[jacquesm]

There is a good chance that with present day technology we could satisfy all of our energy needs using HVDC transmission lines. The main problem is that these are going to be easy infrastructure to attack in case of war or through terrorism.

[natmaka]

True, however continental-scale grids interconnecting more and more interdependent nations/states are needed whatever the type of energy source used (even nuclear), and at least as exposed to terrorism as long-haul (U)HVDC lines.