The Energy Vault is a Dumb Idea, Here's Why

> Or lifting a really heavy thing and letting it fall slowly. I challenge you to run the numbers on this. Or at least read or watch someone who has. Whenever you’re certain you know the answer, it behooves to try to prove yourself wrong. Unsurprisingly, gravity is an extraordinarily weak force. It merely appears otherwise because the total mass of the Earth is literally astronomical at around the 5.9722×10^24 kg mark. Concrete blocks hanging from a crane, much less so. Don’t believe me. BIY - Believe It Yourself here: ▶ this video Pumped hydro is a nonstarter: do you see any suitable geography anywhere ? Yep, they’ve already been dammed damn it. So approximately no one ^ can have their existing hydro upgraded to pumped hydro retro fitted to pumped, and have the surrounding landscape covered in solar and wind. How helpful! Chemical batteries? South Australia has a decent sized one. I think it can power some of the state for about 12 seconds.^^ ^okay, not no one: Hydropower accounts for approximately 15% , but you have to choose pumped hydro sites where it also makes sense for wind and / or solar, so it’s clearly not an answer for everyone everywhere. Not even close. ^^hyperbole! I know. Look, it’s actually around 1–1.5 hours, which is statistically closer to my estimate of 12 seconds than anything actually useful like a day or a week.

My thoughts exactly. It makes the engineer in me go mad if I see projects like Energy Vault [1] getting massive funding that could be used to try and develop technologies that make sense. Thankfully there are some people who see through the charade [2]. If you are into this thing and looking for an even more stupid idea to store energy, I present to you the StEnSEA [3]. Rolls right off the tongue, right? It is a hollow concrete sphere that is lowered to the bottom of the lake. Pumps then remove water from it, creating a vacuum. Letting the water back in and using the pumps as generators, the energy is reclaimed. Curiously absent from all documentation of this project is the amount of energy stored. I did some back of the envelope calculations a while back and it is 3.8kWh, for a multi-million-euro prototype! [1] link [2] ▶ this video [3] link

This is a stupid idea, and there are some great YouTube videos that explain why[1]. tl;dr We already move enormous amounts of drinking water, and reservoirs are much better (and cheaper) candidates for batteries than sand/cement/etc. 1. ▶ this video

> But if you have an abundance of electrical power you can literally lift up concrete blocks with a crane and generate electricity by letting them down. That doesn't seem like the best idea if you think about it: ▶ this video

Not worth it, easier to scale up battery manufacturing (which the world also needs for all vehicles to transition to electrification). ▶ this video

▶ this video link link Softbank invested. What else do you need to know? By contrast, this is not stupid: link They might still not execute well, but the idea is sound. What is different? They use a single weight, up to thousands of tons. It is suspended in a disused mineshaft, up to a kilometer deep, protected from weather. The one weight just goes up and down, i.e. it has just two moving parts, the weight and the winch. Winches are extra-mature technology. They are talking about sealing the shaft and compressing hydrogen into it. And, maybe storing heat there, besides. Both ideas are also simple, but they don't have to work for the product to be viable; if they do work, they add value. My impression is they added those so their solution could seem more "innovative": the weight in the shaft, by itself, is a sure thing , so probably missed out on some long-shot seed subsidies. Funding in the energy sector is not well aligned. They will probably need to figure ways to get their cost lower. Batteries are approaching $200/MWh, with people expecting that to hit $100. Certain chemistries ("Form") are quoting $20, but are probably over-optimistic. 50 years operation with no degradation could beat a nominally cheaper system that needs the expensive part replaced regularly.