Why are the CH4 and N2O coefficients for U.S. vehicles different in the Emissions Tracker than they are in the Local Government Operations Protocol?
In terms of CH4 and N2O, the LGO Protocol lists emissions factors by vehicle Model Year–so that you can calculate emissions from a fleet of 2005 Toyota Priuses, for example. Project 2 Degrees uses a weighted average emission factor for all vehicles on the road in a given year. Thus, when you are calculating emissions for passenger cars for a 2005 inventory in Project 2 Degrees, the emission factor used assumes some of those passenger cars are model year 2005, some are 2004, etc. In the U.S., both numbers come from USEPA–they are just different numbers. We haven’t implemented the model year calculation in Project 2 Degrees. We’d be interested to know if that is something your city needs.
