Part 2: What’s up with the new 100% ZEV mandate in California? An Internal Stillwater Conversation

September 24, 2020 By ,

September 24, 2020
By Kendra Seymour

Yesterday, shortly after California’s governor Gavin Newsom announced his Executive Order mandating 100% ZEV car sales by 2035, I caught up with a few of my colleagues via Slack to get a better understanding of the issues around electrification. Thinking that this dialogue might be of interest to our readers, we published that initial back-and-forth. Our conversation spilled over into today, though, so here is Part 2. The conversation has been edited for clarity and length.

Slack conversation morning of Thursday, September 24, 2020

Kendra Seymour: So, my real burning question from yesterday has not yet been answered: In a future world with 100% renewable electricity mix (which is the goal, if I’m not mistaken), would EVs then offer more carbon- and emission-reduction benefits than diesel engines running on RD/BD? And, secondly, at what grid-average CI (or at what level (%) of renewable electricity generation) do EVs outperform their ICE peers on a car-to-car basis. This is what I was trying to get at with my Oregon questions, but we got sidetracked.

Adam Schubert: All current RD and BD pathways have a positive CI. Accordingly, a diesel vehicle fueled on 100% RD/BD would have higher emissions than an EV charged with 100% renewable power. In principle, however, it is possible to produce RD and BD with a negative CI; that would require a pathway including several elements such as a very low, or negative, CI feedstock, renewable hydrogen (for RD) or renewable methanol (for BD), renewable power, renewable fuel at the plant, carbon capture and storage, etc. A diesel vehicle fueled with 100% negative CI RD/BD would have lower emissions than an EV charged with 100% renewable power. (It is, of course, also possible to produce negative CI electricity through generation from negative CI RNG or waste biomass diverted from a landfill with carbon capture, etc. – current power market regulations, however, generally focus on whether or not production is renewable and don’t provide incentives for production of negative CI electricity.)

Kendra: Got it. One last stream of thoughts before I call it a day: I understand that for the purposes of this conversation (and for CEC’s / CARB’s purposes, too) we’ve been comparing EVs to RD/BD based on the calculated carbon intensities of each. It’s important to note, however, that these calculations don’t count the tailpipe emissions from RD because it is renewable carbon (would have eventually been emitted anyway) rather than petroleum (which could stay sequestered but for our drilling. In reality, though, diesel vehicles running RD do emit GHGs from their tailpipes, and if we just didn’t turn those feedstocks into RD, they might not be produced in the first place (meaning the carbon was generated in order to be burned as RD and could otherwise be avoided). EVs, meanwhile, have no tailpipe emissions. Their carbon intensity comes entirely from the method of generating the electricity used to charge them. As such, it makes sense to me that in a world with 100% renewable energy, EVs would be far more beneficial to the environment than even the GREET calculation would show? An EV charged on electricity produced using RNG with a negative CI (like dairy biogas), for example, might actually have a negative lifecycle carbon footprint (meaning it would be cleaning the air of powerful GHGs like methane). Point being: It seems to me that RD is given an artificial “boost” in the lifecycle CI calculation compared to ACTUAL carbon reduction. So we can discuss calculated benefits all we want, but real world benefit may be different.

Adam: If the crop grown to produce RD was not grown, then it wouldn’t have pulled CO2 out of the air.  The only net CO2 savings associated with not growing the crop are from less fossil-derived fertilizer used, less diesel used to power the tractor and haul the crop to market, etc.

Kendra: But that crop could still be grown and then used in a way that wouldn’t generate tailpipe emissions, right?

Adam: Unless it was converted into a non-biodegradable plastic, the crop would decompose into CO2 and water one way or another.

Kendra: Ok. Makes sense. In the case of UCO or tallow, though, could we not compost it (sequestering the carbon in the soil?) or decrease the quantity of cattle raised (which is already happening due to decreasing demand for beef as food, etc.)

Adam: Cattle aren’t raised to produce tallow, so we wouldn’t grow fewer cows if the tallow was not used for RD.  Composting it, it still biodegrades, just more slowly.

Kendra: Yeah, I get that we wouldn’t raise fewer cattle because of decreased demand for tallow… I’m just saying that if fewer cattle are being raised for other reasons (mostly environmental but for reasons other than the tallow aspect), then that “new carbon” isn’t being created and then burned, exiting via a tailpipe. (Yes, I know I’m getting granular. I promise I’ll stop soon. This really does point toward painting the bigger picture….)

Adam: The only way new carbon is created in the ecosphere is if we mine fossil fuels. Everything else we do just circulates carbon that’s already present.

Kendra: Right! Excellent reminder.

Miriam Stern: My head is spinning, but this is all great info. There’s a big variety of electric and hybrid vehicles around here in northern California, and we all charge our cars overnight because, as I understand it, it puts less strain on the grid and is also/therefore cheaper. But, if I understand Gary correctly, electricity generated at night has the highest CI. So, if I wanted to use “greener” electricity what time of day would I charge?

Adam: Early evening is highest demand, when it’s still hot, people are home and awake. Middle of the night is lowest demand, most people are sleeping, temperatures are cooler and most businesses are closed.

Kendra: So, middle of the night is lowest demand, but not necessarily the “greenest” electricity hours. Right?

Adam: Depends on where you are. No solar and much less wind during the night. Coal, nuclear and geothermal tend to run relatively constant rates. Hydro can be adjusted somewhat, gas-fired can be quickly adjusted up or down. So, it depends on the local mix.

Leigh Noda: 4 PM to 9 PM is the period that is not good for charging EVs since that’s when solar is on the decline and the demand goes up when people get home from work. The best time is midday when there is actually an excess of solar. In fact, the California Independent System Operator (CAISO) which oversees the operation of California’s bulk electric power system, transmission lines, and electricity market generated and transmitted by its member utilities, has had to pay other states to take that surplus power. This video explains it well.

Miriam: I wonder if that is still the case with most of the Bay Area working from home.

Adam: EIA data says electric demand has not really changed with the pandemic; commercial and industrial use are down but residential increased to largely offset that.

Miriam: Makes sense.

Kendra: Makes sense to me, too! I’m gonna sign off for the day. As always, thanks for the enlightening conversation!

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