Environmental Impact of Glass Production
From Wikipedia, the free encyclopedia:
As with all highly concentrated industries, glassworks suffer from moderately high local environmental impacts. Compounding this is that because they are mature market businesses they often have been located on the same site for a long time and this has resulted in residential encroachment. The main impacts on residential housing and cities are noise, fresh water use, water pollution, NOx and SOx air pollution, and dust.
Noise is created by the forming machines. Operated by compressed air, they can produce noise levels of up to 106dBA. How this noise is carried into the local neighborhood depends heavily on the layout of the factory. Another factor in noise production is truck movements. A typical factory will process 600T of material a day. This means that some 600T of raw material has to come onto the site and the same off the site again as finished product.
Water is used to cool the furnace, compressor and unused molten glass. Water use in factories varies widely, it can be as little as one tonne water used per melted tonne of glass. Of the one tonne roughly half is evaporated to provide cooling, the rest forms a wastewater stream.
Most factories use water containing an emulsified oil to cool and lubricate the gob cutting shear blades. This oil laden water mixes with the water outflow stream thus polluting it. Factories usually have some kind of water processing equipment that removes this emulsified oil to various degrees of effectiveness.
The oxides of nitrogen are a natural product of the burning of gas in air and are produced in large quantities by gas fired furnaces. Some factories in cities with particular air pollution problems will mitigate this by using liquid oxygen, however the logic of this given the cost in carbon of (1) not using regenerators and (2) having to liquefy and transport oxygen is highly questionable. The oxides of sulfur are produced as a result of the glass melting process. Manipulating the batch formula can effect some limited mitigation of this; alternatively exhaust plume scrubbing can be used.
The raw materials for glass making are all dusty material and are delivered either as a powder or as a fine-grained material. Systems for controlling dusty materials tend to be difficult to maintain, and given the large amounts of material moved each day, only a small amount has to escape for there to be a dust problem. Cullet is also moved about in a glass factory and tends to produce fine glass particles when shovelled or broken.
From AGC Glass Europe:
The major environmental impact of glass production is caused by atmospheric emissions from melting activities:
· The combustion of natural gas/fuel oil and the decomposition of raw materials during the melting lead to the emission of CO2. This is the only greenhouse gas emitted during the production of glass.
· Sulphur dioxide (SO2) from the fuel and/or from decomposition of sulphate in the batch materials can contribute to acidification and formation of SMOG.
· Nitrogen oxides (NOx) due to the high melting temperatures and in some cases due to decomposition of nitrogen compounds in the batch materials also contribute to acidification.
· Evaporation from the molten glass and raw materials can cause release of particles in the atmosphere.
Other environmental issues are water pollution, the use of non renewable natural raw materials such as sand and minerals, production of solid waste and emission of volatile organic compounds (used in production of mirrors and coatings).
Although a lot has already been achieved, further reductions in emissions of SO2, dust particles, NOx and CO2are still the main environmental objectives for our flat glass activities. Minimising and controlling these emissions in an integrated way is a complex matter. The development of environmental techniques is still ongoing, and AGC Glass Europe actively participates in the dynamic process of developing new techniques. Most of these technologies, however, have disadvantages as well as advantages. For example:
· Switching from heavy fuel to natural gas reduces CO2 and SO2, but increases NOx.
· Some technologies that reduce NOx can cause an increase in CO2 when extra energy input is needed.
· Technologies that reduce SO2 can produce non-recyclable waste.
· Some technologies for reducing SO2 are not compatible with end-of-pipe de-NOx technologies.
· Some technologies can affect the lifetime of the furnace or the quality of the glass.
From Environmental Impact:
The common glass (soda-lime glass) is surprisingly friendly when it comes to the environment. It uses common, easy to extract materials, the production process does not generate much waste, and the recycling ratios of glass are one of the highest of all materials (about 50% in US, 60% in UK, up to 95% in Switzerland).
Glass is composed of about 70% silica (silicon oxide, or, basically, sand), 15% soda (sodium carbonate), 15% lime (calcium oxide, usually made on site from limestone), and minor amounts of other additives. Thus the name of the common glass: soda-lime glass. Glass is used in huge variety of product, but vast majority is made into windows or into containers. For many uses glass needs to be made with different additives. For example, replacing the lime with lead oxide produces "crystal" glass, replacing soda and lime with boron oxide produces borosilicate glasses such as Pyrex, etc. However, we do not consider these specialty glasses in this article. The production of glass is composed of three major parts:
· preparation of raw materials (here, for example, a lot of water is used -- to wash the recycled bottles...);
· melting (here the most energy is used - usually in form of burning of natural gas);
· forming and annealing (where the products assume their final shapes).
The information about the production process of the glass is taken from the British Glass website, and in particular, from excellent publication "UK Manufacture - a mass balance study 2008". We realize that the data contained there is specific to the UK, however, glass production is mature and standardized enough to extend this data to cover the world average.
Impact of one pound of "Glass, soda-lime":
Overall impact (CEII): 110.56
Depletion (DI): 274.92 Pollution (PI): 109.18 Entropy (EI)): 0.02
Ecotip: Glass - What's the Environmental Impact?
…The environmental impact of glass is, however, more translucent than completely clear. A recipe of sand, soda ash, limestone, with a dash of dolomite and feldspar is concocted and then baked - in something a tad more fierce than your Mum's kitchen oven - a blast furnace at temps over 1500oC (~2730oF). Marshmallows beware! A couple more such furnaces and ovens round out the process, before the glass is cooled. All this heat requires phenomenal energy consumption and resulting greenhouse gas emissions. Some calculate this could be as much as 2 tonnes of CO2, per 1 tonne of glass, when transport of such a heavy product is factored in. All this gives glass an Embodied Energy of about 12.7 MJ/kg. (By comparison aluminium is 170 (!!), cement 5.6 and kiln dried sawn softwood 3.4). Sand mining is not the most benign of raw material extraction methods either. So where's the good news?
Well, quite a bit, as it turn out. Glass is the prime ingredient in 'passive solar' designed buildings, that harness the heat of the sun to warm structures, without need of machine-based heating and air conditioning. Not to mention that wonderful hard-to-quantify joy of simply seeing the outside world, regardless of the weather. Given that modern persons spend 90% of their lives indoors, the sanity provided by glass is worth more than any phalanx of therapists.
Finished glass is inert and non-toxic. It is easy to clean and maintain, having a dense surface, which inhibits contamination. Glass is vastly recyclable and scrap glass, known as cullet, is a key production ingredient added to the raw materials noted above. Some standard glass production uses over 45% recycled post consumer content. Specialised production can ramp this up to 100%...
From Uroboros Glass, a manufacturer of art glass:
WE BELIEVE IN GREEN!
We at Uroboros strive to minimize the environmental impact of our glass production activities. In fact, we were qualified as a 'Green Company' by the City of Portland Bureau of Planning and Sustainability for 2011, and earned Portland's Sustainability at Work Silver Certification for 2012. Below are some highlights of what we've accomplished.
Decreased energy consumption by some 20% with waste heat recovery measures and improved insulation design on our glass furnaces, and through ongoing conversion to more energy efficient motors, plant lighting, copiers and etc.
By careful segregating and sorting of all our glass waste materials we have enabled 100% recycling of these by-products into useful products made by ourselves or others.
Decreased garbage volume by one-third, while increasing recyclables volume by two-fold.
Decreased process water consumption by utilizing water recycling and cooling equipment.
Developed a process for internal glassification of all hazardous waste materials resulting in zero hazmat disposal needs.
Converted scores of packaging materials and consumable items into recyclable or biodegradable materials. Examples are starch based 'Taterware' packing peanuts, lunchroom cups and utensils, paper packing sheets, unbleached cardboard packing boxes, and recycled office paper.
From Spectrum Glass:
Spectrum Green Statement
Spectrum® Glass Company is a manufacturer of specialty sheet glass for use in architecture, fine arts, hobby-craft, lighting and other applications. We produce over 450 glass products, including Waterglass®, Baroque™, Artíque®, Iridescent Glass, multi-color mixes and textured colors. As the world’s leading manufacturer of these specialty sheet glasses, we are committed to operate our facilities in ways that:
· Prevent harm to public health and the environment
· Conserve energy, water and raw materials
· Integrate pollution prevention
· Comply with environmental regulations at the national, state, and local levels
Key elements of Spectrum’s environmental assurance process include:
· Air Programs - Spectrum routinely evaluates equipment and process modifications that reduce emissions, conserve energy and provide environmental benefit.
· Waste Programs – Spectrum focuses on the use of raw materials and product yields to minimize the generation of waste.
· Water Programs – Spectrum carefully reviews and manages how water is treated, used and discharged from our operations. Cooling water used in glass production is re-circulated in a closed system, thus saving approx. 2,000 to 5,000 gallons of water per hour. Spectrum’s monitored water program has improved Storm water quality for 2007.
· Glass Recycling Programs – Spectrum recycles all waste or trimmed glass. The majority of waste glass is recycled in our manufacturing operation, with lesser amounts recycled to glass blowers, glass tile manufacturers, glass marble manufacturers, and pipe contractors. Recycled glass results in energy savings of approx. 15% and lowers emissions by approx. 25%. Glass recycled, as a % of total materials used, is up for 2006-2007, compared to 2004-2005 and prior years.
· Other Recycling Programs – Spectrum recycles wooden glass cases, wooden pallets, all iron and steel waste, and all paper and cardboard products.
Recent highlights from Spectrum’s environmental efforts:
· Spectrum is an advocate of oxygen-fuel furnace technology and one of the first manufacturers of specialty sheet glasses to install this technology. This technology is in operation on three of our furnaces, reducing fuel consumption by 38 percent, reducing carbon dioxide emissions by 10 percent, and reducing emissions of nitrogen oxides by 50 percent.
· Spectrum has made large investments to improve energy use, including heat recovery from our furnaces, improved means to recycle more of our glass waste in manufacturing, added insulation for our furnace crowns, purchase of Variable Frequency Drive motor controls to reduce electrical use, and low energy facility lighting