CEH

[dtsintsk]

Hello, I have a little difficult question to formulate. For combined heat and power sector I was applying CEH=0 and everything was okay, until I started running emission files. Basically, I observed that when I put CEH=0, my original input data for CO2 emissions was not matching with the results after the TIMES run. However, when I was putting CEH=1 or CEH=blank, they were matching. CEH=1 is not something that I want to apply, because it messes up the model in other ways. The documentation says that CEH=0 and CEH=blank is the same thing. Could you explain, why my results differ between CEH=0 and CEH=blank and what should I do to make the emission files work correctly under the assumption that CEH=0

[Antti-L]

It is not clear why your results would differ between CEH=0 and CEH=blank, without some more info. Could you thus provide more information, to understand where the issue is?

Therefore, in the first place, could you post the full data from Item Details for an example CHP process where you see the issue, so that one can see all the technology parameters and how the emissions are defined for the process?  Please show the data section with all dimensions expanded.

A full example model case manifesting the issue would of course be ideal, if you can provide such. Thank you.

[dtsintsk]

Hopefully I understood your request and sending you one example. Unfortunately, currently I have all CEH blank, so I cannot provide an opposing instance. I will give an additional information that with heat plants emissions were matching the input data. So, the problem really has to do with some CHP parameter

[Antti-L]

Thanks for the additional information!

I made myself some tests with a CHP process having either a blank NCAP_CEH and with NCAP_CEH=0, and some emissions defined both for 'ACT' and for an input flow, like you had.

However, I could not produce any difference in the resulting model. Could you therefore please confirm again that you see a difference between using a blank NCAP_CEH and with NCAP_CEH=0?

On the other hand, I can well confirm that the emissions results will be different for the emissions defined per unit of input fuels, if you use NCAP_CEH=1. That is because the process efficiency will then represent the total energy efficiency, which become much smaller when keeping the same ACT_EFF parameter(s) but changing CEH from zero to 1.  This is as expected.  However, note that the various emissions specified for 'ACT' are in both cases defined for both members of the PG (electricity and heat), using directly the emission factor specified. This has been an intentional design choice for CHP, but I can see this may cause confusion, because for all other processes, emissions specified for 'ACT' are defined strictly per unit of activity.

Concerning the example CHP process you showed, you have probably intended to define the ACT-based emissions per electricity produced? If so, the easy fix to the problem is to keep NCAP_CEH=0 but define those emissions per the ELCHIG output instead of for 'ACT' (the 'ACT' probably resulting from using ENV_ACT).

In summary: I could not quite reproduce the problem, other than for the obvious difference between NCAP_CEH=1 and NCAP_CEH=0.  I suspect that the issue here is related the use of ENV_ACT for CHP, and if so, you can define FLO_EMIS on the electricity output instead, or maybe even better, define all emissions for the input fuels (because combustion emissions are in general proportional and specific to the input fuels used).

Please let me know whether that can resolve the problem for you or not.  And could you also confirm whether you are, in fact, seeing a difference between using a blank NCAP_CEH and with NCAP_CEH=0, because I could not reproduce such in my tests at all.

[dtsintsk]

Hello Antti, thank you so much for this thorough explanation. I was working on emissions a month ago, currently I am focused on some other parts of the model. I will soon get back to this problem and will inform you on everything. I can confirm that the first time I realized the problem was between definitions of CEH was when I was comparing in my results two facilities, where in one occasion, I had forgotten to give value to CEH, therefore it was blank and everything was okay for that facility, while for all those, where CEH=0, it was not okay