3.4.4 Conclusion..............................................................................................................
Composting, landfill and incineration with energy recovery are well covered by the selected scenarios with on
average ten cases assessed while recycling and anaerobic digestion are represented in five and three cases,
respectively.
The results highlight the good environmental performances of mechanical and chemical recycling
regarding energy demand, depletion of natural resources and climate change potential. On the contrary, the use
of biopolymer waste as a reducing agent in blast furnaces in the feedstock recycling scenarios does not bring
substantial benefits and incineration and anaerobic digestion are preferable.
Composting does not appear to be advantageous for energy demand and depletion of natural
resources compared to the other alternatives. However, composting presents an advantage over
incineration with energy recovery regarding GHG emissions, under the condition of a low
degradation rate (<50%).
Anaerobic digestion is only assessed in studies 3 and 7, for PLA and maize starch respectively and performs
better than composting regarding both indicators analysed, i.e. climate change and energy demand. The
advantage of anaerobic digestion over composting comes from the recovery of the biogas produced
via electricity and heat production.
3.4.5 Data gaps/further research......................................................................................
Key parameters
The importance of the degradation rate has been highlighted for the evaluation of composting and landfill, thus
there is a real need for evidence based information regarding this parameter.
Coverage of the various end-of-life alternatives
Anaerobic digestion has been assessed in only two scenarios and seems a more promising option than
composting. However, it should be noted that there is still a lot of uncertainty about the behaviour of biopolymers
when undergoing anaerobic digestion. It would also be beneficial to investigate further the impacts of recycling
since there seems to be some real potential for environmental benefits. There is a need for reliable scientific
information to determine whether it would be beneficial to develop a recycling channel for biopolymers. In
addition, no study assessing pyrolysis or gasification has been found so this could be another area for further
research.
Environmental indicators
It should also be noted that water consumption has not been taken into consideration in any of the selected
publications. As biopolymers are based on crops, water consumption may be of significant importance. It would
also be interesting if more studies took into consideration a large panel of indicators. Many studies give priority to
climate change. The risk of focusing on a single indicator is that an improvement regarding this indicator might
lead to an increased environmental burden for another indicator.