How big is the z library archive, anyway?
Edit: fixed my math
Also, there are plenty of drives with under $10/TB listed here some looking legit: https://diskprices.com/
So it is actually only $1200
You can also get dual-drive USB adapters for $20.
I very nearly bought a second one to replace an actual designed-for-NAS case which only has room for 8 HDD; the only reason I didn't is because that older Fractal Design case still works fine. It lives in the living room in the open without shame, and the Design 7 would look even better.
That probably is the real problem. Although you could plop them in some separated utility space like a garage.
Donation drive?
https://torrentfreak.com/z-library-raises-tens-of-thousands-...
My calculation off a Dell 2U was something like 195W idle - ~900 kWH / year. I'm in California so paying 50 cents per kWH, that would be ~$450 per year -- decided to scale back to a low power tower with huge disks. More upfront, but less annually. More disk drives (6tb vs 18tb) increased that to the point where I figured it was better to have fewer larger disks, even if they are pricier, because of the cost to run them.
You have identified the problem.
I did some rough estimates to see if the big disks were more cost effective than the 6tb ones and came to the conclusion small disks were worth it for me. The long term cost was pretty close though in the midwest where electricity is like 15 cents per kWh, giant disks would definitely be the better choice in CA.
It's easily within the means of relatively affluent professionals anywhere.