Duke Energy Carolinas LLC reached an agreement with environmental groups June 1 to cut the price tag of its Power/Forward Carolinas grid modernization plan to $2.5 billion, from $7.8 billion, and scale back the initiative to three years, from a decade. Duke’s updated plan includes voltage optimization, electric-vehicle charging infrastructure and at least 300 megawatts of energy storage, which is still subject to the approval of the North Carolina Utilities Commission. The Environmental Defense Fund, Sierra Club and the North Carolina Sustainable Energy Association argued that the original plan was too costly, focused too much on reinforcing infrastructure and undergrounding wires in hurricane-prone areas, while featuring too little investment in renewable generation. Duke Energy Carolinas is a subsidiary of Duke Energy Corp.