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The Great East Japan Earthquake

Expandable Power Supply Systems through Local Production for Local Consumption
- Building Networks that are Resilient against Disasters

Ryuichi Yokoyama
Professor, Faculty of Science and Engineering at Waseda University

For a century, Japanese electric power utilities (electric power companies) have been striving to build electric power systems that can stably supply consumers with high-quality electric power at low rates, which is a very difficult task. Our country, which was rich with water resources, began this endeavor with the development of hydraulic power generation, but as the resources were later exhausted, 75% of our electric power had to be generated with petroleum by the time we entered a period of high growth. However, oil crises struck with conflicts in the Middle East and nuclear power generation, which has matured technologically, as well as newly developed forms of natural gas have replaced petroleum as a result of the breakaway from dependence on oil. Furthermore, large-scale power generation facilities that exceed a million kilowatts for producing low-cost electric power were constructed in pursuit of economies of scale. They were naturally located in remote areas such as Fukushima and Kashiwazaki, and so stable and enormous systems that were both large in size and range were widespread.

Nuclear and thermal power generation facilities, however, were easily damaged by the 2011 off the Pacific coast of Tohoku Earthquake, and the capacity to supply energy in areas serviced by TEPCO decreased by about ten million kilowatts. As a result, the demand for power exceeded the capacity to supply, and all power systems became unstable, causing concern over widespread major power outages. This led to implementing planned outages (rolling blackouts) where power fed from electric power substations in the systems was sequentially cut off by consumer blocks. This shortage of electricity will not be resolved any time soon, so electric power companies are taking all kinds of measures to maintain their capacity to supply. There is also the need to cut down on power consumption by 15% in all fields, including industry, business, and in residence. It is also unfortunate that the emission of radioactive pollutants from the Fukushima No. 1 nuclear power plant cannot be suspended because of the fatal blow from the tsunami. Even three months after the disaster, many refugees still need to be rescued, crops and fishery products are contaminated, and there seems to be no end to the harmful rumors that worsen the situation. The government estimates the total costs to cover the damages at four trillion yen-with TEPCO being responsible for about two trillion yen-and so each power company must ultimately continue paying compensation for the next ten years. In addition, the decommissioning costs for machines 1 to 6 at the Fukushima No. 1 nuclear power plant are expected to be 1.5 trillion yen and the increase in fuel costs for thermal power generation should be about one trillion yen per year. There would still be losses of 1.2 trillion yen per year and a hundred and fifty billion yen by the next fiscal year with corporate downsizing, even if about six hundred billion yen were gained through activities such as sales in real estate and stocks. This means that if they were passed on to electricity rates, the rates in areas serviced by TEPCO would rise by about 24%.

A scheme where electric power companies can support each other with power interchanges even if there is an unanticipated natural disaster must be reexamined. This is likely to be followed by the advocating of measures such as the unbundling of power generation and power transmission, and the opening of power transmission grids by economists. On the other hand, this widespread shortage of electricity has made us keenly aware of the need for households, offices, factories, and local governments to maintain their own power sources that are not completely dependent on electric power companies. If this were accomplished and the local production of renewable energy such as solar and wind power were incorporated for local consumption, fluctuation in the output of power generated would affect the electric power networks and there would be concern over the quality of electric power (frequency and voltage) being affected-calling for a new reform of the infrastructures of power supply companies. It would therefore be suitable to create supply networks (known as clusters) that are of appropriate scale for their respective regions and towns instead of large-scaled and costly networks all at once, to add new clusters when needed, and to have them collaborate with each other when developing power supply systems where regional governments are the main entities. Such cluster-expandable power supply systems have been proposed and are now being proven in terms of applicability by the research group led by Professor Ryuichi Yokoyama of the Faculty of Science and Engineering at Waseda University (see diagram below). If such power networks that can work to serve one another were to be built, power supplies to various regions from power sources with renewable energy at relatively low costs, electric power interchanges between clusters through interconnection, the effective utilization of power shortage systems, and the rapid charging of electric vehicles could be made possible. Vital lifelines (electricity, water, and communication) could be secured even during large-scale natural disasters if such administrative agencies, hospitals, police stations, schools, evacuation centers, communication bases, and elderly housing facilities were completed centering on "Our Village Power Plants" operated by regional governments. This capability is known as "resiliency," and it will one day be the guideline for building the social infrastructure. I believe that these ideas must be utilized for the restoration of the afflicted towns in the Tohoku area, which is now underway.

Configuration and interconnection of the electricity cluster-oriented power supply network

Ryuichi Yokoyama
Professor, Faculty of Science and Engineering at Waseda University


Completed the Doctoral Course at the Graduate School of Science and Engineering, Waseda University in 1973. Doctor of Engineering. Taught at the Tokyo Metropolitan University after retiring from the Mitsubishi Research Institute in 1978. Appointed to current post as Professor on the Faculty of Science and Engineering at Waseda University in April 2007. Engages in the planning, operating, controlling, and simulation analyses of power systems, markets, and next-generation energy distribution systems along with applied research on large-scale systems of advanced mathematical programming techniques. IEEE Fellow, member of the IEEE Fellow Commission, Senior Member of the Institute of Electrical Engineers of Japan, member of the Institute of Electrical Installation Engineers of Japan, member of the CIGRE, commissioner of the Ministry of Economy, Trade and Industry's New and Renewable Energy Division, and chairman of the Agency for Natural Resources and Energy's Transformer Judgment Standards Subcommittee. Won the Achievement Award of the Institute of Electrical Engineers of Japan in 2009