One other option. Get some big electric extension cords / net metering and sell that 20 kw back to the grid
20kw at 12 cents per kWh is about 21,000$ a year. You wont get that though depending on local laws you might on net metering plans
25 x l3+ antminers in free electricity of 20 kw earns about $15k right now less cost of 25 antminers ($3k used on eBay) So net $12k year one
You are better off selling the electricity to neighbors if you can back feed it some how like solar net metered services include
If you go crazy and put out in some bigger miners that cost way more up front and longer roi maybe you can out pace that for profit of just selling the the electricity
Sell back electricity to the person who gave it to you for free!
This is actually an awesome idea in theory. Not sure how and why power companies would allow it though, because even with solar net metering setups, the power companies are thorough and inspect the power feeds because obviously it could affect them negatively as well.
But most likely the OP doesn't really have free electricity and sooner or later it will bite him back in the butt.