Carbon dioxide emissions arise directly from the glass making process and indirectly from the generation of electricity used in the process. During glass making, emissions occur as a result of the decomposition of raw materials and fuel combustion.
Carbon dioxide emissions may be reported in two ways, reflecting variations in policy in different countries. The first includes carbon dioxide emitted both by the glass making process and by the generation of electricity used in the process. This method, used in this review, indicates carbon dioxide emissions of 4.2 million tonnes in 2005, an increase of 6.4 per cent over last year.
The second method excludes carbon dioxide emitted during electricity generation. Emissions measured in this way amounted to 3.1 million tonnes in 2005, an increase of 5.4 per cent.
These increases in carbon dioxide in 2005 were less than would have been expected from the nine per cent increase in production, as a result of more efficient overall use of combustion fuel. This was despite the increased use of heavy fuel oil, which is a greater source of carbon dioxide than natural gas. As a consequence, CO2 per tonne of glass produced fell by some six per cent in 2005.
For given output, emissions arising from the decomposition of raw materials can only be reduced by increasing the proportion of recycled glass used in place of raw materials. Frequently, recycling is limited by the availability of recyclable glass of acceptable quality.
The increase in oil firing also caused the increase in air pollutants, principally sulphur dioxide. Further progress was made in reducing overall levels of waste and increasing the level of recycling. In Tampere, Finland production of hazardous waste was reduced by 80 per cent and smaller plants also contributed, such as Örja, Sweden where the number of chemicals used has been reduced by 20 per cent.