The case for bottle-to-bottle is that glass can be remelted indefinitely without losing quality. In practice, each cycle earns a modest amount, some glass is lost every time around, and later cycles are worth less in present value terms, so the loop has a finite total value no matter how long it runs. In Queensland’s container scheme, where about 69% of glass returns to the loop each cycle, one tonne is worth about $139 in present value. Even if no glass were ever lost, bottle-to-bottle recycling running forever would generate a present value of only about $810.
The same tonne of glass, turned into silicon fertiliser and applied to a crop like sugar cane, is worth around 50 times that or more in our analysis, depending on which cases are compared. The reason is that silicon persists in the soil and keeps lifting yields for several years.
The case does not depend on large yield gains. The fertiliser only needs to lift cane yields by about 0.1% to match bottle-to-bottle recycling, while published Australian field trials of silicon on cane have measured gains of more than 50% on silicon-deficient soils.
The extra cane also matters beyond the farm gate. Queensland’s sugar mills crushed 28.7 million tonnes in 2020 against about 34 million tonnes of capacity. With 60 to 75% of milling costs other than cane being fixed, unused capacity is expensive, and the sector lost $0.97 on every tonne it crushed between 2018 and 2020. One far north Queensland mill was crushing at 43% of its capacity in 2020 and went into liquidation in 2024. A new bottle made through bottle-to-bottle recycling, by comparison, is worth no more than any other bottle once it leaves the bottling line.
Bottle-to-bottle recycling is an important part of the solution and handles large volumes of glass effectively. The assumption that bottles are therefore the highest-value use of glass does not hold, especially in regional areas far from glass processing plants.
The key to unlocking that value is new regional value chains that keep the glass local and the benefits local. That is the change we are working on.
Source: Resilien analysis, drawing on published industry, government and research data. Figures describe the current industry.