Is landfill or incineration of plastic waste preferable?

A UK study found that separating plastics in household waste for recycling was a better environmental option than incineration in a waste-to-energy facility.[1] Nevertheless, if contaminated and mixed plastic cannot be recycled into high quality recyclate, it remains an open question as to whether it should be landfilled or incinerated in a carefully controlled environment with energy capture (also called thermal valorisation). In line with the waste hierarchy, LCA studies indicate that landfilling of waste is generally the worst end-of-life management option. However, it could be argued that landfilling represents a way of sequestering the carbon in the plastic; alternatively, this can be regarded as unsustainable because it passes the problem of plastic waste management on to future generations.

There are no publicly available LCAs assessing whether landfill or incineration with energy capture is a better environmental option for Aotearoa New Zealand. Such a study would be needed to better understand the relative environmental performance of each option in our local context – particularly since the results would be influenced by the transportation requirements between points of waste generation and incineration plants or landfills.

There are no publicly available LCAs assessing whether landfill or incineration with energy capture is a better environmental option for Aotearoa New Zealand

The conclusions may also change depending on new materials and new technology. Right now, we would have to factor in that the economics of incineration plants would probably mean that only one or two plants would be feasible around the country and therefore there would be emissions related to transport. In the future, if smaller scale plants were economic that would change the outcomes, as would an electric vehicle fleet powered by renewable energy. Alternatively, there may be an increase in biodegradable or compostable plastics that enter landfill, and outcomes of the analysis may change, particularly if all waste was disposed to modern landfills with methane capture.