A lot of great minds play Factorio.

[ColonelSandersLite]

Nobody has addressed the question of whether a tank (25 K litres, this is Factorio) full of water is sufficient storage for a house. I can go investigate but physics is my achilles heel... I am reading physics for dummies, it makes me feel dumber.

What you're looking for is called Pumped-storage hydroelectricity. It is currently the most used bulk energy storage in the world, at about 95% of our total storage capacity. That being said, it's not really as much as that might seem. Since the vast majority of our energy is produced from chemical sources on demand, only about 2% of our (U.S.) power capacity is in the form of bulk storage. Efficiency is about 80%.

As for use, well it has big problems with economy of scale.


The relevant formula is:

Potential Energy (joules) = Mass in kg X 9.8m/s X height in meters

A single AA battery has about 13,000 joules of energy (varies a bit!).

100 kilos of water would have to be raised 13 meters (220 pounds 42 feet) and then be turned into kinetic energy and then used to produce electricity with 100% efficiency (it won't, but let's ignore that for now) to do what a single AA battery can do.

The average US household uses about 29.47 kWh of electricity (47608163 joules) per day. Let's say that the tank on is on your roof, 40 feet (12.192 meters) above the ground. To have enough power to run the house for a full day, you would need 398,456.021kg or about 105,260 gallons of water up there. A typical tanker truck holds about 9,000 gallons of water, so you would need to put about 12 full tanker trucks of water up on your roof.

Let's assume that you don't need the total electric capacity to come from this storage method, after all, it's just to even out the day/night cycle, and throwing in the inevitable inefficiencies. Off the cuff? let's just say that you can get away with maybe only needing only 4 full tanker trucks of water on your roof.


At industrial scales, Pumped-storage hydroelectricity is totally feasible. At a household scale? Well... I don't want to have the tanker trucks of Damocles hanging over my head.

Edit: Just a quick note - all numbers just came from a quick google search. Caveat emptor and all that!

[darkfrei]

See also https://en.m.wikipedia.org/wiki/Energy_ ... lid_masses

[ColonelSandersLite]

Well, solid masses have, broadly speaking, the same fundamental problems, and then some. Notice that, even there, they're using fairly extreme builds to accomplish the goal (a 13,000 foot drop!).

Let's just run with the example numbers I gave above, just changing from liquid weight to solid weight.

The mass is smaller due to the increased density, but the mass remains unchanged. Instead of needing 150 tons of water on your roof, you would just need 150 tons of something else, like lead. The machinery would be more complex than the water based equivalent but it would be more compact.

I still don't think I would want the 150 ton lead block of Damocles hanging over my head.

On the plus side, it might be useful if anyone ever attacks you with a raspberry.

[darkfrei]

The mass is smaller due to the increased density, but the mass remains unchanged. Instead of needing 150 tons of water on your roof, you would just need 150 tons of something else, like lead. The machinery would be more complex than the water based equivalent but it would be more compact.

I still don't think I would want the 150 ton lead block of Damocles hanging over my head.

It's much easier as you think https://interestingengineering.com/conc ... ge-problem

You can have the electric train with water tanks or concrete masses wagons, 1000 tons, 5000 tons, not a problem. If you have 1-3 km mouintin in the near, than you have a lot of power. Double it for nice electric breaking with recuperation brake system.

[ColonelSandersLite]

We're talking about the viability of using some sort of gravity battery (water in the OP) as a solution to energy storage for individual houses. Not particularly applicable, unless you happen to own your own mountain!

[Nefrums]

As far as I know H2 is the best currently available method of storing large amounts of energy.

I recentlly read a story of a guy that whent "off grid" by using solar panels, batteries and hydrogen. Batteries to store energy for the night, and hydrogen to store energy from summer to winter.

If we accept the law of conservation of energy, we will never inventory a magic mashine that generates energy from nothing, and it will all be about transforming kinetic energy, positional energy, radiation, chemical or mather to electric energy.

Another thing to consider, what is a renewable energy source? Is it using a fussion reactor to create radiation that we harvest thou photovoltaic panels, or thou movmets in gasses heated by the radiation?

Would it then also be a renewable energy if we used the heat directly from a fussion reactor, or does it have to be fussion->radiation(->heat-> kinetic) in order to count as renewable?

[Koub]

I'm keeping an eye to inertial flywheel storage. A French startup claims to be able to make a concrete inertial flywheel that could keep energy long enough for nighttime, at very competitive costs.
http://www.energiestro.net/products/
I'll wait and see, is sounds promising, but not everything keeps its promises as Factorio did .
I know the technology is used elsewhere, but usually with shorter conservation duration. Now we're talking 8-10 hours. That's a lot for a flywheel.

[Dry Hairy Tree]

Thank you people I really appreciate the time you took to reply.

Wow that's a lot of water for a household, just what kind of insane capacity do our dams hold? Just thinking about it is how I considered gravity/water as a viable option on smaller scale. A quick look shows there are an order of magnitude more dams here than I knew of...

Again, thanks for the input I could have been stuck in wonky math for days.

I'm a fan of the bio-batteries myself, but their efficiencies are dire, and set-up even worse (using sludge or other biological waste). I like them because I'm a microbe nut, not because they work...

Who saw the Lemon Car Mark Rober tried. He got a high performance sports car and tried to run it on lemons. That was an eye opener the lemons had no chance despite vast numbers.

I guess a lot of our economies with regards to power are only just coming out now as well. Engineers might care for efficiency but the general public never did until recently. Now it's a benchmark for an appliance to be very efficient, likewise a typical vehicle. I remember when hybrids first arrived bogans (petrolheads, boys who drive cars in circles on Friday night while playing hair rock) took offense and were picking them up and putting them in moats and ditches. The general public cannot be relied on to embrace common sense or changes that may very well save their lives. The zeitgeist is changing now, however. Nobodies arrived to accuse me of being a communist yet, this is a change from not that long ago...

I'm also a big fan of biodigestors. India has hundreds of thousands of working models, our scientists have dithered over one for decades. In the interim our main power consumer (Dairy farms) is missing out on free power, free fertiliser, carbon credits, pathogen and thus veterinary reduction, etc. And they're under tremendous pressure from the general public to clean their act up. We have a viable solution, but it's not even talked about. The trolls that throw hybrid cars in ditches are embedded in every industry. Power industries have very powerful lobbyists. Everyone else misses out.

[ColonelSandersLite]

Wow that's a lot of water for a household, just what kind of insane capacity do our dams hold?

A helluva lot.

Let's just go with hoover dam as the example as it's the most iconic in the US. Hoover dam's reservoir is called lake Mead and is the largest in the country. Going by the wikipedia numbers, it contains 8.51585e+12 gallons of water. If we wanted to pack it all into tanker trucks for some reason, we would need a fleet of a million of them.

[Dry Hairy Tree]

Koub - that flywheel does look promising.

We've obviously got a multitude of 'clean' power solutions: tidal, solar, wind, geothermal, hydro, gravity (the train), pressurized air, bio-conversion, bio-digestion, and soon to be water cracking...

Storage is key to unlocking a clean future. Affordable and available storage. Fingers crossed this flywheel, or similar, will work.

A successfully sustainable and affordable storage solution will change the face of the planet, so there's bound to be a breakthrough sooner or later. I encourage all to encourage all to ponder this issue, who knows, your next door neighbor might be the next nobel laureate.

Mine drinks till he drools, fingers crossed there's hope for all of us

[Dry Hairy Tree]

I talked to an expert.

In terms I understand: It takes approx a 1/4 acre pond at 2 meters depth dropping 50 ft to power an average American household.



You guys need to stop heating your toilet seats and harden up.

[lovewyrm]

Rev up those thorium reactors.