Our Approach
The challenge with assessing the environmental impacts of a waste or by product of a system is that one series of processes creates two separate outputs - and we need to assign the impacts generated to one or the other. We wanted to understand how different assumptions and different Life Cycle Assessment methods of quantifying environmental impacts of two different outputs might affect the results of an analysis. We therefore decided to compare a commonly used approach - economic allocation - with an approach we call "substitution".
Economic Allocation
Impacts from processes prior to the point of separation are split between multiple outputs based on their relative prices.
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Substitution
Impacts from alternative materials that serve the same function as the waste in another industry are assigned to waste.
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We analyzed four different sourcing scenarios using these two methods: grape pomace from the wine making industry, coffee cherries, olive pomace from the olive oil industry, and cocoa husks. All four materials can be composted and used as a fertilizing agent or mulch, so we ran the substitution method analysis twice for each, once assuming it might be used as fertilizer and once assuming a different possible use.
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Hover over each feedstock to learn more about their common fate and possible alternate use
grape pomace
Most grape pomace produced during the wine making process is sent to the landfill, however in some cases it can be used as an additive to cattle feed.
coffee cherries
Coffee cherries can be used as an additive to cattle feed as well, although often times they are dumped in landfills or waterways, causing possible contamination
olive pomace
Olive pomace is sometimes pressed into a second, lower quality cooking oil. However it is also often times dumped in landfills.
cocoa husks
Cocoa husks can be burned as a biofuel alternative, sometimes even helping power chocolate processing facilities where they are created.
What we found
Our main take away from our dual analysis was that using just one method or the other might result in an organization missing information. The choice with the lowest impacts changed based on which method was used.
If an organization analyzed these four scenarios using only the subsitution method, they might select cocoa husk
If an organization analyzed these four scenarios using only economic allocation, they might select olive pomace
Results for climate change impacts
