All types of carrier bag, whether made from plastic, paper or jute, will have some impact on the environment during the manufacturing process, transportation and ultimate disposal. The best way to reduce their carbon footprint is to simply re-use them as many times as possible and then recycle them at the end of their useful life.
Plastic carrier bags
While plastic carrier bags use 70% less plastic than they did 20 years ago, they are still made from polyethylene (PE) which is derived from non-renewable oil and require energy to manufacture.
Plastic bags are recyclable and are increasingly being recycled, but the majority still end up in landfill where they may take hundreds of years to break down. Increasing the recycled content of new plastic bags is a way of using fewer natural resources and reducing the environmental impact of bags.
Degradable PE carrier bags
There are a number of retailers who provide ‘degradable’ PE carrier bags, (also known as ‘oxo-degradable’, ‘oxo-biodegradable’ or ‘UV degradable’). Degradable bags are made from oil-derived PE but also contain additives that act as catalysts to accelerate the degradation process. These additives break down under UV exposure, oxygen, heat and/or mechanical stress, leaving small particles of plastic. These may then potentially biodegrade, reducing the material to water, CO2, biomass and trace elements. This process can take several years.
It is unknown what the full impact of mixing degradable and conventional plastic carrier bags will have if they enter the plastic recycling system in large numbers. Degradable bags are not certified as ‘compostable’ and do not conform to the recognised European standard for biodegradable plastics EN 13432.
Compostable carrier bags
These bags are not so commonly used by retailers as they are less strong for the same gauge of material. They are made from renewable crop-derived sources (e.g. corn starch). They are usually designed to biodegrade in aerobic industrial composting conditions and may conform to EN 13432. The bags are not designed to degrade in landfill conditions. They may be compostable in home composting conditions. At present, there is only a UK specification for home compostability, not a standard.
While paper carrier bags are from a renewable source and are biodegradable, compostable and recyclable, they require significantly more energy to manufacture and transport than plastic bags and normally have limited reusability. If disposed of in landfill, they are likely to degrade and release methane.
Jute and cotton are made from plants which need a lot of water and fertiliser to grow and energy to harvest and process into bags. They encourage re-use, and can be reprocessed at the end of their useful life as, for example, blankets used by removal companies. If disposed of in landfill, they are likely to degrade and release methane.