I don't quite see ConEd getting into Bitcoin mining :) However, it's possible for an entrepreneur to get discount off electricity during non-peak times.
High frequency traders have colocated their machines directly inside stock exchanges to take advantage of the low time latency. I wonder if there's any potential to be had in power stations offering colocation services for customers with very specific uses for either "low latency" excess power or much cheaper power (since it hasn't had to be transported anywhere or had any losses).