Everything that powers up, gets warm, or moves uses energy. All we have to do is gather it up and put it to work. And that’s the good news: we already have the technology we need to capture free energy. The bad news isn’t news anymore. Climate change is no longer something for future generations to worry about or in far-off places like the Arctic. It’s a clear and present danger with record-high temperatures, wildfires, and water supplies dwindling. Climate change is here now—but so are the sustainable technologies we need to solve it. Alternative energy sources such as wind, solar, and geothermal alone may not be enough, but additional power can come from innovative new places: small nuclear reactors the size of an office desk, or space-based solar power satellites that can capture sunlight, convert it to microwaves, and beam it to the ground. Here, Bob McDonald turns his focus to global energy sources to show us that a greener future is achievable.