3 ms·

I am not sure that this form of storage is comparable to a traditional dam. The fact that blocks of matter need to be physically moved by a crane severely limi

I am not sure that this form of storage is comparable to a traditional dam. The fact that blocks of matter need to be physically moved by a crane severely limits the total capacity of the system. The most dense metals are only about 20x as dense as water, so we are not talking about a huge volume of water. The equivalent mass of water can be stored in a tank - no dam required and moved through a pipe - no river required.

imtringued 6y ago
Paying for 20 denser material is usually more expensive than just "buying" 20 times as much material. Gravity storage will always be a scaling problem because you would rather have 1000 times the material than 20 time the density. Doing something as nonsensical as using a mine shaft whose size is fixed is not going to work out. The crane system could work out in theory if you make the crane arms 200m or longer. The covered surface area grows much faster than the length of the crane arm. In practice it's an engineering nightmare. The piston idea has the benefit that you just use a wire saw and cut out a circle. The primary challenge is building what is basically the largest seal on the planet. The pressure itself is not a problem but the sheer size is. Compared to hydrogen, reflow batteries, compressed air, heat storage, etc gravity energy storage is extremely questionable unless it's pumped hydro.
- ChrisFoster 6y ago
  The piston idea seems like a appealing design requiring minimal new technology. The plant is the same as existing pumped hydro plant, the weight can come from the native rock. Using a rolling membrane for the seal is discussed at https://heindl-energy.com/technical-concept/engineering-challenges/ https://heindl-energy.com/technical-concept/engineering-chal... Naively that does seem plausible but it's a very large sheet of material to manufacture. What are your thoughts on that approach?

imtringued 6y ago

Paying for 20 denser material is usually more expensive than just "buying" 20 times as much material. Gravity storage will always be a scaling problem because you would rather have 1000 times the material than 20 time the density. Doing something as nonsensical as using a mine shaft whose size is fixed is not going to work out. The crane system could work out in theory if you make the crane arms 200m or longer. The covered surface area grows much faster than the length of the crane arm. In practice it's an engineering nightmare. The piston idea has the benefit that you just use a wire saw and cut out a circle. The primary challenge is building what is basically the largest seal on the planet. The pressure itself is not a problem but the sheer size is. Compared to hydrogen, reflow batteries, compressed air, heat storage, etc gravity energy storage is extremely questionable unless it's pumped hydro.

ChrisFoster 6y ago
The piston idea seems like a appealing design requiring minimal new technology. The plant is the same as existing pumped hydro plant, the weight can come from the native rock. Using a rolling membrane for the seal is discussed at https://heindl-energy.com/technical-concept/engineering-challenges/ https://heindl-energy.com/technical-concept/engineering-chal... Naively that does seem plausible but it's a very large sheet of material to manufacture. What are your thoughts on that approach?