01-06-2019, 06:52 PM
Thank you Antti for your reply.
I have a few questions based on my observations with my model and the answers provided by you. Please find my responses and further queries below each point. Could you kindly clarify? I have mentioned the name of the processes wherever I am mentioning a problem.
For your reference, I am attaching my base year templates, sub_Res file, .dd and .run files.
For your information, I am trying to model hydrogen storage. One for a hydrogen refuelling station for transport (in this case I want to represent my storage in terms of maximum hydrogen that could be stored at a time) and other for the industrial feedstock hydrogen (in this case I am representing storage capacity in terms of stored hydrogen in a year).
1) If you define any NCAP_AFC (i.e. a flow-based availability factor), your capacity will be flow-based. To have the capacity instead represent the amount of storable energy, you should not define it to be flow-based. And, when the capacity is the amount of storable energy, of course the Var_Fin, Var_Fout and Var_Act are usually all larger than the capacity (unless you would have only a one storage cycle in a year/season). For example, many batteries are typically charged/discharged on a daily basis, and not only once per year or season. For a DAYNITE storage, the input/output flows thus obviously become usually much larger than the capacity, as described in the documentation. For example, if the summer season is 92 days long, and the DAYNITE cycle under it is a representative summer day, assume that a certain storage is fully charged and discharged once each day. Then the input/output flows within the summer would be 92 times as high as the capacity.
Yes, now I understand the logic. Thanks for this. But there is an observation in my model results. In some years, I have Var_FIn, Var_Fout and Var_Act (extremely small values, like 0.00004). But Var_cap is not reported (Process is HYGNSTG_new). Is this possible? This means my INVCOST is also 0 which should not be the case. In this case, I have not defined NCAP_AFC and I want my storage capacity to represent the maximum energy that can be stored. Also, the process set membership is inputted as STS.
2) I am not able to confirm you findings. If I put NCAP_AFC=1 (and STG_EFF=1, PRC_CAPACT=1), I am getting capacity equal to Var_Fout as you said, but if I define NCAP_AFC=0.33, I am getting capacity equal to Var_Fout/0.33. Thus, I am not seeing the capacity unit changing from PJ to GW, as you claimed. Please provide a reproducible test case demonstrating the issue.
In the example provided in the advanced documentation, NCAP_AFC is 0.33. But in the results shown in page number 27, I cannot see such a relationship between Var_Fout and Var_Cap. Here there is a small efficiency loss. I guess here the Var_Cap in GW units unlike PJ which is the unit of Var_Fout. I found that there is a CAP2ACT 31.536 defined. So now I understand.
I have another observation. When I define the process as STS, NCAP_AFC=1 and eff=1, in some years my Var_Cap is higher than Var_Fout (Process I have checked is HYGNINDSTGcap_new). But this is not happening when I define my storage process as STG. Why this is so?
3) You are not saying which table you are using (e.g ~TFM_INS, ~FI_T), but looking at 2), it looks like you are already able to define NCAP_AFC. There is no difference in defining it for the input or output commodity (unless they are the same, but you said you have them different). Thus, I don't quite understand the question, and perhaps it would indeed be better to post it on the VEDA Forum. Anyway, I just made a quick test with a ~TFM_INS, and specifying the commodity for NCAP_AFC worked equally well both in the Cset_CN and the Other_Indexes column.
Sorry, my table is ~FI_T .
4) The PCG of a storage process should include the charged and discharged commodities. So, if you have com1 as a charged commodity and com2 as a discharged commodity, you should thus define them both in the PCG. If they are both of type NRG, usually defining PCG=NRG would be the best choice.
Thanks for clarifying this.
5) Yes, if STG_EFF=1 and STG_LOSS=0 and PRC_ACTFLO©=1, Var_Act (T1)+Var_FIn(T1)−Var_FOut(T1) = Var_Act(T2), in consecutive time slices T1 and T2, as you can see from the equation formulation presented in the documentation.
I checked my results for this. But in some time slices (I have 20*24=480 time slices), I am getting a small difference. For example, my Var_Act(T1)+ Var_FIn(T1)-Var_FOut(T1)-Var_Act(T2) is not always 0. I am getting numbers like 0.0002 in some time slices. Is that possible? I have tried this by defining storage process as both STG and STS. This is violated more when the process is defined as STS (Process I have checked is HYGNINDSTGcap_new). I understand that for STS, the storage can be carried over between seasons.
I have a few questions based on my observations with my model and the answers provided by you. Please find my responses and further queries below each point. Could you kindly clarify? I have mentioned the name of the processes wherever I am mentioning a problem.
For your reference, I am attaching my base year templates, sub_Res file, .dd and .run files.
For your information, I am trying to model hydrogen storage. One for a hydrogen refuelling station for transport (in this case I want to represent my storage in terms of maximum hydrogen that could be stored at a time) and other for the industrial feedstock hydrogen (in this case I am representing storage capacity in terms of stored hydrogen in a year).
1) If you define any NCAP_AFC (i.e. a flow-based availability factor), your capacity will be flow-based. To have the capacity instead represent the amount of storable energy, you should not define it to be flow-based. And, when the capacity is the amount of storable energy, of course the Var_Fin, Var_Fout and Var_Act are usually all larger than the capacity (unless you would have only a one storage cycle in a year/season). For example, many batteries are typically charged/discharged on a daily basis, and not only once per year or season. For a DAYNITE storage, the input/output flows thus obviously become usually much larger than the capacity, as described in the documentation. For example, if the summer season is 92 days long, and the DAYNITE cycle under it is a representative summer day, assume that a certain storage is fully charged and discharged once each day. Then the input/output flows within the summer would be 92 times as high as the capacity.
Yes, now I understand the logic. Thanks for this. But there is an observation in my model results. In some years, I have Var_FIn, Var_Fout and Var_Act (extremely small values, like 0.00004). But Var_cap is not reported (Process is HYGNSTG_new). Is this possible? This means my INVCOST is also 0 which should not be the case. In this case, I have not defined NCAP_AFC and I want my storage capacity to represent the maximum energy that can be stored. Also, the process set membership is inputted as STS.
2) I am not able to confirm you findings. If I put NCAP_AFC=1 (and STG_EFF=1, PRC_CAPACT=1), I am getting capacity equal to Var_Fout as you said, but if I define NCAP_AFC=0.33, I am getting capacity equal to Var_Fout/0.33. Thus, I am not seeing the capacity unit changing from PJ to GW, as you claimed. Please provide a reproducible test case demonstrating the issue.
In the example provided in the advanced documentation, NCAP_AFC is 0.33. But in the results shown in page number 27, I cannot see such a relationship between Var_Fout and Var_Cap. Here there is a small efficiency loss. I guess here the Var_Cap in GW units unlike PJ which is the unit of Var_Fout. I found that there is a CAP2ACT 31.536 defined. So now I understand.
I have another observation. When I define the process as STS, NCAP_AFC=1 and eff=1, in some years my Var_Cap is higher than Var_Fout (Process I have checked is HYGNINDSTGcap_new). But this is not happening when I define my storage process as STG. Why this is so?
3) You are not saying which table you are using (e.g ~TFM_INS, ~FI_T), but looking at 2), it looks like you are already able to define NCAP_AFC. There is no difference in defining it for the input or output commodity (unless they are the same, but you said you have them different). Thus, I don't quite understand the question, and perhaps it would indeed be better to post it on the VEDA Forum. Anyway, I just made a quick test with a ~TFM_INS, and specifying the commodity for NCAP_AFC worked equally well both in the Cset_CN and the Other_Indexes column.
Sorry, my table is ~FI_T .
4) The PCG of a storage process should include the charged and discharged commodities. So, if you have com1 as a charged commodity and com2 as a discharged commodity, you should thus define them both in the PCG. If they are both of type NRG, usually defining PCG=NRG would be the best choice.
Thanks for clarifying this.
5) Yes, if STG_EFF=1 and STG_LOSS=0 and PRC_ACTFLO©=1, Var_Act (T1)+Var_FIn(T1)−Var_FOut(T1) = Var_Act(T2), in consecutive time slices T1 and T2, as you can see from the equation formulation presented in the documentation.
I checked my results for this. But in some time slices (I have 20*24=480 time slices), I am getting a small difference. For example, my Var_Act(T1)+ Var_FIn(T1)-Var_FOut(T1)-Var_Act(T2) is not always 0. I am getting numbers like 0.0002 in some time slices. Is that possible? I have tried this by defining storage process as both STG and STS. This is violated more when the process is defined as STS (Process I have checked is HYGNINDSTGcap_new). I understand that for STS, the storage can be carried over between seasons.