You must pay the elecricity bill with real money ($,€ or other ).
You can convert
BTC to $/€/CNY on
coinbase.com or you can use bitfinex/bitstamp/cex/btc-e/ or kraken.
Coinbase is easy to use
I know, but for such amount I'd be wary of using 3rd party site for conversion... and the fee would be quite high...
and the calculation doesn't take into account cost of cooling, as such a number of ASICs would require some decent cooling power.