McKinsey: Cullet volume, quality mars flat glass recycling

Global recycling firm McKinsey & Co. says increased recycling outcomes for glass used in recycling and automotive applications are possible, but cooperative systems will need to be formed to overcome existing barriers.

In the fourth report in its planned six-part series on “Materials Circularity,” McKinsey says the use of cullet (recycled glass) “lowers energy consumption and avoids the release of process emissions” at glass furnace locations, especially when cullet displaces synthetic soda ash, reducing emissions that stem from that raw material’s production.

Cullet use rates “stand to be much improved,” write the four McKinsey co-authors, but boosting that rate ties to cost competitiveness factors that “strongly” depend on the location of the production facility.

The four authors—Jeffrey Lorch of the firm’s Boston office; Peter Spiller in Frankfurt, Germany; and Madicke Embrechts and Michel Foucart with McKinsey in Brussels—say carbon reduction policies also play a role.

“Using cullet can be more cost-effective than virgin raw materials in most regions, especially in densely populated areas close to float operations,” writes McKinsey. The authors say in a scenario where the production line is running exclusively on cullet, Scope 1, 2 and 3 emissions can be reduced by from 30 to 40 percent.

While that may be an encouraging figure, the report pegs the average recycling rate for flat glass as currently about 20 percent in Europe.

The authors say they have identified two main reasons: a lack of discarded flat glass collection and the “downcycling” into packaging applications for those windows or windshields that are collected.

“In many countries, there is no postconsumer collection system for flat glass, so flat glass waste ends up in landfills,” write the consultants.

Regarding its direction toward bottle glass plants, they say flat glass has more stringent quality constraints in window making compared with packaging glass, such as a lower tolerance for ceramic inclusions and more stringent specifications on chemical composition.

More attention to collection and diversion is possible, add Lorch and his co-authors, and they point to a system in the Netherlands as an example.

There, they say, initiatives such as return systems operated by glass installers and producers have boosted flat glass collection rates to about 75 percent.

“Unlocking the full potential of cullet as a cost-effective decarbonization lever will require the setup of new supply chains that enable economical collection of flat glass and reduce the risk of contamination,” writes McKinsey.

In Europe and elsewhere, McKinsey also suggests that governments can help accelerate collection by putting in place policies pertaining to the use of recycled content or target recycling rates, or “increasing overall awareness of the positive impact of glass recycling for stakeholders along the entire value chain.”

The report’s authors conclude, “Creating the future glass industry will take collaboration and a value chain approach to truly scale solutions and build circularity—and value—for everyone.”

Other reports in the McKinsey “Materials Circularity” series have examined recycling prospects in the copper, plastics and overall basic materials sectors, while reports are coming soon focusing on aluminum and rare earth elements.