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Defining dynamic emission factors
Dear community,

I'm struggeling to define dynamic emissions related to a bioenergy technology. I want to leave the decision on when to install a new bioenergy project to the model. However, the emission factor related to the output of that technology changes over the lifetime of the technology, while the output remains the same. A short example: process BIONRG starts operating in time t with and output of 50 PJ. I want the emission factor at time t  to be 100 kt/PJ. But for t+5 (next milestone year), the emission factor decreases to 10 kt/PJ, while the output remains 50 PJ. 

What is the exact way to model this?

Thanks in advance!
OK, if you want emission factors related to the output of that technology to be changing over the lifetime of the technology, then you need to shape those emission factors.

Shaping a flow attribute, such as an emission factor, is only possible for vintaged processes, because only in that case the flow variables are vintage-specific. Shaping an attribute involves defining the base development of the attribute for the process, a generic SHAPE index, and an attribute linking a SHAPE index to the process-specific attribute. An example is given in the thread below, for the CH4 emissions from the OILDST input of the process EGASOIL005 in the DEMO model:

I do acknowledge that in that thread, you claim that the shaping of emission factors is not working as you expect, but you don't produce any evidence or detailed argumentation supporting your claims. I would be happy to investigate and/or explain any issues you see in the TIMES shaping functionality, if you can provide a reproducible case manifesting the issues you are wishing to be explained.

But anyway, if you are indeed wishing to model age-dependent emission factors (as opposed to calendar year-dependent), the appropriate way to model a process BIONRG, which starts operating in time t with an emission factor 100 kt/PJ at time t but for t+5 the emission factor decreases to 10 kt/PJ, is thus to use a SHAPE index, where you define the age-dependency multipliers for the emission factor.  It is not exactly the same as you describe (because period lengths D(t)>1 cause some averaging in the age-dependency), but it is the closest one available.
For those who might be interested, please see below another simple example.  It is again based on the DEMO model, and because in that model all periods after 2005 have a length of 5 years, we can model any desired age-dependencies on a 5-year basis exactly as desired. The figure below shows an illustrative "jumpy" age-dependent trajectory for the emissions of an example vintage, and the TFM_INS table defining the Shaping data for that trajectory.
As one can see, it is actually quite easy to define almost any kinds of age-dependent relations between process flows with the TIMES SHAPE facility.

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