OK; let's suppose you're right. Where and how can we get the amount energy we curently consume? Especially with the current technology (forget fusion). I see no other option than nuclear. Wind is volatile, solar takes up a lot of space and doesn't work at night, river dams fuck up the river ecosystems, everything else is experimental at best.

What B says, anonymus or not, is quite right in my eyes. The best option would be to decentralise the network with small scale wind/solar generators (on the level of households), combined with DC house appliances. But that too is a serious disruption into the current infrastructure and takes a lot of investment to implement.

The third option is to scale down to the pre-WWII level of consumption, which nobody wants.