Investigate need to impute missing hourly net generation in CEMS

In certain limited cases, some CEMS generators report heat input, but no gross generation or steam load in an hour, which seems to suggest that the gross generation data might be missing (if there is fuel consumption, there should in theory be some gross output).

We had previously implemented a function data_cleaning.impute_missing_hourly_net_generation(cems, eia923_allocated), but this is currently removed from the data pipeline.

To determine if we should address this we need to:

[ ] attempt to understand what might be going on in practice if there is heat input but no gross generation
[ ] Understand how common this is. If this only affects a small amount of heat input at a small amount of plants, it might not be worth spending a lot of time on (at least in the short run).

If/when we focus on this issue, one of the first changes we would need to implement to the existing function would be to perform the matching on the unit or subplant level rather than the plant level. One example of why this is important is the Ivanpah concentrating solar plant (plant id 57075), which primarily consumes solar energy, but also runs some fossil generation at night to keep the thermal storage warm.

singularity-energy / open-grid-emissions

Investigate need to impute missing hourly net generation in CEMS #32