General Electric on Monday announced that Jeff Immelt, its chief executive for 16 years, will be replaced later this summer by GE veteran John Flannery, signaling potentially big changes ahead at one of the world’s most important renewables companies.

During Immelt’s tenure, which began just days before the 9/11 terrorist attack in New York City, he transformed GE into a renewables powerhouse as part of a broader return to the company’s industrial roots, pivoting away from the financial services businesses that had become central under prior CEO Jack Welch.