Wind turbines are a zero emissions solution to energy needs. But with solutions, new problems always arise. We’ve all seen the giant wind turbines towering into the sky and with any tower, there is a risk for air traffic. And how do we solve that problem? With lights. Sometimes blinking. And that has been a problem for residents in Germany who live near them. Thomas Herrholz and Dark Sky GmbH from Germany is a company that has been developing techniques to activate obstacle lighting only when it is really needed for air traffic. Their solution enabled them to realize that the lights on some wind-turbines can be turned off up to 98% of the night time. So most of the time the obstacles are illuminated for nothing!