With millions already without power, [Prime Minister] Kan said Japan would undergo planned outages in the coming days to preserve what electricity remained.
Large areas of the quake area are without power. This lessens demand. When those areas come back online, more power will be needed. But several nuclear reactors, which supplied 20% of Japan’s power, are down and they may stay down.
For Japan to institute 3-hour rolling blackouts in Toyko during a period of less demand nationwide means their power situation is beyond perilous.