The taller a wind turbine is, the more efficient it is. In fact, for every three feet increase in turbine height, annual energy output increases up to 1 percent. With that in mind, a German company has built the world’s tallest wind turbine, standing at 178 meter (584 ft). The single turbine is the tallest part of a group of four units that are expected to generate €6.5 million a year in revenue.