Tokyo Electric Power Corp.’s Remarkable Smart Grid Achievement

To put the Japanese nuclear crisis in context, consider how amazingly technically competent the Japanese are with other aspects of their power system.

Japanese electricity consumers pay some of the highest prices in the world for service. In return, Japanese utilities provide unparalleled service.

One element of the energy infrastructure in Japan that survived the earthquake of March 11 with extremely limited damage was Tokyo Electric Power Corporation’s (TEPCO) distribution network.

At about 1.75 hours after the quake, TEPCO reported 4.05 million households without power, which is about 14.1% of the company’s customers.

Within 48 hours of the earthquake, about 0.9% of TEPCO’s customers were still disconnected.

The Japanese government ordered very significant capital investment in reliability improvements starting in the mid-1980’s. Something like $20 billion was spent reinforcing TEPCO’s already good system. The reliability of TEPCO’s power distribution system prior to the accident was far better than any comparable utility in the world.

This chart shows reliability data for 2008. TEPCO reported improved results in 2009. SAIDI and SAIFI are standard measures of service interruption duration and frequency.

City SAIDI (minutes) SAIFI
Toronto 74.5 1.76
Hong Kong 5.37 0.093
New York 16.6 0.139
Paris 17 0.3
London 34.44 0.32
Tokyo 2 0.05
Miami 67.8 No Data
Vancouver 102.6 0.54
Montreal 147.14 2.44


    • Hydro Quebec’s radial system cannot operate to the same reliability standards as the rest of the NA grid, which is why Quebec is electrically isolated from the Eastern Interconnection.

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