Everyone loves to travel, and the industry's room for growth seems almost limitless--except that flying will soon be responsible for 19 percent of global emissions. Some people have even decided never to fly. Over the coming decades, aviation will witness more innovation than at any time since the invention of the jet engine in the 1940s, transforming the way planes are powered and the way they look. In Flying Green, Christopher de Bellaigue meets the inventors, visionaries, and entrepreneurs who are at the frontier of new technologies, from a European startup that makes fuel out of thin air, to a California firm using hydrogen to power flight, and an airship called the Flying Whale. What will it take for a new generation of travelers to fly guilt-free? This is the story of the search for a way to fly green.