By Francesca Landini and Giancarlo Navach MILAN (Reuters) -Italian gas and electric utility Edison plans to replace some gas volumes from pipeline contracts with liquefied natural gas to gain more flexibility in managing demand, its CEO said on Wednesday. The company earlier announced a 15-year agreement with Shell to purchase around 0.7 million tonnes a year of U.S. LNG starting in 2028. European companies are stepping up LNG purchases to gain flexibility, so they can resell cargoes to other markets wh ...