The famed futurist Ray Kurzweil’s ‘Singularity’ makes Kaku’s predictions seem modest. Kurzweil postualtes that somewhere around the middle of this century, Artificial Intelligence will have progressed to the point that it exceeds human intelligence. Additionaly, the AI will be able to improve itself at exponential speeds. Thus, huge advances in technology will be (are, in fact) happening at exponentially increasing speeds.
The energy crisis will be easily solved. But there will certainly be new problems cropping up.
Kurzweil’s ‘Singularity’ explained here