The United States became the world’s largest exporter of liquefied natural gas a year ago amid a flood of cheap natural gas from the shale wells of Texas and New Mexico that prompted a series of LNG projects along the Gulf Coast. Lately, however, the industry has started to lose momentum—because of regulations and a federal government that’s all sympathetic ears to climate activists claiming that natural gas is even worse for the atmosphere than coal. In early August, NextDecade announced a $4.3-billion contract with Bechtel Energy…