The generation and delivery of electric power is going through a transformation, according to Lynn Good, CEO and President of Duke Energy (DUK). Good is increasing the use of natural gas and renewables at Duke as she seeks to modernize the electric grid. The modernization process has been helped by low natural gas prices and low interest rates, enabling the company to step up its investments while continuing to deliver returns to shareholders. ‘Renewables will be an increasing part of the portfolio,’ said Good. ‘We’ve invested to date about $4 billion. We see another $3 billion in investment over the next five years.’ Good has also been replacing coal plants with facilities that are run by natural gas. ‘Based on the regulations that exist today, building new coal is almost impossible,’ said Good. ‘We’ve retired about half of our coal units in the Carolinas, 40 units across our system, and are introducing natural gas.’ Good said as a result, Duke’s carbon emissions are down 20 percent and will continue to drop. TheStreet's Rhonda Schaffler spoke with Good at Fortune's The Most Powerful Women conference in Washington.