Energy Conservation Measures for CO2 Reduction
Energy conservation and reducing CO2 emissions to address global warming
Since the fabrication processes of semiconductors and HDDs (hard disk drives) require high energy consumption, such as air-conditioning a clean room, we have implemented various measures such as designing an energy-efficient clean room and waste heat recovery system during the production processes in order to reduce environmental impact.
The Semiconductor & Storage Products Company Group set a target to reduce CO2 emissions per unit of output normalized by deflator (Note) by 47 % by FY 2012, with FY 1990 as the reference year, for our semiconductor products. We also set a target to reduce CO2 emissions by 3 % per unit of production by FY 2012, with FY 2009 as the reference year, for our hard disk drives and SSD products for enterprise (business servers). We have reduced by 73 % the CO2 emissions per unit of output normalized by deflator in FY 2010 for our semiconductor products, and we are developing activities to further reduce these emissions in the future.
- (Note) Emissions per unit of output normalized by deflator: an indicator calculated based on production output normalized by deflator and is considered to indicate CO2 emissions per unit closer to actual value.
- Amount of CO2 emissions per year (1 = 1000 tons)
- CO2 emission coefficient: For fuel and heat, it is based on the Law Concerning the Rational Use of Energy and the Law Concerning the Promotion of the Measures to Cope with Global Warming. (A value provided by the supply company is used as the unit heat quantity of city gases.) For domestic electric power, it is based on the data (receiving end) provided by the Federation of Electric Power Companies of Japan. For overseas electric power, it is based on the data reported from GHG protocol.
- (The above data covers all manufacturing sites in Japan and overseas and some parts of non-manufacturing sites)
Pioneering cross-platform project for energy saving
The Semiconductor & Storage Products Company Group launched the cross-platform energy saving project in FY 2004 to reduce greenhouse gas emissions. The project implements not only conventional energy saving in individual power systems or facilities but also expertise gathered across the organization and combined through the collaboration of production engineers, production equipment manufacturers, and other facilities and equipment manufacturers.
- Case example: Temperature control simulation of clean rooms to optimize the use of air conditioning energy
The air in the clean room is controlled by two systems, the outdoor air conditioning unit and the FCU (fan coil unit), to keep a constant temperature and humidity level in the room. The outdoor air conditioning unit removes dust in the air and controls the air temperature and humidity while the FCU controls the temperature inside the clean room to make it constant at all times. In the case of the conventional clean room system of the Yokkaichi Plant, the cold water coil (item 1 in the figure) in the outdoor air conditioning unit is used to cool and dehumidify the air introduced from the outside and then the temperature is adjusted using the reheat coil (item 2 of the figure) before sending the air into the clean room. The reason the reheating process is used is to control partial temperature irregularities (e.g., the prevention of overcooling) that may be caused by the layout of production equipment and the FCU and their operation methods.
In this improvement case example, a simulation was conducted to optimize the control and operation of the FCU based on the analysis of relevant data including interaction between the related systems, and the resulting temperature irregularities were successfully and significantly reduced.
As a result, the use of heating energy in the outdoor air conditioning unit was reduced and operation of the FCU was optimized to reduce energy consumption. CO2 emissions have been reduced by approximately 2,300 tons per year as a result of all the measures implemented.
Outdoor air conditioning unit