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Minimizing Environmental Impact

Glass manufacture is an energy-intensive process, with raw materials melted at high temperatures. Principal emissions to air arise from the combustion of fuel and as CO2 from the decomposition of carbonates. 

environmental impact 

recycling 

 

 

Recycling

Glass for recycling is a valuable resource. Wherever quality allows, we recycle any glass off-cuts or cullet within our own glass melting lines. Glass from our downstream operations and from our customers represents a potentially useful resource to us.

We gain a double benefit from the use of such cullet. Its use to make glass reduces the requirement for raw materials and avoids disposing of what would otherwise be a waste material. 10 percent cullet use saves 3 percent furnace energy and leads to reductions in CO2 emissions.

Glass for recycling is a valuable resource. Wherever practicable, we recycle any glass off-cuts or cullet within our own glass melting lines. We also recover glass from our downstream operations and from those of our customers.

In 2011 we sent 506,000 tonnes of glass for recycling and bought in 200,000 tonnes. 27,300 tonnes of glass could not be successfully recycled so was sent for disposal.

Waste

The glass manufacturing process itself produces very little waste material. All trimmed glass is recycled back into the melting process and waste is limited to maintenance waste, occasional off-specification raw material that cannot be blended and packaging waste.

If glass is produced that cannot be remelted on-site, it is sent, where practicable, for external recycling. We use the waste hierarchy to guide our disposal options. In this system, landfill is the least favored option.

However, with significant tonnages of mineral materials arising for disposal, we have not eliminated landfill completely.

We disposed of 57,146 tonnes of non-glass waste (a 14 percent increase on 2010), of which 1,771 tonnes of hazardous and 30,483 tonnes of non-hazardous waste were sent to landfill. We disposed of 12,139 tonnes of hazardous waste in 2011.

Emissions to air

These arise primarily from the combustion of fuel in melting the raw materials. The principal materials emitted are oxides of sulphur and nitrogen. Some particulates arise partly from trace components in the fuel and some from the glass formation itself.

Oxides of sulphur and nitrogen

The fuels we use — oils and natural gas — all contain sulphur compounds as contaminants. Natural gas, our preferred fuel, contains less sulphur than oil. Heavy fuel oil contains the highest levels of sulphur of all our fuels, especially that readily available in Japan. Our furnaces in Japan are therefore fitted with efficient
emission gas-cleaning equipment. The combustion of such fuels can produce a mixture of sulphur oxides (SOX).

Most sulphate arising from soda lime glass manufacture is released as sodium sulphate, which is of low toxicity. Nitrogen compounds released arise from the combustion air in which the fuel is burnt. At the high temperatures used in glass-making, the nitrogen in combustion air is oxidized to a mixture of nitrogen
oxides (NOX). Actions we take to reduce or prevent the emission of these oxides of nitrogen are detailed on our website.

principal emissions

Reducing carbon emissions

In 2011, the NSG Group was responsible for the direct and indirect emission of 5.0 million tonnes of CO2
. This represents a 3 percent increase on 2010, but is mainly due to increases in production levels.

Our direct emissions were 3.9 million tonnes (a 4 percent increase on 2010). Direct emissions occur from our furnaces and from fuel used in bending and toughening furnaces in Automotive and Architectural Glass. In Europe, externally verified, direct 2011 CO2 emissions from the Emission Trading Scheme were increased by 4 percent compared to 2010 but reduced by 13 percent compared to 2007.

In the operation of our float plants, heavy oil to natural gas conversion has helped to reduce carbon emissions by around 50 percent over the past 40 years, and a combination of design and operational innovations has made further progress.

glass melting carbon emissions

Waste Heat Recoverywaste heat boiler

The recovery of waste heat is a key aspect which can improve the overall efficiency of the float process.
The majority of the heat is recovered through the regenerative process, while a high proportion of the
remaining heat can be recovered to generate hot water and/or steam.

Most recently, at Weiherhammer in Germany, a waste heat boiler has been installed to replace the existing package boiler system to generate hot water. The system has resulted in reduced CO2 emissions of 2,800 tonnes.

 

The Float Glass Process

One of the 49 float lines owned or operated by the

A float plant, which operates non-stop for between 10-15 years, makes around 6,000 kilometers of glass a year, in thicknesses of 0.4mm to 25mm and in widths up to 4 meters.

In the operation of our float plants, heavy oil to natural gas conversion has helped to reduce carbon emissions by around 50 percent over the past 40 years, and a combination of design and operational innovations has made further progress.