Even long before climate change made it clear that constant burning of fossil fuels was wreaking havoc on Earth's climate, scientists and engineers wondered whether humankind might power our civilization with the same kind of energetic reaction that takes place in the sun. While fusion power, as it is known, is technically not a "renewable" form of energy like wind or solar, it is far more energy-dense. And unlike nuclear fission, which requires politically troublesome and hazardous uranium, nuclear fusion relies on lightweight elements, like hydrogen, which can be extracted from water.
Fusion happens in our sun through the constant collision of light elements like hydrogen, which are smashed together to form heavier elements. When this happens, it releases a burst of energy so powerful that it can fuel stars like our own for billions of years. It is also an efficient process: half of a gram of hydrogen could yield 500 megawatts of power. For comparison, the largest solar facility in the United States, the Copper Mountain Solar Facility in Nevada, takes up 4,000 acres of land and yet generates slightly more power (802 megawatts).
