For Mexican industrial park owners like Sergio Bermudez, business is booming amid a wave of U.S businesses setting up over the border. So-called nearshoring has pulled over $9 billion into Mexico since last October by manufacturers like Unilever , Barbie maker Mattel , and Tesla , lured by its proximity to the giant U.S market, cheap labor, and geopolitical stability. Yet Bermudez and many of his 400-strong cohort have a serious cost issue on their hands: energy.