negative emission - land use

[srchlela]

Hello, 

I am representing the land use emissions/removals thus I defined the according processes that have only an emission commodity as output "AGRCO2P". 
Note that this commodity is also emitted by other processes in the model. 

Then, I created a UC_FLO for fixing the values throughout the time horizon. 

My questions would be: 

• I need to have negative values. How can I set "AGRCO2" to be negative in this case ?
  


• Is it better to declare a dedicated emission commodity ?
  

Thanks a lot for your help 

Sophie

[Antti-L]

> I defined the according processes that have only an emission commodity as output "AGRCO2P".

Carbon dioxide removals can be modeled either by processes consuming CO2 (often TOTCO2, but could be some sectoral CO2 commodity as well), or by processes producing negative amounts of CO2 (TOTCO2 or sectoral CO2).  I have usually found it convenient to model such processes with CO2 consumption, because then they are more clearly distinguished in the emission balances:

   Net CO2 emissions  = Gross production − Consumption =  Emission Sources − Emission Sinks

However, of course modeling with negative output emissions is equally possible. Do you mean that in your case these process(es) should have a negative output of AGRCO2P?  If so, the output cannot be the PCG (PCG flows cannot be negative), but it should then best be modeled by using a negative FLO_EMIS on either PCG or some other process flow.  From your description it is not clear to me how these processes are thought to be modeled.

> Then, I created a UC_FLO for fixing the values throughout the time horizon.

Sorry, not quite sure what you mean by "fixing the values throughout the time horizon" here, and why that UC is needed.

> I need to have negative values. How can I set "AGRCO2" to be negative in this case ?

Here, I am not sure what you mean. Do you mean the process flow of AGRCO2, or the aggregate Net amount of AGRCO2?  If you mean the process flow, it would be a positive flow if modeled with CO2 consumption, and negative only if you want to model it as an output production flow.  As said above, if the AGRCO2 flow is modeled as a negative output, then it cannot be the PCG, but should be modeled by using a negative FLO_EMIS on either PCG or some other process flow. However, if you mean that the aggregate Net amount of AGRCO2 should be allowed to go negative, you can enable negative Net AGRCO2 by using COM_BNDNET for defining negative lower bounds for VAR_COMNET(r, t, AGRCO2).

> Is it better to declare a dedicated emission commodity ?

That could be useful in some cases (it might make reporting and policy modeling easier), but I don't see any need for such based on your description.

[Neha Jaggeshar]

Hi, 

I am working with land-use emissions and removals and encountered an issue with how forest carbon sinks are being calculated - the sink is being linked to the activity of harvesting processes. As a result, sequestration is calculated only for the harvested area needed to meet roundwood demand, not the total standing forest.

--> Forest chain overview in my model:
FORLANDPOT → FORLAND_Hub → AFORNATREG / AFORPLAN → AFORRWOOD_NAT / AFORRWOOD_PLN → downstream processing (AFORRWOOD_PROC, wood products, residues)
Harvested land (VAR_Act) drives roundwood production.
FORSINKCO2 is currently attached to the harvest activity (VAR_Act) rather than the total forest stock. 

Is there another method i could model CO₂ removals from standing forests so that sequestration is based on total forest stock and not linked to harvesting activity?


Thanks, 
Neha

[srchlela]

Dear Neha,

Thank you for your message.

Since I use TIAM with the climate module, the forest sink value is included in the biosphere reservoir.
For the land-based carbon dioxide removal, my processes are linked to the reduction of deforestation with respect to the base year and the afforestation activity.
In other terms, the variation in forests and land-use are what can alter the forest sink and have effect on carbon removal. Are you representing the competition with agriculture activities or the forest fires?


Kind regards,
Sophie Chlela