Tests start with an existing cruise ship in 2017, although you'll have to wait considerably longer for Icon-class ships to take to the seas. Shipbuilder Meyer Turku won't deliver the first example until the second quarter of 2022, and you'll have to wait until 2024 for the second. Still, it's an important step. Pollution is a serious problem in the cruise ship industry, and it may only get worse as the ships get larger. Fuel cells could turn that around very quickly -- you could go on vacation without worrying quite so much about hurting the planet.