There is always a loss of electricity as it travels through wires. The natural resistance of the material and other factors cause this. It has nothing to do with how the power was created. The electrical power, large scale grid power, we have is always the same thing basically, always created the same way. Coiled wires and magnets with a spinning motion, be it hydro power spinning it, nuclear steam spinning it, coal steam spinning it, wind turbine spinning it, etc. They all have a loss over wiring, and yes depending on the material, and the gauge of it, and etc., the loss can be calculated and predicted. This is why Tesla's work on how to send electricity without wires is such a big deal. Though it's never moved forward since then and Tesla passed before getting it 'ready for prime time'. Some of the stuff from the movie 'The Prestige' deals with some of the work he did in Colorado Springs where he powered lights on the ground with electricity from distant transmitters using no wires.