy not publicly traded as of yet) Gravitricity:

BBC headline: Can gravity batteries solve our energy storage problems?…

There is a riddle at the heart of the renewable energy revolution. When the wind blows, the sun shines, and the waves roll, there is abundant green power to be generated. But when skies darken and conditions are calm, what do we do?

The answer, today, is to ramp up conventional power production, supplying the grid by burning fossil fuels. It is a 20th Century solution to a 21st Century problem – one that sits in sharp contrast with plans for carbon neutrality.

A cleaner future will mean focusing on ever-larger lithium-ion batteries, some energy experts say. Others argue that green hydrogen is the world’s best hope. And then there are those placing their bets not on chemistry, but the limitless force that surrounds us all: gravity.


From the same article, this paragraph tells me just one building could power every home in the Florida Keys. We’ve got plenty of sunshine to fill the warehouse with extra energy during daylight hours:…

“Think of it as a warehouse of energy elevators,” says Robert Piconi, Energy Vault’s CEO. “When clean electricity is coming in, the blocks – made of recycled material – go up, and when the grid needs supply, they go back down. An EVx with a storage capacity of 100MWh can power around 25,000 homes for a day.”


It’s a message that seems to be resonating: Energy Vault’s order book is filling up fast, with interest coming in from across Europe, America, the Middle East, Australia, and China. The latter is particularly exciting, says Piconi, who is hopeful that it could signify a change of direction for the world’s largest emitter of greenhouse gases.

My charts for $NRGV:

1) $NRGV crossed my scans last week for bullish 20 x 50 EMAs. The more I look into their business, the more I love this idea of gravity based energy storage.

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(Discussion of Q1 earnings by $NRGV CEO)

That’s an excellent article. Note that mechanical systems require maintenance. Many other systems have been proposed–

  1. Electric engine that pulls a train up a hillside. Or reverses to regenerate electricity. Diesel electric locomotives already do this when they use dynamic braking.
  2. Pumping compressed air into large underground chambers.
  3. Note that cable cars benefit from cars descending the hill while one is climbing the hill. The cable cars that climb steep hills in Pittsburgh could easily be adapted to store energy. Do they run in winter? In ice and snow? How big can you build them?

Cables used for cable cars wear out and must be replaced frequently.

I would think the simplest elevator system would be on a hydraulic jack. Then mostly you maintain the pump. Cables for very heavy weights seem problematic.

Recall the days of the inclined planes that were used to lift rail cars or canal boats up steep hills in the early days. It amounts to an outdoor elevator. They still have one on display in Madison, Indiana (Indiana’s first capital on the Ohio River). Imagine what happens if a cable breaks.

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Corydon not Madison was Indiana’s first capital.


Thanks, you caught me. I was misinformed. The inclined plane is still there I think.

This is one of the goofier ideas I’ve seen. It costs money to erect a building. It costs money to maintain it. The idea that we’re going to build skyscrapers just so we can haul bags of sand or water up and down strikes me as, uh, ridiculous.

By the way, where does all the sand/water go? If you have 10 stories worth up top, it’s going to fill up the bottom 10 stories when it comes down. So a 30 story building is at best going to give you maybe 15 stories of drop. (There are “lost” floors required for infrastructure; elevator housings, and so forth.)

Oh wait, they’re going to use already built buildings that have vacancies? I’m sure the tenants will just love the idea of decreased elevator service because it’s time for the bags of sand to go to the 23rd floor.

If you want a gravity fed system there are tons of ways to do it, most involve horizontal plays: pumping water uphill and releasing it later, inclined railways, and so forth. You could easily find land as big as a skyscraper to make a pond or a lake, yes, you might have to add to the high voltage lines coming in, but then that seems it would be incredibly, gigantically, fabulously less expensive than building skyscrapers in dense urban areas.


How do I short this idea?

I thought recycling the abandoned mine shafts was a pretty good idea.

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I thought recycling mine shafts was a pretty good idea

With only a few exceptions, mine shafts are not very wide, and therefore have limited volume potential. The horizontal shafts are useless, of course (except for air pressure storage or the like). Even the deepest ones aren’t straight vertical because of the problem of cable storage and stresses on a thousand feet of rope/cable, so it’s done in increments: two or three different elevator shafts to get to the bottom.

How do you move the “stuff” (water, sand, concrete blocks, etc.) from one to the other? People have feet and can move fairly efficiently. “Stuff” doesn’t, and requires energy and time to move.

The largest mining elevator I have heard of holds 120 people (but stacked with 3 cars, so 40 people, or about 10’x10’). Now you get to the bottom and you fill the bottom now your next load goes not as deep. Repeat and the next load goes not even that deep. By the time it’s over you’re height constrained and the “super deep mine” is just a (admittedly significant) fraction of the depth. You’re working against yourself at every turn.

Ironically, I call this idea goofy. - Goofy