3 ms·

Similar to pumped water storage I wonder if we could do a household version with weight. Something like the gravity light (gravitylight.org) but on larger scale

Similar to pumped water storage I wonder if we could do a household version with weight. Something like the gravity light (gravitylight.org) but on larger scale. I wonder if we could see a resurgence of chimneys on houses except now instead of letting smoke out they contain a XY ton weights that gets pushed up by excess solar capacity during the day, and then drops by evening powering the house. I have no idea if that's realistic. Does someone know what the weight/distance to power output would be limited at...

rm445 11y ago
The potential energy of a mass m at height h is mgh. Play with this and you'll immediately see it doesn't seem useful. e.g. storing a 50-tonne weight at 10m gives you less than 1.5 kWh of energy.
- Gustomaximus 11y ago
  So probably needs in excess of 750 ton. And more likely twice as a house would more likely have a 5m 'chimney'. Clearly not viable. Thanks.
swombat 11y ago
A much better and denser option for storing energy mechanically is flywheels. I haven't researched what happened to this option since but when I was looking into it 15 years ago it seemed like a good option that needed more R&D into frictionless axles and vacuum chambers.
- dredmorbius 11y ago
  Excellent rapid response, second only to capacitors. But pretty poor densities, and hugely significant engineering challenges. Flywheels that don't become fly-apart wheels is one problem. Containment of fly-apart wheels another. Buried concrete pipes are usually what you're looking at. You need mass to contain these things. The per-kg energy densities just aren't all that high. If you want reactive load to soak up very short-term demand / supply fluctuations, you can get that. And you've got crazy charge-discharge cycles. Bearings are mostly solvable with magnets, as I understand. But you still lose a given percentage of storage over short time -- ~1% per hour or so, within a few powers of 2. Enough that long-term storage isn't viable. And the thing that really screws you over is that the Earth moves. Geometric precession of your flywheel is something you've got to deal with. There's a place, but I don't think it's large-scale, long-term grid storage.
- pjc50 11y ago
  The Formula 1 "KERS" system is based around high-speed flywheels and seems to work quite well.
thinkcontext 11y ago
You are referring to a hydraulic accumulator[0], such systems were built in the 19th century, though not for household use. There is a modern effort to use the technology in a massively scaled up fashion by Heindl Energy[1]. Their concept uses pumped water to raise a rock weight 100 meters or more in diameter. [0] https://en.wikipedia.org/wiki/Hydraulic_accumulator https://en.wikipedia.org/wiki/Hydraulic_accumulator [1] http://www.heindl-energy.com/hydraulic-rock-storage/overview.html http://www.heindl-energy.com/hydraulic-rock-storage/overview...

rm445 11y ago

The potential energy of a mass m at height h is mgh. Play with this and you'll immediately see it doesn't seem useful. e.g. storing a 50-tonne weight at 10m gives you less than 1.5 kWh of energy.

Gustomaximus 11y ago
So probably needs in excess of 750 ton. And more likely twice as a house would more likely have a 5m 'chimney'. Clearly not viable. Thanks.

swombat 11y ago

A much better and denser option for storing energy mechanically is flywheels. I haven't researched what happened to this option since but when I was looking into it 15 years ago it seemed like a good option that needed more R&D into frictionless axles and vacuum chambers.

dredmorbius 11y ago
Excellent rapid response, second only to capacitors. But pretty poor densities, and hugely significant engineering challenges. Flywheels that don't become fly-apart wheels is one problem. Containment of fly-apart wheels another. Buried concrete pipes are usually what you're looking at. You need mass to contain these things. The per-kg energy densities just aren't all that high. If you want reactive load to soak up very short-term demand / supply fluctuations, you can get that. And you've got crazy charge-discharge cycles. Bearings are mostly solvable with magnets, as I understand. But you still lose a given percentage of storage over short time -- ~1% per hour or so, within a few powers of 2. Enough that long-term storage isn't viable. And the thing that really screws you over is that the Earth moves. Geometric precession of your flywheel is something you've got to deal with. There's a place, but I don't think it's large-scale, long-term grid storage.
pjc50 11y ago
The Formula 1 "KERS" system is based around high-speed flywheels and seems to work quite well.

thinkcontext 11y ago

You are referring to a hydraulic accumulator[0], such systems were built in the 19th century, though not for household use. There is a modern effort to use the technology in a massively scaled up fashion by Heindl Energy[1]. Their concept uses pumped water to raise a rock weight 100 meters or more in diameter. [0] https://en.wikipedia.org/wiki/Hydraulic_accumulator https://en.wikipedia.org/wiki/Hydraulic_accumulator [1] http://www.heindl-energy.com/hydraulic-rock-storage/overview.html http://www.heindl-energy.com/hydraulic-rock-storage/overview...