This method of calculation still uses USD as a common denominator between BTC and kWh.

Instead of asking "how many kWh can BTC buy", ask "how many kWh applied to a current gen ASIC can mine 1 BTC".

Example: 100 TH antminer s19 runs on 3.25 kW. In theory, it would take 6.17 years to mine a BTC (ignoring halvings, assume difficulty is constant). That's about 54,000 hours.

So 1BTC = (54,000hrs x 3.25kW) = 175,000 kWh = 175 megawatt hours = 7.29 megawatt days = 1.29 megawatt weeks