Help using COM_TAXPRD

[Abdulaziz]

Hello,

I am trying to implement carbon tax using COM_TAXPRD.

Let us assume that carbon  tax is $50 per tonne.
The emissions are defined with commodity set and the unit is kilo-tonnes.

Then the value for COM_TAXPRD should be 0.05, right?

Thank you very much.

[Antti-L]

Depends on your currency unit.  If it is just "$", the tax input parameter for a tax of $50 per tonne should have the value 50,000. This is because your emission unit is kt, and the tax would be $50,000 per kilotonne.

However, note that it is recommended to :

  1) distinguish between currency units by year, e.g. CAD-2020 for Canadian dollars of 2020 value
  2) for better scaling of input data, use MCAD(2020) (millions of 2020 dollars) instead of CAD(2020)

Indeed, if the unit would be MCAD-2020, the value would then be 0.050 (but 50,000 if the unit is "$").

Furthermore, assuming that you want to impose a tax on true emissions, and not for e.g. any captured CO2 or CO2 used for electrofuels, I think you should define the tax with COM_TAXNET instead of COM_TAXPRD.  However, even though in most models VAR_COMNET does represent the emissions released into the atmosphere, it may also depend on the approach chosen for modeling various emission flows. But for example, the TIMES climate module only works when the total emissions are modeled with VAR_COMNET variables.