Mapping the flat glass value-chain: A material flow analysis and energy balance of UK production

Abstract Glass is one of the UK’s eight energy-intensive industries. As such, it is under scrutiny to decouple growth in production from greenhouse gas (GHG) emissions. The energy input associated with glass production can be reduced by using recycled glass (cullet) in new glass production, which enables lower furnace operating temperatures and reduces demand for primary raw materials. However, efficient systems for flat glass collection are yet to be established in the UK, resulting in a limited supply of cullet available for the flat glass markets and missed environmental opportunities. This study identifies the existing supply-chain inefficiencies of the UK glass industry in three stages. Firstly, the mass flows of materials within the three main glass sectors: container glass, flat glass and glass wool, are mapped from natural resource through to primary application and subsequent endof-life management based on a reference year of annual production figures. The map is presented in the form of a Sankey diagram which draws attention to several opportunities for increasing resource efficiency; namely in the stark contrast in glass collection rates between the flat and container glass industry. Using the collected data on the annual mass flows of materials in the UK flat glass sub-sector, the energy (MJ) and GHG emission (CO2-eq) saving potential of enhanced end-of-life collection methods are assessed, based on three alternative recovery scenarios. These scenarios consider the use of alternative distributions of recovered flat glass cullet in the three primary glass sub-sectors. The emission savings resulting from each recovery scenario is evaluated, based on the estimated tonnage yield of finished flat glass products. It is shown that together with improved manufacturing yield, the reutilization of end-of-life flat glass as cullet in new production could reduce the annual emissions of the UK flat glass value-chain by up to 18%. Finally we review the existing barriers to recycling different glass types based on acceptability criteria and available take-back infrastructure, and thus find that the advancement of improved recycling rates will rely on establishment of the business opportunity and/or supporting policy for efficient systems of flat glass collection.