[furiousjulius]

Reminds me of this dam operation around here that pumps water up to a mountain top reservoir during the day when power is cheap and then lets it go at night when it can generate and sell the electricity for more money. I was always in awe of the lake size battery they created.

[tshaddox]

Pumped hydro is really cool. Also really bad when it fails:

https://en.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Power_...

> ... catastrophic failure of a triangular section of the reservoir wall and the release of 1 billion US gallons (3,800,000 m3) of water in 12 minutes. The sudden release sent a 20-foot (6.1 m) crest of water down the East Fork of the Black River.

> A broad swath of dense forest was washed away and scoured to bedrock by the escaping flow.

A tidbit that will be interesting to any programmer or engineer: one of the causes of the failure was that the high-water gauges were moved to above the height of the dam wall because someone was annoyed by false positives.

[jashephe]

Taum Sauk is unusual in that the dam fully surrounds the upper reservoir (i.e. the lake was made from scratch), although certainly all types of dam can fail.

[bigiain]

All types of dams can be shittily maintained:

https://en.wikipedia.org/wiki/Oroville_Dam_crisis

[bqmjjx0kac]

Sounds like they hired Homer Simpson to operate the plant.

[dreamcompiler]

Pumped hydro is one of the cheapest ways to store electricity iff you have the topography available to create the uphill lake and plenty of water available to compensate for evaporation.

[codeismath]

> I was always in awe of the lake size battery they created.

This is exactly the feeling I had when visiting the Seneca Pumped Storage Generating Station that I mentioned in one of my other comments that I just posted before seeing your post. Truly awe inspiring. (Links provided in my other comment). Do go visit one of these!

[rpmisms]

Maybe this could be applied to water towers? That's a lot of potential energy just sitting there.

[Guvante]

So I did the math and the average water tower holds something like 1/2 kWh worth of power. (50m tall, storage of 1m gallons, efficiency of 90%)

Hydro power storage is fantastic but needs truly ridiculous amounts of water and height deltas to make sense.

[hnuser123456]

https://www.wolframalpha.com/input/?i=gravitational+potentia...

I got 450 kWh? Maybe you meant 1/2 MWh

[Guvante]

Must have been a bad calculator. It claimed 1000L/s was 400W.

[avalys]

You’re telling me I could fill a typical water tower in 1 hour with a 500 W pump running off a kitchen outlet?

[ClumsyPilot]

500W is a lot, it is hypothetically enough to move 10 liters of water 50 meters up every second. A motor on a cycle an electric bike is 250w.

A kitchen tap provides like what, 0.2 liters per second?

[bigiain]

So in an hour that's 36000L of water pumped up into the hypotheticals 1 million gallon tank. Right on the three orders of magnitude short that a previous commenter pointed out.

[ClumsyPilot]

Sounds like they confused W and kW then?

[rightbyte]

Really good sanity check concept!

[Guvante]

Calculator said 400W for 1000L/s and my mental sanity check missed the duration units and thought 400W can move a ton of water.

[Aperocky]

You probably made a mistake somewhere.

3.8Mg * G * 50m ~ 1700M Joules which is about 500kWh.

[NemuriBaku]

I suspect the k in kWh leads to the occasional factor of 1000 error.

[dharmab]

Water towers are already used that way- water is pumped in during off-peak time and used during peak time.

[mikepurvis]

Right, but that's about maintaining pressure and supply when everyone wants a shower at the same time in the morning, not about harvesting the energy of it all flowing downhill.

[ClumsyPilot]

Pressure is energy

[bigiain]

Nope.

Energy is force times distance. You need to know more than just pressure to calculate energy.

(A bicycle tire at 120psi has a lot less energy than a truck tire at 90psi.)

[sigstoat]

pumped storage systems are so large as to be geographic features.

there isn't much energy in a water tower. and that water is already doing work, pressurizing the water system.

[twobitshifter]

Before electricity there were many household appliances that operated on water pressure.

[mr_toad]

Water wheels were used in industry for over two thousand years.

[cobaltoxide]

Not enough volume.

And you have to maintain water in the tower in order to keep the water distribution system pressurized.