A few weeks ago we reported that decision was coming: The Navajo Generating Station in Arizona, the seventh largest individual source of climate pollution in the U.S. will close in 2019, decades before it was originally planned to close. By some estimates, shutting it down will save more than $127 million a year in health costs for the people living nearby affected by air pollution. The decision to close was not a case of regulation, but rather due to the expensive costs of keeping it open.