How many wind turbines are needed to power the world’s major cities?

http://www.pennenergy.com/articles/pennenergy/2018/04/wind-power-how-many-wind-turbines-are-needed-to-power-the-world-s-major-cities.html?cmpid=enl_pennenergy_pennenergy_research_2018-04-17&pwhid=1e90004a8e081f3272fb5f8e0e9a20316c85258cc50faf993491663afd10a38f41b62c13180d825ec81f1c72848099c33ec83965e1b8e8ff4a01aa5c32296aec&eid=288118515&bid=2069403