 U.S. energy company Duke Energy Corp said Monday it took a 1.6-billion after-tax charge in the second quarter for the cancellation of the Atlantic Coast natural gas pipeline from West Virginia to North Carolina. Atlantic Coast was the most expensive U.S. gas pipeline under construction when Duke and partner Dominion Energy Inc exited the 8-billion project in July due to regulatory uncertainty following years of delays and billions of dollars of cost overruns. 