Power prices are about $0.24 KWh in London for a standard domestic electricity tariff but my friend uses a power broker to negotiate much lower rates than that because his farm is in his industrial printing plant and his farm uses a small percentage of his overall consumption.

As to why he is backing out of mining I'm not sure but I suspect he doesn't have the time to dedicate to mining to justify the slimmer profit margins.  I'll try to have a proper discussion with him about it before he pulls the plug .  He's a canny businessman so I'm sure his reasons are sound and personal to his own circumstances.

I'm not sure on numbers but I think he has a lot of hardware.  I remember him saying something about 30 S4s at some point.  When he finds out how much I'll charge him in commission to sell them maybe he'll change his mind