Have the Environmental Benefits of Electric Vehicles Been Finally Established?
Micah (a subscriber since August, 2009–one of our very first) writes:
Hi Craig, Could you point me to the body of facts that point to electric vehicles being dirtier than gas vehicles? This is news to me that it had been effectively decided. Thanks.
Micah: Here are five posts in chronological order. If you read them, and all the dialog in the comments between Glenn Doty and me, you will understand this. (Please be sure to read all Glenn’s comments on the first one, to both me and to “Richard”; he explains this very carefully and thoroughly.)
http://2greenenergy.com/2014/12/28/fits-starts-electric-transportation/
http://2greenenergy.com/2014/12/31/fits-and-starts-in-electric-transportation/
http://2greenenergy.com/2015/01/01/oil-and-terrorism/
http://2greenenergy.com/2015/01/05/electric-vehicles-environmentally/
http://2greenenergy.com/2015/01/05/electric-vehicle-car-dealership/
Btw, I actually wouldn’t say that it’s been “effectively decided”—in fact, quite the contrary. Over 99% of the material in this, whether it’s from an OEM (e.g., GM), a lobby group (e.g., EDTA or Plug -In- America), an environmental group (e.g., TreeHugger), or a government department (e.g., DoE), contains this argument, either explicitly or implicitly: because the average grid mix in the U.S. is only 31% coal, EVs must be environmentally better than ICEs, since the balance (69%) is cleaner than oil (natural gas, nuclear, hydro and renewables).
There is a fallacy here that most people don’t grasp, however: the average grid mix is irrelevant. EVs aren’t charged with the average grid mix. EVs (or any other incremental loads on the grid) are charged with the way grid operators deal with incremental loads, which is almost always 100% coal.
If you read and understand this material, you’ll become another in a very slim minority of people who can make that claim.
At the same time, you’ll come to understand that I’m correct in that there are numerous other reasons to support electric transportation, which is why I continue to do so.
Thanks for this very important question, and for being a long-term subscriber.
Thanks Craig for referencing this post. I look forward to digesting all the comments. But as I start I would like to understand exactly what you mean by this:
“There is a fallacy here that most people don’t grasp, however: the average grid mix is irrelevant. EVs aren’t charged with the average grid mix. EVs (or any other incremental loads on the grid) are charged with the way grid operators deal with incremental loads, which is almost always 100% coal.”
I am trying particularly to understand your assumption that “incremental loads” are satisfied using coal as this runs contrary to my understanding that coal (Rankine Cycle) is used “almost 100%” to satisfy base load. I have read reports that describe boiler tube damage and consequent economic loss when such plants attempt to load follow. It also seems that it takes about 2 weeks to properly (warm up) start up a coal fired power plant and this kind of time frame is inconsistent with the demand for load following.
Rather it has been my understanding that gas fired turbine power plants (Brayton Cycle) have been used for peaking power needs which has also been called load following simply because such plants can be turned on and off in 15 minutes or less.
It seems as if you are using the term “incremental loads” from a power demand perspective in the same situations as from a power supply perspective they may need to apply “load following” power solutions. But this seems inconsistent with your suggestion that coal is used almost exclusively. This has been somewhat perplexing every time you use the term “incremental load.” Perhaps you can offer a definition or some further clarification.
I don’t mean peak loads; I mean incremental loads that require more baseload, e.g., lots of EVs changing at night. If that doesn’t answer your question, please call me on the phone: 805-691-9381.
OK, thanks for that. I tend to read a bit but “incremental loads” is not a term that I have encountered and you have made it perfectly clear. An environmental rational for an EV is a bit like a long term investment. You hope it will come through eventually but don’t expect immediate returns. A change in the grid structure would ensure the investment but unless the investment in EV transportation is made a change in the grid will fall short of its full potential. I don’t think there is any real disagreement here.
But I continue to be interested in how you see the details. As I continue to digest this material, it seems that if the assumption of incremental loads being satisfied by new coal plants were accurate we should see a rise in the use of coal as a fuel for power production. From a high of about 55% of the energy grid mix in 2005 the figure has dropped to present day levels of 37% but I have also seen you suggest 31% of the national energy mix. From these numbers it seems that coal is not being used to supply additional base load power.
Rather, as you have pointed out elsewhere natural gas is filling in the void. We now have all sorts of natural gas power plants. It seems that natural gas has become cheap enough to now use as base load power. Perhaps you are expecting a sudden rush of new EV demand that will require taking old coal plants out of a mothballed state?
Actually the rationale is simpler than that. The ~400 coal plants in the US coal plants operate continuously, but they are tamped back a little at night due the diminished demand. When an incremental but predictable load comes on the grid at night, e.g., a certain number of EVs to be charged, those plants are tamped back less, according to the size of this new demand. Thus charging EVs at night (in the US) is almost entirely accomplished by increasing the consumption of coal accordingly.
Now your other point is spot-on, i.e., once this ceases to be the case, the eco-benefit of EVs will be extremely large. For that reason, I don’t have a problem with amping up EV sales now, especially considering that:
some are charged during the day (with NG), and
some are charged with solar PV that was installed specifically and only because of its use in charging EVs.
Craig, I appreciate your walking me through this as I come up to speed with your previous posts.
You are assuming that the off peak demand is less than the potential turn-down capability for a coal fired plant.
In additional “incremental load” I have also noticed another new term for me. I was familiar with the concept of a turn-down ratio but unfamiliar with the term. When it comes to power plants certainly coal fires can be turned down. In addition generators can be tuned down, off or even disconnected. But I have also come across several papers that describes boilers and their tubes to heat steam. Those papers described the costly damage done to boiler tubes by changing heat levels. Replacing boiler tubes involves turning off the plant entirely. Heating up a Coal plant from a cold start seems to take about 2 weeks. So there seems to be another limit as to how much a plant can lower its heat output and then rise it again within 24 hours.
This leads to some questions. Off peak demand can be more than 60% lower than daytime peak demand. In places where there is an 80% or 90% coal mix most of this change will affect the coal power plants. Certainly we can simply turn generators off and we will not be producing electricity that is not needed.
But I suspect that there are places and times where the off peak demand is lower than the turn down capacity of a coal fired power plant. In this case the coal fire will not be turned down to match generation but only turned down within guidelines to prevent boiler tube damage. In such a case rather than adding to more pollution from coal use the incremental load of that off peak EV charging is producing no additional pollution. This is only a suspicion based upon what I have read. If you have some additional sources or information I would welcome the clarification.
I have noticed how Glenn sometimes seems to selectively apply a similar “practical outlook.” For example when discussing what vehicle type an EV is replacing but then including the inefficiency of “house wiring” as an average rather than the 6′ from the meter panel in a garage to a charging port (which is the practical aspect rather than the average.)