What are dealing with?

Nowadays glass is much less expensive and is taken for granted as a packaging material in addition to its use in windows and other applications. New glass is made from a mixture of four main ingredients: sand, soda ash, limestone and other additives. These additives include iron for colour (brown or green), chromium and cobalt for colour (green and blue respectively, lead to alter the refractive index, alumina for durability and boron to improve the thermal options.

Annually, total glass use in the UK is estimated at around 3.6 million tonnes.

Why should we recycle Glass?

Using present technology the UK glass industry has the capacity to recycle over one million tonnes of glass each year and this coupled with the materials unique ability to be infinitely recycled without compromising its quality creates a compelling case for the recycling of glass. Despite this, glass makes up around 7% of the average household dustbin and in 2001 over 2.5 million tonnes of this material was landfilled.

The manufacture of glass uses energy in the extraction and transportation of the raw materials, and during processing as materials have to be heated together to a very high temperature. Large amounts of fuel are used and the combustion of these fossil fuels produces carbon dioxide - a greenhouse gas. In 2002 the glass industry consumed a total of 8611,000,000 kWh of energy including electricity and carbon dioxide emissions totalled 1.8 million tonnes from the fossil fuels burnt in the factories. An efficient furnace will require 4 GJ of energy for each tonne of glass melted.

Glass can be recycled indefinitely as part of a simple but hugely beneficial process, as its structure does not deteriorate when reprocessed. In the case of bottles and jars, up to 80% of the total mixture can be made from reclaimed scrap glass, called "cullet". Cullet from a factory has a known composition and is recognised as domestic cullet. From bottle banks it is known as foreign and its actual properties will not be known.

If recycled glass is used to make new bottles and jars, the energy needed in the furnace is greatly reduced. After accounting for the transport and processing needed, 315kg of CO₂ is saved per tonne of glass melted.

Recycling reduces the demand for raw materials.  There is no shortage of the materials used, but they do have to be quarried from our landscape, so from this point of view, there are environmental advantages to recovering and recycling glass. For every tonne of recycled glass used, 1.2 tonnes of raw materials are preserved.

Recycling reduces the amount of waste glass which needs to be landfilled.  Although glass is inert and is not directly hazardous to the environment, it will remain there indefinitely.

Recycling two bottles saves enough energy to boil water for five cups of tea

How is Glass recycled?

Bottle banks are emptied by glass collection companies, or by the reprocessors, and the local authority or other party operating the bank is then paid by the tonne for the 'cullet'. When glass cullet reaches the plant it is monitored for purity, contaminants are removed and it is crushed and added to the raw material mix in the melting furnace.  It is then moulded or mechanically blown into new bottles or jars. For more information contact the organisations and websites at the end of this data sheet.

Colour imbalance The main barrier to recycling glass is the shortage of clear cullet collected in the UK. The UK predominantly produces clear and amber glass but because the UK exports a lot of clear glass, in the form of spirit bottles, and because consumers are also reluctant to deposit jars in bottle banks, little clear cullet is produced. The UK imports twice as much green glass as is manufactured, mainly in the form of wine bottles. In the past this has lead to a surplus of green cullet. The industry has worked hard to increase the amount of green glass recycled and currently all the green bottles we make in the UK contain at least 85 per cent recycled green glass.

Glass cullet can also be used for aggregate in the construction industry, and the new road laying material glasphalt. Glasphalt comprises around 30% recycled glass and it has been estimated around 14 million crushed bottles were used in this way during construction in the M6 motorway project. These materials can use mixed coloured and contaminated glass, and may be a good market for green glass.  

How you can help

Deposit glass at your nearest recycling bank by throwing them into the appropriate container.

If a bottle is returnable it is usually preferable to return it, rather than to recycle it.

Most home recycle bins, provided by your local council, usually accept glass.

Make sure you wash out the bottle or jar before putting it into recycling bins.

Reuse glass whenever possible. Jars can be used as small containers and bottles can be used as vases.

Wherever possible, remove metal or plastic tops, corks and rings from bottles or jars. Any tops which remain will be removed by magnets, vibratory screens or other methods, but they can cause damage to furnaces if any get through.

Never deposit light bulbs or cookware such as 'Pyrex' or 'Visionware'. These have different properties to the glass used to make bottles and can contaminate a load, resulting in a sub-standard finished product. Flat glass, such as window glass, whole or broken, should not be put in bottle banks either - see below.