Shredding misconceptions about electricity and motor fuel

And there are one hell of a lot of them out there; few things are so ubiquitous yet opaque to the layman.  Reposting some blog comments in case they are of more general interest:

Ominous Cowherd:

Using Pierre's numbers, 1 gallon of diesel equals 10kWh, so the overnight charge would be 7kWh equals about three quarts.

The EIA says a gallon of diesel is 137452 BTU, or just over 40 kWH(th).  Converted to work in your typical light-duty engine you might get 16 kWh out of it.  Your usual "convenience cord" is capable of 1440 W (120 VAC @ 12 A) so a 7-hour charge can yield as much as 10 kWh from a standard wall outlet.  PHEV batteries have widely varying capacities; the Prius+ has just 4.4 kWh, the Ford Energi models started out at 7.6 kWh and are going up to 9 kWh next year, and the Pacifica plug-in has 16 kWh.  These figures correspond to just over a quart, just under half a gallon and a gallon, respectively.

I used to drive a Passat TDI.  I drove the automatic like a stick and averaged 38 MPG city or highway.  Half a gallon of fuel would take me about 20 miles.  I drive a Fusion Energi now and that's about how far the battery power will take me (depending on speed, terrain and weather of course), so that seems like a pretty fair equivalence.

you spend 18 hours charging to get energy equivalent to roughly 1.2 gallons of diesel per day.

If you had a Chrysler Pacifica charging off a standard wall outlet for 18 hours a day, you'd get up to about 1.6 gallons-equivalent.  Vehicles with smaller batteries would reach full charge and have to stop; the Fusion reaches full in about 5 hours from your garden-variety wall outlet and about 90 minutes on a Level 2 charger.

1.6 gallons a day 250 days a year is 400 gallons-equivalent.  The EPA-rated fuel consumption for the Pacifica hybrid is  32 MPG, so for 15,000 miles/year the expected fuel consumption is about 470 gallons.  Replacing 400 of those gallons with electric power slashes the net fuel requirement by 85%.  My experience is consistent.  The standard drivetrain in my car is rated at 26 MPG, and I'm averaging just over 130 MPG per the dash display.

To compete with IC, you need to be able to drive hundreds of miles, with a heater blasting hot air, then fuel up in a few minutes and do it again. To get a 300 mile range, you need ten times that amount of energy, or more.

You don't need to compete with IC to replace most of your fuel.  Most trips are short trips, and engines are very inefficient when cold.  If you electrify most or all of the short trips and eliminate most of the cold starts, you've eliminated most of the fuel consumption with it.  If you delay the engine starts until the vehicle has left the city, you get rid of the pollution generated in the city.  The engine also warms up faster if run under load, improving the efficiency.

Our existing grid is generally pretty heavily loaded.

Back in 2004 it would have taken ~180 GW to replace all US gasoline and diesel with electricity.  Average electric consumption last year was 458 GW but nameplate generating capacity was 1074 GW.  Some of that is unreliable wind and PV and more is loaded-to-max nuclear and limited hydro, but finding 180 GW in that 616 GW difference wouldn't be all that hard.  Ironically, it would probably be hardest in California which has lots of vehicles but not much electric demand anymore after chasing out so much industry.


Dirk Manly:

switching over to electric cars will require HUGE increase in the electricity distribution infrastructure, right down to the wall-sockets in every home where the cars are sucking down triphase AC-220 or even 440.

Most homes don't have 3-phase service.  Your run-of-the-mill Level 2 charger is 208 or 240 VAC 32 A, which is overkill for anything short of a Tesla (most PHEVs only take 16 amps max).  You can handle your average commute with a hardware-store extension cord to a NEMA 3-prong outlet.  I know this because I do it.

(Don't even say aluminum wiring....we tried that in the 60's and 70's and the result was a lot of burned down houses).

Aluminum wire has long been the standard for transmission and has been moving down the chain.  Seriously, this stuff is a lot closer than you think.

James Dixon:

I assume you actually mean 140KWH, since you don't specify a time frame

The latest Tesla Supercharger is rated at 145 kW.  The cars still can't take juice that fast, though.

Dirk Manly:

"Try under 7% losses."

That doesn't even pass the laugh test.

That number came with a link to an authoritative source for transmission losses.  It's correct.

As battery charge approaches full charge, power conversion loss approaches 50%

This page claims 86% round-trip efficiency for the Tesla roadster.  It is probably representative of Li-on batteries.



Dirk Manly:

It also wears faster, running while the parts are cold and out of spec.

Manufacturers and mechanics recommend driving off as soon as the engine has adequate lubrication.  I thought this was common knowledge; I've certainly been reading it for decades.

In the conventional Fusion hybrid the engine starts and runs at what sounds like fast idle as soon as the key is turned and stays on until warm, even when the transmission is in park.  I'm assuming the engineers at Ford know what's good for their cars (I was one of them for a while).  Warranty claims on engines tend to be expensive.

Once you start working with high currents (like the 440 on the telephone pole coming out of the local substation), you HAVE to work in copper.

You haven't been in Home Depot's electrical department lately.  They sell a lot of aluminum wire for going from the pole to the meter, and meter to distribution panel.  If your house was built in the last 20 years, that's probably what it's got.  As I said, this stuff is closer (to you) than you think.

Speaking of substations, mine is about 4.5 miles away as the wire meanders.  The distribution is at 13.2 kV 3-phase, but only one phase of that gets to my pole.  That's 7600 V phase-to-ground.  The pole pig converts that to 240 VAC split phase, which is what gets to my meter.

if you want PRACTICAL, all-around, ONLY CAR IN THE FAMILY electric-vehicles, as opposed to a glorified golf cart, then you need 440 triphase to deliver the necessary amount of electrons into those batteries every night.

Would you say a Ford Fusion is "a glorified golf cart"?

If you're a crazy Californian who has to commute 250 miles a day to be able to afford a mortgage, you still wouldn't need 480 V charging; you'd go with something like an electric stove circuit at 240 V 50 A because the power company isn't going to run a dedicated circuit just for you and you'd still get 100 kWh in about 8 hours.  This list of average commute distances puts Atlanta at the longest, at just 12.8 miles.  If you assume that's one-way and the vehicle consumes 300 Wh/mile, you'd need just 960 watts over 8 hours to refill the battery.  18 ga lamp cord can handle that but nobody would wire with anything smaller than 14 ga.

I have many days when I burn more than 1 gallon of fuel (most days, in fact).

Well, fine.  If the first 20 miles of each leg didn't burn any fuel, how much would you save?  How about 30 miles?

It is absolutely NOT a substitute for a primary, must-be-able-to-travel 300 miles in one day, stay overnight, and come back the next day.

I've done over 800 miles in a day in the Fusion, and still averaging 80% fuel savings over the conventional drivetrain.  Most days I burn no fuel at all.  Last summer my lawn equipment used more fuel than my car (and so did my PWC).

An all-electric vehicle can only handle 20 miles out, stay overnight, and 20 miles back.

The Tesla Model 3 is rated at 220 miles range, and the Chevy Bolt is rated 238 miles.

You realize that an increasing number of hotels have chargers, don't you?  They're cropping up all over around me.  I even saw one that wasn't free, but it was replaced by a free one.  That would let you take your 220-mile EV, drive 150 miles to someplace, stay overnight and drive back the next day.

And you know what, I'm ALWAYS going to beat you at this analysis, because I'm an engineer, too.

In reality, you get schooled over and over and post not one hyperlink in support of your claims.  Facts trump analysis.  This stuff is here and it works.  5 years from now you probably won't be able to buy a new vehicle that ISN'T at least partly electric, any more than you can buy leaded mogas at the corner.  When your neighbor tells you how great it is to not have to pump gas every few days because he just plugs in the car when he hits the garage, you'll browse plug-ins when you hit the dealership.  When you drive one you'll marvel at the quiet and never want anything else.

The only thing you won't be able to do is buy a car that makes the Jetsons car bweep-bweep-bweep noise when creeping on battery power, because Hanna-Barbera isn't going to license it.  But you know people are going to make the safety noisemaker systems do that, and the tie fighter noise too, unless it's specifically outlawed.  Hackers gonna hack.

All of this talk about electric vehicles is silly

Until you start talking about replacing petroleum with stuff that's cheaper, cleaner, more widely available and not subject to foreign embargoes.  You probably have to go a half-mile or more to get gasoline.  I'll bet that there's electric power running within 20 feet of your home parking spot, and within 100 at work, the store, and most other places.  You might not be able to plug into it (yet), but it's there.

The reason why my total lack of enthusiasm for electric cars is because even getting rid of the 1st and 2nd laws of thermodynamics for electric vehicles, and ONLY electric vehicles, they still can never achieve range and performance beyond glorified golf carts.

Tesla P100D 0-60 in 2.28 sec.  We really have to catch you up to this century.

That's what's known among the common folk as a bald-faced lie.

It's what's known as common knowledge.  Lithium-ion battery charge/discharge efficiency, 80-90%.  Dunno why you don't bother looking things up, it's all right there.

I suggest you take a course in thermodynamics.

Why don't you?  I have put a Kill-A-Watt on my home charger a few times, and get reports from ChargePoint when I'm taking power away from home.  I know how much energy is going into my car.  I also know approximately how much it takes to move the car.  The numbers aren't all that different.  On a leg with speed limits mostly 45-55 MPH it comes to about 270 Wh/mile at the socket.  Figuring 75% battery and drivetrain efficiency that comes to about 200 Wh/mi at the motor shaft, or ~12 hp to cruise 45.  Sound about right to you?  Because if it's not, then the car is getting by on a lot less energy than these figures suggest... and ought to have truly ridiculous fuel economy at cruising speed on gas power.  It's good but not THAT good.

You think batteries are like heat engines.  They're not.  As I cited above, 86% is firmly in the ballpark for Li-ion.  You'd know this if you bothered to look.

We've got a freaking millenial ENGINEER who is only aware of only the "good" sides of electric vehicles

Millenial?  HA!  You are trying to get EVERYTHING wrong, aren't you?  I watched live TV of men walking on the freakin' moon.  I know the good stuff about electric vehicles because I've owned a plug-in for 5 years and can contrast my experience with half a million personal miles driving both gassers and diesels.  I can also tell you what's bad about it (like lack of trunk space, which is already going away as car bodies are redesigned to accomodate batteries elsewhere).

You, OTOH, don't have this experience.  You are repeating what passes for wisdom among your peers and on blogs like this one.  It ain't what you don't know; it's what you know that ain't so... and that's nowhere more true than here & now.  Supposedly it takes hearing a thing dozens to hundreds of times before it finally breaks through into consciousness.  What I've written here counts as maybe 2-3, so your process of awakening will be just a little quicker.  You can even take the credit as long as the necessary gets done.

James Dixon:

That's because transmission is done at EXTREMELY high voltages with extremely low current (to cut down on resistance losses).

Yes. That's also the reason the quoted transmission losses are so low.

Good, you stipulate that they actually are that low.  And I know what the distribution voltage is, because when a squirrel took out my power by immolating itself on the pole-pig and blowing the fuse, I asked the guy who came out to fix it.

7600 volts isn't EXTREMELY high; it's about 1/100 of the highest AC transmission voltages.  OTOH you can transmit half a megawatt with only 66 amps of current.  It's numbers like this that make it obvious why electricity does the heavy lifting in our industrial society, and will be doing it in transportation sooner than you think.


Dirk Manly:

Wow. You can't even seen the difference between what is being recommended, and what Ford is having their engine do in a vehicle that has to have the absolute highest reliability possible, to overcome consumer distrust of an unproven platform.

Manufacturer says: Don't warm up your engines before driving.
Ford engine control on hybrid: Warms up the engine in a no-load condition.

This is where your understanding fails:  it's NOT in a no-load condition.  It has MG1 (motor-generator 1) as a load† even if the transmission is in park, and if the traction battery isn't at the top of its charge window it has someplace to save MG1's output.  Rather than running without load at 750 RPM idle, it's going faster and lightly loaded for warmup—exactly what the mfgr calls for drivers to do, but under much finer control.  (Also important for fuel economy; fast idle is wasteful of fuel, but if the car can squirrel away the power then it isn't being wasted.)

Are you SURE you're an engineer? Because you certainly don't seem to have the observation, logic, and critical thinking skills of anyone I've ever known who actually made it through engineering school.

Anyone reading this thread is going to ask YOU that question.  Your "questions" have answers, but I'm not sure you're paying any attention to them.

You keep making pronouncements which are easily refuted with a minute on a search engine even without knowing anything about the topic beforehand.  That's not the sort of mental discipline which produces successful designs.

"Would you say a Ford Fusion is "a glorified golf cart"?"

You're moving the goalpoasts. We were talking about plug-in electrics. Now you're trying to count a hybrid with an ICE as an electric.

The Fusion Energi, Prius+ and Chrysler Pacifica plug-in Hybrid ARE plug-in electrics.  They also have gas engines.  Did you think these things could not exist together?

They have been on the market for years now, yet you're still ignorant of them.  They're not just closer than you think, they're HERE.   You could order one today.  Yet you have no idea what they could do for you.

I'm sure you're familiar with the crazy Greens claiming that the difficult-to-impossible (e.g. all "renewable" electric grid) is easy.  They are soaking up the propaganda without analyzing it.  The flip side of that coin is people claiming that easy things are difficult or impossible.  That's where you are.  You're dismissing established fact without analyzing it.  All you have to do is open your eyes.

Once you've seen what you were ignoring, you ought to have other questions.  One of them is "why is this so obscure, and who is served by hiding it?  Cui bono?"  That has an answer too.

It's a hybrid. Hybrids have been pulling freight across this country since the 1930's

Diesel-electrics are not hybrids; they do not have batteries.  Railpower Technologies got into the hybrid field a while back with the "Green Goat", and GE wasn't about to be out-done.  However, both efforts have languished; GE now says it will build hybrids when customers ask for them.  That will be when diesel gets expensive, or government demands emissions cuts that can't be met otherwise.

That shit still isn't allowed in Michigan.

Go to your Home Depot in Michigan.  I guarantee you'll find aluminum wire there.  If I'm doing this right, you can stroll into the store in Dearborn Heights and buy a roll today.

Kill-A-Watt only tells you how much power is going through the plug. It does NOT tell you how much of that power becomes charge in the battery, and how how much of that power is transformed into waste heat.

Yes.  The energy that goes through the plug is a CEILING on the energy available to drive the wheels.  Which I went through in our last exchange.  Will you stipulate to that, or are you just disagreeing to be disagreeable?

The first coulomb of charge put onto a dead battery is close to 0% loss by heat. The last coloumb of charge put battery as V(batt) approaches V(max) is at a cost of P(heat) approaches 100%.

There you are simply wrong.  The loss is the sum of (a) the coulombic loss times the charging voltage and (b) the delta-V between the charging voltage and the discharge voltage at the same point in the charge curve.  Li-ion batteries have close to 100% coulombic efficiency (charge returned over charge input).  You've already been given info on battery efficiency, there is nothing more I can do for you.

you seem to think that batteries are correctly modeled as ideal capacitors

Quote me to that effect (and no, capacitors have far less than 10% losses or you'd never be able to create e.g. high-Q filters).  I'm citing reliable info to you.  Facts matter, why do you deny them?

Worse, EVERY SINGLE BATTERY CHEMISTRY has some serious deviation from the ideal battery model.

You're flailing here.  Why do you bring up irrelevancies?  Do you think that anything non-ideal is useless?  That makes the engine in your vehicle useless, because it's a long way from an ideal Carnot or even theoretical Otto cycle.

Obviously, it doesn't matter.  What matters is fitness for purpose, not whether it is ideal or not.

FWIW, the memory-effect problems with NiCd are why conventional hybrids started out with NiMH chemistry instead.  IIUC they're moving to fast-charging Li-ion chemistries, like lithium titanate.

a fully charged NiMH battery will be fully discharged within several days

Weeks, not days.  The high rate capability of NiMH is more important to conventional hybrids than self-discharge because the batteries are so small.  My suspicion is that they will soon switch to ultracapacitors for non-plug ins, as they are already doing on some hybrid and even all-electric buses.

Batteries suck.

Yet you must own a dozen or more items which are useless without batteries.  Batteries are the only power source that's fit for purpose.  Could you put a combustion engine on your laptop?  Would you?

The power company would run at even higher voltage than 7600 V, but doing so would guarantee arcing to ground.

Power companies run AC lines as high as 765 kV.  The dielectric strength of air is about 3 megavolts per meter.  This doesn't mean you can run a 1 megavolt wire a meter off the ground because the electric field is most intense at the conductor and breakdown will start there and arc over.  The multiple-conductor lines you see with spreaders between the wires reduce the field intensity and reduce corona loss.

the power companies ALWAYS run with the voltage level as high as they can get away with for the connections

Not always.  The higher the voltage, the more stringent the requirements of the transformers.  This generally means bulk (more turns and more air or oil between conductors) which means bigger cores and everything else.  That can wipe out savings from using less mass of wire.

The only reasonable use for electricity being the mainstay for propulsion in transportation is electrified railroads and trams.

... physics and thermodynamics don't give a shit about your preferences and desires for the abolition of hydrocarbon fuels, and people in this country cannot live within the ranges offered by battery-powered vehicles with no ICE.

So?  Don't demand the full jump to battery-powered vehicles with no ICE.  Plug-in hybrids are the sweet spot; aim there.  Change point of aim if circumstances change.

PHEVs offer a host of advantages on multiple levels:

• They reduce the amount of liquid fuel required, which has the potential to eliminate US oil imports.
• They reduce the amount of liquid fuel moving through the system, meaning fewer spills, less evaporative emissions from transfers, etc.
• The reduced flows mean that the existing inventory in tank farms lasts longer in case of supply or transport disruptions, increasing security.
• They can eliminate a lot of engine starts and operation, and change where they occur.  This allows the related emissions to be moved outside of areas with lots of people, reducing exposure to pollution.
• They eliminate a lot of visits to filling stations, which is a major convenience.
• They make a lot of the vehicle's mileage "fuel agnostic"; it doesn't matter what the electricity comes from, so it can be changed at will.  This increases energy security.
• There is no sacrifice in driving range; it actually increases because the engine is generally more efficient.
• And last but not least, PHEVs use batteries 1/4 to 1/10 as big as BEVs, so the battery fabs which would support a fairly small fraction of BEVs in the fleet would be sufficient to turn every last one into a PHEV.

Can you seriously argue that any of these things is undesirable?

I've been an engineer for 35 years.

Me too.

Solving the problem would mean a 3 magnitudes or better increase in the capabilities of batteries.

You seriously think so?  Look, what we had 5 years ago was good enough to cut fuel consumption by 80%.  Today's stuff is better.  Supposedly you're a smart guy, but you have a LOT of trouble getting around your preconceptions.  Take a closer look at what's already on showroom floors.  Run the numbers.

A 20% (k= 1.2) improvement doesn't mean diddly squat when what is needed is a k=1000 improvement.

See, this is how I know you didn't run the numbers.  Today's LIBs are about 400 Wh/liter; 1000x that is 400 kWh/liter.  Gasoline is less than 9 kWh/liter, of which maybe 3-3.5 is usable!  Face it, if you could get a 5x improvement in batteries they would wipe the floor with everything else except in a few niche applications.

A 1.5x improvement takes a Tesla from 400 miles to 600 miles of range.  Can you drive 600 miles at a sitting?  I can't.  A Tesla can also recharge 50% in 30 minutes, about 17% in 10 minutes.  If you start with a full battery and charge over a 30-minute lunch and a couple of 10-minute bathroom breaks, that adds 74% to your range and takes you over 1000 miles in a day.

But Teslas are big, heavy, expensive and require lots of relatively rare materials per vehicle.  Suppose you put those batteries in what was a 30-mile PHEV, so now it has an electric range of 45 miles.  You can do your 20 miles out and 20 miles back with range to spare without burning a drop of fuel.  If you need extra range or cabin heat you've got it, but mostly that fuel sits in your tank.  Can you seriously argue that this is not worth pursuing?

The fact is, all of the relevant electronegativity spreads between chemicals are in the range of 1.0 to 2.0 volts.

Lithium-ion cells already reach 4.3 volts at full charge, and there's a lot of room to improve electrodes by replacing e.g. graphite with silicon or sulfur.  This packs more ions into the same volume/mass.

There are ions which transfer 2 or more electrons each.  Magnesium and aluminum are attractive candidates.

James Dixon:

And that's where it stops. Everything past the breaker box is copper.

Not true, I have seen aluminum wire on heavier circuits indoors as well.  I think it was on a stove.

The Fusion is a hybrid, not an electric car.

DING DING DING DING DING!  That's what I've been TELLING you!  The Fusion Energi is a plug-in hybrid and it's not terribly hard to get 80% fuel savings over the base model.  I should know, I'm doing it.

The USA consumes about 9.3 million barrels of gasoline per day.  80% savings is 7.4 mmbbl/d.  US net petroleum imports are between 3.7 and 5 million bbl/d,  so achieving 80% savings in the gasoline-powered sector would be sufficient to eliminate imports.

> Well, fine. If the first 20 miles of each leg didn't burn any fuel, how much would you save? How about 30 miles?

The improvement in gas mileage from the Toyota Yaris to the Toyota Prius C is roughly 35mpg to 50mpg.

That is completely non-responsive to the question.  How far are you driving on your typical leg?  If the first 20 miles didn't burn any fuel, how much would you wind up consuming?

As I note above, for comparable vehicles, it's more like a 60% improvement.

You don't define "comparable vehicle".  I'm comparing my dashboard readings to the EPA rating of the base model of the same car.

When will we see a Tesla in the Daytona 500?

Before you'll see a street-legal Daytona car.  Indy cars are already hybrid.

> That shit still isn't allowed in Michigan.

I don't think it's allowed anywhere in the US.

All I can say is that I've seen it with my own eyes, and for a professionally-installed circuit with heavier conductors it is probably just as good as the aluminum service wires.  That definitively settles the problem of getting industrial quantities of juice to within 20 feet of the car, and there's more than enough copper to go around to handle the rest.

† Terminology time.  The Toyota-style eCVT used in all Ford hybrids has two motor-generators.  One of them, MG2, drives the output shaft through a gear reduction.  MG1 sits on a planetary differential between the engine and the final drive.  It can be allowed to spin freely (neutral), it can drive (which is used for engine starting) or it can be driven (which generates electricity).  Here is is a video about the HF-35 transmission and how it works.



  ¶ 6/16/2018 01:02:00 PM