Charging with the sun…really!


Severin Borenstein at the University of California’s Energy Institute at Haas posted on whether a consumer buying an electric vehicle was charging it with power from renewables. I have been considering the issue of how our short-run electricity markets are incomplete and misleading. I posted this response on that blog:

As with many arguments that look quite cohesive, it is based on key unstated premises that if called into question undermine the conclusions. I would relabel the “correct” perspective as the “conventional” which assumes that the resources at the margin are defined by short-run operational decisions. This is the basic premise of the FERC-designed power market framework–somehow all of those small marginal energy increases eventually add up into one large new powerplant. This is the standard economic assumption that a series of “putty” transactions in the short term will evolve into a long term “clay” investment. (It’s all of those calculus assumptions about continuity that drive this.) This was questionable in 1998 as it became apparent that the capacity market would have to run separately from the energy market, and is now even more questionable as we replace fossil fuel with renewables.

I would call the fourth perspective as “dynamic”. From this perspective these short run marginal purchases on the CAISO are for balancing to meet current demand. As Marc Joseph pointed out, all of the new incremental demand is being met in a completely separate market that only uses the CAISO as a form of a day to day clearinghouse–the bilateral PPAs. No load serving entity is looking to the CAISO as their backstop resource source. Those long term PPAs are almost universally renewables–even in states without RPS standards. In addition, fossil fueled plants–coal and gas–are being retired and replaced by solar and wind, and that is an additional marginal resource not captured in the CAISO market.

So when a consumer buys a new EV, that added load is being met with renewables added to either meet new load or replace retired fossil. Because these renewables have zero operating costs, they don’t show up in the CAISO’s “marginal” resources for simple accounting reasons, not for fundamental economic reasons. And when that consumer also adds solar panels at the same time, those panels don’t show up at all in the CAISO transactions and are ignored under the conventional view.

There is an issue of resource balancing costs in the CAISO incurred by one type of resource versus another, but that cost is only a subcomponent of the overall true marginal cost from a dynamic perspective.

So how we view the difference between “putty” and “clay” increments is key to assessing whether a consumer is charging their EV with renewables or not.


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