The energy intensive glass industry accounts for approximately 1% of total industry energy consumption.*1Taking this fact seriously, the AGC Group is proactively implementing measures to save energy in its manufacturing process, in addition to contributing to prevent climate change through its glass technology.As a result of improving the process, CO2 emissions from Asahi Glass (unconsolidated) decreased by 36% in fiscal 2008 from the fiscal 1990 level.We cannot, however, deny the fact that there is a limit to such improvements. Accordingly, we will review the glass manufacturing method itself and strive to reform it drastically to reduce our use of energy in a substantial manner.

*1 Actual result in Japan

Glass manufacturing process (float method)

Glass manufacturing gives the biggest impact on the environment mainly due to the process of melting materials, such as silica sand and soda ash, by fuel oil to produce chemical reactions, as well as the process of keeping the melted materials in the melting tank for long hours to manufacture homogenous glass without air bubbles. During these processes, the large melting tank of over several ten meters in length, has to be kept at a high temperature for many hours.

Reducing CO2 Emissions by Improving the Manufacturing Process

Fuel conversion

Some of our facilities have replaced heavy oil used for glass melting with natural gas. Through the use of natural gas, we can reduce CO2 emissions from combustion by 20% compared with the use of heavy oil. Moreover, we can reduce the emissions of sulfur oxide (SOx) from glass melting to nearly zero, which will in turn reduce the total emissions of SOx.

All-electric melting

In the all-electric melting method, electric current is directly applied to glass materials to melt them. This method is suitable for relatively small furnaces. Materials are heated directly instead of indirectly by the heat radiated from the combustion flame, and this improves the energy efficiency. At present, we are operating all-electric furnaces in Japan, Thailand, and other regions.

Total oxygen combustion

The total oxygen combustion method uses only oxygen for fuel combustion in glass manufacturing. This method is more energyefficient because it does not heat nitrogen, which accounts for approximately 80% of air and is not necessary for combustion.Also, this method is effective in reducing NOx because the combustion gas contains almost no nitrogen, thus helping to curb NOx generation itself. Asahi Glass introduced this method to the Keihin Plant in 2001, a first in flat glass production in Japan. This has resulted in reducing energy consumption and CO2 emissions per unit production of glass by about 30% each.