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CCHP
#1
Dear All,


I put a CCHP (Combined Cooling Heating and Power) system on SubRES_New-CCHP in my model, but I little bit confused about how TIMES can calculate the joint cost for each commodity. Can someone please explain this to me? Thank you.
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#2
what attributes have you used to characterize the Process. Can you elaborate the question a bit? "joint .. for each" is confusing.
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#3
In TIMES, process-specific costs are accounted in terms of direct costs at each individual process. Thus, the costs of producing any input commodities are not accounted at the processes consuming these commodities, but at the upstream processes producing those commodities.

The total (variable) cost of producing three outputs at quantities q1, q2 and q3 can be expressed by the Joint Cost Function JC=F(q1,q2,q3). In TIMES, this joint cost function for the direct variable costs is quite simple, and can be in simplified terms written as follows:

JC = VAR_ACT×ACT_COST + SUM(ICi, VAR_FLO(ICi) × FLO_COST(ICi)) +
                 SUM(OCj, VAR_FLO(OCj) × FLO_COST(OCj))


Here, ICi denotes the input commodities i, and OCj denotes the output commodities j. How all these commodity flows and the activity relate to each other is defined by the modeller, by using various process transformation and efficiency parameters (and CHP parameters, if they are used), as explained in the documentation.  For example, the modelling of CHP operation when using the dedicated CHP parameters is described there in detail.

Investment and fixed costs are not included in such operational joint cost function, but are related to the capacity requirements, normally defined by the process activity.

I fully agree with Amit that you could elaborate the question a bit furher, and also show which attributes you have used to characterize the Process.
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#4
Dear Amit & Anty

I try to input CCHP model by using TIMES Demo template no. 009 (SubRES_New-CHP-DH) by using Backpressure mode. In the left-hand of ~FI_T table, natural gas as commodity input, and the commodity outputs are electricity, heating, and cooling. While in the right-hand of ~FI_T table, I put efficiency (EFF) for each commodity, CHPR~FX (I declared it as 1.2), and INVCOST, FIXOM, VAROM, LIFE, CAP2ACT, and PEAK.

I need your kind advices to help me understand modeling a CCHP in a tropical country (cooling demand > heating demand).
Thank you in advance.


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#5
To start with, browse this process in VEDA. Please remember that this step (browse) is compulsory to make sure that things have been understood the way you intended.
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#6
Well noted, Amit
Thank you
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#7
Ok, so you are trying to use the Backpressure mode example in the TIMES Demo template no. 009 for modelling a CCHP process.

As explained in the documentation, if CEH is zero or missing as in that example, the activity represents the electricity generation and the capacity represents the electrical capacity. So, the parameter EFF=0.4 in the example represents the electrical efficiency.  And the ratio of heat produced to electricity produced is defined by a fixed CHPR=1.2, and therefore the "heat efficiency" and the total CHP efficiency are both then implicitly defined. The total efficiency is EFF × (1+CHPR) = 0.88.

In your case, you have three outputs (ELC, HET, COL), which apparently are all in the PG. You have decided to use the same CHPR (and no CEH) as in the example. That means that your activity would still represent the electricity generation, and the capacity is the electrical capacity.  But as you have two non-electricity outputs, CHPR now represents the ratio of (HET+COL) / ELC.  EFF = x would still represent the electrical efficiency. However, you have defined three different values for EFF, 34.86%, 49.92% and 0.18%. I am not able to see what is the intended purpose of these three values, but clearly, the current specification with three different values for the electrical efficiency is incorrect.

In the outputs, the share of electricity is fixed (45.5%), but the mix of HET and COL is flexible in the remaining output (54.5%), unless you define an additional constraint for bounding their shares. You could use FLO_SHAR to define any desired bounds for the HET / COL shares (normally at the process timeslice level, but also annually if desired).
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#8
Dear Anty,

I try to fix it, thank you for helping Smile
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