Originally Posted by Brink

One of the biggest pet peeves in a technology enthusiast's life is the plethora of proprietary power cables that plague the consumer market, each with a slightly different design. Can't we all just get along and charge via USB? That utopian vision took one step closer to becoming reality yesterday, as the USB 3.0/2.0 Promoter Groups announced a USB power delivery spec that makes the every-port capable of delivering up to 100W of pure power. Yep, your PC can now charge a notebook. Heck, a laptop could even theoretically charge another notebook.

Read more at:
Maximum PC | 100W Power Delivery Spec Approved For USB 2.0 And 3.0

This old electronics tinkerer has a problem with this. Mr Ohm's Law says that for 100W at 5 volts, you need 20A of current. 20A of current through those dinky USB cables would melt them, (and potentially set your PC or desk on fire) as the wires are small. The cross section of the contacts in the USB plug aren't big enough for that kind of current either, inserting and de-inserting them would risk welding them.

Unless they intend to bump up the voltage, I can't see how this is going to work with new cables, let alone existing ones.