Claude Davis 9/18/2009

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We have two questions/problems

When displaying environmental results for methane they are as expected when displayed "where they occur", but when allocated, the results show negative values for projected years (and as expected positive values for historical data).

We have location-specific vehicle class/pollutant emission factors from a MOBILE model in g/mile for each pollutant and have entered these as Key Assumptions. However, it does not seem possible to use these emission factors since the environmental loading entry in the demand module allows only "Per unit energy consumed" or "Per unit travel" (in vehicle-km). Should there not be another option that allows g/mile or g/km as the method - so the MOBILE emission factors can beused?

Charlie Heaps 9/22/2009
 

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Hi Claude,

>> When displaying environmental results for methane they are as expected when displayed "where they occur", but when allocated, the results show negative values for projected years (and as expected positive values for historical data).

This does sound like a problem in LEAP's allocation calculations. This part of the calculation are somewhat heuristic in ho they allocate supply side emissions back to the demand side and I have seen a few data sets where the allocation process does not work well. I would suggest for now that you do not reference that particular result. If need be I suggest you take the supply side emissions from the report "Environmental Loadings: where emissions occur" and then manually allocate them to demand branches in a spreadsheet. I will try to improve this particular algorithm in a future version of LEAP.

>> We have location-specific vehicle class/pollutant emission factors from a MOBILE model in g/mile for each pollutant and have entered these as Key Assumptions. However, it does not seem possible to use these emission factors since the environmental loading entry in the demand module allows only "Per unit energy consumed" or "Per unit travel" (in vehicle-km). Should there not be another option that allows g/mile or g/km as the method - so the MOBILE emission factors can be used?

If you specify emissions per unit travel then you can specify emissions either per vehicle-mile or vehicle-km. The denominator can be pretty much any mass unit (grammes/kg, lbs, etc.) NB: Make sure you are in Current Accounts if you want to change the units.

I hope this helps,

Charlie