EVs indirectly pollute, and the Tesla Model S appears to result in greater effective CO2 emissions than an SUV
Guest post by Nathan Weiss
The EPA tells us 51% of total CO2 emissions result from motor vehicle use. As a result, many environmentally-aware consumers buy hybrid and electric vehicles, including the Tesla Model S, in an effort to reduce their CO2 emissions. One can easily picture these consumers exclaiming “wealthy Republicans are destroying the planet!” when they find their Prius driving next to a ‘one percenter’ in a BMW.
According to the EPA, the Toyota Prius V generates 212g of tailpipe CO2 emissions per mile driven, while BMW offers a host of vehicles that generate less than 140g of CO2 per km (225g per mile) driven. In fact, there are now quite a few new vehicles on the road that emit between 240g and 280g of CO2 per mile driven, including the Chevy Cruze and the base model Honda Civic. Hop into a Honda Civic hybrid and your tailpipe CO2 emissions fall to just 202g per mile. So where does the Tesla Model S stand in terms of effective CO2 emissions?
Tesla Motors implies that the Model S sedan effectively emits 176g of CO2 per mile driven, although we believe the power consumption estimate Tesla uses for these calculations – 300 miles per 85 kWh consumed – is unrealistic. Furthermore, unlike gasoline-powered vehicles, electric vehicles utilizing lithium-based batteries suffer charging inefficiencies of roughly 10% to 20% and often consume meaningful amounts of energy when they sit idle – especially in cold weather. If we incorporate charging and idle losses, using data provided by Model S owners, we calculate that the effective CO2 emissions of an average Model S are roughly 394 g per mile. It gets worse: Other research shows the massive amounts of energy needed to create an 85 kWh lithium-ion battery results in effective CO2 emissions of 153g per mile over the life of a Model S battery, based on our assumptions. When the CO2 emitted during the production of the battery pack are incorporated, we believe the total effective CO2 emissions of an 85 kWh Model S sedan are 547g per mile – considerably more than a large SUV, such as a Jeep Grand Cherokee, which emits 443g per mile!
Despite the substantial effective CO2 emissions of the Model S sedan, Tesla received $465 mln of low-interest loans from the DOE and the $82,000 average list price luxury sedan benefits from a $7,500 Federal tax credit, as well as various state and local incentives – including a $2,500 tax credit in the state of California. In addition, government environmental credit schemes required other auto makers to pay Tesla more than $40 mln in 2012 to “offset” the emissions of their gasoline engine-equipped vehicles with credits from the more heavily polluting Model S.
More:
http://www.uniteconomics.com/files/Tesla_Motors_Is_the_Model_S_Green.pdf
“””””…..richard verney says:
April 10, 2013 at 3:37 pm
Jim Smothers says:
April 10, 2013 at 10:40 am
/////////////////////////////////
Jim
The Citroen was a great car, but the most innovative car of the last century was the Lancia Lambda. That was the brith of the modern motor car as we would recognise it today…….”””””
So what year did this Citroen introduce independent front suspension. The VW had both independent front suspension, (trailing arm, and torsion bar “springs”; front and rear. The design of course was lifted straight out of the 1934-1938 rear engined 6 litre supercharged auto union grand prix car.
By the way, Tesla claims that their battery plan involves a provision for recycling the batteries for the lithium. I used to recycle scrap gallium arsenide, and gallium arsenide phosphide (from LEDs) to get six and seven nines purity raw gallium. We supplied about 50 % of our total gallium input from recycling.
Know nowt about lithium chemistry, but is recycling any more difficult than cycling rocks to get it in the first place. But that’s another energy input problem.
“””””…..
Stephen Richards says:
April 10, 2013 at 1:31 pm
george e. smith says:
April 10, 2013 at 12:01 pm
I had a rotary converter some 50 years ago. It was a double ended dynamo……”””””
So Stephen, if the DC in produces rotation and torque (has to under load), why the hell would you not just use the rotation, and leave the alternator end off. Makes entirely no sense to me, unless you actually have a use for three phase or even one phase AC. Dunno where the power control electronics is; on the DC in or on the AC out side.
To merit the name Tesla, that car should be able to go back & forth 60 times a second.
“””””…..William C Rostron says:
April 10, 2013 at 1:27 pm
george e. smith asks why use a 3-phase motor and not a brushless dc motor?
Well, the 3-phase motor used in the Tesla *is* a brushless DC motor. It just happens to employ 3 field coils instead of two (4-quadrant arrangement) or more……”””””
William, it is trivial electronics to produce three phase AC from DC. So you can drive your three phase AC brushless DC motors, just fine using electronic inversion.
I understand why three phase works; same reason that straight six cylinder engines work smoothly.
Still seems like unnecessary steps to me.
The Tesla S AC motor produces 290 -300 KW ; well actually they don’t say whether that is AC power in or rotary power out. Well that is 400 horsepower. My high compression 3.4 litre 1956 Jaguar XK 140 hard top coupe came up with 210 BHP, and that was enough to scare the horses.
So if you use your Tesla S for zero local pollution round town, when do you get to use the other 360 HP ??
But as I said before, I am quite im[pressed by the quality and cleanliness of most of the TS engineering design, which doesn’t change the fact I think it is a silly idea.
That 300 mile (epa says 276 I think), is really only 138 mile range, because your own garage is the only place you know you can recharge it.
Even fighter pilots know that you need to get back to the carrier to refuel; betting on the air tanker, can get you wet.
http://wattsupwiththat.com/2013/04/10/is-the-tesla-model-s-green/#comment-1271486
Why use 3 phase motors and go to the trouble of running an invertor to go from DCVolts (not to mention the loss of efficiency) ?
Well I woudl guess that it would be to do with speed control.
The DC motor driving the 3 phase invertor can run at constant speed (how do you change the speed of a DC motor again ?).
Modern 3 phase drive controllers are pretty amazing and very efficient; so running the 3 phase motor under light load will cause lttle to no current to be drawn from the battery – compared to when under heavy load. It is just so much easier to do good speed control with a modern low voltage drive unit; I would guess the loss in efficiency from having all that mechanicl spinning around stuff is easily made up by efficient 3 phase motor control. Effectively the drive control will ALWAYS follow the most efficient sped/torque curve when responding to demand. Of course it could also be programmed to give high acceleration for those who want the ‘sports car’ feeling
Common in industry now days – rip out the old DC drives and old in-efficient AC drive controls & replace them with the ultra high efficient low/medium/high voltage 3 phase motor control systems. A boiler/gen set in a factory I look after is saving 5% of its oil/gas use by running new drive controllers for the induced & forced draft motors – they used to control air flow by using dampers & constant speed motors.
“””””…..peter_dtm says:
April 10, 2013 at 5:05 pm
http://wattsupwiththat.com/2013/04/10/is-the-tesla-model-s-green/#comment-1271486
Why use 3 phase motors and go to the trouble of running an invertor to go from DCVolts (not to mention the loss of efficiency) ?…..””””‘
Well Peter, I will take your word for it. I did say it’s been 60 years since I seriously studied rotary things. And if you say it’s best this way, that works for me.
So let’s say I can make an efficient constant speed DC-three phase AC motor drive power inverter. Why would I want to integrate it into the AC motor itself, rather than put in a pair of AC motors, 86 the differential, even possibly the step down gears, and directly drive the separate drive shafts from separate motors. Then the rotary inverter can be located anywhere; no need to be part of the drive train. Close so no long wire runs.So does the AC run at fairly constant frequency: it would seem you would want to, but don’t need precision frequency control.
As I recall, magnetic type things are most efficient, when copper (resistance) losses are equal to Iron losses, (hysteresis, and eddy current losses), and efficient small magnetic things do run hot.
Tesla are confident they don’t have the Boeing dreamliner battery problem. Battery is liquid cooled, so it has a radiator heat exchanger, which is modest in size, but seemingly vulnerable right out in front, in the fender bender zone. I think they could find a safer place, given what a loss of coolant failure might do to the battery; not to mention the car. BUt EM IS a smart guy, so I am sure they tried out in spirit, all the possible architectures. It’s a royal frustration, walking into the showroom, and finding nobody who knows the design. They ALL were enthusiastic folks, and they didn’t mind me photographing the chassis, up the ying yang, which I did.
george e. smith says:
Hi George
can’t say about the mechanical arrangements – as described it does sound overly complex. I just work for a controll company that also does a lot of drives (though process is my baby not drives & motion).
Supposition time – Frequency will presumably have been chosen to give a good weight/size factor for the AC motor – doesn’t need to be too accurate – but since it is probably part of the dc drive controll side it may well turn out to be very stable; just because it doesn’t cost anything less not to do it properly ! And if the frequncy is steady; the chopped wave form driving the motors will be just that bit more efficient and easier to predict (bet they have a nice model built in to the AC drive; one with few enough parameters that it actually describes the real world pretty well !)
I would have expected (again drives are not my speciality; just things I need to know about) each wheel to be direct driven by its own motor; and as you rightly point out; you can put the dc inverter anywhere you want ( design considerations : gyro effects and weight for the invertor may influance how they’ve done it – how fast does that dc motor run ?).
Why have gears on an electric motor ? Again may be some efficiency calculation using a faster running motor – or they just decided they didn’t want direct drive because of ?? space constraints ???
My first experience of a set up like this was a Kelvin Hughs marine radar set about 1978-ish which used an invertor to get from :
ship’s 440 3 phase 50 Hz to DC.
Then from DC to several different ac voltages
so it actually did everything twice !
– up to 1.5KV – down to dc through an scr & caps … iirc for the magnetron drive; and what was to become the 12V power rail; and supply the 3 phase scanner motor at some very exact frequency so the radar plot ran at an exact refresh rate; way way more acurate than anyone needed. BUT it was done like that so they could put the same set up on any ship – 330V- 440V 50-60 Hz and not worry that ships power can be filthy ( nominal 440/50Hz clould be down to 330V 40 Hz for a few 10s of cycles — ugh !) but it was fun listening to the thing running when the ships power was fluctuating all over the show … the DC-AC invertor stage ran as solid as a rock – load variations weren’t much – 20%ish on the scanner per rotation; in near gale conditions and around 80% step changes going from stand-by to full pwer….
Once I got used to the idea it was actually quite a smart (for its time) solution. Just horribly mechanical ! I have a vague memory they described the whole thing as a Rotorary Transformer
peter_dtm says:
April 10, 2013 at 5:05 pm
Why use 3 phase motors and go to the trouble of running an invertor to go from DCVolts (not to mention the loss of efficiency) ?
Well I woudl guess that it would be to do with speed control.
Also torque, (that pete did mention) I work with elevators and for the last 10 to 15 years all the DC motors and drives are being replaced with 3 phase AC motors and drives. The buzz word is Vector drives with encoder feedback, which alows for full torque at 0 rpm. The DC motors and drives can’t meet that low rpm torque control.
I don’t know what the other dc motor is for unless they are using it for regenating power back to the battery, but some ac drive put regerated power back on the grid now, so one would think it would be easier to do that electronically.
Anthony Watts says:
> Other research shows the massive amounts of energy needed to create
> an 85 kWh lithium-ion battery results in effective CO2 emissions of 153g
> per mile over the life of a Model S battery, based on our assumptions.
> When the CO2 emitted during the production of the battery pack are
> incorporated, we believe the total effective CO2 emissions of an 85 kWh
> Model S sedan are 547g per mile – considerably more than a large SUV,
> such as a Jeep Grand Cherokee, which emits 443g per mile!
Can someone show me these calculations? Or how to do them for
myself?
Such claims remind me of ridiculous claims as to how much energy is
needed to manufacture a CFL.
However, I do see that conversion efficiency from heat energy to electricity
is almost 50% when and where that’s going well, and there are transmission
and distribution losses. From heat source to wall plug, the efficiency is
typically of a percentage in the mid 30’s.
George/ pete
My typing took to long & missed your last comments,
An Ac drive will change the voltage and frequency signal for proper control.
The speed of an AC motor is related to the frequency of the supply, ie a 60 HZ motor run at 30 HZ will run at 1/2 full speed. the voltage is also adjusted roughly in line with the frequency (voltage is changed for proper control).
A DC motors speed is related to the voltage, a 100 VDC motor will turn at half speed at 50 volts,
to try and put it a little better.
The speed of an AC motor is based on the frequency supplied to the motor.
Drives also adjust voltage and current going out for torque control only.
Plus, drives hooked up to the grid, will take AC in, turn it into DC, and convert the DC back into a digital AC signal for exact control of the frequency.
To add math, an AC motors speed is calculated by RPM = (Frequency x 120)/Poles.
RPM= revolutions per minuet, frequency in HZ and number of poles in the motor(always an even number). so a 4 pole motor @ur momisugly 60 HZ will run at 1800 RPM, there is some slip so actual will be around 1750 +/-.
One of these passed me the other day. The way he was driving, he wasn’t reducing anything.
“””””…..DJL says:
April 10, 2013 at 6:38 pm
George/ pete
My typing took to long & missed your last comments,…..”””””
I believe you are correct on that DJL. A DC motor winding; assuming a permanent magnet motor, has near zero resistance (ideally), so at zero speed (clamped) the current draw is astronomical, so it creates enormous torque, so unclamped it starts turning in a hurry, and once rotating, it acts asa generator, and generates a back EMF directly proportional to rotation speed. That opposes most of the applied Voltage. So you have I = ( V – BEMF) / R and the speed will run up until the current is reduced down to what is needed to maintain the load torque.
In the AC case, you get a rotating field at the drive frequency / pole pairs Ordinary AC motors run at a slip frequency so as you say a 60 Hz two pole does about 3500 rpm instead of 3600, and < 1800 for the four pole. Then there are AC synchronous motors, that have no frequency slip, but have a rotor phase offset, that grows with load, so the 4-pole locks onto 1800. Since the force- phase slip relationship is non-linear, and depends on field and pole geometry, the actual phase offset is a property of that motor design.
I have two AC synchronous motors, one is two pole 3600 rpm, and the other is six pole 1200 rpm.
Both designed for 24 Volts rms at 60 Hz. They are little jewels; size 5 motors ( 0.5 inches diameter). They drive a pair of worm gears on the ends of a differential, that then drives a big 360 tooth spiral bevel gear to run a telescope drive. The both motors runs off a crystal controlled roughly 60 Hz two phase drive to run 26 seconds per day slower than the earth's rotation rate. That compensates for the atmospheric refraction for about three hours each side of the zenith, so you can follow a star for about six hours total with only about one arcsecond error. The 3600 rpm motor is used for fast slewing back and forth. The 1200 rpm motor drives a single start worm, while the 3600 rpm drives a four start worm, so they actually have a drive ratio of 12, between drive and slew.
Bjorn Lomborg: Green Cars Have a Dirty Little Secret (WSJ March 11, 2013 Opinion page)
is a great piece on how ALL electric cars come off the assembly line with a huge carbon footprint thanks to the CO2 generated in the creation of the battery components.
His main point was that a Prius has a footprint of 30,000 lbs of CO2 on the showroom floor, while a similar sized gasoline engine has only 14,000 lbs. The gasoline car generates more CO2 per mile, but the electric car needs to be recharged usually from a fossil fuel source. He figures the battery powered car emits 6 ounces CO2 per mile, the gasoline car 12 ounces CO2 per mile. Given that, you must drive the battery powered car 90,000 miles before it will have a full-life carbon footprint less than driving a gasoline powered car the same 90,000 miles. —– PROVIDED you don’t have to replace the battery in those 90,000 miles — and you will.
Lomborg also referenced a study by the BBC about the practicality of charging times and long trips:
… commonly found in today’s top-of-the-line clothes washers was well, to the consternation of hams (owing to the EMI produced that is apparently not, or not-so-well filtered/shielded form escaping or propagating from those units!)
Sample: http://lists.contesting.com/_rfi/2009-09/msg00019.html – Note also the discussion which follows at that link.
These 3-phase motors (with solid state controllers) are also the basis for the new small, high-power “brushless” motors used to power _electric_ RC (remote control) model aircraft (vs the small gas engines or DC brush-type motors as well).
Brushless 3-phase motors work in conjunction with an “ESC” – Electronic Speed Controller
http://en.wikipedia.org/wiki/Electronic_speed_control#Brushless_ESC
Perhaps a little intro now for those not steeped in this motor technology and also includes a pro/con list of attributes:
http://www.thinkrc.com/faq/brushless-motors.php
.
Lomborg also referenced a study by the BBC about the practicality of charging times and long trips:
To that I have a Solution: U-Haul Battery Pack Trailors !!!
Instead of waiting for an hour for a recharge, you check in one trailer and get another. Once you get good at it and are a customer in good standing, It ought not take more than 10 minutes. There will probably be a Full Service Lane, too. It also eliminates lots of problems with battery packs that get old. Of course, the theft risk of towing a $20,000 lithium-ion battery trailer will give you pause. And there is the chance that a charged trailer isn’t available when you drop one off.
Finally, there is that pesky image of a Tesla pulling a U-Haul, even if it has racing stripes. I won’t be able to look at a Tesla without the mental picture of it pulling that trailer. 🙂
DirkH
“So why can’t they sell them for 5000 if the resource usage is as low as you claim, John? Enquiring minds want to know.”
And just how low did I claim they were Dirk?
The author adds the CO2 cost of the batts on the EV, “based on our assumptions”. That “assumption” needs some supporting documentation. He also talks about “idle” losses of lithium ion batteries in the 20-30 percent range. Lithium ion batteries are known to have very low “idle” losses. It’s why the can sit on a store shelf 10 years and still be guaranteed. He needs to support that claim too. If the owner of the Tesla installs a PV system like Anthony’s, this author’s figures get blown away faster than a Tesla blows away that Honda Civic he compares it to.
He goes on to list a number of tiny cars that have tailpipe emissions nearly that of the Prius. But, the Tesla S is an extremely fast, large luxury car (0-60 in 4 sec.) He fails to compare it to vehicles of a similar category.
Anyway you cut it though Dirk, an emerging technology is going to cost more than a mature technology. When economies of scale become equal, that equation can reverse. Governments often underwrite or otherwise support emerging technologies until they become tenable for the private sector. Examples: Fracking technologies, space technologies (such as GPS) even the Internet.
The Tesla S is a very cool car. JP
John Parsons:
At April 10, 2013 at 11:08 pm you say
One could debate the value of such an “underwrite”. But in this case there is nothing to debate.
Electric cars are NOT an “emerging technology”.
Electric motors pre-date internal combustion engines
and
electric cars pre-date diesel and petrol cars.
Does that mean that Ford and GM need subsidies so their “emerging technology” of internal combustion engined cars?
There are more internal combustion engined cars because they are cheaper, more efficient and have longer range than electric cars.
Richard
@John Parsons:
The problem is that the battery is not like a regular car engine, it is more a ‘consumable’. My old Diesel had over 400,000 miles on it when it met it’s demise. That was about 25 years after it was made. For the cost of a single battery pack, the whole engine could have been redone for another 400,000 miles. Now compare to the battery pack: They do not last decades. They are consumed in years. So a consumable of which you will consume many.
Also those 10 year lithiums are NOT the rechargeable ones. Rechargeables have a fairly stiff static loss. They are often flat in weeks or months.
As I type this, I’m using my (fairly good maker) laptop on “life support” power cord. It is about a year old and has a 20 minute max battery life now, then dies suddenly (so the auto shutdown can’t work and it’s a crash). That isn’t unique…
@All:
From what I remember of the Eng. Society meeting at Tesla, where the engineers talked to us (a couple of years back) the reason for the AC motor was low current drain at starts along with great speed control, while being efficient. The reason for the other one was to be a very efficient DC generator to recharge the batteries in a controllable and battery kind way. IIRC (that is a bit suspect for a one off meeting a few years back…) it was hard to get both into one motor/generator skin while being both electrically efficient and battery kind.
Also, IIRC, there is a enough waste heat to be sucked out of their high density battery pack and motor cooling to act as cabin heat. Say you are pulling 40 kW and have 10% loss, that’s 4 kW of heat. Like 2 electric stove burners on high… They spent a lot of time talking about heat management in the battery pack… and some way cool things in the drive motor optimizing.
Less sure about this, but I think the reason for the gearing was that it gave you 3? things. A smaller more efficient motor since rotation rate optimum was decoupled from vehicle wheel speed, better ground clearance for the motors, and better sprung weight since the motors were not part of the sprung axle parts. (Diff. gear has swing arm, IIRC, though that was an early prototype model we saw… so don’t know if this is the same…)
Something like that, anyway… (Never expected to need to remember any of that years later 😉
Really neat car. Then again, with California electricity hitting $0.39 / kW-hr now and headed for $1/2 per kW-hr “soon”, not going to be charging a “electron guzzling car” any time soon…
Oh, and another musty thing: From years and years ago, the total efficiency of a mechanical drive Diesel beat the pants of an electric motor drive due to the chain of losses in the electric system (most of them ignored when people talk e-Cars). Fuel to heat engine (loss) to generation (loss) to transformer (loss) to transmission (losses and more transformers) to home transformer (loss) to charger (loss) to battery charging (loss), to idle standing (loss), to battery discharge (loss) to motor controller (loss) to motor (loss) to shaft / wheel drive. At even small percents, all those steps of losses multiply… and some, like the controller, can be 10% easy; as can battery charge / discharge / standing. It’s just not a very efficient process. Fuel in Diesel to wheels is very effiicient. (Large ship engines even more so at over 50%).
Neat toy for around town and in the local hills if you make $1 Million a year and have a second car for longer trips and skiing…
If you buy a Tesla you will need to walk a lot whilst it recharges. Trips over 50 miles are out at night or in cold weather. A horse is better.
Subsidies aside, CO2 is not the point of Tesla cars (all models, S, X, Roadster). It was always to demonstrate that electric cars do not need to look or perform like milk floats. Detroit Electric seems to get that too. Of course they still have a very long way to go to be practical but then how practical is a Bugatti Veyron 16.4 Super Sport (similar performance on public roads and similar miles per fill-up).