The interesting thing is that while there is a 'practical' length, it varies depending on the application. So if you want to put a wind turbine every 1km along

The interesting thing is that while there is a 'practical' length, it varies depending on the application. So if you want to put a wind turbine every 1km along the coast, and a lamp post every 100m along the coast, the number of lamp posts you need won't be 10 times the number of wind turbines. It will be more.