By way of example some states have discounted rates / special rates for cotton gins. Here is one. https://www.epelectric.com/files/html/Rates/TX_Tariff_Schedu...

Such things are complicated to figure out fully, the subsidized power might not be subsidized directly by the power generators / power distributors. In some cases two bills are generated for the duration of the power subsidy so the subsidized part only sees the subsidized rate.