Not sure which way you are surprised but I was surprised how low it all is. Originally wondering about lifting a weight at home, on a chain, using solar or wind to winch it up by a house story or two, to store power; then lower it down to generate electricity.
Surely that would store a lot of power, right? Lifting stuff is hard work, I thought. Showing my working so people can poke holes in it:
1000kg is a ton x 5 metres is two storey of a house x 9.8 Earths gravity constant = 49000 Joules is 13.6 Watt hours is …
… not going to power a house very long. it might mostly charge an iPhone 13 mini battery.
Lifting a Ford F-150 at 2.2 tons (5000 lbs) gets to 30 Watt Hours.
A household might use 10kWh in a day, or 660 tons lifted 5 meters to store that and round it up to roughly 1000 tons to give room for conversion losses to get that much electric power out of the system.
So 400+ Ford F-150s lifted up two storeys to store a house’s power for a day.
Convert that to water (1litre weighs 1kg and a cubic meter to a ton) and we are back in the realms of an Olympic swimming pool as a standard size, 40% of one going up 5m this time.
At home, the scaffolding required to take that weight and the space required to lift hundreds of cars or hundreds of tons of water would be immense. We’re talking a town water tower.
And of course you can trade less water going higher but then need more vertical space and if it’s on a hill, more sideways space for the gradient.
The other way I’m amazed is how energy dense LiIon batteries are, fossil fuels are way more dense, and human bodies are very efficient at 2000 Calories/day is about 2.2 Watt-hours.
Surely that would store a lot of power, right? Lifting stuff is hard work, I thought. Showing my working so people can poke holes in it:
1000kg is a ton x 5 metres is two storey of a house x 9.8 Earths gravity constant = 49000 Joules is 13.6 Watt hours is …
… not going to power a house very long. it might mostly charge an iPhone 13 mini battery.
Lifting a Ford F-150 at 2.2 tons (5000 lbs) gets to 30 Watt Hours.
A household might use 10kWh in a day, or 660 tons lifted 5 meters to store that and round it up to roughly 1000 tons to give room for conversion losses to get that much electric power out of the system.
So 400+ Ford F-150s lifted up two storeys to store a house’s power for a day.
Convert that to water (1litre weighs 1kg and a cubic meter to a ton) and we are back in the realms of an Olympic swimming pool as a standard size, 40% of one going up 5m this time.
At home, the scaffolding required to take that weight and the space required to lift hundreds of cars or hundreds of tons of water would be immense. We’re talking a town water tower.
And of course you can trade less water going higher but then need more vertical space and if it’s on a hill, more sideways space for the gradient.
The other way I’m amazed is how energy dense LiIon batteries are, fossil fuels are way more dense, and human bodies are very efficient at 2000 Calories/day is about 2.2 Watt-hours.