Provide control over how displaced electricity emissions are handled for Combustion process

[WesIngwersen]

Background

Some combustion processes in WARM generate electricity which in turn feeds into the grid. The way this is represented in WARM however differs across combustion processes for different materials. For asphalt shingle combustion, for example, it is represented by a negative amount of the elementary flow 'GHGs, unspecified',

See for MSW combustion of shingles for instance that flows under the outputs

This issue is only applicable to those combustion processes where this offset is represented in this way.

Issue

Just like in issue #2 , the way this is modeling does not provide the modeler with the flexibility of modeling according to other assumptions. This needs to be made more flexible.

[bl-young]

By my read of the database, this issue applies to three processes (and cannot exclusively be determined by a negative value for GHGs, unspecified on the emissions side). So perhaps the logic should be when this flow appears as a negative emission for processes that relate to combustion. (not entirely different than what you said above, just wanted to be explicit about the logic).

[bl-young]

Adding @a-w-beck comment: Per the Background Chapters WARMv15 uses AR4 GWP factors, so combining those with the GHG flows out of the "Electricity generation, at grid, National" process we get 1.376E+03 kWh/MTCO2E of unspecified GHGs.

[a-w-beck]

Upon further review, while most WARM MSW combustion processes generate an avoided grid electricity product, asphalt shingles and tires are instead modeled as fuel substitutes in other industrial processes [WARM Construction Materials Chapters, s.2.4.4][WARMv15 Tires Chapter, s.1.4.4]