They are not equivalent, since every other source of energy is more expensive and harder to get. This changes the dynamics of the system drastically. Your 10 or 20 years of crap would erode the legacy of public cooperation and peace to the point where organized approaches to energy (such as a smart grid, or taking solar energy from the desert for use in cloudier regions) would no longer be possible.. Enough riots and rationing, and public order collapses.