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Feature: Building solutions for glass

As you stand in the supermarket deliberating between a merlot and a shiraz, you may be forgiven for forgetting the recycling constraints should you opt for the wrong bottle. Put simply, if you buy the clear glass bottle then recycling should be an option (dependant on collection methods).

But if you leave the store with the green glass alternative, you will add to the UK glass recycling industry's much-discussed colour imbalance.

The problem is this: unlike our mainland European counterparts, much of the UK's glass production industry uses clear glass. In contrast, many of the bottles imported into the UK are green or brown and so are of no use to our indigenous industry when recycled.

This, combined with a boom in mixed glass collections, continues to provide the glass recycling sector with a logistical headache.

Of course there are historical and well-documented markets for mixed coloured glass, with much written about its use as a fine or course aggregate or as a partial cement substitute in concrete-based products. Despite this, the Waste and Resources Action Programme (WRAP) is forecasting that "a surplus of more than 550,000 tonnes of green and amber glass is anticipated by 2008".

Alternative markets need to be found.

In an ideal world, local authorities and householders would segregate their glass at source.

But is this realistic in a market where we accept that simplicity of recycling directly affects volume?

Mixed kerbside collections are financially attractive to local authorities and practically appealing to householders, suggesting that the problem needs to be solved from a different angle.

But the news isn't all bad.

WRAP has been researching a number of alternative uses for coloured glass, and one project offers not only an end market but also a slight panacea to the spiralling forward gas prices currently being endured by many UK manufacturers.

Using glass cullet as a fluxing agent within the brick manufacturing process is not a new concept.

As early as the 1930s, studies showed that glass could be added successfully into the clay body of bricks before firing.

The process, however, was not considered economically viable - a situation that was to remain the same when further studies were undertaken in the 1990s.

But changes in the economic climate may now make the addition of recycled glass a more viable option.

According to the recent WRAP study, the UK brick industry makes approximately 2.85 billion bricks (2004 figures) and consumes almost eight million tonnes of raw materials each year.

Planning constraints for new quarries and stricter environmental impact conditions of the working of clay pits and quarries mean that the value of the workable reserves in the ground are as high as ever, it reports.

"An alternative to using virgin raw material, even at a level of 5%, potentially reduces the year-on-year consumption of the clays by 350,000-400,000 tonnes," the report concludes.

And there are benefits in terms of energy consumption: "The UK brick industry has a yearly consumption of approximately 4.06 billion kWh equivalents of natural gas (around 138.7 million therms = around £52 million) based on fourth quarter 2004 energy prices. Any potential savings on the volume of the energy used to manufacture the bricks would therefore offer significant financial savings."

That's a factor that will be welcomed by any financial director keeping an eye on the escalating forward gas price.

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