Unlike plastic, glass has no chemical properties that make it difficult to recycle. According to the Glass Manufacturing Industry Council, it is possible to melt and recycle glass endlessly. That is, recycling glass doesn’t degrade it in any way.
And yet, Americans recycle very little of their glass waste. Some municipalities have stopped accepting it in their recycling programs.
The city where I live is a case in point.
Effective July 1, 2019, the City of Greensboro, North Carolina will no longer accept glass for curbside recycling. What’s more, it has decided to close all 20 recycling drop-off locations.
I admit I haven’t visited a lot of other recycling drop-off centers, but they all require patrons to sort the materials they bring. Greensboro simply has recycling dumpsters next to trash dumpsters. That seems like a recipe for maximizing contamination at those sites.
Like most single-stream recycling programs, Greensboro collects recycling and takes it to a Material Recovery Facility (MRF) operated by a commercial company. In the past, that contractor paid the city a share of the revenue from selling the recyclables. Now, the city must pay the contractor $30 per ton to haul and process everything. And glass makes about 25% of the weight of the recyclables.
Temporarily, the city is instructing residents to put glass in the trash. Because it is inert and can’t leach chemicals into the groundwater, landfilling it creates no environmental hazard. Eventually, Greensboro plans to set up drop-off locations for glass only.
Why the glass industry needs recycled glass
Glass recycling is an old technology. In fact, nearly all new glass is made in part from old glass. Crushing bottles and jars from recycling programs results in a granular material called cullet. Using cullet in glass making has many benefits.
For one thing, one kilogram of cullet saves 1.2 kilograms of sand, sodium carbonate, and limestone, the major raw materials of glass making. Cullet melts at a lower temperature than the raw materials. So using cullet saves energy. Lower operating costs reduce the price of glass for manufacturers and consumers.
What’s more, raw materials release carbon dioxide, which can trap unwanted bubbles in the finished glass. Cullet doesn’t. So using it improves the quality of the finished glass.
Finally, some of that carbon dioxide from raw materials escapes into the atmosphere as greenhouse gases. Every six metric tons of cullet eliminates one metric ton of carbon dioxide emission. So using 10% cullet in glass making reduces emissions by about 5% and energy usage by about 3%.
The process of glass recycling in the US
Two basic reasons make glass recycling difficult in the US. We have too few facilities to produce cullet, and they’re too far apart. Also, our reliance on single-stream recycling lowers the quality of the glass available to produce cullet.
Here is the basic process of glass recycling:
- Consumers set glass among other things out for recycling.
- Trash haulers take the recycling to a MRF.
- The MRF sorts all the recyclables. The sorting process includes attempting to remove everything that should never have been put in recycling containers to begin with. These contaminants include Styrofoam™, plastic bags, and very likely bottles and jars that are still half full of whatever product they contained.
- The glass goes from the MRF to a facility that sorts it by color, crushes it, and cleans it to make cullet.
- Glass manufacturers purchase cullet and use it as already described to make new bottles and jars.
- Food and beverage manufacturers, among others, buy the bottles and jars to fill them with their products.
- Consumers buy products at the store, use them, and put the empties out for recycling.
The trouble with glass recycling in the US
I toured Greensboro’s MRF a couple of years ago. Glass drops off the conveyor belt—literally—in the first step of the sorting process. It falls on a concrete floor and breaks. At intervals, someone pushes it outside with a front loader.
The glass pile outside didn’t look much like glass to me. I saw fruit, potatoes, plastic pill bottles, and all kinds of other contaminants. These fall off the conveyor with the glass because they’re either heavy or small. The glass, being the densest material in the pile, sinks to the bottom. Everything else rises to the top.
At other facilities, removing the glass is the last step, not the first. Some of them have a glass crusher at that point. In any case, the resulting glass shards are coarser than finished cullet.
The problem of contamination in glass recycling
Contamination from the single-stream recycling process is so serious that only about 40% of the glass collected actually gets made into new glass products.
Besides fiberglass or new jars and bottles, other uses for recycled glass include aggregate for asphalt or concrete, sandblasting, filtration, and tile. These uses command lower prices.
The comparatively few places in the US that require source separation put out a much cleaner product. Very little of their glass gets wasted.
Single stream recycling costs much less to collect, but much more to sort and process. Source separation works well at drop-off centers, but source-separated collection at the curbside would be so much more expensive and less convenient that most municipalities won’t try it. But it works in Europe.
As a result, manufacturers complain that they can’t get the quality of cullet they need in the quantity they need.
The problem of distance in glass recycling
Lower contamination rates from multi-stream collection may explain in part why Europeans recycle so much more of their glass than we do. But they are also much smaller countries geographically.
European glass makers are spread out more than American factories. It’s easy to build cullet processors reasonably close to both the factories and the companies that handle the recyclables.
I have also toured the MRF in Bowling Green, Ohio. Bowling Green doesn’t accept glass at the curbside, but people can take it to the drop-off center and put it in the appropriate bins.
At the time I visited, the center had just started accepting glass again. For most recyclables, the buyer pays for the shipping freight on board. But MRFs have to pay to ship glass. Although nearby Toledo calls itself the glass capital of the world, it has no cullet producer. So the MRF has to ship glass to Dayton, which is nearly 130 miles away. That facility pays $10 a ton for the glass, but it costs $40 a ton to ship it there.
The county pays a subsidy of $30 a ton for the glass. At one point, the commissioners decided to discontinue the subsidy. The non-profit organization that runs the recycling program has a policy that everything has to pay its way. With no subsidy, it stopped accepting glass. Five months later, after public outcry, the county agreed to restore the subsidy. Glass recycling resumed.
Some possible solutions to the glass recycling problem
Ten states have passed “bottle bills,” which require that customers pay deposits on beverage bottles. Theoretically, they return the bottles to the store to get their deposit back. But now, fewer and fewer products come in glass bottles. I can remember when any other beverage packaging was rare except for very small containers of milk.
Bottle bills don’t cover catsup bottles or pickle jars. Nonetheless, it appears that states with bottle bills achieve a higher rate of glass recycling than the others.
Some municipalities offer drop-off centers, where patrons must place their various recyclables in separate bins.
North Carolina recently passed a law that requires holders of alcoholic beverage permits to recycle bottles and cans.
These laudable state and local efforts won’t make much difference any time soon. In Europe, national governments set recycling goals and recycling policy. Federal legislation would have a greater and faster impact on glass recycling rates.
European landfills also have higher tipping fees than American landfills. They make recycling automatically cheaper than sending heavy glass to landfills.
Government programs might put more glass in the recycling stream, but they can’t solve the shortage of processing capacity.
Boulevard Brewing of Kansas City, Missouri took a different approach. Kansas City had no cullet processor. That’s because it had no local glass recycling program. And, of course, there was no recycling program because there were no cullet processors to buy recycled glass.
So about ten years ago, Boulevard decided to launch a cullet supplier, Ripple Glass. Ripple placed 60 large drop-off facilities around the area dedicated to collecting glass. Then it mounted a publicity campaign to tout the advantages and availability of glass recycling.
As a result, Ripple collects glass, makes cullet, and sells it primarily to two buyers. Kansas City’s Owens Corning plant uses some of the cullet to make fiberglass. The rest goes to the bottle making company in Tulsa, Oklahoma, more than 250 miles away, that supplies Boulevard with its beer bottles.
Since Ripple owns and operates the collection centers, it doesn’t have to pay any MRF for the glass. Of course, it does pay for shipping.
Boulevard Brewing didn’t establish Ripple Glass because of any ideological attachment to recycling. It got tired of seeing its empty bottles landfilled when they could be recycled to reduce the cost of new empty bottles.
May more manufacturers show the same imagination and initiative.
Recycling / Glass Packaging Institute
Reset. Recycle. A whole new way to recycle in Greensboro / City of Greensboro. May 2019
Why glass recycling in the US is broken / Mitch Jacoby, Chemical & Engineering News. February 11, 2019
No glass recycling sign. Some rights reserved by Bart Everson
Glass jars and bottles. Public domain from Wikimedia Commons
Commingled recycling bin. U.S. Marine Corps photo by Marianne Weaver
Greensboro MRF. Supplied by ReCommunity
Sorted glass. Some rights reserved by Derek Harper
Bowling Green drop-off center. My photo
Kansas City drop-off center. Kansas City, Missouri Public Works. Link no longer works.
Cullet. Public domain from Wikimedia Commons