(Deng et al., 2019)

In theory, glass can be infinitely recycled in a closed loop, but only so long as the material can be kept sufficiently free of impurities which would otherwise detrimentally impact the remelted glass. The majority of UK container glass waste is collected via mixed recycling streams, which results in some degree of unavoidable material contamination. The technology currently used to optically sort the colour of the glass and remove contaminants is only effective above a certain particle size (approximately 10mm).

Glass larger than this size can be cleaned and colour sorted. Clear glass is typically recycled by the UK glass industry, whereas green glass is more often exported to Europe for the production of glass for beer and wine (which the UK imports). On some occasions, clean green glass can also end up recycled for non-remelt applications, such as a sand/aggregate replacement. Whilst this offers the opportunity to re-use the material closer to home and avoid the associated transport emissions of exporting glass waste to Europe, overall this recycling route offers less than 1% of the carbon savings of remelt applications and should be avoided (Butler and Hooper, 2005).

Alongside closed-loop recycling into container glass products, 'remelt' glass can also include recycling into glass wool insulation and glass beads, this breakdown is not currently published.