The study by Californian consultants SRI Consulting suggests in certain countries disposing of PET (polyethylene terephthalate) plastic bottles in landfill generates the least carbon.

This is true for most countries where there are few space limitations and limited recycling infrastructure, the report says.

Mike Arné, assistant director of SRI Consulting’s Carbon Footprint Initiative, said: “The key to this is not in raising collection rates, but in improving yields, especially in sorting and to a lesser extent in reprocessing.

“For countries without a recycling infrastructure, the best choice may well be to landfill bottles.”

This is most likely to be the case in the developing world or in countries with large, sparsely populated areas of land such as Canada and parts of the USA.

In another controversial finding, the report also finds controversially that shipping waste plastics is not a significant contributor to their overall carbon emissions compared to other parts of their lifecycle.

This means the common practice of sending waste to China and other Asian centres for recycling is less damaging than often assumed.

The report also suggests incineration is the worst option in terms of greenhouse gas emissions, as burning the bottles releases the carbon they contain straight back into the atmosphere.

Finally, the report looked at the effectiveness of curb side recycling programmes and found this form of collection typically displaces less than 50 per cent of new PET.

But community programs with plastic bottle take-back, mandated separate collection or deposits on bottles tend to report much higher displacement rates.

David Gibbs

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