I got the results of total CO2 emission in 2050. The total CO2 emissions include upstream emissions (NGCO2) from natural gas mining and downstream emissions (NH3CO2) from ammonia production technologies. In 2050, only two technologies are deployed under a high carbon price case, which are water electrolysis and ATR_CCS_New. Therefore, the only source for NH3CO2 emission is from ATR_CCS_New and the emission factor is 0.12 t CO2/t NH3. When I check the total NH3CO2 value, which is 513080.97 t CO2, then I back calculated the emission factor of ATR_CCS_New that equals to 513080.97/2640000 (this is the ammonia amount produced from ATR_CCS_New in 2050)=0.19 t CO2/t NH3. Why the CO2 emission factor is not consistent? I may put something wrong in the model but I cannot find the bug so far. Looking forward to explanations and solutions!!
13-05-2023, 10:47 PM (This post was last modified: 14-05-2023, 01:12 AM by Antti-L.)
First of all, you have some ugly domain violations in your model, due to placing SysSettings before Base in the VEDA Case settings. SysSettings should always be placed after base and any Subres scenarios. Fortunately, you were lucky in your test case, as it had no impact on the solution.
Concerning your question "Why the CO2 emission factor is not consistent?", you are just jumping to a false conclusion, which is explained below.
>In 2050, only two technologies are deployed under a high carbon price case, which are water electrolysis and ATR_CCS_New.
Yes, correct. Moreover, the ATR_CCS_New process is a vintage process, and it has capacity installed only of a single vintage, namely 2021.
>Therefore, the only source for NH3CO2 emission is from ATR_CCS_New and the emission factor is 0.12 t CO2/t NH3.
No, that is not correct. It is indeed the only source for NH3CO2, but the correct emission factor is 0.194349 t CO2/t NH3. For the 2050 vintage, the emission factor would be 0.12, but in your model, all of the ATR_CCS_New capacity is of the 2021 vintage, which has the emission factor 0.194349 (directly from your model data).
>I back calculated the emission factor of ATR_CCS_New that equals to 513080.97/2640000 (this is the ammonia amount produced from ATR_CCS_New in 2050)=0.19 t CO2/t NH3.
Yes, correct. That is the correct emission factor according to your input data (including the vintaged characterization).
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As illustrated above, FLO_EMIS is a vintage-specific attribute, like many others in TIMES. That means that when you define a process vintaged, the technical characteristics modeled with those vintage-specific attributes will remain at their original values throughout the lifetime of each vintage, unless they are shaped according to age (or in some cases, provided with a year multiplier).
I am not quite sure what is the actual reason behind the process-specific emission factors decreasing over time in your model. I would think that usually such emission factors should, indeed, be tied to the process vintage (because reducing emissions would usually require technical changes in the process). However, I guess there could be some cases where emission factors can be assumed to decrease over time even during the lifetime of a given singe process vintage. Maybe you can explain if that is the case in your model?
If you are sure that such emission factors decreasing over time, regardless of the vintage, would be valid for your model, there are several options you can consider:
• Model the process as a non-vintaged process, if appropriate
• For vintaged process, you could shape the emission factors according to age
• For vintaged process, you could define the emission factor by FLO_FUNC instead of FLO_EMIS, and requesting a non-vintaged coefficient via FLO_FUNCX
• If the reduction in the emission factor results from a change in the quality of some inputs, you could consider modeling the emissions upstream of the vintaged process.
If you need assistance in using any of the options, please let me know. But for now, as I don't even yet know whether the emission reduction should actually be vintage-specific or not, I cannot really suggest any individual option. Therefore, can you first explain what is the explanation for the decrease in the CO2 emission factor of ATR_CCS_New? For example, if it happens to be related to assumed specific emissions of electricity generation, I would say a better approach would be to model those electricity emissions upstream of the ammonia production, where the electricity is produced/supplied.
(13-05-2023, 10:47 PM)Antti-L Wrote: First of all, you have some ugly domain violations in your model, due to placing SysSettings before Base in the VEDA Case settings. SysSettings should always be placed after base and any Subres scenarios. Fortunately, you were lucky in your test case, as it had no impact on the solution.
Concerning your question "Why the CO2 emission factor is not consistent?", you are just jumping to a false conclusion, which is explained below.
>In 2050, only two technologies are deployed under a high carbon price case, which are water electrolysis and ATR_CCS_New.
Yes, correct. Moreover, the ATR_CCS_New process is a vintage process, and it has capacity installed only of a single vintage, namely 2021.
>Therefore, the only source for NH3CO2 emission is from ATR_CCS_New and the emission factor is 0.12 t CO2/t NH3.
No, that is not correct. It is indeed the only source for NH3CO2, but the correct emission factor is 0.194349 t CO2/t NH3. For the 2050 vintage, the emission factor would be 0.12, but in your model, all of the ATR_CCS_New capacity is of the 2021 vintage, which has the emission factor 0.194349 (directly from your model data).
>I back calculated the emission factor of ATR_CCS_New that equals to 513080.97/2640000 (this is the ammonia amount produced from ATR_CCS_New in 2050)=0.19 t CO2/t NH3.
Yes, correct. That is the correct emission factor according to your input data (including the vintaged characterization).
---------------
As illustrated above, FLO_EMIS is a vintage-specific attribute, like many others in TIMES. That means that when you define a process vintaged, the technical characteristics modeled with those vintage-specific attributes will remain at their original values throughout the lifetime of each vintage, unless they are shaped according to age (or in some cases, provided with a year multiplier).
I am not quite sure what is the actual reason behind the process-specific emission factors decreasing over time in your model. I would think that usually such emission factors should, indeed, be tied to the process vintage (because reducing emissions would usually require technical changes in the process). However, I guess there could be some cases where emission factors can be assumed to decrease over time even during the lifetime of a given singe process vintage. Maybe you can explain if that is the case in your model?
If you are sure that such emission factors decreasing over time, regardless of the vintage, would be valid for your model, there are several options you can consider:
• Model the process as a non-vintaged process, if appropriate
• For vintaged process, you could shape the emission factors according to age
• For vintaged process, you could define the emission factor by FLO_FUNC instead of FLO_EMIS, and requesting a non-vintaged coefficient via FLO_FUNCX
• If the reduction in the emission factor results from a change in the quality of some inputs, you could consider modeling the emissions upstream of the vintaged process.
If you need assistance in using any of the options, please let me know. But for now, as I don't even yet know whether the emission reduction should actually be vintage-specific or not, I cannot really suggest any individual option. Therefore, can you first explain what is the explanation for the decrease in the CO2 emission factor of ATR_CCS_New? For example, if it happens to be related to assumed specific emissions of electricity generation, I would say a better approach would be to model those electricity emissions upstream of the ammonia production, where the electricity is produced/supplied.
Hi Antti,
Thanks for your reply. Your explanations are really clear. I think I can simply change the ATR_CCS_New as a non-vintaged process. For the emission change in the this process over time, it is the reason of electricity emission reduces over time. I can remodel the emission of electricity as a upstream emission for ammonia production.
