The one where Thunderf00t tears apart the “Energy Vault.”

If, like me, you were unaware of the “Energy Vault” prior to this, here’s the short form: it’s a “battery” for the storage of excess power from weather-based power systems like wind and solar. It takes excess power generated when it’s sunny/windy, and uses that power to lift heavy “bricks” of concrete up to 100 meters from the ground to a stack; when power is needed, it reverses the process, turning the gravitational potential energy of the massive bricks into electricity in much the same way that regenerative braking systems in electric cars  can charge up batteries when going downhill. it’s not bad physics. Everything here is perfectly possible. It’s just not a good design:

1. It takes bricks from one stack and raises/lowers them to another stack. Which means it almost never raises/lowers them the full 100 meters, wasting a good fraction of the potential energy that can be collected
2. It requires a cable-based crane system to maneuver multi-ton bricks (that may be dangling from 100 feet of cable in windy conditions) to positions with tolerances measured in at most millimeters
3. Multi-ton bricks of concrete are expensive and, when dangling from a hundred meters of cable, reletively easily damaged

The biggest problem here is that this is a problem that has already been solved. Want to use gravitational potential energy to store excess electricity? Great! PUMP WATER UPHILL.

You don’t need to locate your “battery” right next to the wind farm. It just needs to be hooked into the grid. So… driving across the US, the two biggest regions I’ve directly seen for wind generation are in Iowa and Wyoming. Now, Iowa is flat. So you would need to build a series of water towers, with enclosed subsurface water tanks below them; nothing here is new. There are a *vast* number of municipal water towers in the US; these are essentially catalog items at this point. Granted getting them a hundred meters tall might be a bit tricky, but if you build them in joined clusters, they’ll be good and strong, resistant to storms. So you could have something like a forest of supports, holding aloft a cluster of tanks covering several acres.

But in Wyoming, the wind farms are located within just a few miles of *mountains.* In this case, you could simply build a few vast cisterns thousands of feet above similarly sized cisterns at the base of the mountains, with high pressure pipes, pumps and turbines. Easy. Works all-weather for decades on end.

The “Energy Vault” appears to me to be someone trying to show how clever they are, rather than how practical they are.