Shocking : Tesla Model S gets 26.5 mpg

huh, doesn't work for me.

 

What we have one

That's true, and I am sure glad you California boys are not adding more poop to the air before we get it. Unfort I cannot say the same for my Kentucky friends. When we lived in NJ we were really end-of-the-pipe and you could feel it. You can measure it, universities would collect dust and use neutron activation which is a fabulous analytical technique allows trace measurement of elements ...and you just can see what you got and where it came from.

 

I think it's actually 5-7kWh of electricity that could be made/delivered with the electricity and natural gas from gasoline refining and extraction.

It is interesting that the energy of nat gas used in refining is roughly equivalent to the energy of other energy sources like H2, still gas, steam, etc... I'm curious how much electricity could be generated by those, especially since they could probably be fed into the same CC generator that was burning the nat gas.

 

I've seen no evidence to suggest that's plausible. Do you have a citation or link in support of that idea?

We know that EPA and GREET say that burning a gallon of gasoline directly results in about 19.4 pounds of carbon dioxide and all other refining, extraction, and other related upstream CO2 emissions amount to approximately another 5 pounds for a total GREET estimate of about 24.4 pounds (I forget the exact amount offhand but that's very close).

We know that most of the energy used that results in the upstream CO2 emissions is fossil fuel that emits about 1.2-1.6 pounds of CO2 per kWh of energy (methane, petroleum distillates, U.S. average grid electricity) so it seems that the 5 pounds of extra upstream CO2 must not be more than about 4-5 kWh of energy. And it is mostly fossil energy.

So conversion to electricity would, again, end up being around 2-3 kWh at most.

This implies that there just isn't that much energy being used upstream of the refining process on a per-gallon basis.

 

efficiency / inefficiency are somewhat subjective. I'd have to base my view by the stat's. From model S wiki;

Tesla Model S - Wikipedia, the free encyclopedia
Also it appears its drag cd is @ 0.24
That gas equivalent doesn't seem inefficient so much as it seems astonishing

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i would think the larger/heavier the vehicle, the less efficient. amount of energy to move it. is there another way to measure efficiency?

 

Those are definitely factors, but drag, or the lack thereof , plays a good part as well.
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Not really - prius phv 3200 lbs - 50 mpg after 94 mpge plug power is gone - passenger room 94 cu feet
toyota yaris 2300 lbs 32 mpg - passenger room 85 cu feet
Compare Side-by-Side

To me the prius plug-in is bigger on the inside, on the outside, heavier, and gets better fuel economy.

Don't be fooled. compare on your commute. drag, engine efficiency, transmission efficiency, regen braking over come the mild inefficiency of higher rolling resistance of the prius. Tesla 70D has the same drag (cdA) as a prius, but is much heavier and luxurious, but seems to be pretty efficient despite the higher rolling resistance.

 

Theoretically - Yes. The more the mass -the more energy will be needed to accelerate .. it is classic physics .. Force = mass * acceleration

However Real world energy requirement equation also have aerodynamic drag load and rolling resistance plus power plant efficiency with each different type of power plant exhibiting a different kind of power curve - change the road surface from flat and straight to hilly and curvy and thing get trickier -but that is the basics. The design strategy of making a more fuel efficient vehicle by just lower its mass to use less energy - is exactly what the Progressive X 100 mpg Challenge Edison2 VLC team used to win - but you can't buy that car for the love of Mike.

The biggest energy loss source in all road based transportation systems is doing a full stop - the lower the initial speed is from a full stop AND the lighter the mass of vehicle stopping - the less the energy lost is. Because of this - the most important hypermiling skill to master is Driving without brakes and smart braking. FWIW - a hybrid like the Prius can only recover at best 50% energy lost from a complete stop. Audi-Porsche flywheel race car were designed to recover even more energy from a slowdown or full stop ( but I was never able to find any performance data on it)

If you want to go to the extremes energy optimization -
drop EVs (and hybrids, FCV, and plugins for that matter too) and look at a Human powered Vehicle (HPV) - now those contraptions are really strange stuff!
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Seems the new 70d is rated 100 mpge !! .... or $3.97 per 100miles, based on averaging national kWh prices. I'm having a tough time working these numbers into the OP's 26mpg. Maybe his oil fired electric plant is HEAUUUUGELY inefficient?

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My guess is the orig calc is from a CA concerned citizen group, perhaps based on one CA refinery that may actually consume a lot of elec with the heavy crude out there, then they exaggerated that by some statistics conversions of natural gas to Kwhrs, and then someone else took that and said every single refinery is like this.

 

That's about right. From my earlier post (So what is your carbon footprint? | Page 3 | PriusChat"), extraction alone requires ~8.7kWh of natural gas per gallon of fuel (diesel, gas, and jet fuel, excluding products that aren't used for generation), which has ~4lbs of Carbon.

CC natural gas generation sis at ~47% efficiency as of 2011 (http://www.energy.ca.gov/2013publications/CEC-200-2013-002/CEC-200-2013-002.pdf), so that ~8.7kWh of gas would be ~3.9kWh at the plug. The nat gas in refining bumps that up by another ~1kWh(and lb)/gallon.

Electricity has is ~.6-.9lb/kWh, so the .5kWh/gallon for refining/extraction adds another ~.3-.5lbs. All told, that's ~5.5kWh at a consumer's home per gallon of gas. It ticks up a bit when you compare the efficiency of gasoline refining to the efficiency of refining diesel/jet fuel. I tossed the extra kWh on there for that and transportation/discovery.

Those numbers match up pretty well with the 5+lbs from the greet model. Granted, it could be that extraction is more NG intensive in CA, so the country average could be ~1lb/gallon less for that, but ultimately, ~5+-7lbs and kWhs per gallon appears to be accurate.

 

I found the math errors in a link above. But we can go through it again..

89 mpge tesla model S 85. The US grid produces 0.4% of electricity using petroleum liquids, but these average 32% efficiency both eia 2014 numbers, if grid losses are 7% we have 89 x 32% x 93% = 26.5 mpg on petroleum liquids.

Now there is a reason the US only uses a little bit of petroleum liquids, they are hugely inefficient and expensive.

In 2014 about 67% of electricity in the US came from fossil fuel, 40% of it coal, coke, and petroleum liquids at about 33% efficiency and 27% natural gas at about 43% efficiency then we can take the 7% grid efficiency hit. The other 33% is nuclear, big hydro, and renewable. That makes electiricty to the plug about 50.5% efficient on fossil, but using a lot of nuclear, hydro, and renewables. Redoing this we get

89 x 50.5% = 45 mpge (fossil fuels on the grid), but wait their is more gasoline is only 83% efficient in getting from oil, so we need to divide by this to compare with gasoline mileage.

89 x50.5%/83% = 54 mpge (fossil fuel equivalent of gasoline from the "national grid") Of course this 54 mpge is improving

 

It's based on all electricity/nat gas used in CA for extraction and by refineries in the late 90s/early 2000s. This was published on a state website. Things could be different, but seeing as the oil industry is on the defensive and stopped publishing that data, my guess is that it's not a whole lot better these days.

 

The number is usually misquoted as he amount electricity an average refinery uses, but yes it could be what someone in CA estimated for heavy crude extraction plus refining, using conversion factors for coverting nat gas used into KWhr. And who knows if anyone agreed with the calcs (normally nobody converts nat gas cubic ft into kilowatt hours, so that calc alone was probably done to make a political point) . Nissan ran with it for a brief while.

 

I think you're making this way too complicated.

The simpler explanation is that someone read somewhere that refining a gallon of gasoline takes" ~5 kWh of energy" but instead their brain understood that it takes "5 kWh of electricity" because everyone knows, right?, that kWh always means electricity.

It just doesn't really make sense for a refinery to use almost entirely or mostly electricity for its process energy. Most of that energy will probably be used for generating heat to cook the crude oil and cause different "fractions" to be evaporated and captured.

Refineries are largely like distilleries except that instead of evaporating alcohol off of fermented mash at a lower temperature than water they are instead evaporating, separating, and recapturing hydrocarbon molecules in the crude that have differing evaporation points. Doing that takes heat and they normally get that by burning the natural gas and previous refinery leftovers.

They also typically want hydrogen either purchased or made from natural gas on the site for use in "cracking" stages where they modify the molecules into more economically desirable hydrocarbon flavors in order to make more gas (or more diesel) at various octane specifications depending on market needs.

 

And how do you know that "they stopped publishing that data"? Did you get that from the FullyCharged "Volts for oil" episode?

I've seen zero evidence that oil companies somehow "stopped publishing that data". I'd love to see a link documenting that assertion.

Lots of data about energy industries, refinery process input energy, and all the rest continues to be gathered, collated, and published by the U.S. government in great detail and from other governments which is then published by the UN at data.un.org. Aside from geeks like us, government planners and Wall Street traders demand access to this kind of raw data.

 

Jeff- You absolutely have the right idea, but nobody would even say making gasoline takes 5 kwhr of elec. Might say xx BTU of heat or something like that. Once you get into kWhr per gallon it's probably something some concerned citizen generated to make a point. Presumably the concerned citizen was not even advocating elec cars at the time, probably was not the intent, as you say this goes back some years. Just the number got hijacked and used by some EV advocates as a talking point.

 

Not to go too far, OT, but before you do, please join and watch Log into Facebook | Facebook and possibly BMW i3 Forum • View active topics (except for the major spam attack it just got). I watch the former and can tell you it seems like the i3 REx is very unreliable. There's a decent chance that you'll have a new "hobby" of taking it to the "spa" (dealer) fairly often for all sorts off maladies like drivetrain errors, check engine light (pointing to any # of issues like loose gas cap, condensation in engine, needing a new camshaft (IIRC), etc.), restraint system malfunctions, car dying, broken motor mounts, blown on-board chargers (EME and KLE), etc.

The pure BEV version seems better...

Numerous folks (including someone I personally know) have gotten their '14 i3 (usually REx?) bought back by BMW due to all the time in the shop and repeated visits. However, it doesn't seem like all the probs have vanished w/the '15 REx.

It's almost comical. @F8L (IIRC) has watched and can tell you basically the same thing.

 

stick with leaf.