Let’s dive into the big question: What would it take to reach 100% fossil fuel-free energy, and is it even possible? With renewable energy costs dropping, we explore the challenges, future growth, and what a fully green grid might cost. Coal use in U.S. power plants peaked in 2005 and has since been on a steep decline, while wind and solar are steadily rising. Yet, non-fossil fuel sources like wind, solar, and nuclear still make up only 39% of electricity production.