I would nitpick a little bit what Okumura-san had to do regarding the positive impact that the vertically integrated nature of the Japanese power utilities allowed the electricity to flow "with reasonable regularity" despite regional mismatches.

I have not crunched any numbers so far here, but instinctively i find it hard to believe that the power demand in the Kanto area would have not been met more successfully if there had been more transmission capacity between the various utilities.

Okumura-san does have a point that the Japanese power industry has provided some of the most steady and stable electricity anywhere. When word of mouth about the need to stimulate the development of smart grid technology (allowing the integration of renewable sources with fluctuating output, net metering and demand-side management) started spreading, the Federation of Electric Power Companies derided this by claiming that in Japan smart grids had already been achieved through finely honed, yet conventional means:
Indeed, utilities were able to dispatch extra power at a moment's notice, meeting any conceivable momentary spike in demand in their region thanks to comfortable margins of spare capacity. No need for renewables, DRM, etc.

Yet the obverse is also true: All of the spare capacity (btw, very expensive) allowing utilities to meet their own demand swings on their own also allowed these companies to relatively neglect the development of ties with each other. So when the cries for help from Tohoku and TEPCO came, there simply were not enough pipes to squeeze the available juice through.

Naturally, my claims here would look a lot better if i put some numbers on them. However, anecdotal evidence from one of Japan's two wholesale power companies does confirm that transmission capacity in Japan is insufficient. If that's not enough for you, take the METI figures for setsuden in Kyushu or Shikoku, for instance. If Kanto and Tohoku had to do double-digit consumption savings, turning off lights and thinning out trains, how come those other regions got by with less than 3%?

It is transmission, not generation, capacity that is lacking in Japan - and the source of that problem is the utilities' desire to maintain their insular fiefdoms. The Japanese grid needs a lot of work.

Alex Luta,
Ph.D. Cand.
Tokyo Institute of Technology.