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About Toshiba > Social and Environmental Activities > Environmental Management > Eco Processes > Mitigation of Climate Change:
Toshiba Group is working to introduce energy-efficient processes and equipment in order to reduce CO2 emissions originating from energy production per unit production by 45% by FY2010 and 47% by FY2012, to 53% of the FY1990 level. In FY2008, it reduced CO2 emissions originating from energy production by 12% compared to the previous year. As a result, it reduced CO2 emissions per unit production by 44%, achieving the target for the year.
It is expected that more energy will be used in the future as business expands, mainly in the area of semiconductors, but Toshiba Group aims to attain its goals by making further efforts to apply energy-saving measures.
The CO2 emission coefficient for fuel and heat is based on the Act on the Rational Use of Energy and the Act on Promotion of Measures to Cope with Global Warming (Figures provided by suppliers are used for the unit calorific value of city gas). That for electricity in Japan is based on data from the Federation of Electric Power Companies of Japan (power station side) (3.35 t-CO2/10,000 kWh in 2008). That for overseas electricity is based on data from reports of the Japan Electrical Manufacturers' Association.
Clean rooms at semiconductor factories consume a large amount of energy for air-conditioning throughout the year. The Oita Operations substantially improved the overall efficiency of air-conditioning mainly by increasing the efficiency of refrigeration equipment and supplementary machine systems and establishing energy-saving automatic control systems. Through these measures, the factory reduced annual CO2 emissions by 12,291 tons.
High-efficiency inverter refrigerator
Efforts to reduce energy for air conditioning have been made at clean rooms in semiconductor factories. In the Oita Operations, a reduction of 1,811t-CO2/ year has been attained through settings varying according to the equipment thermal load of the air circulation flow and control performed while monitoring particles in the wafer transfer area. To achieve this, the Oita Operations won the Director-General of the Agency for Natural Resources and Energy Award, in the “Successful Case of Energy Conservation in Factory & Building for Fiscal 2007”.
At Toshiba Dalian Television Corporation, which is Toshiba’s TV production base in China, CO2 emissions decreased by 88% owing to the air conditioning of the newly introduced production line, via an intake of cold open air into the intra-room air conditioning for the heat application line during wintertime.
Clean rooms at semiconductor manufacturing plants use a lot of steam for humidifying in order to maintain a consistent level of humidity. Toshiba sought to reduce the consumption of city gas used for generating steam by changing the outdoor unit's humidifying method to a pure water drip method that dispenses with the use of steam.
With this new system, great energy saving was achieved by efficient use of waste heat generated at the plant as the heat source for heating pure water. For this achievement Oita Operations received the Director-General of the Agency for Natural Resources and Energy Prize in Japan for Successful Case of Energy Conservation in Factory & Building.
| Improvement measure | energy saved (t-CO2) | Effect (million yen) |
|---|---|---|
| Reduction of steam consumption owing to the change of the humidifying method | 1,545 | 36.3 |
| Energy saving of pure water equipment (greater recovery of waste heat from the refrigerator) | 447 | 9.8 |
| Energy saving of pure water equipment (recovery of waste heat from the manufacturing equipment) | 326 | 6.7 |
| Total | 2,348 | 52.8 |
(l to r) Hiroyuki Goto, Koji Gohyakuji, Yujiro Sakai, and Shinji Goto Facilities Management Group, Facilities Management Department, Oita Operations, Toshiba Corporation
Clean Room
AFPD Pte., Ltd., a Singapore-based subsidiary manufacturing low-temperature polysilicon TFT LCD cells, introduced dryers with no purge loss in fiscal 2006. As a result, the company reduced the amount of energy used to produce high-pressure dry air used in the manufacturing process.
Previously, adsorption-type heatless dryers were used for production of high-pressure dry air. However, 16% of the high-pressure dry air produced was used for treating the adsorbent. Thanks to the introduction of dryers with no purge loss that use reduced pressure for treating the adsorbent, high-pressure dry air is no longer used for that purpose. Measures implemented to enhance the overall efficiency of the high-pressure dry air production system have led to a 19% reduction in energy consumption. This translates into a 1,460t-CO2 reduction in CO2 emissions a year.
Toshiba Matsushita Display Technology Co., Ltd.
“From now on we need to sharpen our focus on safety and maintenance so that we can look back in five or 10 years time and see that this investment was successful. The effectiveness of what we are doing here will be revealed as time passes.” (Masaki Yasuda)
“What we have achieved at the new production line is not attributable to a single organization. It is the fruit of collaboration among people from various organizations across the business.” (Kazuhiko Tomita)
Masaki Yasuda (left) Facilities Management Group Product Control Department Ishikawa Works Kazuhiko Tomita (right) Integration Engineering Group Process & Manufacturing Engineering Center
The need for air conditioning is minimized by enhancing the cleanliness of a limited area, not of the entire clean room.
In semiconductor manufacturing plants, the energy consumption of cooling facilities is exceeded only by that of semiconductor manufacturing equipment. To reduce the energy consumption of these cooling facilities, Toshiba has introduced inverter refrigeration equipment. First, cold load in the future was estimated based on the actual measurement in the area where refrigeration equipment has already been installed and is in operation. Taking into consideration the characteristics of inverter refrigeration equipment, operation has been optimized: conventional refrigeration equipment is always operated at 100% utilization rate and inverter refrigeration equipment is operated to accommodate the fluctuation of load. As a result, energy consumption has been reduced by 16%, which translates into reduction of CO2 emissions by 1,700 t-CO2 per year.
Inverter refrigeration equipment
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