Sherry I understand the point you're trying to bring out, but am dismayed at your uncritically repeating the misleading marketing euphemism "100% carbon free." While different in degree and subtlety, this resembles in kind the mind-set of some electric-vehicle owners who think their cars lack carbon footprint, because the carbon burden is out of sight and mind. Renewable energy sources can certainly be cleanER than classic fossil-fuel plants (though with some exceptions even there), but that isn't the same as genuinely carbon-free.

To seriously call wind, hydro, or solar power generation systems "carbon-free" requires examining them in isolated operation, as if the equipment (a) came into existence by magic and lasts forever, and (b) is not actually sourcing power into a wholesale grid. You then deliberately neglect the carbon-emission costs of, respectively, (a) manufacture, maintenance, and decommissioning ("life cycle"), and (b) indirect consequences of use as wholesale power sources.

Wind and solar sources have their own issues. (1) wind generation is unpredictable ("chaotic"), so to provide the stability required for wholesale use, it's customarily backed-up by associated fossil load-following plants of the same capacity; those plants' fast-start features render them less clean than conventional counterparts. (This inherent problem is sometimes, lately, obscured by accounting games.) Solar generation is increasingly problematic, as California's large volume of it increasingly swamps demand, collapsing wholesale market prices (there is nowhere to sell the excess). Even hydroelectic power entails lifetime and maintenance-related carbon footprints.

Again: These sources can be genuinely cleaner, but it is not nearly as simple as clean vs. unclean, or "100% carbon-free."

@Max -- Great point, and I agree! These sources are not carbon free, either in their production or in their lifecycle. Storage, as you point out, is becoming critical, and can be carbon-intensive, though options are developing. For example, excess renewable power can be used to create hydrogen fuel (for storage) or push water uphill for hydropower at a later time (sounds nuts, but they are doing that today at pumped hydro facilities, four of which are in California). And building and maintaining these renewable (or non-renewable) plants causes emissions. One promising thing on that front is that, starting in 2020, retail power suppliers will report their emissions.

I do plan to cover the issue of storage soon, and the issue of implicit costs (e.g., plant development) some time later. But until then, I will add a footnote to this blog post.

Embarrassed to report my results on the quiz--none right on the first, half right on the issue of 2012 ( I got the drought) and half right on the third--got Weaverville and Healdsburg. But I learned something from this as well as from Max Hauser's comment.

We can all help by consuming less power. Turn off the lights when you leave the room. Unplug appliances that have LEDs and clocks (why?) that run constantly. These are energy vampires. If you are not using it, turn it completely off.

More importantly, if you want to reduce carbon emissions, drive less. The biggest source of Bay Area carbon emissions is transportation. Bike and walk more for shorter trips. Ride transit when you can. (You have to know local bus, train and shuttle schedules to this, but that's not so hard.)

Max Hauser and We're all in this together nailed it. Other than the small contribution from in-city solar during daylight, all our electric power comes from the same grid as our neighbors tap into. Turning on a light in Palo Alto causes the same incremental increase in carbon emissions as turning on an identical light in Menlo Park, Mountain View, etc. Not turning on that light in any of those cities avoids that CO2 emission spike.

That's plain physics. Accounting gimmicks like RECs have no effect on actual emissions. We gotta quit fooling ourselves with comforting mirages and get with realizing a true carbon-free state grid. Well-regulated modern nuclear is our best option.

And many thanks for providing this forum.

@Curmudgeon -- So glad that you are enjoying the forum, and thank you for contributing!

You say that "all our electric power comes from the same grid as our neighbors tap into". Do you want to add a level of detail to that, and/or a reference? The utilities around here do share some of the same transmission lines. But the (contractual) sources for the power are generally different, and they are all very explicit about these. (Managing their power portfolio is what they spend much of their time on, partly because there is a thicket of regulations around it, and partly because it is the heart of their business.) I view contracts as pretty meaningful, and many of them are long-term, which also entails a good amount of risk and investment. It's also the case that PCE, SVCE, and Palo Alto all own some of their own power facilities, but imo that is not necessary to have meaningful ownership for the energy they are contractually purchasing.

Unbundled RECs are indeed controversial, but those are not lately an issue, at least in our area. Max is likely talking about something more subtle, which can happen even when no unbundled RECs are involved, related to how we account for emissions throughout the day and year. The next blog post will be about PCE (Peninsula Clean Energy) -- the CEO there, Jan Pepper, has some very audacious goals in this regard, having worked in/around the utility industry for 30 years. The trick is to be clean in a way that doesn't require anything else to be dirty.

Nuclear is also controversial, and imo a very interesting topic. I can't figure out if I should cover it before or after population growth :)

BTW I think a very weird thing that Palo Alto does is claim carbon-neutral gas. The electricity claim is a very real one. But the gas is just weird, and arguably besmirches the (real) electricity story by association.

Purchasing indulgences always seemed weird to me too. Guess I'm a denier.

Here is a very helpful reference for the topic that @Curmudgeon is alluding to, namely whether any electricity not purchased on-site ("behind the meter") can be considered green. IMO of course it can. You can see how in this case they use the concept of additionality to think about whether their "clean" purchases just result in someone else's "dirty" purchases. In general, the point is that you want (aggregated) marginal clean purchases to increase supply. Supply is increasing like crazy. Would that happen without the power market?

"You say that "all our electric power comes from the same grid as our neighbors tap into". Do you want to add a level of detail to that, and/or a reference?"

CPAU can confirm that to you. It is also shown on the maps available at Web Link specifically Web Link Our power comes in at the Colorado gateway via a PG&E line from the Cooley Landing PG&E substation, which is in turn fed from their big Ravenswood facility by the Dumbarton Bridge, etc., etc.

"The utilities around here do share some of the same transmission lines. But the (contractual) sources for the power are generally different, and they are all very explicit about these."

True. But the whole point is that the entities they write their checks, to and the entities that put the energy they consume onto the grid that feeds them, are not congruent. The Venn circles overlap but don't coincide. As your Google reference points out, "... we know from physics that on a pooled electricity grid we can't tell if energy came from a “green" or “brown" source, ..." Like, if you pour a glass of Chardonnay into a swimming pool, and someone else fills their glass from that pool, what have they got? (PA consumption is about 0.3% of the grid content Web Link

To the point: Paying suppliers to put green energy on the grid is a very good thing. It displaces the black kind. But we must not fool ourselves that the energy actually lighting our light bulbs is all green. It is whatever gray mix is in the grid pool at the moment.

In particular, we must resist the impulse to 100% electrify our city because "it's totally green." As with anything in the physical realm, decisions to replace gas with electric must be based on objective analysis, not solely on (otherwise laudable) eco enthusiasm.

@Curm -- It seems to me that if you are looking at the electricity mix statewide (53% carbon-free), then you should also be looking at EV adoption statewide (5% or so). That would argue that we are way behind on EV adoption, no? It's not like we want to wait for the state to be 100% carbon-free, and then suddenly all rush out and get EVs.

"That would argue that we are way behind on EV adoption, no?"

Way behind what?

EVs are excellent things. They're smooth running, lively driving, very low maintenance, and zero stinking. The big hangup is getting energy into them.

It takes 5 minutes or so to fill up a gas burner, perhaps on top of a similar wait if someone else already has the pump. Not too bad.

EV charging times are tens of minutes, depending on the charger and the car, perhaps on top of a similar wait if someone else already has the charger. That really bites into the day, especially on intercity trips. Running dry means calling a tow truck.

The answer is to replace roadside chargers with battery quick-swap stations. But that requires a high degree of battery and chassis standardization among manufacturers, plus a significant infrastructure startup capitalization. We'll see what happens.

EVs are still the coming thing. Meantime, I favor plug-in hybrids.

Charging times are changing.

An earlier report about Tesla's upcoming fast-chargers: Web Link
and in today's Mercury News, an article about even faster chargers from Australia for other EVs.

Let's keep an open mind.

great post