Obj value with tax/subsidy

[qzaus]

Hi, I am comparing the obj value of a scenario where I include tax/subsidy to incentivize the use of low-carbon technologies to a BAU scenario. Hence I get a model run with a lower objective value with lower GHG emissions, compared to a BAU scenario.

I am curious whether it will be possible to come up with a method to exclude the tax/subsidy values (imposed either through commodity or process flow) from the objective function so that I can calculate the cost of mitigating the GHG emissions.

I am able to track down all the tax/subsidy values, but they are all undiscounted. Thanks for your time.

[Antti-L]

Of course, just subtract the tax/subsidy components of the reported objective function by component (REG_WOBJ).
See the picture here for the cost component mapping: Cost mapping

[qzaus]

Of course, just subtract the tax/subsidy components of the reported objective function by component (REG_WOBJ).
See the picture here for the cost component mapping: Cost mapping

Thank you, Antti for providing the picture. Since the REG_WOBJ is discounted, should I first discount all the subsidy/tax values (Cost_comx, Cost_flox, Cost_Invx) and then subtract from REG_WOBJ? I did this (Cost_comx, Cost_flox, Cost_Invx in each region to the base year and subtract them from the REG_WOBJ component). Since the sum of all the REG_WOBJ values is the ObjZ of the system, if I subtract all the discounted subsidy/tax values directly from the ObjZ, I get the same result.

Just wondering whether I have missed anything. Thanks!

[Antti-L]

I am sorry, but I don't understand the question.
REG_WOBJ already includes the objective function components, split into the various cost and taxes/subsidies components.  So, to subtract the tax/subsidy components of the reported objective function by component, just exclude (unselect) those OBJ component(s) you want to be subtracted.

In other words, I cannot see why you would suggest to discount all the subsidy/tax values (Cost_comx, Cost_flox, Cost_Invx) and then subtract from REG_WOBJ, because you already have those discounted subsidy/tax values reported separately. Could you please explain what you are actually trying to do and why?  

[qzaus]

I am sorry, but I don't understand the question.
REG_WOBJ already includes the objective function components, split into the various cost and taxes/subsidies components.  So, to subtract the tax/subsidy components of the reported objective function by component, just exclude (unselect) those OBJ component(s) you want to be subtracted.

In other words, I cannot see why you would suggest to discount all the subsidy/tax values (Cost_comx, Cost_flox, Cost_Invx) and then subtract from REG_WOBJ, because you already have those discounted subsidy/tax values reported separately. Could you please explain what you are actually trying to do and why?  

Sorry if it's not clear. I have the subsidy/tax values (Cost_comx, Cost_flox, Cost_Invx), and I refer to the documentation part II and it says they are undiscounted. That's why I am thinking that I need to discount them and then subtract them from REG_WOBJ.

[Antti-L]

Yes, but the REG_WOBJ components are discounted.  So, why not just subtract from the total OBJ the relevant tax/subsidy components of REG_WOBJ, as they are already all discounted?  

[qzaus]

Yes, but the REG_WOBJ components are discounted.  So, why not just subtract from the total OBJ the relevant tax/subsidy components of REG_WOBJ, as they are already all discounted?  

I get it now. You are suggesting looking at what Cost_INVX... corresponds to the components in the REG_WOBJ and subtract from there. No need to use the undiscounted components anymore. So much easier than I thought. Thanks very much!