Emeritus Professor John Parker, a world renowned academic specialist in the world of glass, gave us a look into the sustainability of glass both as a product and in the course of its manufacture.
Prof Parker is the curator of the Turner Museum of Glass at the University of Sheffield. Professor William E S Turner was arguably the most knowledgeable person of his era on the history of glass. His collection of glass objects, acquired throughout a lifetime of travels and research during the first half of the 20th century, makes up the basis of the museum’s exhibits.
Sustainability is a complex problem as there are several strands which have to be met to ensure that it is right for the world in terms of not only cost, but also health and wellbeing and keeping glass the industry solvent and commercially viable in the face of competition. particularly from the ever growing use of plastics.
The history of glass making goes back over 3,000 years. The main constituent of glass is sand, which is heated with – amongst other things limestone and soda ash. In the earliest times wood was the main fuel used to fire the process; however this was inefficient, with it taking ten tons of wood to produce one ton of glass.
In this country during the reign of Henry VIII this proved to be unsupportable as the king was intent on expanding the navy and ship building was a greater priority. From the 1550s coal became the fuel of choice until the 1950s when furnaces moved over to the use of gas, a cleaner fuel especially with the introduction of North Sea gas in the 1970s.
More recent innovation is the use of electricity, which with the introduction of additives can be as efficient as 85-90 per cent. One of the earliest known uses of glass in this country dates back to around 1350 when monks would use glass magnifiers to complete the writing and illustration of the scriptures. More modern uses apart from the obvious include the use of various types of glass in toothpaste, dental fillings, bone fracture repairs, the treatment of diabetic sores and in EPI pens.
Glass production spread across the UK and is still manufactured in several different locations but particularly in the north west in St Helens, where Pilkingtons have a large plant, and where the government have set up a research centre after South Yorkshire for some incomprehensible reason turned down the opportunity despite Sheffield university and the Glass Association having long established research facilities in place.
Glass is used not only in windows and bottles, of which some twelve million are manufactured in the UK, but also in wind turbine blades, the storage of nuclear waste which can be encased, shielding radiation for many years, and the use for, pipework, in the growth of algae and plants to be used for bio-fuel and food.
One of the main challenges for the industry is the provision of green electricity, either from solar farms – which themselves utilise glass in their manufacture – wind, nuclear plants and possibly, in the future, tidal generated power. One example given was the construction in China of a vast array of concave mirrors set out in a remote dessert which concentrates sunlight and projects it to a centrally located tower which then can generate heat up to some 5,000 degrees C to produce power. This facility can also be set up where there is a good supply of sand referred to as “silver sand” given its suitability in the glass making process.
Improvements are also being made to the furnaces used, and the methods of heating and attempting to minimise heat loss during manufacture. However restrictions in the supply of electricity, especially green electricity via the national grid could slow up further progress given the competing demands for power, not only across industry but also the domestic supply as we move away from fossil fuels.
Regarding the sustainability of glass itself, the product is 100 per cent recyclable and can be remelted and re-used without any loss of product ad infinitum. Recycling from domestic users via the “green bin” system is beneficial but currently inefficient, with glass still going to landfill at great cost, the government charging local authorities £125 per tlonne of waste going to landfill when all glass should be recycled.
This was an informative talk from a highly qualified international expert, enjoyed by all in attendance. For further reading, Prof Parker recommended a book that has been put together by the International Journal of Applied Glass Science and is available for free download on the internet. Search for: Welcome to the Glass Age via the following website: www.iyog2022.org.