 Main Members of the Team that Conducted the Testing
"Nature's Wisdom" was the main theme of Expo 2005 Aichi, Japan, which was held over the course of six months. While many of the exhibits dealt with how humankind and nature can coexist, one of the highlights of this "environmental expo" was a research project to verify the Distributed Energy-supply System Using New Energy, which created electric power from new-energy sources, exhibited by the Japanese government at the Nagakute Japan Pavilion. It was the world's first large-scale experiment to control multiple sources of new energy in combination, and NTT Facilities had the vital role of energy control.
Officially, the verification testing of the distributed energy-supply system was called as the demonstrative project of distributed energy supply system using new energy sources, and was conducted under contract from the New Energy and Industrial Technology Development Organization (NEDO). Run by Chubu Electric Power Company, nine companies and organizations participated in the project, including NTT Facilities. Incidentally, after Expo 2005 Aichi ended, the project is planned to be moved to Central Japan Airport City (Tokoname City), where verification testing will continue, researching it as a community energy system of the future using new energy.
Three people from the NTT Group participated in the verification testing: Jiro Sumita, senior research engineer at the R&D Headquarters, NTT Facilities; Yoshitsugu Yoshimoto, head of the General Engineering department, Energy Business Headquarters, NTT Facilities; and Akira Takeuchi, senior researcher at NTT Energy and Environmental Systems Laboratories. Sumita was in charge of research, and control system design and evaluation; Yoshimoto was in charge of project management; and Takeuchi was in charge of research, design, and assessment of the power-generation planning logic.
 Yoshitsugu Yoshimoto
Energy Business Headquarters
Yoshitsugu Yoshimoto speaks about the aims of the verification testing:
"We are introducing a number of new forms of energy, including solar and wind power, in order to reduce CO2; but the amount of power that can be obtained via natural energy differs depending on the weather conditions, and these fluctuations could impact the power grids of affiliated power companies. This verification-testing project has built and verified an energy control system that uses a combination of fuel cells and power-storage batteries to compensate for these fluctuations in natural energy and minimize the load on the commercial grid."
According to Sumita, the verification-testing power plant combines three power-supply systems, based on the concept of "microgrids* ": fuel-cell generators, solar-power generators, and a power-storage system.
(1) There are three types of fuel-cell generators. The first is a Molten Carbonate Fuel Cell (MCFC), which is fueled by gas obtained from a methane-fermentation system using food waste from restaurants and the like at the Expo venue, and by high-temperature gasified gas, obtained from scrap wood from the construction of the venues, and empty PET plastic bottles and other plastics from the venue site. The second is a solid-oxide fuel cell (SOFC), with a high operating temperature and the highest electricity-generation efficiency. The third is a phosphoric-acid fuel cell (PAFC), which has excellent load-following performance.
(2) Three types of solar-power generators are used: polycrystalline, monocrystalline, and amorphous.
(3) Electric power is stored in natrium-sulfur (NaS) batteries to regulate power fluctuations, serving to balance power-generation facilities with power demand within the microgrid.
The total power generation is 1,670 kW; of this, 1,340 kW are from fuel cell generators, and 330 kW are from solar power generators. The NaS batteries have input/output capacity of 500 kW. This supplied all power needs of the Nagakute Japan Pavilion, and also supplied power to the NEDO Pavilion. As the total demand for electric power at the Expo venues was 24,700 kW, the microgrid supplied about 10% of this demand.
Taming the Wild Horse of Fluctuations in Power Generation
"The power generated from solar and other natural forms of energy," says Sumita, "fluctuates from one moment to the next. The most important thing is not to regulate power output by controlling each of these individually, but to control energy coordinating each of these power systems, maintaining control of fluctuations in the microgrid as a whole."
On top of this, the control method must be designed to forecast power usage, and minimize the overall generation of CO2. Fuel-cell power generation is tracked by the minute, and the power-storage system by the second. Scheduling is used for overall management.
"Controlling fluctuations in power-generation levels is like trying to calm a wild horse," laughs Takeuchi.
"Unlike fuel cells, for which power-generation levels can be predicted to some extent, solar-power generation varies depending on the weather. So we would predict solar-power generation levels from the next day's weather forecast, and assign demand to each power-generation system, including power released from the power-storage batteries. We have got to think of the optimum scheduling method for minimizing final CO2 emissions. This was the world's first verification experiment of a control method incorporating forecasts of solar-power generation levels."
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- Microgrids ... A system that makes power-supply systems more economical and improves the reliability of the power supply, more effectively meeting the needs of power consumers by controlling and operating combinations of multiple distributed power generators and the like, in order to supply power within a fixed area
 Jiro Sumita
R&D Headquarters
NTT Facilities' participation in the experiment to verify the Energy Control System at Expo 2005 Aichi, Japan, was "... [Truly] due to our commitments to creating new forms of energy in our main role of managing the NTT Group facility power and buildings," says Yoshitsugu Yoshimoto, head of project management.
NTT Facilities has long been committed to building fuel-cell, solar-power, and wind power generation systems. It has deep knowledge of the challenges of distributed power, and its control. Then in July 2000, the company founded Ennet Co., Ltd., which retails electric power to Tokyo Gas Co., Ltd., Osaka Gas Co., Ltd., and others. "We not only run distributed-power generation," says Jiro Sumita. "We also have unique expertise in such methods as how to balance power gaps between power-generation systems."
"We applied optimum scheduling technologies being researched to minimize the cost of fuel-cell power generation," says Akira Takeuchi, who headed control logic for the project, "to microgrids and the concept of minimizing CO2."
It was decided that the verification testing would be conducted at Expo 2005 Aichi in 2003. In fact, the Expo Committee had been making overtures about the possibility of making an exhibit related to new energy as much as a year prior to that. The initial exhibit plan called for monitoring of CO2 over the entire central Aichi region, and virtually controlling electric power in response to this. Under contract from NEDO, however, an actual power plant was built, and verification testing carried out.
Continuous Operation Experiment
 Akira Takeuchi
NTT Energy and Environment Systems Laboratories
After the launching of the Expo, the verification experiment tracked issues with the project. The nine companies and organizations participating in the project convened a general conference about once every two months, and a committee consisting of expert researchers met about twice every month.
"Just the fact that we were running fuel-cell generators on this scale," says Sumita, who headed overall research, "including solar-power generators, was an experiment in and of itself. Each of the generators was distributed, and we had to see whether they were operating as expected. And actually, although the generators started running right away, at first they were putting out maintenance-request signals and such, and we had to scramble to adjust the control parameters. I got a renewed sense that just getting the system operating continuously was an experiment."
Representatives from NTT Facilities and the other participants maintained personnel on site 24 hours a day, monitoring the system. "Each of the companies participating in the research project," says Yoshimoto, "had expertise on controlling multiple distributed generators. The goal of the research was to develop a distributed energy-supply system using new energy sources, and I believe were able to produce results as a consortium, gathering together our expertise by having representatives of each company share issues at the 24-hour monitoring station."
By participating in the research project, NTT Facilities obtained a number of concrete results, including expertise on how to keep a large new-energy power plant operating stably, identification of reasons for discrepancies between predictions and results, measures to enhance power quality in a microgrid, and autonomous operational verification.
"The plant we were verifying," says Sumita, "is for a future system, so it won't lead to a commercial application in the near future. But we have long been committed to clean energy, fuel cells, and other aspects, and we got invaluable real-world data from a future energy system, which adds greatly to our store of technology in this area. I think that linking the environment with IT matches our corporate philosophy."
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