Carbon stored in biomass is often referred to as a carbon sink. This is because it effectively removes CO2 from the atmosphere, reducing the negative impacts associated with an excess of CO2. The carbon remains stored in the biomass for an indefinite period of time until it is released back into the atmosphere either through decomposition or combustion. The longer the carbon remains in the biomass, the longer it is removed from the atmosphere, contributing to a reduction in atmospheric CO2 concentrations.
It is important to note that the carbon stored in biomass is not a permanent solution to reducing atmospheric CO2. Eventually, the stored carbon will be released back into the atmosphere, either through natural decay or human activity. However, the longer the carbon remains stored in the biomass, the longer it contributes to a reduction in atmospheric CO2, providing a potential opportunity to mitigate the effects of climate change. As illustrated on the right image below:
The downside of calculating the carbon uptake for bio-genic, is that at the factory gate there is a misleading negative carbon, since the end-of-life did not took place yet.
Recently, the government and interests group are questioning whether temporary biogenic storage of CO2 in materials should be included in the LCA methodology.
The guidelines that are being developed are mostly focused on building materials since they are most likely to have a significant lifetime, which is an important criterion for carbon sequestration. SGS Search carried out an investigation on behalf of the Ministry of Foreign Affairs (BZK). The purpose of it research is “an opinion on the technical elaboration of the valuation of the environmental impacts of the sequestration of carbon in biobased materials within the current determination system of the environmental impact of construction works”.
Their report can be found here. In the report, it is highlighted that :
The calculation of the fixed amount of biogenic carbon in biobased building materials is already part of the current LCA methodologies (material/production phase). A method is developed apart from the LCA method to consider the amount of captured biogenic carbon in a separate indicator (the GWP biogen) that can be applied to all types of materials but will be zero for 100% biobased materials.
The critical lifetime is the time span up to the year in which it is assumed that CO2 emissions are no longer a problem. This period has a relationship with the national climate targets as laid down in the Climate Act. It is proposed to set this period at 100 years. However, it's important to note that even after this critical period, there is no evidence to suggest that the issue of climate change will be completely resolved or that greenhouse gas emissions will cease. This creates a risk of temporal shifting, where the problem may persist beyond the critical period.
For biomass, such as wood, the absorption of CO2 in the production phase is valued and CO2 emissions, for example, when the discarded material is completely incinerated, are written down in an equal amount. Balance over the entire life cycle, looking only at the material itself, is then 0.
Plastic from petroleum (= fossil) should not be appreciated based on carbon sequestration; the absorption of CO2 does not take place as a result of that use and the CO2 emissions from the end-of-life (for example combustion) are taken into account. Therefore, there is on balance a contribution to climate change over the entire life cycle, looking only at the material.
What does this mean for packaging materials?
The figure below illustrates why carbon sequestration cannot be accounted for in the LCA-based method. The lifespan of packaging is not expected to be greater than 100 years. Moreover, CO2 capturing is already taken into account in the materials' life cycle and biobased materials get negative end-of-life values by credit/debit of the system expansion. Therefore, it would be double counting if the method would include this as a separate phase.
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