It's not a given that increased load is going to be disproportionally dirty. Wind farm output typically peaks at night. Wind is a great match for night time battery energy vehicle charging and it has the lowest life cycle CO2 footprint of any electricity source:
I do like your emphasis on marginal effects. As renewables and BEVs grow it will be a balancing act to pick the most marginally effective resources for emissions abatement. California may soon reach a point where an additional dollar invested in solar doesn't abate as much CO2 as the same dollar invested in transmission, storage, or wind -- even if solar has the lowest instantaneous generation cost.
Is this generally true, or does it depend on geography (e.g. being near the coast)? Where I am in the midwest, it seems that the air normally gets very calm after sunset.
I think that it is generally true for land based turbines. Turbines are so tall that wind conditions at hub height can't be easily estimated by what we experience on the ground. Here's a somewhat dated study that shows hourly patterns for wind generation on the ERCOT grid in Texas, which has the largest wind fleet of any state:
"The Relationship between Wind Generation and Balancing-Energy Market Prices in ERCOT: 2007–2009"
See Figure 5. Hourly generation reaches a minimum from about 1:00 to 5:00 PM and reaches its maximum around 1:00 AM.
Offshore wind output changes less from short term day-night cycles, and generally achieves a higher capacity factor. It is also more expensive to build than onshore wind and no large projects have yet been built for the US, though several are on the drawing board.
https://en.wikipedia.org/wiki/Life-cycle_greenhouse_gas_emis...
I do like your emphasis on marginal effects. As renewables and BEVs grow it will be a balancing act to pick the most marginally effective resources for emissions abatement. California may soon reach a point where an additional dollar invested in solar doesn't abate as much CO2 as the same dollar invested in transmission, storage, or wind -- even if solar has the lowest instantaneous generation cost.