The sudden realization that LWS is a good option is going viral “The global gravity energy storage market is experiencing explosive growth, projected to expand from $385.3 million in 2024 to $12.2 billion by 2030.”   It is simply a matter of lifting weights on pulley systems for energy storage when solar supply exceeds demand and then allowing the weights to drop and turn a generator when you want to use the stored energy. 

The same electric motor that lifts the weights during charging can function as a generator during discharge, making the system highly efficient and cost-effective.

Charging Mode: Motor consumes excess solar electricity to lift weights (converting electrical → mechanical → gravitational potential energy)

Discharging Mode: Same machine operates as generator when weights descend (converting gravitational potential → mechanical → electrical energy). 

This eliminates the need for separate lifting and generating equipment

Tech

Reversible AC Motors: Induction motors or synchronous motors can easily switch between motor and generator modes

Power Electronics: Variable frequency drives (VFDs) can control the bidirectional power flow

Cost Savings

Single machine serves dual purpose, reducing capital costs by ~40-50%

Simplified installation and maintenance (one system vs. two)

Reduced space requirements in building design

Lower electrical infrastructure complexity

Efficiency benefits

Round-trip efficiency of 80-90% achievable with good motor-generators

No energy conversion losses between separate motor and generator systems

Direct mechanical coupling minimizes transmission losses

Levelized Cost Of Storage (LCOS) Comparison

Superior economics for long-duration applications, with LCOS ranging from $0.05-0.20/kWh compared to pumped hydro at $0.17/kWh and lithium-ion batteries at $0.25-0.35/kWh.

Energy Vault claims LCOS below $0.05/kWh for their systems.

Running Costs

The absence of capacity degradation provides significant economic advantages over chemical batteries. Gravity systems maintain full capacity throughout their 35-50 year operational life, eliminating costly battery pack replacements every 10-15 years. Operational expenses remain minimal due to mechanical simplicity, with maintenance costs typically 1- 3% Of Capital cost annually.

Capital Cost Comparison

Capital expenditure varies significantly by technology and scale.  Lift Energy Storage Technology (LEST) for building integration ranges from $21-128/kWh depending on building height, compared to $345/kWh for4-hour battery systems.

 

Tony,

Although plausible, I doubt if what you've stated above would be practical. Consider the following (and hoping that I did not make any calculation error 😁)

- System losses: Considering that one would need a geared system (hoist) to lift even a reasonably light mass (say 1000kg), friction and heat loss would be in the order of 50% (or even more, taking into account that losses would be equally "up" and "down"...).

- Very low energy density: For a single house, lifting even a 1000 kg weight 10 m high would store only:

E=1000kg x 9.81 x 10m = 98,100 J = only 27.25 Wh... only sufficient to power a 10W LED for less than 3 hours...

- Power is intermittent (you can’t lift and drop the mass at the same time).

Due to the mass required for practical purposes (say 5000 -10 000 ton mass), it's only (possibly) viable at grid-scale, and mainly where other storage such as (pumped water storage) is impractical.

I will rather stick to my solar system, thank you.

Reminds me now, years ago my high school physics teacher taught the class this lesson on energy conversion. We were asked to push him in his VW Kombi up a steep driveway, a height difference of around 5m. After much huffing and puffing he was gracious enough to replenish the energy we had expended, and walked us through the calculation showing why we should share 30ml of Liqui-Fruit juice between us.

26 minutes ago, GreenFields said:

Reminds me now, years ago my high school physics teacher taught the class this lesson on energy conversion. We were asked to push him in his VW Kombi up a steep driveway, a height difference of around 5m. After much huffing and puffing he was gracious enough to replenish the energy we had expended, and walked us through the calculation showing why we should share 30ml of Liqui-Fruit juice between us.

Life lessons are always better learned the hard way, by doing, rather than by reading 😆

12 hours ago, HennieL said:

Life lessons are always better learned the hard way, by doing, rather than by reading 😆

Or you are prepared to listen to guys that can do the calculation like you have shown earlier.

In this case the hard way can be a VERY costly experiment. 🙄🙄

18 hours ago, HennieL said:

- System losses: Considering that one would need a geared system (hoist) to lift even a reasonably light mass (say 1000kg), friction and heat loss would be in the order of 50% (or even more, taking into account that losses would be equally "up" and "down"...).

- Very low energy density: For a single house, lifting even a 1000 kg weight 10 m high would store only:

E=1000kg x 9.81 x 10m = 98,100 J = only 27.25 Wh... only sufficient to power a 10W LED for less than 3 hours...

- Power is intermittent (you can’t lift and drop the mass at the same time).

I think the last is not that much of a consideration, otherwise nobody would bother with pump storage. You just have to use the systems appropriately IE for extra generation during times of peak demand.

The second seems right. Think of pump storage. You are moving a LOT of mass there because the dams hold a lot of water.

How does friction/heat compare for pump storage? I'm guessing that it's confined to the internal losses inside the pump/generators.

I worked with a guy who had this idea that he is going to invent free power... he had a (diy) magnet driven flywheel connected to a generator to prove his theory. He gave up after 20yrs 😃

8 hours ago, Scorp007 said:

Or you are prepared to listen to guys that can do the calculation like you have shown earlier.

In this case the hard way can be a VERY costly experiment. 🙄🙄

Yes, you certainly have a point there ☺️

8 hours ago, Bobster. said:

I think the last is not that much of a consideration, otherwise nobody would bother with pump storage. You just have to use the systems appropriately IE for extra generation during times of peak demand.

You're probably right, Bobster... although probably just for grid-scaled projects only discharging for peak demands. For home use, my battery regularly jumps in to help when a cloud floats past the sun and the wife happen to have a stove plate or oven on at the same time, even when the battery is still charging. I'm not sure how feasible it would be to stop and start the (say) 10 ton mass while it is still being winched up (charging), or to stop further discharge whilst falling, and continue to be charged to the top.

8 hours ago, Bobster. said:

How does friction/heat compare for pump storage? I'm guessing that it's confined to the internal losses inside the pump/generators.

Yes, most of it would probably be in the turbine/pump/generator, but water flowing in a pipe or channel also has a "skin" friction close to the contact area of the water with the concrete/plastic wall of the pipe, etc. There is thus a continuous, though small, power loss as long as the water is flowing. Come to think of it, one could also classify the evaporation from the surface of the dam as a loss, if one would like to calculate accurately...

Edited June 23Jun 23 by HennieL
spelling correction

8 hours ago, Demo said:

I worked with a guy who had this idea that he is going to invent free power... he had a (diy) magnet driven flywheel connected to a generator to prove his theory. He gave up after 20yrs 😃

As Albert Einstein famously said: "The definition of insanity is doing the same thing over and over again, but expecting different results" 😄

17 hours ago, HennieL said:

You're probably right, Bobster... although probably just for grid-scaled projects only discharging for peak demands. For home use, my battery regularly jumps in to help when a cloud floats past the sun and the wife happen to have a stove plate or oven on at the same time, even when the battery is still charging. I'm not sure how feasible it would be to stop and start the (say) 10 ton mass while it is still being winched up (charging), or to stop further discharge whilst falling, and continue to be charged to the top.

Sure. That's why this sort of techology - weights, pumped water - are appropriate for use in grids, not in domestic installations.

With explosive growth “projected to expand from $385.3 million in 2024 to $12.2 billion by 2030.”  With “Proven Levelized Cost Of Storage (LCOS) dropping from 35 cents for li-ion batteries to less than 5 cents for LWT” + all the other “proven” positives.  With the negatives coming through in the posts, I can now see why that guy was telling me “This LWS explosive growth fits exactly with Edwin Land’s brainy quote saying this paradigm shift to LWS is the sudden cessation of stupidity”.   Sorry guys, I am not suggesting this applies to you, but the is/ought fallacy is a common constraint. 

Well Tony, there is science, and there is hyperbole... List the "proven" positives, and show actual science supporting your statements, and we might re-consider. Just appearing in a discussion forum and posting two blatant copy and paste advertisements for a "new technological breakthrough" is not going to earn you any respect, or help to sell your promotions.

On 2025/06/22 at 3:20 PM, HennieL said:

E=1000kg x 9.81 x 10m = 98,100 J = only 27.25 Wh... only sufficient to power a 10W LED for less than 3 hours...

You must earn your wings, so to speak... so disprove my calculations above...

Oh, and just who the heck is Edwin Land - never heard of him...

45 minutes ago, HennieL said:

so disprove my calculations above.

What is obviously correct cannot be disproved. Your calculation is spot on. (or I want a refund for my engineering degree...)

So, to replace my current 28kWh battery storage, I just need to build a tower 10000m high that can carry a 1000kg mass. Or 1000m high to carry 10000kg mass. Obviously cheaper than the R65k that 2 Dyness Powerbricks will set you back.🤣

LWT energy storage may have some application on industrial scale (e.g. using disused mine shafts) but for residential use it ranks up there with the horse-drawn zeppelin.