State power utility Zesco and Copperbelt Energy Corporation (CEC) have agreed to come up with a new Bulk Supply Agreement (BSA) to replace the current 20-year power supply deal which expires next month, according to sources close to the negotiations.The BSA makes CEC the single biggest buyer of power from Zesco. The government wanted Zesco to start selling power directly to mining companies in a bid to bolster its finances, while the miners prefer to continue their current agreement with CEC.