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This is part three of a three-part series exploring the environmental lifecycle analysis completed by Divergent. It will get into some technical detail, but is intended for anyone who has an interest in total system environmental and health damages for manufacturing.

Before reading this section, please read our lifecycle analysis overview, Part 1, and Part 2.

Modeling philosophy: change as few variables as possible

There are obviously many ways to create and modify models. Thankfully, by using GREET and AP2, we were able to leverage decades of existing work. These peer-reviewed, published, and transparent models have inputs, calculations, and outputs that have been highly vetted.

When modifying an existing model, it behooves the modeler to make as few changes as possible. That is the philosophy we used at Divergent when making modifications to include our vehicles in the existing models. By reducing changes, you’re reducing chances for error and reducing the number of assertions you need to make. It’s also easier to delineate the full set of changes you made so that others can review and understand your work.

Similarities and differences between our analysis and NAS analysis

We based our modeling on the method used in the 2009 report by the National Academy of Science (NAS), Hidden Costs of Energy: Unpriced Consequences of Energy Production and Use. They used GREET for lifecycle emissions calculations and APEEP (the predecessor to AP2) for health and environmental system damage cost calculations.

We used updated versions of those same two models, GREET and AP2. The models have not fundamentally changed in structure since 2009, though some of the content has been updated with more recent calculations (e.g., the environmental cost of CO2 emissions).

We updated GREET to include modern electric vehicles with 85 kWh batteries and to also include the Divergent vehicles, both compressed natural gas (CNG) and gasoline.

cents per vmt graph-1

Delineation of variable changes

In keeping with the modeling philosophy above, we limited the set of changes in the GREET model to only those changes necessary to include modern EVs and our Divergent vehicles. We used the existing lightweight car vehicle type in GREET and modified it to suit the Divergent Blade. No changes were made to AP2, as it takes inputs from GREET. Below is a table delineating the exact changes we made.

That’s all. By limiting the number of changes, we have a strong and defensible modeling technique. Divergent vehicles drastically reduce the environmental and health damages compared to existing, traditional vehicle manufacturing. Keep in mind that we modeled the Divergent Blade, a 0-60 in 2.5 seconds 700 horsepower supercar. We can expect that future Divergent vehicles will have even lower total system damage numbers.

Summary

Thank you for joining us in our mission to reduce the environmental impact of automobile manufacturing. We hope this blog series has been informative, and welcome your thoughts and comments in the space below.

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