[yongjik]

I don't know how much a typical house weighs, but assuming 100t, raising it by 30m will give you potential energy of ... 8.2 kWh, or about $1.6 in today's electricity rate.

Gravity is weak.

[jacobolus]

I was estimating based on a 200-ton house, 30 kWh/day electricity use, and a need to store up to half of daily energy at any one time.