Actually I was off by a factor of 1000. That Camry needs to be raised to 7.3 km. Or you need 1000 of them. Or some combination of increased weight and height.

You’re absolutely right.

I don’t know why I thought to use grams instead of kilograms. I knew kg was the base unit for these conversions but just slipped for some reason.

Sorry whoops I was off by a factor of 1000 because I used grams instead of kilograms. The Camry needs to be raised 7.3 km. Or you need 1000 of them in one house.

is it really easier and cheaper to store the energy needed for a home in a chemical battery?

Yes. A 5kwh battery is about 50kg and smaller than a carry-on suitcase. String 6 of them together and you’ve got 30 kWh stored with no moving parts. Anker has that for about $15,000, maybe $30k installed.

How much does a 3-story elevator cost? What about one that can capture the stored potential energy on the way down, and not break down?

Potential energy (in joules) is mass (in g) times height (in meters) times 9.8 m/s^2 .

So in order to store the 30 kWh per day that the typical American house uses, you’d need to convert the 30 kWh into 108,000,000 joules, and divide by 9.8, to determine how you’d want to store that energy. You’d need the height times mass to be about 11 million. So do you take a 1500 kg weight (about the weight of a Toyota Camry) and raise it about 7.3 meters (about 2 stories in a typical residential home)? (this is wrong, it’s only 0.001 as much as the energy needed, see edit below)

And if that’s only one day’s worth of energy, how would you store a month’s worth? Or the 3800kwh (13.68 x 10^9 joules) discussed in the article?

At that point, we’re talking about raising 10 Camrys 93 meters into the air, just for one household. Without accounting for the lost energy and inefficiencies in the charging/discharging cycle.

Chemical energy is way easier to store.

Edit: whoops I was off by using grams instead of kg. It actually needs to be 1000 times the weight or 1000 the height. The two story Camry is around a tablet battery’s worth of storage, not very much at all.

That’s one of my pet peeves, when people use relative comparisons to overstate things that have very small absolute differences.

55g of CO2 is basically nothing. A gallon of gasoline represents about 2400g of CO2 emissions when burned. So for a typical vehicle that gets 30 miles per gallon, 55g of CO2 is basically the equivalent of driving 0.6875 miles (1.1km).

It’s less than the carbon footprint of a cup of coffee (60g).

Or, alternatively, eating a single quarter pound hamburger would be about 3 kg of CO2, or 55 hours of video viewing at this rate.