Product Design/Research
Life Cycle Assessment (LCA)
I use the current human waste management on the ISS as the LCA benchmark. The condition is defined according to the lunar outpost mission, in which there will be 4 crew members rotating every 6 months.
Benchmark
The human waste management on the International Space Station (ISS)
Scope
The evaluation focus on the disposable products which go into the process in a year. However the following variables are excluded since the information is inaccessible or irrelevant to the project:
- Product for air filtration
- Refill Water Pouch
Functional Unit
Impact
Waste in human waste process/4 crewmembers-year (lb)
The Current Process
The Simplified Flow Diagram
LCA process tree - the waste system
LCA process tree - input materials
Impact Matrix
The new process
Comparison of Okala score
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Note:
The actual input and output from Torrefaction Processing Unit (TPU) and Heat Melt Compactor (HMC) still need more information and study to precisely conduct LCA and Okala score.
*Replaced with related process to roughly measure the scale of the impact since the item is not included in Okala Factor.
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Conclusion
The Okala score of the new solution has demonstrated a huge decrease in environmental impact. This improvement resulted from the effective processing of Torrefaction, and the possibility of applying repurposed human waste product in lunar habitat.
The new closed-loop process has eliminate the needs for storage canisters and the trip for destructive re-entry to Earth, which the impact mainly came from.