Even with free power you still have the cost of the money you put in place and your time along with any import fees and rental costs.

As a space heater then it works well at 9500 USD/BTC getting you a small profit of 0.04BTC over the course of 1.5 years of babysitting.

Antminer V9 4TH 1.5 years operation you save $1,069.72 in power costs if it was 0.10 /KWH

https://i.imgur.com/Og7qGzQ.png

Antminer S9 13.5TH 1.5 year operation you save $1531.00 at 0.10 / KHW original power costs.

https://i.imgur.com/KRG1Ug1.png