In April of this year, the Union of Concerned Scientists put out a report describing how renewable energy is being reliably integrated into America's electric grid. According to this report,
"Renewable energy is providing reliable electricity today in the United States and around the world. From 2007 to 2012, electricity from renewable sources such as wind and solar nearly quadrupled nationally. This growth is part of a transition away from dirty, coal-burning power plants—which harm public health and destabilize our climate—toward cleaner, more sustainable sources of electricity. Using existing technologies and smart policy decisions, the United States can continue this clean energy transformation while maintaining a reliable and affordable electricity system."