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Comment by f6v | Hacker News Reader

> That's the issue with gravity: it's really not that strong

The weakest of all forces, isn’t it?

Does that matter though? If it is weak to extract energy with gravity, then it should also be weak to “charge” the system against gravity. The weakness may push these systems to less “instantaneous” loads, but I don’t see why it would necessarily be bad to use gravity storage (as opposed to another mechanical method like pressure).

I’d love for someone to explain more though.

It's just impractical. You only need a 21x21 foot square of ground covered in solar panels to generate the same amount of electricity this does.

It doesn't make sense to invest so much land, machinery, and labor into something that generates and stores so little energy

While I don't disagree with your general sentiment of the viability of gravity batteries. I don't think its a very good comparison. One is all about electricity generation and the other is all about storage. If gravity batteries ever become used in practice it would probably be in tandem with solar. You would charge the battery during the day off solar and allow it to discharge at night when there is no sun to stabilize the grid.

Because gravity is so weak, in order to store a meaningful amount of energy, the lifted object has to be very heavy or very high. Building large tall structures is expensive, and we just don't have objects that are dense enough to make the system small.

Okay, so the question isn’t “can you get out what you put in”, but rather “is the amount of energy you can store worthwhile”?

Yes. The efficiency is OK (nothing amazing), it's really the scale requirements for anything useful which are problematic.

Yes, by many, many, many orders of magnitude.

It depends on the distance

We should always hold out for some new discovery that is weaker.

Design forces are very weak...

btw anyone saying that gravity is weak should try getting of this planet...

anyone saying gravity is strong relative to the other forces should ask themselves why they don't keep sinking or get crushed when gravity pulls there feet back to the ground.

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