The one illustrated above shows supply against percentage used. At the time of taking the screen shot we were using about 82% of the supply – that's with convenience stores, department stores and trains switching off lights, stations and stores cutting escaltors or lifts, and all companies and residents saving lights and switching off things normally on standby. So we're getting by. (And learning what power we waste.) The problem is that in Tokyo's hot summer, consumption usually goes up to 6,000 kW – and the power just isn't there. (As you can see, there is 3,800 available.)
We've already had one threatened all-Tokyo blackout, avoided by a TV announcement to save power. The summer might make it inevitable. (And believe me, anyone reading this in temperate climates, with 50+ consecutive days last year when the temperature never dropped below 30 degrees, even over night, you need some cooling simply to function.) So Tokyo's nervousness is far from over yet.
via Japan Probe