A lot of grid is wasted during off peak times. Energy is stored or sold in inefficient manners. Instead, they should use any excess energy in mining bitcoins to sell. Rather than raising electric rates, they can increase their customer base. Their price discovery will be the electricity/btc pair. They can choose which will be most profitable. Storage can then be bought by customers for their needs based on rates. This just seems more efficient than being forced to sell to only one market.
Yeah, you are right. There are times when it costs you money to produce electricity and people get money for consuming electricity. At those times you could power up your rig with hardware no matter how old. You could even use old BFL gear or outdated KNC hardware... Man this would mean double the profit for you!