Mass/gravity generator

With a new trend of renewable energy storage, an innovative storage solution that is being scaled up is using a motor as both for electricity generation and to lift mass.

While it would be cool to build a multi KW generator that has 20KW of potential energy storage, I would like to build a small one with about a 1-2m drop that would allow a surplus preloved solar panel to store energy during the day by lifting the mass using the motor.
At times when my project needs additional power to operate the mass that was lowered to generate electricity for the project.
Concept is to not require a chemical battery.

What I need is an idea of what motor to use, and a way to do power management.
I would imagine that others have done similar projects or may have done power management projects that might be able to give me some pointers.

Thanks in advance

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Hi David,

Sounds like a super neat project - there have been a couple of kind of similar projects posted previously where other designers wanted to generate something in the KW range (this is a TOOOON of power for a small setup).

Just to confirm were you looking to extract 20KW (kW’s are a measure of power, whereas kW/h is a capacity).

To put some numbers to your project:

Calculate the potential energy of a lifted mass:
E = m g h
20k = m (9.8) (2)
m = ~1000 kG

The motor you use will be dependent on your peak load, and power management is soooo deep - the easiest way to reduce power consumption as much as possible.

I suppose that opens up a couple of other questions:

  • Is this more of a commercial project or something that will be used to power bits around the house?
  • What kind of peak output is required?
  • Could you use water instead?

I’m keen to see it done!

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Sounds like a great project, however, just making sure that you know that the losses of lifting the weight from direct solar and then spinning a generator afterwards are way more than going directly to a battery.

That said, you’ll want something that spins fast and is super geared down to do the lifting, and the weight would need to be JUST heavy enough for the motor to be backdriven.

You might need to work out a brake to hold the mass if the sun went behind a cloud, and also regulate the output otherwise the motor will stall at some times.

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Hey Liam, apparently my finger did too much walking. The figure should have been 20Watts

I’m going to revive this thread…

In E = mgh what is the unit measurement of E?

I have recovered from Long Covid so I can start to research again.

My prototype will likely be incorporate:
M = 10Kg
G = 9.8 m/s^2 (naturally)
H = 2m

Our farm location, does not have enough head of storage (space for additional storage tanks up on our hill) to produce any meaningful energy (although if we were to be able to, we have a solar pump that delivers probably 60L/min+) but that being said we would have to trench over undulating land to run 3 phase power cable from out solar array and a water wheel that would have to be installed close to our 5ML dam.

What we do have is quite a few solar panels that have been retired from a panel upgrade.
Given disused solar panels are a big environmental issue, cherry-picking panels of matched size that are still at 80%+ of rating would provide potentially 20KW of panel space on our shed.
Installing a series of rails to load and unload mass carts onto a lifting carriage would allow us to use a few lifting carriages and a significantly scalable mass carts.
During the day energy from these old panels would lift the mass carts and then be used to feed into a battery system that buffers energy demand at peak times or when power is out entirely.

There are a few commercial projects out there looking at this same technology to buffer energy close/closer to where the energy needs to be used (converting old warehouses, old mine shafts, using a crane method etc.

I’m after building something that anyone can potentially utilize for off-grid storage or minimizing battery waste (which is now starting to kick us in the nuts).

Like everything, projects that are scalable and have redundant systems because of that scalability are able to have longer project lives. Just hoping that this project might be a viable one, that we can all benefit from.

For your units of mgh (kg, m/s/s, m) E will be in Joules (J).