Position Papers
Comparison of Oxo-Biodegradable and Hydro-Biodegradable Plastics
|
OXO |
HYDRO |
| Usually made from a by-product of oil or natural gas | Usually made from vegetable products such as starch |
| Can be recycled as part of a normal plastic waste-stream | Damages recyclate unless extracted from feedstock |
| Can be made from recyclate | Cannot be made from recyclate |
| Emits CO2 slowly while degrading | Emits CO2 rapidly while degrading. As 90% of it must convert to CO2 within 180 days in order to comply with the Standards for compostable plasitc, these plastics contribute to climate change but do not improve the soil. |
| Inert deep in landfill | Emits methane deep in landfill |
| Can use same machinery and workforce as for conventional plastic | Needs special machinery and worforce |
| Suitable for use in high-speed machinery | Usually not suitable |
| Compostable in-vessel | Compostable (but not for home composting) |
| Little or no on-cost | Four or five times more expensive than conventional plastic |
| Same strength as conventional plastic | Weaker than conventional plastic (unless mixed with oil-based plastic) |
| Same weight as conventional plastic | Thicker and Heavier |
| Leak-proof | Prone to leakage |
| Degrades anywhere on land or sea | Degrades only in high-microbial environment |
| Time to degrade can be set at manufacture | Cannot be controlled |
| No genetically modified ingredients | Possibility of GM ingredients |
| Safe for food contact | Safe for food contact |
| No PCB's Organo-chlorines, or "heavy metals" | No PCB's Organo-chlorines, or "heavy metals" |
| Can be incinerated with high energy-recovery | Can be incinerated, but lower calorific value |
| Production uses no fertilisers, pesticides or water | Production uses fertilisers, pesticides and water |
| No limit on availability of feedstock | Limited availability of feedstock |
| Demand for oxo-biodegradable plastics does not drive up cost of fuel for vehicles | Demand for hydro-biodegradable plastics drives up price of human and animal foodstuffs |
In June 2009 a Life-cycle Assessment was published by Germany's Institute for Energy and Environmental Research (IFEU), [see link] which concluded that polyethylene sacks made from Post Consumer Recyclate have generally the smallest environmental impact profiles and can be considered the most "eco-friendly" materials for waste bags; provided the bags can be made and also perform (i.e. are technically fit for purpose) at thicknesses similar to those made from virgin materials. (Oxo-biodegradable garbage sacks are made from polyethylene and can be made from either recycled or virgin material).
They added that "The current bags made from bioplastics have less favourable environmental impact profiles than the other materials examined" and that this is due to the process of raw-material production.
The packaging manager of Tesco (Britain's largest supermarket) said on 20th October 2009 that the supermarket "does not see the value in packaging that can only be industrially composted" and that "local authorities do not want to touch it, as it can contaminate existing recycling schemes." A few days earlier, Tesco's head of waste and recycling had told a conference that the supermarket group was "not taking compostable packaging any further."