BLOG: Glass Recycling

Glass Recycling – The Rocky Mountain Bottle Company Wants Your Glass

By Julie Smith, Golden, CO

Located just a couple miles north of Golden, in Wheat Ridge, the Rocky Mountain Bottle Company (RMBC) recycles massive amounts of glass. To learn more about the glass recycling process and how it fits into traditional manufacturing processes, I visited the RMBC, and met with two Batch and Furnace Manufacturing Specialists, Ryan Schneider and Keith Cembalisty. They generously shared their extensive knowledge of glass manufacturing and recycling, with a passion that is nothing less than contagious. 

Glass is made by melting raw materials, mainly sand, soda ash and limestone, in huge furnaces that are heated with natural gas. The blend of raw materials used to make the glass melts at around 2800 ºF, while cullet, or ground-up recycled glass, melts at a much lower temperature, around 1500 ºF, so the addition of cullet to the blend helps to reduce the melting temperature, saving natural gas.

Currently the RMBC includes about 27% cullet in the blend with raw materials. It turns out that glass is infinitely recyclable, and a lot of energy and raw materials are saved in glass-making when recycled glass is used instead of raw materials. The RMBC would be happy to use up to 70% cullet in their blend, if they could get it. Currently, only about 40% of the recycled glass is from local sources, and the rest is imported from other states, such as Oregon, Michigan and Wisconsin. Sadly, Colorado has one of the lowest glass recycling rates in the country, 16% at most, compared to the national average of 34%.

RMBC currently averages about 750 tons/day of glass production, around 200 tons of which is recycled glass, with only 80 tons coming from Colorado. For every ton of glass that is recycled, more than a ton of mined raw materials are saved, including 1,400 LBS of sand, 430 LBS of soda ash, and 400 LBS of limestone. How can more than a ton of resources be saved for a ton of glass? That’s because, in making the glass from raw materials, the raw materials (primarily soda ash, limestone, and sand) release carbon dioxide (CO 2 ) emissions in a complex high-temperature chemical reaction during the glass melting process, according to Ryan. This reaction releases about 300 LBS of CO 2 /ton of glass, in addition to the manufacturing energy.

What if Colorado recycled ALL of our glass, so that RMBC could get the 70% cullet that is needed from within the state?

  • We would increase recycled glass to RMBC by 117,713 tons per year.
  •  Recycling 1,000 tons of glass creates 8 jobs, so hundreds of local jobs would be created.
  • Carbon footprint of electricity and natural gas would be decreased by 67,000 tons CO 2 per year.
  • There’s a 9.5% reduction in raw materials for every 10% increase in recycled glass, so the
    additional recycled cullet from within Colorado would offset 111, 827 tons of raw materials,
    which is a carbon footprint savings of 14,055 tons per year to mine the raw materials.
  • There’s a 10% decrease in sulfur dioxide (SO 2 ), 6% decrease in nitrogen oxide (NOx), and 17%
    reduction in carbon dioxide (CO 2 ) for every 10% increase in recycled glass, which works out to
    16,774 tons of carbon footprint reduction per year.
  • Carbon footprint reduction from transporting cullet and raw materials from out of state would
    be 3,250 tons per year.
  • All these carbon footprint savings add up to 101,079 tons per year!
  •  Land for Mining – raw materials used to make glass are mined and then refined in industrial
    operations, typically in open pit mines that scar the land and make it unusable for wildlife,
    adding to the many stresses we are placing on wild species that are driving them to extinction.
  •  Landfill Space – currently glass makes up 4 – 5% of municipal solid waste. Like land for mining,
    landfills take up yet more precious land that our wildlife so desperately needs to survive and
    avoid extinction.

Given all these benefits, Colorado, with one of the biggest glass plants in the west, currently has the lowest recycling rate of any state in the country. By far. The current national glass recycling rate is about 34%, while here in Colorado it’s an embarrassing 16%, at best, less than half the national average. Currently, the glass plant only gets 40% of its cullet from within Colorado. The rest comes from Oregon, Wisconsin and Minnesota. What a pathetic waste to send all that glass to landfill, while the glass plant imports more than 40,000 tons of recycled glass per year, adding 2,000 tons/year of CO2 emissions in transportation. In Golden, the only glass that is recycled is from residential single stream bins and single-family residences, and through glass collection bins located in a few places in the area. This means that, if we go to any restaurant or bar in Golden, and are served a drink in a glass bottle, that bottle will go to landfill. Unless, of course, we choose to take the bottle home with us and recycle it ourselves.

Why wouldn’t local businesses and residents want to take responsibility for the containers they buy and sell with every consumer choice they make? You’d think that recycling glass would be the ultimate low-hanging fruit to help reduce our planet’s runaway global warming.

How to Recycle Glass
The best way to recycle glass is to place it in a glass bin. There are 6 glass bins in the area that
are currently accessible to the public:

  • Behind Bill Coors Wellness Center, 12th and Ford, Golden
  • Rocky Mountain Bottle Company, 10619 W. 50 th Ave, Wheat Ridge
  • Lakewood Recycling Center, 1068 Quail St., Lakewood
  • Arvada Elks Lodge 2278, 5700 Yukon St, Arvada
  • Arvada Zero Waste Center, 6240 W. 54 th Ave., Arvada
  • Eco Cycle, 6400 Arapahoe Rd., Boulder

If you don’t have access to a local glass bin, you should at least place the glass in a single stream bin. In the recent past, most of the glass in single-stream collection systems ended up as road-fill, or, worse, ultimately landfilled. Now, the separation technology is advanced enough to recover glass from single-stream efficiently and provide a decent quality of cullet. More processing is needed to recover glass from single stream, so it’s always better to put the glass in a dedicated bin, if possible.

A new company in Broomfield, Glass to Glass (, is providing a glass collection service in Colorado. They provide collection bins at no cost, and they pick up the glass when the bins are full. They take the glass to their facility, where they clean it, remove the lids, labels and other contaminants, and grind the glass into cullet, which is then sold to the RMBC, where it is melted back into bottles. Often, the recycle glass is made into a new bottle in as little as 2 – 4 weeks. If you have a suitable location for a bin, you can contact Celene Peck-Andreano at Glass to Glass, (720) 580-0545, [email protected].

Responsible Glass Recycling
Before recycling, glass containers should be rinsed and free of residue. Please don’t toss contaminants, such as porcelain, mirrors, windows, pyrex, glass cookware, spectacles, drinking glasses and vases, light bulbs into the glass bin, or into the single-stream recycling bin. This is important, because these are made of different materials than glass bottles and jars, or are treated to withstand extremely high temperatures, and should be recycled separately. For example, a small amount of porcelain can ruin an entire batch of glass, by creating unmelted “stones” in the glass. Also, previous attempts at placing unsupervised recycling bins in Golden have seen problems with trash and other inappropriate items in the bins, which makes cleaning and separation more difficult, and ultimately can result in removal of the bin. We are lucky to have a nearby glass plant that provides the opportunity to keep single-use containers within a circular economy that minimizes the use of raw materials and reduces the carbon footprint of these containers. If we recycled all the glass bottles and jars in Colorado, we would save more than 200,000 tons of CO 2 emissions per year, which would go a long way towards reducing our carbon footprint and helping our planet. Together, we can make a difference on our planet by recycling glass responsibly.

About the Author: Julie Smith is a retired sustainability, energy, water and wastewater engineer,
currently writing and blogging about sustainability