Renewable Certificate Tracking Zones

PR #614 introduced Renewable Energy Certificates (REC) when implementing the RPS constraint. My question is the regions included when calculating the RECs.

I am def not an expert on RECs, but I understood the EPA regulations to be applied to the entire trading regions (for example WREGIS); regardless if the state within the trading region has a RPS. But I believe we calculate the demand based at a state level (rather than trading zone level).

https://github.com/PyPSA/pypsa-usa/blob/8befa84b0b1d9c492d87c763a26e27198195f624/workflow/scripts/opts/policy.py#L289-L314

For example, consider that if the two RPS are configured as given below:

I think the current functionality is:

(Gen_CA renewables) + (Gen_OR renewables) >= (Load_CA * 0.50) + (Load_OR * 0.50)

But it seems like based on the EPA literature, it should be:

(Gen_CA renewables) + (Gen_OR renewables) + (Gen_WA renewables) + (Gen_AZ renewables) + (Gen_NV renewables) + [remainder of states in WREGIS] >= (Load_CA * 0.50) + (Load_OR * 0.50)

@ktehranchi any thoughts? I may just be misunderstanding either the implementation logic and/or the EPA rules! I also do get if we balance at a trading level, that comes with its own issues. For example, having to track RECs by carrier, or how to balance if you run models with only a subset of regions, ect.

Start with workflow/scripts/opts/policy.py lines 289-314 and the linked EPA energy-attribute tracking guidance. Compare the current state-level REC calculation with the proposed trading-region interpretation, including the implications for partial-region models and carrier tracking. Done requires an agreed regional accounting rule and a corresponding implementation plan.