Glass – Environmental Friend or Foe

Originally Published August 9, 2012    Serving a large purpose with little consideration, glass is a key ingredient in many of our everyday products. Tableware, light bulbs, mirrors, stovetops, windshields, windows: the list is large for something not given a second thought. Friend or foe, we need to consider the implications of glass making on the environment. 

The ‘What Is’ of Glass

Glass is a combination of three types of substances that occur naturally in North America;

• silica, the most popular being white sand
• alkali, such as sodium bicarbonate
• limestone

Sometimes a metallic oxide (lead) is added to the mix. Depending on which alkali is used and whether or not lead is added, the clarity or color cast of the glass changes. The expense of producing and the quality of the glass is determined by the choice of alkali and the percentage used, combined with the choice and percentage of silica used.

The ‘How’ of Glass Production

A silica, an alkali and limestone are first crushed into a powder form, sifting out any coarse particles. They are then blended and put into a furnace at an extremely high temperature for as long as 24 hours. This yields molten glass which is then cooled several hundred degrees resulting in a thick liquid. The resulting matter is called frit which is then blown, pressed, drawn, molded or rolled into glass objects. If the glass is to be molded the molds are also heated at high temperature so the liquid poured into them does not wrinkle. The cooling process involves washing with water.

Environmental Impact of Glass Production

The process of making new glass is not at all environmentally friendly. The initial crushing and grinding step sends particulates of metals, chemicals, acids and dust into the air. These can be easily inhaled causing irritation to the nose and throat, potentially causing damage to the lungs. The particles of metals are hazardous to the environment as they can find their way into surrounding soil and water. The need for extremely high temperature furnaces to melt the mixture of substances makes the melting stage of the glass making process very energy intensive. It is estimated to take 15.2 million BTUs of energy to produce one ton of glass. During any one of the formation processes the glass may need to be reheated to keep it in liquid form. This means the heat in the furnace must be kept up until the process is complete. Discharges from the glass making process may find their way into the aquatic environment during the cooling and cleaning processes where the most significant amounts of water are used. Discharges may contain some pieces of glass, some solubles used in the production like sodium sulfate, lubricant oil used in the cutting process, dissolved salts and water treatment chemicals. Glass manufacturing processes also emit a significant amount of greenhouse gases especially carbon dioxide. Additionally, the processes spit out air-polluting compounds like nitrogen oxide, sulfur dioxide and particulates.

Benefits of Glass

Glass is nonporous making it impermeable to other substances. For this reason glass is a very hygienic surface as any bacteria and germs that come in contact are not absorbed into its structure. Glass surfaces take to strong cleaning with a disinfectant and hot water with no effect on its quality. For this reason glass containers can be easily reused many times over. The impermeability of its structure eliminates any interaction with the stored contents. This, along with glass being made from nontoxic raw materials, dismisses concern of leaching chemicals into the contained substances. In the case of food storage, this also insures the freshness and uncompromised taste of the stored substance. Glass containers also do not absorb the smells of the foods in or around them. Unlike other materials, glass used in the microwave does not leach any toxins into contained foods or liquids. Nor does it stain, corrode or deteriorate no matter how many times it is reused. Glass dishes and containers are very versatile as they can go from freezer to microwave or oven. Glass is very attractive looking beautiful on table top or as decorative pieces like candy dishes, storage jars, vases and mirrors. And glass is 100% recyclable.

Turning Foe into Friend

Many manufacturers have put into place practices to reduce the negative environmental impact of glass making. Consideration has been given to use of more efficient furnaces to cut energy use, producing thinner glass to employ lower temperatures and reduce transport costs, use of air and water purification systems and use of recycled glass to make new. Here are some ways to reduce the environmental effects and still enjoy the benefits of glass products:>

1. Reuse glass food and storage containers. Because of its natural properties there is no chemical reaction with the contents and the glass container and glass is nontoxic. Glass items at home can be safely used over and over with no loss in the quality of the glass. Once washed out, it is safe to reuse glass bottles and containers many times over.
2. Recycle your glass containers. Glass is 100% recyclable and can be reused to make new glass. Unlike other types of materials, the reuse of glass in no way degrades the integrity of the material. Glass can be melted and reused over and over again. A glass bottle ending life in a landfill can take one million years to breakdown. But a recycled glass bottle has about a 30 day turnaround time from recycle bin to being a new bottle on a store shelf. Every ton of glass that is recycled saves more than a ton of the raw materials needed to create new glass. Because cullet (glass pieces for reuse) melts at a much lower temperature, making glass products from cullet consumes 40 percent less energy than making new glass from raw materials.
3. Reduce the amount of new glass products you purchase. Because it has found its way into so many commercial uses it is now easy to find products made from recycled glass. Look for tableware from cullet, recycled glass jewelry, decorative tiles, counters and landscaping materials that utilize recycled glass.

Glass is a versatile and beautiful material to use in many facets of our lives. Let’s do our part to turn glass production from foe to friend.