United States, Jan. 14 -- Duke Energy has brought on line a 50-megawatt, four-hour battery energy storage system (BESS) at its former Allen coal plant on Lake Wylie, serving customers in North Carolina and South Carolina, and has unveiled plans for additional battery storage and new jobs at the Gaston County site.What's happening: The first BESS, at a cost of approximately $100 million, was completed under budget and ahead of schedule, serving customers beginning in November. Final testing is being completed this month. Construction of a second BESS - Duke Energy's largest, a 167?MW, four-hour system - will begin in May on 10 acres where the coal plant's now-demolished emissions control system once stood.Both lithium-ion battery systems qua...