## Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

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• Hi Ernie,   Thanks for the number crunching.  Seems Like a deja vu situation from a few years back.  But let s take a look at what you have.  The EV plug
Message 1 of 19 , Oct 16, 2010
Hi Ernie,

Thanks for the number crunching.  Seems Like a deja vu situation from a few years back.  But let's take a look at what you have.  The EV plug to shaft efficiency numbers appear to be suspect.  Allow me to explain.  A good 3 phase AC sychonous motor is 98% efficient.  Cars like the EV-1 and other mass produced electric cars would use such motors.  Meanwhile the 92% electric motor efficiency figure you offered would apply to a decent DC motor perhaps used by an EV enthusiasts in his own retrofit EV.  I'm not sure what you mean by battery cycle efficiency.  Do you mean charger loss or round trip charge to motor loss?  I would use .9 for a good charginging system, not .8 if so.  The conditioning numbers are also a mystery to me.

So I come up with .98 X  .9  = .88 (not .7)
.
Also, where do you get 3.56 miles/kWh for the Prius?  Most good EVs typically get 200 Wh per mile fuel economy which is like 5 miles/kWh.  The EV-1 I think got 125 Wh/mile.  So those numbers appear suspect too.

As far as the 14.1 kWh figure you derive, in my opinion all it represents is the electrical energy the the car would need to travel 50.15 miles.  The correct figure in my mind is the actual identical energy from a gallon of gasoline converted to electrical energy and that figure is 34 kWh.  So then the the fuel economy would be 121.1 miles/34 kWh .  You could say 14.1kWh from generated electrical energy from gasoline onboard motor perhaps if the efficiency from the motor generated electricity is around 50%.   But I think your number of 29% efficiency for a gasolne engine is also suspect.  I am including a link which basically addresses the very subject we are discussing, and in the writeup it is shows that EVs are are at least twice as efficient on same source fuel.  In fact the 39% powerplant efficiency he uses is actually conservative as newer dual cycle turbines have improved power plant turbine efficiciency to as high as 60-65% !

So I would say to you that perhaps the numbers look good for ICE and diesels because you yourself are an enthusiast and champion of diesels, but when a more objective look is taken we can see that EVs are at least 2 times more efficient than diesels or other ICEs.

Here is the link to Chip Gribben-  Debunking of EVs and Smokestacks:

http://www.evdl.org/docs/powerplant.pdf

Yodda

--- On Fri, 10/15/10, Arcologic@... <Arcologic@...> wrote:

From: Arcologic@... <Arcologic@...>
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers
To: future-fuels-and-vehicles@yahoogroups.com
Date: Friday, October 15, 2010, 10:28 PM

Oh, my,

I was hoping to avoid complexity. But I think we need to talk more about how efficient cars are, and why. One way to try to compare efficiency of a gasser against an electric car would be to carefully look at one car design, and how well it will do as a conventional car with regen braking, and how it will do as an electric car with regen braking. I will assume for simplicity that the two forms have the same vehicle weight, the same drive train efficiency (of gears and bearings), and that all driving characteristics are about the same. Then I can just look at the effect of putting in an electric power source or a gas engine.

I have an Excel spread sheet for calculating the effects of rolling friction and aero drag, and can put in the other parameters for internal losses. The car I chose to model is a Prius, either as it is or converted to run as an EV. I am attaching the spreadsheet. If it won't go through the email, it may be that a version of it is already stored at the forum web site or can be. Here are the numbers I input--

Car frontal area....................23.5 sq.ft
Drag coefficient...................0.26
Rolling resistance coef........0.0085
Drive train efficiency.............0.85 (gears and bearings)
Gas engine efficiency..........0.29
EV plug to shaft eff..............0.70
Gas BTU /gallon..............116090
Assume kWh per gal =........34

The EV plug to shaft efficiency includes four steps--

Battery cycle efficiency..............0.80
Power conditioning in.................0.97
Power conditioning out...............0.97
Electric motor efficiency.............0.92

0.80 x 0.97 x 0.97 x 0.92 = 0.69, Close enough to 0.70

Calculations are for steady driving on the highway. Here are the results at 60 mph--

Prius running on gasoline........................50.15 miles per gallon
Prius running on electricity (EV)................3.56 miles per kWh.
Prius as EV rated using 34 kWh /gal......121.1 miles per gallon

Actual kWh per gallon can be calculated by dividing--

( 50.15 mi /gal) / ( 3.56 mi /kWh) = 14.1 kWh /gal

Or, cutting through all the balony,

( 34 kWh /gal) x ( 0.29 /0.70) = 14.1 kWh /gal

Oh, so far I haven't even looked at the power loss that occurred back at the power plant, that is, the effciency from power plant fuel to the plug where the EV is charged.

Bottom line: Most careful analyses show that EVs and gassers are about equivalent in efficiency when everything is taken into account. EVs usually look better when an EV promoter does the calculation.

My spreadsheet is attached, or I will send it to anyone that sends me an email directly, at arcologic@...
When you have the spreadsheet, you can play with changing the parameters in the yellow-shaded fields.

Ernie Rogers

-----Original Message-----
From: Oliver Perry <perrydap@...>
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Fri, Oct 15, 2010 2:28 pm
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Thanks Yodda for making a great simple comparison... an electric car being about 6 times more efficient for the same amount of energy purchased in the form of gasoline or kw-hr, which is what the customer can relate to.

Ollie Perry
EEVC
On Oct 15, 2010, at 3:21 PM, Yodda Pierce wrote:

> Hi Oliver,
>
> Well, I understand what you mean if the 17kWh is" generator derived electricity" but I think many people that do not use hybrids get their electricity from other sources other than oil or gasoline, so I would still use the 34 kWh figure myself when doing and heat derived energy comparison, but I do think the 17 kWh figure might be useful for hybrid ICE derived electricity.
>
> I was actually thinking the other day about energy used for electric cars vs. ICE and I thought about gasoline having about 114,00 BTU and its current costs vs. how much a similar amount of electricty would cost. At the 34 kWh figure it would be (34 X \$.075) or \$2.55. Currently that is the price for a gallon of gasoline where I live. So cost for gallon of gasoline or its BTU or heat equivalent is about the same. The advatage is that the good electric car motor is 98% efficient while the ICE gasoline car motor is about 17% efficient resulting in the electric car engine being about 6 times more efficient for the same amount of energy.
>
> Yodda
>
> --- On Fri, 10/15/10, Oliver Perry <perrydap@...> wrote:
>
>
> From: Oliver Perry <perrydap@...>
> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers
> To: future-fuels-and-vehicles@yahoogroups.com
> Date: Friday, October 15, 2010, 11:03 AM
>
>
>
>
>
>
> Hello Yodda and Ernie,
> I am assuming that Ernie's value of 34 kWh for the energy in gasoline is the theoretical energy available if you converted 100 % of the chemical energy in gasoline to electrical energy. But since a heat engine burning gasoline cannot take 100 % of the heat and turn it into the mechanical energy needed to run a generator... it is impossible according to thermodynamic laws.. you cannot turn all of that heat into electrical energy. Am I correct Ernie that you feel that about 50 % of the heat energy in gasoline can be turned into useful electrical energy? That is where the 17 kWh comes from ? and that would be using a diesel engine?
>
> O.H.Perry
> EEVC
> On Oct 15, 2010, at 9:59 AM, Yodda Pierce wrote:
>
>> Hi Ernie,
>>
>> I would agree with most of what you said here, but I would disagree with your view on equivalance energy between a gallon of gasoline and similar energy for an electric car I think 34 kWh is about right for the conversion based on heat or BTU yeild. Depends on the gasoline though, but I think gasoline is about 114,000 BTU so 34 kWh would put us about there. (34 X3.412). Why do you think 17 kWh is the correct figure? Aren't you a proponent of diesel engines?
>>
>> Well, I would also like to ask the group if anyone has any good info. on electric vehicle chargers. I'm involved in a project to install them at Clemson University, South Carolina and the city of Clemson. I know about some of the chargers, but not sure on the availability and production dates for the models. If anyone knows of any specials for 220 V chargers, let me know. I'm getting some matching funding from a utility sponsored group in the state.
>>
>> Yodda
>>
>>
>>
>> --- On Thu, 10/14/10, Arcologic@... <Arcologic@...> wrote:
>>
>>
>> From: Arcologic@... <Arcologic@...>
>> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars
>> To: future-fuels-and-vehicles@yahoogroups.com
>> Date: Thursday, October 14, 2010, 11:35 PM
>>
>>
>>
>>
>>
>>
>>
>> Hello, Oliver,
>>
>> You said,
>>
>> If an EV is rated as having a 70 mpg efficiency, compared to a 35 mpg vehicle, then drivers feel that they are doubling the distance they would have traveled on a gallon of gasoline in a 35 mpg car.
>>
>> You make a lot of good points in this post. Some parts, like this one, I have a problem with. Let's say that a particular car is available either as an EV or a gasser. The energy needed to move the car is exactly the same in terms of the losses at the road and in the air. (If they have equal weight.) The energy going into the power plant is another matter, and is what you are talking about. In order to relate the electric motor to the gas engine, we have to agree on the energy equivalence between the electricity and the heat in the gasoline. BUT electricity is expressed in work units. Gasoline energy is expressed in heat units. You can convert work to heat with 100% efficiency, but you can't convert heat to work that way. If you recognize that electricity (work) is a higher-quality form of energy and that conversion of fuel to electricity as in the power plant requres some waste, then we should be making an allowance for this in the energy equivalence
>> relationship. Most people, including the EPA, set the equivalence at about 34 kWh of electricity equal to a gallon of gasoline according to the 100% efficiency conversion. I think this is the wrong value, and I think somewhere near 17 would be a fairer conversion.
>>
>> By my rules, an EPA ratng of 70 mpg for the EV is exactly the same as a gasser that gets 35 mpg.
>>
>> I suggest that if these two cars are compared on the basis of CO2 emissions, you will find that they are about the same, because in reality, they do use the same amount of energy at the source. (I am assuming a power plant with somewhere near 50% efficiency.) This is a short version, leaving out a lot of details that unfortunately somebody else will almost certainly want to talk about.
>>
>> Ernie Rogers
>>
>> -----Original Message-----
>> From: Oliver Perry <perrydap@...>
>> To: future-fuels-and-vehicles@yahoogroups.com
>> Sent: Thu, Oct 14, 2010 9:05 pm
>> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars
>>
>> Great point ! Apples to apples or apples to oranges???
>>
>> There is a good reason to feel that it makes little sense to describe an electric car's efficiency in terms of miles per gallon.
>>
>> But there is also a good reason to attempt to describe an electric car's energy efficiency in terms of miles per gallon. We are primarily a society moved by gasoline... or the petroleum it comes from.
>>
>> Since almost everyone has an idea of what mpg means in terms of fuel efficiency, it makes sense to allow electric car consumers to compared their EV side by side with ICE cars in terms of how much gasoline or petroleum they are saving themselves by choosing to drive an electric car. If an EV is rated as having a 70 mpg efficiency, compared to a 35 mpg vehicle, then drivers feel that they are doubling the distance they would have traveled on a gallon of gasoline in a 35 mpg car.
>>
>> In the minds of the average consumer efficiency in cars is measured in mpg. In reality true energy efficiency units are joules, BTUs, calories, Ft lbs, or some equivalent which most people cannot relate to highway travel. Most consumers want to know how much gasoline they are saving from consumption if they chose an alternative fuel. Therefore they want to know how many gallons of gas will it take to make the trip with an ICE and what equivalent would it take with electric. People equate gallons of gasoline to energy per mile. So they expect that if a Ford Escort went 25 miles on a gallon of gas with an ICE then it should go twice as far on a gallon of gasoline if it is twice as fuel efficient using an electric motor.
>>
>> If we extend the efficiency situation to include the barrel of oil that the gasoline came from, assume that same barrel of oil will be used to run a generator at a power plant and then figure out how much less of that barrel is used with an electric car plugged into the grid we can make an honest comparison that average Americans will understand.
>>
>> Forgetting saving oil,,, just use dollars per mile and I think the average American will know how to make the best choice in order to save money. But right now the mind set is based upon gallons of oil per mile and we have to create the electricity using the same barrel of oil. The bottom line is that people want to know how many gallons of gasoline they will not have to buy if they purchase an electric car. And I agree, that is hard to figure out with varying costs of both Kw-hr and gasoline.
>>
>> OHPerry
>> EEVC
>>
>> On Oct 14, 2010, at 7:44 PM, k9zeh wrote:
>>
>>> Am I missing something here? Why bother to describe an electric vehicle in terms of miles per gallon efficiency? There are so many factors to consider like heating and air conditioning, terrain, climate, day or night use, etc. There really is no way to equate an ICE vehicle to an EV. If you operate a Volt via the ICE, then you are comparing apples to apples. Otherwise, forget about it. It is what it is.
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• Working on Yodda s questions-- For a car-size engine, up to a small marine engine, using a lab dynamometer is good. The dynamometer is just an electric
Message 2 of 19 , Oct 17, 2010
Working on Yodda's questions--

For a car-size engine, up to a small marine engine, using a lab dynamometer is good. The dynamometer is just an electric generator with readouts for rpm and torque, or AC power sometimes. For a really big engine, I think they measure rpm and torque in actual service.

After an engine warms up, its efficiency is a fairly reliable function no matter how it is used. The efficiency function varies with speed and torque. Every engine manufacturer has an "engine map" for each of its engines. This looks like a contour plot, showing lines of equal efficiency in a graph of torque versus rpm. Torque can be given in different units, and the graphs may take different forms. The rated efficiency of an engine is the "peak" on the map, actually the minimum bsfc, brake specifc fuel consumption typically given these days in metric units like gms per kilowatt-hour. You can find a good engine map by googling "engine efficiency map" The map by Georgi is very good.

For a car, it is almost impossible to operate the engine at peak efficiency. Peak efficiency is usually found at the same rpm as the peak torque, and just a little bit lower torque value than the maximum. When you are driving, you like to be able to step on the gas and have the car accelerate. This doesn't happen near peak torque or efficiency, the engine just lugs, torque drops as you add more fuel. So the practical matter is engines are operated well below their peak torque, and much lower efficiency.

Want to get a lot better mileage on the highway? Change your gear sets so the engine turns much slower and at higher torque at highway cruise. You will need to shift down before accelerating Or, you can try putting on tires with larger diameter. I changed the tires on my Beetle from 205/55 R16 to 205/60 R16. Tire efficiency improved slightly (higher sidewall, the /60 number), and it lowered the rpm at bit. I probably picked up 3 to 5% efficiency gain.

As I mentioned, my engine rated at 43% efficiency is delivering about 33% on the highway, based on measured mpg.

Typical highway mileage is about 60 mpg for my car, at 60 to 65 mph. BUT if I lower the speed, still staying in fifth gear, to about 50 mph, the engine gets closer to the peak efficiency and mileage goes up to about 75 mpg. The improved mileage is from a combination of higher engine efficiency (just a little bit) and much lower aerodynamic drag (the bigger part).

Now, about daily driving-- the brake is where you pick up extra mileage. If you anticipate and coast into stops, your mileage should improve a lot. And run in the highest gear you can manage. I sometimes get over 60 mpg around town in this way.

Ernie Rogers

-----Original Message-----
From: Yodda Pierce <ntsl532@...>
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Sat, Oct 16, 2010 10:05 am
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Hi Ernie,

Thanks for the information. It is very enlightening. I have only just had a chance to scan i,t but looks great. How were the brake efficiency numbers recorded? Dynamometer? Just curious. Also, would such engines produce the same efficiencies if they were in vehicles driven daily?

Yodda

--- On Fri, 10/15/10, Arcologic@... <Arcologic@...> wrote:

From: Arcologic@... <Arcologic@...>
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers
To: future-fuels-and-vehicles@yahoogroups.com
Date: Friday, October 15, 2010, 11:30 PM

Hello, Yodda,

I have a 2003 VW Beetle with a TDI diesel engine. Actually, my own car engine was rated by the factory as 43% efficient (in an SAE paper, dated about 1994), using 1990s motor oil. I estimated my peak engine efficiency as 45% when filled with Elf 0w30 synthetic oil, and about 33% when driving at 60 mph. As I recall, Deutz makes gen sets where the engines are about 45% efficient, and I think modern diesel engines in Class 8 trucks do about as well. The most efficient heat engines on earth that are in production are Sulzer two-stroke diesel engines. A google search will turn up lots of references. Here is a document for the MAN version of this engine, giving the brake specific fuel consumption as 164 gm /kWh:
http://viewer.zmags.com/publication/345f7127#/345f7127/14

With a fuel specific energy of 41,400 kJ /kg, I calculate this to be an efficiency of 53%.

In a paper I published this summer, I showed that a small engine can achieve 150 gm /kWh, or 57% efficiency. But, this engine hasn't been built yet. Oh, I see that a Utah state office has posted my conference paper on line---Oops,

Ernie Rogers

-----Original Message-----
From: Yodda Pierce <ntsl532@...>
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Fri, Oct 15, 2010 4:56 pm
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Hi Ernie,

Can you validate your claim of 40-55% efficiency on large deisel engines with a link to some accreditted site?

Yodda

--- On Fri, 10/15/10, Arcologic@... <Arcologic@...> wrote:

From: Arcologic@... <Arcologic@...>
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers
To: future-fuels-and-vehicles@yahoogroups.com
Date: Friday, October 15, 2010, 2:27 PM

Yes, Oliver,

All correct.

I think we need to be cautious about assuming there are only two (or three, or four) kinds of heat engines. Engine technology is advancing rapidly these days. Currently, electricity from fuel is done by gas turbines (35% efficient?), steam turbines (35%?), both together = combined cycle (55% tops), and large diesels (40% to 55%). In the future, we should have new kinds of engines that can reach about 60%. Add to that things like the "Bloom Box" that converts natural gas to electricity in a fuel cell, maybe at 40% to 50%.

I predict we will have 60% efficient engines for cars within 20 years.

Ernie Rogers

-----Original Message-----
From: Oliver Perry <perrydap@...>
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Fri, Oct 15, 2010 10:03 am
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Hello Yodda and Ernie,
I am assuming that Ernie's value of 34 kWh for the energy in gasoline is the theoretical energy available if you converted 100 % of the chemical energy in gasoline to electrical energy. But since a heat engine burning gasoline cannot take 100 % of the heat and turn it into the mechanical energy needed to run a generator... it is impossible according to thermodynamic laws.. you cannot turn all of that heat into electrical energy. Am I correct Ernie that you feel that about 50 % of the heat energy in gasoline can be turned into useful electrical energy? That is where the 17 kWh comes from ? and that would be using a diesel engine?

O.H.Perry
EEVC
On Oct 15, 2010, at 9:59 AM, Yodda Pierce wrote:

> Hi Ernie,
>
> I would agree with most of what you said here, but I would disagree with your view on equivalance energy between a gallon of gasoline and similar energy for an electric car I think 34 kWh is about right for the conversion based on heat or BTU yeild. Depends on the gasoline though, but I think gasoline is about 114,000 BTU so 34 kWh would put us about there. (34 X3.412). Why do you think 17 kWh is the correct figure? Aren't you a proponent of diesel engines?
>
> Well, I would also like to ask the group if anyone has any good info. on electric vehicle chargers. I'm involved in a project to install them at Clemson University, South Carolina and the city of Clemson. I know about some of the chargers, but not sure on the availability and production dates for the models. If anyone knows of any specials for 220 V chargers, let me know. I'm getting some matching funding from a utility sponsored group in the state.
>
> Yodda
>
>
>
> --- On Thu, 10/14/10, Arcologic@... <Arcologic@...> wrote:
>
>
> From: Arcologic@... <Arcologic@...>
> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars
> To: future-fuels-and-vehicles@yahoogroups.com
> Date: Thursday, October 14, 2010, 11:35 PM
>
>
>
>
>
>
>
> Hello, Oliver,
>
> You said,
>
> If an EV is rated as having a 70 mpg efficiency, compared to a 35 mpg vehicle, then drivers feel that they are doubling the distance they would have traveled on a gallon of gasoline in a 35 mpg car.
>
> You make a lot of good points in this post. Some parts, like this one, I have a problem with. Let's say that a particular car is available either as an EV or a gasser. The energy needed to move the car is exactly the same in terms of the losses at the road and in the air. (If they have equal weight.) The energy going into the power plant is another matter, and is what you are talking about. In order to relate the electric motor to the gas engine, we have to agree on the energy equivalence between the electricity and the heat in the gasoline. BUT electricity is expressed in work units. Gasoline energy is expressed in heat units. You can convert work to heat with 100% efficiency, but you can't convert heat to work that way. If you recognize that electricity (work) is a higher-quality form of energy and that conversion of fuel to electricity as in the power plant requres some waste, then we should be making an allowance for this in the energy equivalence
> relationship. Most people, including the EPA, set the equivalence at about 34 kWh of electricity equal to a gallon of gasoline according to the 100% efficiency conversion. I think this is the wrong value, and I think somewhere near 17 would be a fairer conversion.
>
> By my rules, an EPA ratng of 70 mpg for the EV is exactly the same as a gasser that gets 35 mpg.
>
> I suggest that if these two cars are compared on the basis of CO2 emissions, you will find that they are about the same, because in reality, they do use the same amount of energy at the source. (I am assuming a power plant with somewhere near 50% efficiency.) This is a short version, leaving out a lot of details that unfortunately somebody else will almost certainly want to talk about.
>
> Ernie Rogers
>
> -----Original Message-----
> From: Oliver Perry <perrydap@...>
> To: future-fuels-and-vehicles@yahoogroups.com
> Sent: Thu, Oct 14, 2010 9:05 pm
> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars
>
> Great point ! Apples to apples or apples to oranges???
>
> There is a good reason to feel that it makes little sense to describe an electric car's efficiency in terms of miles per gallon.
>
> But there is also a good reason to attempt to describe an electric car's energy efficiency in terms of miles per gallon. We are primarily a society moved by gasoline... or the petroleum it comes from.
>
> Since almost everyone has an idea of what mpg means in terms of fuel efficiency, it makes sense to allow electric car consumers to compared their EV side by side with ICE cars in terms of how much gasoline or petroleum they are saving themselves by choosing to drive an electric car. If an EV is rated as having a 70 mpg efficiency, compared to a 35 mpg vehicle, then drivers feel that they are doubling the distance they would have traveled on a gallon of gasoline in a 35 mpg car.
>
> In the minds of the average consumer efficiency in cars is measured in mpg. In reality true energy efficiency units are joules, BTUs, calories, Ft lbs, or some equivalent which most people cannot relate to highway travel. Most consumers want to know how much gasoline they are saving from consumption if they chose an alternative fuel. Therefore they want to know how many gallons of gas will it take to make the trip with an ICE and what equivalent would it take with electric. People equate gallons of gasoline to energy per mile. So they expect that if a Ford Escort went 25 miles on a gallon of gas with an ICE then it should go twice as far on a gallon of gasoline if it is twice as fuel efficient using an electric motor.
>
> If we extend the efficiency situation to include the barrel of oil that the gasoline came from, assume that same barrel of oil will be used to run a generator at a power plant and then figure out how much less of that barrel is used with an electric car plugged into the grid we can make an honest comparison that average Americans will understand.
>
> Forgetting saving oil,,, just use dollars per mile and I think the average American will know how to make the best choice in order to save money. But right now the mind set is based upon gallons of oil per mile and we have to create the electricity using the same barrel of oil. The bottom line is that people want to know how many gallons of gasoline they will not have to buy if they purchase an electric car. And I agree, that is hard to figure out with varying costs of both Kw-hr and gasoline.
>
> OHPerry
> EEVC
>
> On Oct 14, 2010, at 7:44 PM, k9zeh wrote:
>
>> Am I missing something here? Why bother to describe an electric vehicle in terms of miles per gallon efficiency? There are so many factors to consider like heating and air conditioning, terrain, climate, day or night use, etc. There really is no way to equate an ICE vehicle to an EV. If you operate a Volt via the ICE, then you are comparing apples to apples. Otherwise, forget about it. It is what it is.
>>
>>
>>
>>
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• Hello, Yodda, Ahh, you have a good memory, all of these points have been discussed before. Let s talk about that 0.7 efficiency I used for the EV. Here is
Message 3 of 19 , Oct 17, 2010
Hello, Yodda,

Ahh, you have a good memory, all of these points have been discussed before. Let's talk about that 0.7 efficiency I used for the EV. Here is what I said, with comments added---

The EV plug to shaft efficiency includes four steps--

1. Battery cycle efficiency..............0.80
This is the fraction of input energy returned by the battery. This can vary from 0.6 to 0.9 depending
on the rate of draw. Whenever the driver "steps on the gas" the battery efficiency will drop.
I thought 0.8 would be a fair number for average driving. Careful drivers I'm sure can do better.
2. Power conditioning in.................0.97
This is the battery charger efficiency.
3. Power conditioning out...............0.97
This is the inverter and motor controller, converting DC to drive AC
4. Electric motor efficiency.............0.92
I think this is a fair value for motor efficiency. We have to remember that like the gasoline
engine, the electric motor is not operating at its best efficiency point. And I have lumped
accessory loads in this number too.

0.80 x 0.97 x 0.97 x 0.92 = 0.69, Close enough to 0.70
And this is how the above numbers multiply to give the overall system efficiency, not
including mechanical losses.

You know, I think, that I know comparatively little about EV technology. To validate things, I just found performance numbers for the Tesla Roadster at http://en.wikipedia.org/wiki/Tesla_Roadster We can use this for comparison to see how well my guesses compare.

Energy input per mile..............................3.53 miles /kWh (0.283 Wh /mile)
Energy use from battery to wheels...........0.217 Wh /mile

Remember that I calculated 3.56 miles /kWh for the Prius, using my assumptions. If we divide these Tesla numbers, we get the combined efficiency of #s 1 and 2 above for the Tesla. Let's assume the battery charger efficiency (#2) is 0.97. Then we can calculate the battery cycle efficiency--

(Battery eff) x ( 0.97) = ( 0.217) / ( 0.283)

Battery eff = 0.97

Which is essentially what I had guessed.

So far, I haven't checked the motor efficiency. Based on the 3.53 miles /kWh for this very small car, the motor efficiency is just a bit lower than my last estimate. I can calculate the actual efficiency of the motor (with all other accessory loads included by the way) using the spreadsheet, if anybody really cares to see the number.

Ernie Rogers

-----Original Message-----
From: Yodda Pierce <ntsl532@...>
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Sat, Oct 16, 2010 8:17 pm
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Hi Ernie,

Thanks for the number crunching. Seems Like a deja vu situation from a few years back. But let's take a look at what you have. The EV plug to shaft efficiency numbers appear to be suspect. Allow me to explain. A good 3 phase AC sychonous motor is 98% efficient. Cars like the EV-1 and other mass produced electric cars would use such motors. Meanwhile the 92% electric motor efficiency figure you offered would apply to a decent DC motor perhaps used by an EV enthusiasts in his own retrofit EV. I'm not sure what you mean by battery cycle efficiency. Do you mean charger loss or round trip charge to motor loss? I would use .9 for a good charginging system, not .8 if so. The conditioning numbers are also a mystery to me.

So I come up with .98 X .9 = .88 (not .7)
.
Also, where do you get 3.56 miles/kWh for the Prius? Most good EVs typically get 200 Wh per mile fuel economy which is like 5 miles/kWh. The EV-1 I think got 125 Wh/mile. So those numbers appear suspect too.

As far as the 14.1 kWh figure you derive, in my opinion all it represents is the electrical energy the the car would need to travel 50.15 miles. The correct figure in my mind is the actual identical energy from a gallon of gasoline converted to electrical energy and that figure is 34 kWh. So then the the fuel economy would be 121.1 miles/34 kWh . You could say 14.1kWh from generated electrical energy from gasoline onboard motor perhaps if the efficiency from the motor generated electricity is around 50%. But I think your number of 29% efficiency for a gasolne engine is also suspect. I am including a link which basically addresses the very subject we are discussing, and in the writeup it is shows that EVs are are at least twice as efficient on same source fuel. In fact the 39% powerplant efficiency he uses is actually conservative as newer dual cycle turbines have improved power plant turbine efficiciency to as high as 60-65% !

So I would say to you that perhaps the numbers look good for ICE and diesels because you yourself are an enthusiast and champion of diesels, but when a more objective look is taken we can see that EVs are at least 2 times more efficient than diesels or other ICEs.

Here is the link to Chip Gribben- Debunking of EVs and Smokestacks:

http://www.evdl.org/docs/powerplant.pdf

Yodda

--- On Fri, 10/15/10, Arcologic@... <Arcologic@...> wrote:

From: Arcologic@... <Arcologic@...>
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers
To: future-fuels-and-vehicles@yahoogroups.com
Date: Friday, October 15, 2010, 10:28 PM

Oh, my,

I was hoping to avoid complexity. But I think we need to talk more about how efficient cars are, and why. One way to try to compare efficiency of a gasser against an electric car would be to carefully look at one car design, and how well it will do as a conventional car with regen braking, and how it will do as an electric car with regen braking. I will assume for simplicity that the two forms have the same vehicle weight, the same drive train efficiency (of gears and bearings), and that all driving characteristics are about the same. Then I can just look at the effect of putting in an electric power source or a gas engine.

I have an Excel spread sheet for calculating the effects of rolling friction and aero drag, and can put in the other parameters for internal losses. The car I chose to model is a Prius, either as it is or converted to run as an EV. I am attaching the spreadsheet. If it won't go through the email, it may be that a version of it is already stored at the forum web site or can be. Here are the numbers I input--

Car frontal area....................23.5 sq.ft
Drag coefficient...................0.26
Rolling resistance coef........0.0085
Drive train efficiency.............0.85 (gears and bearings)
Gas engine efficiency..........0.29
EV plug to shaft eff..............0.70
Gas BTU /gallon..............116090
Assume kWh per gal =........34

The EV plug to shaft efficiency includes four steps--

Battery cycle efficiency..............0.80
Power conditioning in.................0.97
Power conditioning out...............0.97
Electric motor efficiency.............0.92

0.80 x 0.97 x 0.97 x 0.92 = 0.69, Close enough to 0.70

Calculations are for steady driving on the highway. Here are the results at 60 mph--

Prius running on gasoline........................50.15 miles per gallon
Prius running on electricity (EV)................3.56 miles per kWh.
Prius as EV rated using 34 kWh /gal......121.1 miles per gallon

Actual kWh per gallon can be calculated by dividing--

( 50.15 mi /gal) / ( 3.56 mi /kWh) = 14.1 kWh /gal

Or, cutting through all the balony,

( 34 kWh /gal) x ( 0.29 /0.70) = 14.1 kWh /gal

Oh, so far I haven't even looked at the power loss that occurred back at the power plant, that is, the effciency from power plant fuel to the plug where the EV is charged.

Bottom line: Most careful analyses show that EVs and gassers are about equivalent in efficiency when everything is taken into account. EVs usually look better when an EV promoter does the calculation.

My spreadsheet is attached, or I will send it to anyone that sends me an email directly, at arcologic@...
When you have the spreadsheet, you can play with changing the parameters in the yellow-shaded fields.

Ernie Rogers

-----Original Message-----
From: Oliver Perry <perrydap@...>
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Fri, Oct 15, 2010 2:28 pm
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Thanks Yodda for making a great simple comparison... an electric car being about 6 times more efficient for the same amount of energy purchased in the form of gasoline or kw-hr, which is what the customer can relate to.

Ollie Perry
EEVC
On Oct 15, 2010, at 3:21 PM, Yodda Pierce wrote:

> Hi Oliver,
>
> Well, I understand what you mean if the 17kWh is" generator derived electricity" but I think many people that do not use hybrids get their electricity from other sources other than oil or gasoline, so I would still use the 34 kWh figure myself when doing and heat derived energy comparison, but I do think the 17 kWh figure might be useful for hybrid ICE derived electricity.
>
> I was actually thinking the other day about energy used for electric cars vs. ICE and I thought about gasoline having about 114,00 BTU and its current costs vs. how much a similar amount of electricty would cost. At the 34 kWh figure it would be (34 X \$.075) or \$2.55. Currently that is the price for a gallon of gasoline where I live. So cost for gallon of gasoline or its BTU or heat equivalent is about the same. The advatage is that the good electric car motor is 98% efficient while the ICE gasoline car motor is about 17% efficient resulting in the electric car engine being about 6 times more efficient for the same amount of energy.
>
> Yodda
>
> --- On Fri, 10/15/10, Oliver Perry <perrydap@...> wrote:
>
>
> From: Oliver Perry <perrydap@...>
> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers
> To: future-fuels-and-vehicles@yahoogroups.com
> Date: Friday, October 15, 2010, 11:03 AM
>
>
>
>
>
>
> Hello Yodda and Ernie,
> I am assuming that Ernie's value of 34 kWh for the energy in gasoline is the theoretical energy available if you converted 100 % of the chemical energy in gasoline to electrical energy. But since a heat engine burning gasoline cannot take 100 % of the heat and turn it into the mechanical energy needed to run a generator... it is impossible according to thermodynamic laws.. you cannot turn all of that heat into electrical energy. Am I correct Ernie that you feel that about 50 % of the heat energy in gasoline can be turned into useful electrical energy? That is where the 17 kWh comes from ? and that would be using a diesel engine?
>
> O.H.Perry
> EEVC
> On Oct 15, 2010, at 9:59 AM, Yodda Pierce wrote:
>
>> Hi Ernie,
>>
>> I would agree with most of what you said here, but I would disagree with your view on equivalance energy between a gallon of gasoline and similar energy for an electric car I think 34 kWh is about right for the conversion based on heat or BTU yeild. Depends on the gasoline though, but I think gasoline is about 114,000 BTU so 34 kWh would put us about there. (34 X3.412). Why do you think 17 kWh is the correct figure? Aren't you a proponent of diesel engines?
>>
>> Well, I would also like to ask the group if anyone has any good info. on electric vehicle chargers. I'm involved in a project to install them at Clemson University, South Carolina and the city of Clemson. I know about some of the chargers, but not sure on the availability and production dates for the models. If anyone knows of any specials for 220 V chargers, let me know. I'm getting some matching funding from a utility sponsored group in the state.
>>
>> Yodda
>>
>>
>>
>> --- On Thu, 10/14/10, Arcologic@... <Arcologic@...> wrote:
>>
>>
>> From: Arcologic@... <Arcologic@...>
>> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars
>> To: future-fuels-and-vehicles@yahoogroups.com
>> Date: Thursday, October 14, 2010, 11:35 PM
>>
>>
>>
>>
>>
>>
>>
>> Hello, Oliver,
>>
>> You said,
>>
>> If an EV is rated as having a 70 mpg efficiency, compared to a 35 mpg vehicle, then drivers feel that they are doubling the distance they would have traveled on a gallon of gasoline in a 35 mpg car.
>>
>> You make a lot of good points in this post. Some parts, like this one, I have a problem with. Let's say that a particular car is available either as an EV or a gasser. The energy needed to move the car is exactly the same in terms of the losses at the road and in the air. (If they have equal weight.) The energy going into the power plant is another matter, and is what you are talking about. In order to relate the electric motor to the gas engine, we have to agree on the energy equivalence between the electricity and the heat in the gasoline. BUT electricity is expressed in work units. Gasoline energy is expressed in heat units. You can convert work to heat with 100% efficiency, but you can't convert heat to work that way. If you recognize that electricity (work) is a higher-quality form of energy and that conversion of fuel to electricity as in the power plant requres some waste, then we should be making an allowance for this in the energy equivalence
>> relationship. Most people, including the EPA, set the equivalence at about 34 kWh of electricity equal to a gallon of gasoline according to the 100% efficiency conversion. I think this is the wrong value, and I think somewhere near 17 would be a fairer conversion.
>>
>> By my rules, an EPA ratng of 70 mpg for the EV is exactly the same as a gasser that gets 35 mpg.
>>
>> I suggest that if these two cars are compared on the basis of CO2 emissions, you will find that they are about the same, because in reality, they do use the same amount of energy at the source. (I am assuming a power plant with somewhere near 50% efficiency.) This is a short version, leaving out a lot of details that unfortunately somebody else will almost certainly want to talk about.
>>
>> Ernie Rogers
>>
>> -----Original Message-----
>> From: Oliver Perry <perrydap@...>
>> To: future-fuels-and-vehicles@yahoogroups.com
>> Sent: Thu, Oct 14, 2010 9:05 pm
>> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars
>>
>> Great point ! Apples to apples or apples to oranges???
>>
>> There is a good reason to feel that it makes little sense to describe an electric car's efficiency in terms of miles per gallon.
>>
>> But there is also a good reason to attempt to describe an electric car's energy efficiency in terms of miles per gallon. We are primarily a society moved by gasoline... or the petroleum it comes from.
>>
>> Since almost everyone has an idea of what mpg means in terms of fuel efficiency, it makes sense to allow electric car consumers to compared their EV side by side with ICE cars in terms of how much gasoline or petroleum they are saving themselves by choosing to drive an electric car. If an EV is rated as having a 70 mpg efficiency, compared to a 35 mpg vehicle, then drivers feel that they are doubling the distance they would have traveled on a gallon of gasoline in a 35 mpg car.
>>
>> In the minds of the average consumer efficiency in cars is measured in mpg. In reality true energy efficiency units are joules, BTUs, calories, Ft lbs, or some equivalent which most people cannot relate to highway travel. Most consumers want to know how much gasoline they are saving from consumption if they chose an alternative fuel. Therefore they want to know how many gallons of gas will it take to make the trip with an ICE and what equivalent would it take with electric. People equate gallons of gasoline to energy per mile. So they expect that if a Ford Escort went 25 miles on a gallon of gas with an ICE then it should go twice as far on a gallon of gasoline if it is twice as fuel efficient using an electric motor.
>>
>> If we extend the efficiency situation to include the barrel of oil that the gasoline came from, assume that same barrel of oil will be used to run a generator at a power plant and then figure out how much less of that barrel is used with an electric car plugged into the grid we can make an honest comparison that average Americans will understand.
>>
>> Forgetting saving oil,,, just use dollars per mile and I think the average American will know how to make the best choice in order to save money. But right now the mind set is based upon gallons of oil per mile and we have to create the electricity using the same barrel of oil. The bottom line is that people want to know how many gallons of gasoline they will not have to buy if they purchase an electric car. And I agree, that is hard to figure out with varying costs of both Kw-hr and gasoline.
>>
>> OHPerry
>> EEVC
>>
>> On Oct 14, 2010, at 7:44 PM, k9zeh wrote:
>>
>>> Am I missing something here? Why bother to describe an electric vehicle in terms of miles per gallon efficiency? There are so many factors to consider like heating and air conditioning, terrain, climate, day or night use, etc. There really is no way to equate an ICE vehicle to an EV. If you operate a Volt via the ICE, then you are comparing apples to apples. Otherwise, forget about it. It is what it is.
>>>
>>>
>>>
>>>
>>> ------------------------------------
>>>
>>>
>>>
>>>
>>
>> [Non-text portions of this message have been removed]
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> [Non-text portions of this message have been removed]
>>
>>
>>
>> ------------------------------------
>>
>>
>>
>>
>
>
>
>
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
>
>
>

[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

(Battery eff) x ( 0.97) = ( 0.217) / ( 0.283)

Battery eff = 0.97

Which is essentially what I had guessed.

So far, I haven't checked the motor efficiency. Based on the 3.53 miles /kWh for this very small car, the motor efficiency is just a bit lower than my last estimate. I can calculate the actual efficiency of the motor (with all other accessory loads included by the way) using the spreadsheet, if anybody really cares to see the number.

Ernie Rogers

-----Original Message-----
From: Yodda Pierce <ntsl532@...>
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Sat, Oct 16, 2010 8:17 pm
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Hi Ernie,

Thanks for the number crunching. Seems Like a deja vu situation from a few years back. But let's take a look at what you have. The EV plug to shaft efficiency numbers appear to be suspect. Allow me to explain. A good 3 phase AC sychonous motor is 98% efficient. Cars like the EV-1 and other mass produced electric cars would use such motors. Meanwhile the 92% electric motor efficiency figure you offered would apply to a decent DC motor perhaps used by an EV enthusiasts in his own retrofit EV. I'm not sure what you mean by battery cycle efficiency. Do you mean charger loss or round trip charge to motor loss? I would use .9 for a good charginging system, not .8 if so. The conditioning numbers are also a mystery to me.

So I come up with .98 X .9 = .88 (not .7)
.
Also, where do you get 3.56 miles/kWh for the Prius? Most good EVs typically get 200 Wh per mile fuel economy which is like 5 miles/kWh. The EV-1 I think got 125 Wh/mile. So those numbers appear suspect too.

As far as the 14.1 kWh figure you derive, in my opinion all it represents is the electrical energy the the car would need to travel 50.15 miles. The correct figure in my mind is the actual identical energy from a gallon of gasoline converted to electrical energy and that figure is 34 kWh. So then the the fuel economy would be 121.1 miles/34 kWh . You could say 14.1kWh from generated electrical energy from gasoline onboard motor perhaps if the efficiency from the motor generated electricity is around 50%. But I think your number of 29% efficiency for a gasolne engine is also suspect. I am including a link which basically addresses the very subject we are discussing, and in the writeup it is shows that EVs are are at least twice as efficient on same source fuel. In fact the 39% powerplant efficiency he uses is actually conservative as newer dual cycle turbines have improved power plant turbine efficiciency to as high as 60-65% !

So I would say to you that perhaps the numbers look good for ICE and diesels because you yourself are an enthusiast and champion of diesels, but when a more objective look is taken we can see that EVs are at least 2 times more efficient than diesels or other ICEs.

Here is the link to Chip Gribben- Debunking of EVs and Smokestacks:

http://www.evdl.org/docs/powerplant.pdf

Yodda

--- On Fri, 10/15/10, Arcologic@... <Arcologic@...> wrote:

From: Arcologic@... <Arcologic@...>
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers
To: future-fuels-and-vehicles@yahoogroups.com
Date: Friday, October 15, 2010, 10:28 PM

Oh, my,

I was hoping to avoid complexity. But I think we need to talk more about how efficient cars are, and why. One way to try to compare efficiency of a gasser against an electric car would be to carefully look at one car design, and how well it will do as a conventional car with regen braking, and how it will do as an electric car with regen braking. I will assume for simplicity that the two forms have the same vehicle weight, the same drive train efficiency (of gears and bearings), and that all driving characteristics are about the same. Then I can just look at the effect of putting in an electric power source or a gas engine.

I have an Excel spread sheet for calculating the effects of rolling friction and aero drag, and can put in the other parameters for internal losses. The car I chose to model is a Prius, either as it is or converted to run as an EV. I am attaching the spreadsheet. If it won't go through the email, it may be that a version of it is already stored at the forum web site or can be. Here are the numbers I input--

Car frontal area....................23.5 sq.ft
Drag coefficient...................0.26
Rolling resistance coef........0.0085
Drive train efficiency.............0.85 (gears and bearings)
Gas engine efficiency..........0.29
EV plug to shaft eff..............0.70
Gas BTU /gallon..............116090
Assume kWh per gal =........34

The EV plug to shaft efficiency includes four steps--

Battery cycle efficiency..............0.80
Power conditioning in.................0.97
Power conditioning out...............0.97
Electric motor efficiency.............0.92

0.80 x 0.97 x 0.97 x 0.92 = 0.69, Close enough to 0.70

Calculations are for steady driving on the highway. Here are the results at 60 mph--

Prius running on gasoline........................50.15 miles per gallon
Prius running on electricity (EV)................3.56 miles per kWh.
Prius as EV rated using 34 kWh /gal......121.1 miles per gallon

Actual kWh per gallon can be calculated by dividing--

( 50.15 mi /gal) / ( 3.56 mi /kWh) = 14.1 kWh /gal

Or, cutting through all the balony,

( 34 kWh /gal) x ( 0.29 /0.70) = 14.1 kWh /gal

Oh, so far I haven't even looked at the power loss that occurred back at the power plant, that is, the effciency from power plant fuel to the plug where the EV is charged.

Bottom line: Most careful analyses show that EVs and gassers are about equivalent in efficiency when everything is taken into account. EVs usually look better when an EV promoter does the calculation.

My spreadsheet is attached, or I will send it to anyone that sends me an email directly, at arcologic@...
When you have the spreadsheet, you can play with changing the parameters in the yellow-shaded fields.

Ernie Rogers

-----Original Message-----
From: Oliver Perry <perrydap@...>
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Fri, Oct 15, 2010 2:28 pm
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Thanks Yodda for making a great simple comparison... an electric car being about 6 times more efficient for the same amount of energy purchased in the form of gasoline or kw-hr, which is what the customer can relate to.

Ollie Perry
EEVC
On Oct 15, 2010, at 3:21 PM, Yodda Pierce wrote:

> Hi Oliver,
>
> Well, I understand what you mean if the 17kWh is" generator derived electricity" but I think many people that do not use hybrids get their electricity from other sources other than oil or gasoline, so I would still use the 34 kWh figure myself when doing and heat derived energy comparison, but I do think the 17 kWh figure might be useful for hybrid ICE derived electricity.
>
> I was actually thinking the other day about energy used for electric cars vs. ICE and I thought about gasoline having about 114,00 BTU and its current costs vs. how much a similar amount of electricty would cost. At the 34 kWh figure it would be (34 X \$.075) or \$2.55. Currently that is the price for a gallon of gasoline where I live. So cost for gallon of gasoline or its BTU or heat equivalent is about the same. The advatage is that the good electric car motor is 98% efficient while the ICE gasoline car motor is about 17% efficient resulting in the electric car engine being about 6 times more efficient for the same amount of energy.
>
> Yodda
>
> --- On Fri, 10/15/10, Oliver Perry <perrydap@...> wrote:
>
>
> From: Oliver Perry <perrydap@...>
> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers
> To: future-fuels-and-vehicles@yahoogroups.com
> Date: Friday, October 15, 2010, 11:03 AM
>
>
>
>
>
>
> Hello Yodda and Ernie,
> I am assuming that Ernie's value of 34 kWh for the energy in gasoline is the theoretical energy available if you converted 100 % of the chemical energy in gasoline to electrical energy. But since a heat engine burning gasoline cannot take 100 % of the heat and turn it into the mechanical energy needed to run a generator... it is impossible according to thermodynamic laws.. you cannot turn all of that heat into electrical energy. Am I correct Ernie that you feel that about 50 % of the heat energy in gasoline can be turned into useful electrical energy? That is where the 17 kWh comes from ? and that would be using a diesel engine?
>
> O.H.Perry
> EEVC
> On Oct 15, 2010, at 9:59 AM, Yodda Pierce wrote:
>
>> Hi Ernie,
>>
>> I would agree with most of what you said here, but I would disagree with your view on equivalance energy between a gallon of gasoline and similar energy for an electric car I think 34 kWh is about right for the conversion based on heat or BTU yeild. Depends on the gasoline though, but I think gasoline is about 114,000 BTU so 34 kWh would put us about there. (34 X3.412). Why do you think 17 kWh is the correct figure? Aren't you a proponent of diesel engines?
>>
>> Well, I would also like to ask the group if anyone has any good info. on electric vehicle chargers. I'm involved in a project to install them at Clemson University, South Carolina and the city of Clemson. I know about some of the chargers, but not sure on the availability and production dates for the models. If anyone knows of any specials for 220 V chargers, let me know. I'm getting some matching funding from a utility sponsored group in the state.
>>
>> Yodda
>>
>>
>>
>> --- On Thu, 10/14/10, Arcologic@... <Arcologic@...> wrote:
>>
>>
>> From: Arcologic@... <Arcologic@...>
>> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars
>> To: future-fuels-and-vehicles@yahoogroups.com
>> Date: Thursday, October 14, 2010, 11:35 PM
>>
>>
>>
>>
>>
>>
>>
>> Hello, Oliver,
>>
>> You said,
>>
>> If an EV is rated as having a 70 mpg efficiency, compared to a 35 mpg vehicle, then drivers feel that they are doubling the distance they would have traveled on a gallon of gasoline in a 35 mpg car.
>>
>> You make a lot of good points in this post. Some parts, like this one, I have a problem with. Let's say that a particular car is available either as an EV or a gasser. The energy needed to move the car is exactly the same in terms of the losses at the road and in the air. (If they have equal weight.) The energy going into the power plant is another matter, and is what you are talking about. In order to relate the electric motor to the gas engine, we have to agree on the energy equivalence between the electricity and the heat in the gasoline. BUT electricity is expressed in work units. Gasoline energy is expressed in heat units. You can convert work to heat with 100% efficiency, but you can't convert heat to work that way. If you recognize that electricity (work) is a higher-quality form of energy and that conversion of fuel to electricity as in the power plant requres some waste, then we should be making an allowance for this in the energy equivalence
>> relationship. Most people, including the EPA, set the equivalence at about 34 kWh of electricity equal to a gallon of gasoline according to the 100% efficiency conversion. I think this is the wrong value, and I think somewhere near 17 would be a fairer conversion.
>>
>> By my rules, an EPA ratng of 70 mpg for the EV is exactly the same as a gasser that gets 35 mpg.
>>
>> I suggest that if these two cars are compared on the basis of CO2 emissions, you will find that they are about the same, because in reality, they do use the same amount of energy at the source. (I am assuming a power plant with somewhere near 50% efficiency.) This is a short version, leaving out a lot of details that unfortunately somebody else will almost certainly want to talk about.
>>
>> Ernie Rogers
>>
>> -----Original Message-----
>> From: Oliver Perry <perrydap@...>
>> To: future-fuels-and-vehicles@yahoogroups.com
>> Sent: Thu, Oct 14, 2010 9:05 pm
>> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars
>>
>> Great point ! Apples to apples or apples to oranges???
>>
>> There is a good reason to feel that it makes little sense to describe an electric car's efficiency in terms of miles per gallon.
>>
>> But there is also a good reason to attempt to describe an electric car's energy efficiency in terms of miles per gallon. We are primarily a society moved by gasoline... or the petroleum it comes from.
>>
>> Since almost everyone has an idea of what mpg means in terms of fuel efficiency, it makes sense to allow electric car consumers to compared their EV side by side with ICE cars in terms of how much gasoline or petroleum they are saving themselves by choosing to drive an electric car. If an EV is rated as having a 70 mpg efficiency, compared to a 35 mpg vehicle, then drivers feel that they are doubling the distance they would have traveled on a gallon of gasoline in a 35 mpg car.
>>
>> In the minds of the average consumer efficiency in cars is measured in mpg. In reality true energy efficiency units are joules, BTUs, calories, Ft lbs, or some equivalent which most people cannot relate to highway travel. Most consumers want to know how much gasoline they are saving from consumption if they chose an alternative fuel. Therefore they want to know how many gallons of gas will it take to make the trip with an ICE and what equivalent would it take with electric. People equate gallons of gasoline to energy per mile. So they expect that if a Ford Escort went 25 miles on a gallon of gas with an ICE then it should go twice as far on a gallon of gasoline if it is twice as fuel efficient using an electric motor.
>>
>> If we extend the efficiency situation to include the barrel of oil that the gasoline came from, assume that same barrel of oil will be used to run a generator at a power plant and then figure out how much less of that barrel is used with an electric car plugged into the grid we can make an honest comparison that average Americans will understand.
>>
>> Forgetting saving oil,,, just use dollars per mile and I think the average American will know how to make the best choice in order to save money. But right now the mind set is based upon gallons of oil per mile and we have to create the electricity using the same barrel of oil. The bottom line is that people want to know how many gallons of gasoline they will not have to buy if they purchase an electric car. And I agree, that is hard to figure out with varying costs of both Kw-hr and gasoline.
>>
>> OHPerry
>> EEVC
>>
>> On Oct 14, 2010, at 7:44 PM, k9zeh wrote:
>>
>>> Am I missing something here? Why bother to describe an electric vehicle in terms of miles per gallon efficiency? There are so many factors to consider like heating and air conditioning, terrain, climate, day or night use, etc. There really is no way to equate an ICE vehicle to an EV. If you operate a Volt via the ICE, then you are comparing apples to apples. Otherwise, forget about it. It is what it is.
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• Oh, my, I made a stupid typo in this calculation and nobody called me on it. Here it is-- (Battery eff) x ( 0.97) = ( 0.217) / ( 0.283) Battery eff = 0.97
Message 4 of 19 , Oct 18, 2010
Oh, my, I made a stupid typo in this calculation and nobody called me on it. Here it is--

(Battery eff) x ( 0.97) = ( 0.217) / ( 0.283)

Battery eff = 0.97

Which is essentially what I had guessed.

The calculated battery efficiency for the Tesla should have been Battery eff = 0.79, which is essentially the same as my guess of 0.80 for the Prius EV example. (Little dyslexia there.)

Ernie Rogers

-----Original Message-----
From: Arcologic@...
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Sun, Oct 17, 2010 4:55 pm
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Hello, Yodda,

Ahh, you have a good memory, all of these points have been discussed before. Let's talk about that 0.7 efficiency I used for the EV. Here is what I said, with comments added---

The EV plug to shaft efficiency includes four steps--

1. Battery cycle efficiency..............0.80
This is the fraction of input energy returned by the battery. This can vary from 0.6 to 0.9 depending
on the rate of draw. Whenever the driver "steps on the gas" the battery efficiency will drop.
I thought 0.8 would be a fair number for average driving. Careful drivers I'm sure can do better.
2. Power conditioning in.................0.97
This is the battery charger efficiency.
3. Power conditioning out...............0.97
This is the inverter and motor controller, converting DC to drive AC
4. Electric motor efficiency.............0.92
I think this is a fair value for motor efficiency. We have to remember that like the gasoline
engine, the electric motor is not operating at its best efficiency point. And I have lumped
accessory loads in this number too.

0.80 x 0.97 x 0.97 x 0.92 = 0.69, Close enough to 0.70
And this is how the above numbers multiply to give the overall system efficiency, not
including mechanical losses.

You know, I think, that I know comparatively little about EV technology. To validate things, I just found performance numbers for the Tesla Roadster at http://en.wikipedia.org/wiki/Tesla_Roadster We can use this for comparison to see how well my guesses compare.

Energy input per mile..............................3.53 miles /kWh (0.283 Wh /mile)
Energy use from battery to wheels...........0.217 Wh /mile

Remember that I calculated 3.56 miles /kWh for the Prius, using my assumptions. If we divide these Tesla numbers, we get the combined efficiency of #s 1 and 2 above for the Tesla. Let's assume the battery charger efficiency (#2) is 0.97. Then we can calculate the battery cycle efficiency--

(Battery eff) x ( 0.97) = ( 0.217) / ( 0.283)

Battery eff = 0.97

Which is essentially what I had guessed.

So far, I haven't checked the motor efficiency. Based on the 3.53 miles /kWh for this very small car, the motor efficiency is just a bit lower than my last estimate. I can calculate the actual efficiency of the motor (with all other accessory loads included by the way) using the spreadsheet, if anybody really cares to see the number.

Ernie Rogers

-----Original Message-----
From: Yodda Pierce <ntsl532@...>
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Sat, Oct 16, 2010 8:17 pm
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Hi Ernie,

Thanks for the number crunching. Seems Like a deja vu situation from a few years back. But let's take a look at what you have. The EV plug to shaft efficiency numbers appear to be suspect. Allow me to explain. A good 3 phase AC sychonous motor is 98% efficient. Cars like the EV-1 and other mass produced electric cars would use such motors. Meanwhile the 92% electric motor efficiency figure you offered would apply to a decent DC motor perhaps used by an EV enthusiasts in his own retrofit EV. I'm not sure what you mean by battery cycle efficiency. Do you mean charger loss or round trip charge to motor loss? I would use .9 for a good charginging system, not .8 if so. The conditioning numbers are also a mystery to me.

So I come up with .98 X .9 = .88 (not .7)
.
Also, where do you get 3.56 miles/kWh for the Prius? Most good EVs typically get 200 Wh per mile fuel economy which is like 5 miles/kWh. The EV-1 I think got 125 Wh/mile. So those numbers appear suspect too.

As far as the 14.1 kWh figure you derive, in my opinion all it represents is the electrical energy the the car would need to travel 50.15 miles. The correct figure in my mind is the actual identical energy from a gallon of gasoline converted to electrical energy and that figure is 34 kWh. So then the the fuel economy would be 121.1 miles/34 kWh . You could say 14.1kWh from generated electrical energy from gasoline onboard motor perhaps if the efficiency from the motor generated electricity is around 50%. But I think your number of 29% efficiency for a gasolne engine is also suspect. I am including a link which basically addresses the very subject we are discussing, and in the writeup it is shows that EVs are are at least twice as efficient on same source fuel. In fact the 39% powerplant efficiency he uses is actually conservative as newer dual cycle turbines have improved power plant turbine efficiciency to as high as 60-65% !

So I would say to you that perhaps the numbers look good for ICE and diesels because you yourself are an enthusiast and champion of diesels, but when a more objective look is taken we can see that EVs are at least 2 times more efficient than diesels or other ICEs.

Here is the link to Chip Gribben- Debunking of EVs and Smokestacks:

http://www.evdl.org/docs/powerplant.pdf

Yodda

--- On Fri, 10/15/10, Arcologic@... <Arcologic@...> wrote:

From: Arcologic@... <Arcologic@...>
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers
To: future-fuels-and-vehicles@yahoogroups.com
Date: Friday, October 15, 2010, 10:28 PM

Oh, my,

I was hoping to avoid complexity. But I think we need to talk more about how efficient cars are, and why. One way to try to compare efficiency of a gasser against an electric car would be to carefully look at one car design, and how well it will do as a conventional car with regen braking, and how it will do as an electric car with regen braking. I will assume for simplicity that the two forms have the same vehicle weight, the same drive train efficiency (of gears and bearings), and that all driving characteristics are about the same. Then I can just look at the effect of putting in an electric power source or a gas engine.

I have an Excel spread sheet for calculating the effects of rolling friction and aero drag, and can put in the other parameters for internal losses. The car I chose to model is a Prius, either as it is or converted to run as an EV. I am attaching the spreadsheet. If it won't go through the email, it may be that a version of it is already stored at the forum web site or can be. Here are the numbers I input--

Car frontal area....................23.5 sq.ft
Drag coefficient...................0.26
Rolling resistance coef........0.0085
Drive train efficiency.............0.85 (gears and bearings)
Gas engine efficiency..........0.29
EV plug to shaft eff..............0.70
Gas BTU /gallon..............116090
Assume kWh per gal =........34

The EV plug to shaft efficiency includes four steps--

Battery cycle efficiency..............0.80
Power conditioning in.................0.97
Power conditioning out...............0.97
Electric motor efficiency.............0.92

0.80 x 0.97 x 0.97 x 0.92 = 0.69, Close enough to 0.70

Calculations are for steady driving on the highway. Here are the results at 60 mph--

Prius running on gasoline........................50.15 miles per gallon
Prius running on electricity (EV)................3.56 miles per kWh.
Prius as EV rated using 34 kWh /gal......121.1 miles per gallon

Actual kWh per gallon can be calculated by dividing--

( 50.15 mi /gal) / ( 3.56 mi /kWh) = 14.1 kWh /gal

Or, cutting through all the balony,

( 34 kWh /gal) x ( 0.29 /0.70) = 14.1 kWh /gal

Oh, so far I haven't even looked at the power loss that occurred back at the power plant, that is, the effciency from power plant fuel to the plug where the EV is charged.

Bottom line: Most careful analyses show that EVs and gassers are about equivalent in efficiency when everything is taken into account. EVs usually look better when an EV promoter does the calculation.

My spreadsheet is attached, or I will send it to anyone that sends me an email directly, at arcologic@...
When you have the spreadsheet, you can play with changing the parameters in the yellow-shaded fields.

Ernie Rogers

-----Original Message-----
From: Oliver Perry <perrydap@...>
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Fri, Oct 15, 2010 2:28 pm
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Thanks Yodda for making a great simple comparison... an electric car being about 6 times more efficient for the same amount of energy purchased in the form of gasoline or kw-hr, which is what the customer can relate to.

Ollie Perry
EEVC
On Oct 15, 2010, at 3:21 PM, Yodda Pierce wrote:

> Hi Oliver,
>
> Well, I understand what you mean if the 17kWh is" generator derived electricity" but I think many people that do not use hybrids get their electricity from other sources other than oil or gasoline, so I would still use the 34 kWh figure myself when doing and heat derived energy comparison, but I do think the 17 kWh figure might be useful for hybrid ICE derived electricity.
>
> I was actually thinking the other day about energy used for electric cars vs. ICE and I thought about gasoline having about 114,00 BTU and its current costs vs. how much a similar amount of electricty would cost. At the 34 kWh figure it would be (34 X \$.075) or \$2.55. Currently that is the price for a gallon of gasoline where I live. So cost for gallon of gasoline or its BTU or heat equivalent is about the same. The advatage is that the good electric car motor is 98% efficient while the ICE gasoline car motor is about 17% efficient resulting in the electric car engine being about 6 times more efficient for the same amount of energy.
>
> Yodda
>
> --- On Fri, 10/15/10, Oliver Perry <perrydap@...> wrote:
>
>
> From: Oliver Perry <perrydap@...>
> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers
> To: future-fuels-and-vehicles@yahoogroups.com
> Date: Friday, October 15, 2010, 11:03 AM
>
>
>
>
>
>
> Hello Yodda and Ernie,
> I am assuming that Ernie's value of 34 kWh for the energy in gasoline is the theoretical energy available if you converted 100 % of the chemical energy in gasoline to electrical energy. But since a heat engine burning gasoline cannot take 100 % of the heat and turn it into the mechanical energy needed to run a generator... it is impossible according to thermodynamic laws.. you cannot turn all of that heat into electrical energy. Am I correct Ernie that you feel that about 50 % of the heat energy in gasoline can be turned into useful electrical energy? That is where the 17 kWh comes from ? and that would be using a diesel engine?
>
> O.H.Perry
> EEVC
> On Oct 15, 2010, at 9:59 AM, Yodda Pierce wrote:
>
>> Hi Ernie,
>>
>> I would agree with most of what you said here, but I would disagree with your view on equivalance energy between a gallon of gasoline and similar energy for an electric car I think 34 kWh is about right for the conversion based on heat or BTU yeild. Depends on the gasoline though, but I think gasoline is about 114,000 BTU so 34 kWh would put us about there. (34 X3.412). Why do you think 17 kWh is the correct figure? Aren't you a proponent of diesel engines?
>>
>> Well, I would also like to ask the group if anyone has any good info. on electric vehicle chargers. I'm involved in a project to install them at Clemson University, South Carolina and the city of Clemson. I know about some of the chargers, but not sure on the availability and production dates for the models. If anyone knows of any specials for 220 V chargers, let me know. I'm getting some matching funding from a utility sponsored group in the state.
>>
>> Yodda
>>
>>
>>
>> --- On Thu, 10/14/10, Arcologic@... <Arcologic@...> wrote:
>>
>>
>> From: Arcologic@... <Arcologic@...>
>> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars
>> To: future-fuels-and-vehicles@yahoogroups.com
>> Date: Thursday, October 14, 2010, 11:35 PM
>>
>>
>>
>>
>>
>>
>>
>> Hello, Oliver,
>>
>> You said,
>>
>> If an EV is rated as having a 70 mpg efficiency, compared to a 35 mpg vehicle, then drivers feel that they are doubling the distance they would have traveled on a gallon of gasoline in a 35 mpg car.
>>
>> You make a lot of good points in this post. Some parts, like this one, I have a problem with. Let's say that a particular car is available either as an EV or a gasser. The energy needed to move the car is exactly the same in terms of the losses at the road and in the air. (If they have equal weight.) The energy going into the power plant is another matter, and is what you are talking about. In order to relate the electric motor to the gas engine, we have to agree on the energy equivalence between the electricity and the heat in the gasoline. BUT electricity is expressed in work units. Gasoline energy is expressed in heat units. You can convert work to heat with 100% efficiency, but you can't convert heat to work that way. If you recognize that electricity (work) is a higher-quality form of energy and that conversion of fuel to electricity as in the power plant requres some waste, then we should be making an allowance for this in the energy equivalence
>> relationship. Most people, including the EPA, set the equivalence at about 34 kWh of electricity equal to a gallon of gasoline according to the 100% efficiency conversion. I think this is the wrong value, and I think somewhere near 17 would be a fairer conversion.
>>
>> By my rules, an EPA ratng of 70 mpg for the EV is exactly the same as a gasser that gets 35 mpg.
>>
>> I suggest that if these two cars are compared on the basis of CO2 emissions, you will find that they are about the same, because in reality, they do use the same amount of energy at the source. (I am assuming a power plant with somewhere near 50% efficiency.) This is a short version, leaving out a lot of details that unfortunately somebody else will almost certainly want to talk about.
>>
>> Ernie Rogers
>>
>> -----Original Message-----
>> From: Oliver Perry <perrydap@...>
>> To: future-fuels-and-vehicles@yahoogroups.com
>> Sent: Thu, Oct 14, 2010 9:05 pm
>> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars
>>
>> Great point ! Apples to apples or apples to oranges???
>>
>> There is a good reason to feel that it makes little sense to describe an electric car's efficiency in terms of miles per gallon.
>>
>> But there is also a good reason to attempt to describe an electric car's energy efficiency in terms of miles per gallon. We are primarily a society moved by gasoline... or the petroleum it comes from.
>>
>> Since almost everyone has an idea of what mpg means in terms of fuel efficiency, it makes sense to allow electric car consumers to compared their EV side by side with ICE cars in terms of how much gasoline or petroleum they are saving themselves by choosing to drive an electric car. If an EV is rated as having a 70 mpg efficiency, compared to a 35 mpg vehicle, then drivers feel that they are doubling the distance they would have traveled on a gallon of gasoline in a 35 mpg car.
>>
>> In the minds of the average consumer efficiency in cars is measured in mpg. In reality true energy efficiency units are joules, BTUs, calories, Ft lbs, or some equivalent which most people cannot relate to highway travel. Most consumers want to know how much gasoline they are saving from consumption if they chose an alternative fuel. Therefore they want to know how many gallons of gas will it take to make the trip with an ICE and what equivalent would it take with electric. People equate gallons of gasoline to energy per mile. So they expect that if a Ford Escort went 25 miles on a gallon of gas with an ICE then it should go twice as far on a gallon of gasoline if it is twice as fuel efficient using an electric motor.
>>
>> If we extend the efficiency situation to include the barrel of oil that the gasoline came from, assume that same barrel of oil will be used to run a generator at a power plant and then figure out how much less of that barrel is used with an electric car plugged into the grid we can make an honest comparison that average Americans will understand.
>>
>> Forgetting saving oil,,, just use dollars per mile and I think the average American will know how to make the best choice in order to save money. But right now the mind set is based upon gallons of oil per mile and we have to create the electricity using the same barrel of oil. The bottom line is that people want to know how many gallons of gasoline they will not have to buy if they purchase an electric car. And I agree, that is hard to figure out with varying costs of both Kw-hr and gasoline.
>>
>> OHPerry
>> EEVC
>>
>> On Oct 14, 2010, at 7:44 PM, k9zeh wrote:
>>
>>> Am I missing something here? Why bother to describe an electric vehicle in terms of miles per gallon efficiency? There are so many factors to consider like heating and air conditioning, terrain, climate, day or night use, etc. There really is no way to equate an ICE vehicle to an EV. If you operate a Volt via the ICE, then you are comparing apples to apples. Otherwise, forget about it. It is what it is.
>>>
>>>
>>>
>>>
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>>>
>>>
>>>
>>>
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>> [Non-text portions of this message have been removed]
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> [Non-text portions of this message have been removed]
>>
>>
>>
>> ------------------------------------
>>
>>
>>
>>
>
>
>
>
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
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> ------------------------------------
>
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>

[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

(Battery eff) x ( 0.97) = ( 0.217) / ( 0.283)

Battery eff = 0.97

Which is essentially what I had guessed.

So far, I haven't checked the motor efficiency. Based on the 3.53 miles /kWh for this very small car, the motor efficiency is just a bit lower than my last estimate. I can calculate the actual efficiency of the motor (with all other accessory loads included by the way) using the spreadsheet, if anybody really cares to see the number.

Ernie Rogers

-----Original Message-----
From: Yodda Pierce <ntsl532@...>
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Sat, Oct 16, 2010 8:17 pm
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Hi Ernie,

Thanks for the number crunching. Seems Like a deja vu situation from a few years back. But let's take a look at what you have. The EV plug to shaft efficiency numbers appear to be suspect. Allow me to explain. A good 3 phase AC sychonous motor is 98% efficient. Cars like the EV-1 and other mass produced electric cars would use such motors. Meanwhile the 92% electric motor efficiency figure you offered would apply to a decent DC motor perhaps used by an EV enthusiasts in his own retrofit EV. I'm not sure what you mean by battery cycle efficiency. Do you mean charger loss or round trip charge to motor loss? I would use .9 for a good charginging system, not .8 if so. The conditioning numbers are also a mystery to me.

So I come up with .98 X .9 = .88 (not .7)
.
Also, where do you get 3.56 miles/kWh for the Prius? Most good EVs typically get 200 Wh per mile fuel economy which is like 5 miles/kWh. The EV-1 I think got 125 Wh/mile. So those numbers appear suspect too.

As far as the 14.1 kWh figure you derive, in my opinion all it represents is the electrical energy the the car would need to travel 50.15 miles. The correct figure in my mind is the actual identical energy from a gallon of gasoline converted to electrical energy and that figure is 34 kWh. So then the the fuel economy would be 121.1 miles/34 kWh . You could say 14.1kWh from generated electrical energy from gasoline onboard motor perhaps if the efficiency from the motor generated electricity is around 50%. But I think your number of 29% efficiency for a gasolne engine is also suspect. I am including a link which basically addresses the very subject we are discussing, and in the writeup it is shows that EVs are are at least twice as efficient on same source fuel. In fact the 39% powerplant efficiency he uses is actually conservative as newer dual cycle turbines have improved power plant turbine efficiciency to as high as 60-65% !

So I would say to you that perhaps the numbers look good for ICE and diesels because you yourself are an enthusiast and champion of diesels, but when a more objective look is taken we can see that EVs are at least 2 times more efficient than diesels or other ICEs.

Here is the link to Chip Gribben- Debunking of EVs and Smokestacks:

http://www.evdl.org/docs/powerplant.pdf

Yodda

--- On Fri, 10/15/10, Arcologic@... <Arcologic@...> wrote:

From: Arcologic@... <Arcologic@...>
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers
To: future-fuels-and-vehicles@yahoogroups.com
Date: Friday, October 15, 2010, 10:28 PM

Oh, my,

I was hoping to avoid complexity. But I think we need to talk more about how efficient cars are, and why. One way to try to compare efficiency of a gasser against an electric car would be to carefully look at one car design, and how well it will do as a conventional car with regen braking, and how it will do as an electric car with regen braking. I will assume for simplicity that the two forms have the same vehicle weight, the same drive train efficiency (of gears and bearings), and that all driving characteristics are about the same. Then I can just look at the effect of putting in an electric power source or a gas engine.

I have an Excel spread sheet for calculating the effects of rolling friction and aero drag, and can put in the other parameters for internal losses. The car I chose to model is a Prius, either as it is or converted to run as an EV. I am attaching the spreadsheet. If it won't go through the email, it may be that a version of it is already stored at the forum web site or can be. Here are the numbers I input--

Car frontal area....................23.5 sq.ft
Drag coefficient...................0.26
Rolling resistance coef........0.0085
Drive train efficiency.............0.85 (gears and bearings)
Gas engine efficiency..........0.29
EV plug to shaft eff..............0.70
Gas BTU /gallon..............116090
Assume kWh per gal =........34

The EV plug to shaft efficiency includes four steps--

Battery cycle efficiency..............0.80
Power conditioning in.................0.97
Power conditioning out...............0.97
Electric motor efficiency.............0.92

0.80 x 0.97 x 0.97 x 0.92 = 0.69, Close enough to 0.70

Calculations are for steady driving on the highway. Here are the results at 60 mph--

Prius running on gasoline........................50.15 miles per gallon
Prius running on electricity (EV)................3.56 miles per kWh.
Prius as EV rated using 34 kWh /gal......121.1 miles per gallon

Actual kWh per gallon can be calculated by dividing--

( 50.15 mi /gal) / ( 3.56 mi /kWh) = 14.1 kWh /gal

Or, cutting through all the balony,

( 34 kWh /gal) x ( 0.29 /0.70) = 14.1 kWh /gal

Oh, so far I haven't even looked at the power loss that occurred back at the power plant, that is, the effciency from power plant fuel to the plug where the EV is charged.

Bottom line: Most careful analyses show that EVs and gassers are about equivalent in efficiency when everything is taken into account. EVs usually look better when an EV promoter does the calculation.

My spreadsheet is attached, or I will send it to anyone that sends me an email directly, at arcologic@...
When you have the spreadsheet, you can play with changing the parameters in the yellow-shaded fields.

Ernie Rogers

-----Original Message-----
From: Oliver Perry <perrydap@...>
To: future-fuels-and-vehicles@yahoogroups.com
Sent: Fri, Oct 15, 2010 2:28 pm
Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers

Thanks Yodda for making a great simple comparison... an electric car being about 6 times more efficient for the same amount of energy purchased in the form of gasoline or kw-hr, which is what the customer can relate to.

Ollie Perry
EEVC
On Oct 15, 2010, at 3:21 PM, Yodda Pierce wrote:

> Hi Oliver,
>
> Well, I understand what you mean if the 17kWh is" generator derived electricity" but I think many people that do not use hybrids get their electricity from other sources other than oil or gasoline, so I would still use the 34 kWh figure myself when doing and heat derived energy comparison, but I do think the 17 kWh figure might be useful for hybrid ICE derived electricity.
>
> I was actually thinking the other day about energy used for electric cars vs. ICE and I thought about gasoline having about 114,00 BTU and its current costs vs. how much a similar amount of electricty would cost. At the 34 kWh figure it would be (34 X \$.075) or \$2.55. Currently that is the price for a gallon of gasoline where I live. So cost for gallon of gasoline or its BTU or heat equivalent is about the same. The advatage is that the good electric car motor is 98% efficient while the ICE gasoline car motor is about 17% efficient resulting in the electric car engine being about 6 times more efficient for the same amount of energy.
>
> Yodda
>
> --- On Fri, 10/15/10, Oliver Perry <perrydap@...> wrote:
>
>
> From: Oliver Perry <perrydap@...>
> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars, Electric Vehicle Chargers
> To: future-fuels-and-vehicles@yahoogroups.com
> Date: Friday, October 15, 2010, 11:03 AM
>
>
>
>
>
>
> Hello Yodda and Ernie,
> I am assuming that Ernie's value of 34 kWh for the energy in gasoline is the theoretical energy available if you converted 100 % of the chemical energy in gasoline to electrical energy. But since a heat engine burning gasoline cannot take 100 % of the heat and turn it into the mechanical energy needed to run a generator... it is impossible according to thermodynamic laws.. you cannot turn all of that heat into electrical energy. Am I correct Ernie that you feel that about 50 % of the heat energy in gasoline can be turned into useful electrical energy? That is where the 17 kWh comes from ? and that would be using a diesel engine?
>
> O.H.Perry
> EEVC
> On Oct 15, 2010, at 9:59 AM, Yodda Pierce wrote:
>
>> Hi Ernie,
>>
>> I would agree with most of what you said here, but I would disagree with your view on equivalance energy between a gallon of gasoline and similar energy for an electric car I think 34 kWh is about right for the conversion based on heat or BTU yeild. Depends on the gasoline though, but I think gasoline is about 114,000 BTU so 34 kWh would put us about there. (34 X3.412). Why do you think 17 kWh is the correct figure? Aren't you a proponent of diesel engines?
>>
>> Well, I would also like to ask the group if anyone has any good info. on electric vehicle chargers. I'm involved in a project to install them at Clemson University, South Carolina and the city of Clemson. I know about some of the chargers, but not sure on the availability and production dates for the models. If anyone knows of any specials for 220 V chargers, let me know. I'm getting some matching funding from a utility sponsored group in the state.
>>
>> Yodda
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>>
>>
>> --- On Thu, 10/14/10, Arcologic@... <Arcologic@...> wrote:
>>
>>
>> From: Arcologic@... <Arcologic@...>
>> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars
>> To: future-fuels-and-vehicles@yahoogroups.com
>> Date: Thursday, October 14, 2010, 11:35 PM
>>
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>>
>> Hello, Oliver,
>>
>> You said,
>>
>> If an EV is rated as having a 70 mpg efficiency, compared to a 35 mpg vehicle, then drivers feel that they are doubling the distance they would have traveled on a gallon of gasoline in a 35 mpg car.
>>
>> You make a lot of good points in this post. Some parts, like this one, I have a problem with. Let's say that a particular car is available either as an EV or a gasser. The energy needed to move the car is exactly the same in terms of the losses at the road and in the air. (If they have equal weight.) The energy going into the power plant is another matter, and is what you are talking about. In order to relate the electric motor to the gas engine, we have to agree on the energy equivalence between the electricity and the heat in the gasoline. BUT electricity is expressed in work units. Gasoline energy is expressed in heat units. You can convert work to heat with 100% efficiency, but you can't convert heat to work that way. If you recognize that electricity (work) is a higher-quality form of energy and that conversion of fuel to electricity as in the power plant requres some waste, then we should be making an allowance for this in the energy equivalence
>> relationship. Most people, including the EPA, set the equivalence at about 34 kWh of electricity equal to a gallon of gasoline according to the 100% efficiency conversion. I think this is the wrong value, and I think somewhere near 17 would be a fairer conversion.
>>
>> By my rules, an EPA ratng of 70 mpg for the EV is exactly the same as a gasser that gets 35 mpg.
>>
>> I suggest that if these two cars are compared on the basis of CO2 emissions, you will find that they are about the same, because in reality, they do use the same amount of energy at the source. (I am assuming a power plant with somewhere near 50% efficiency.) This is a short version, leaving out a lot of details that unfortunately somebody else will almost certainly want to talk about.
>>
>> Ernie Rogers
>>
>> -----Original Message-----
>> From: Oliver Perry <perrydap@...>
>> To: future-fuels-and-vehicles@yahoogroups.com
>> Sent: Thu, Oct 14, 2010 9:05 pm
>> Subject: Re: [future-fuels-and-vehicles] E.P.A. Struggles Over Fuel Ratings for Plug-In Cars
>>
>> Great point ! Apples to apples or apples to oranges???
>>
>> There is a good reason to feel that it makes little sense to describe an electric car's efficiency in terms of miles per gallon.
>>
>> But there is also a good reason to attempt to describe an electric car's energy efficiency in terms of miles per gallon. We are primarily a society moved by gasoline... or the petroleum it comes from.
>>
>> Since almost everyone has an idea of what mpg means in terms of fuel efficiency, it makes sense to allow electric car consumers to compared their EV side by side with ICE cars in terms of how much gasoline or petroleum they are saving themselves by choosing to drive an electric car. If an EV is rated as having a 70 mpg efficiency, compared to a 35 mpg vehicle, then drivers feel that they are doubling the distance they would have traveled on a gallon of gasoline in a 35 mpg car.
>>
>> In the minds of the average consumer efficiency in cars is measured in mpg. In reality true energy efficiency units are joules, BTUs, calories, Ft lbs, or some equivalent which most people cannot relate to highway travel. Most consumers want to know how much gasoline they are saving from consumption if they chose an alternative fuel. Therefore they want to know how many gallons of gas will it take to make the trip with an ICE and what equivalent would it take with electric. People equate gallons of gasoline to energy per mile. So they expect that if a Ford Escort went 25 miles on a gallon of gas with an ICE then it should go twice as far on a gallon of gasoline if it is twice as fuel efficient using an electric motor.
>>
>> If we extend the efficiency situation to include the barrel of oil that the gasoline came from, assume that same barrel of oil will be used to run a generator at a power plant and then figure out how much less of that barrel is used with an electric car plugged into the grid we can make an honest comparison that average Americans will understand.
>>
>> Forgetting saving oil,,, just use dollars per mile and I think the average American will know how to make the best choice in order to save money. But right now the mind set is based upon gallons of oil per mile and we have to create the electricity using the same barrel of oil. The bottom line is that people want to know how many gallons of gasoline they will not have to buy if they purchase an electric car. And I agree, that is hard to figure out with varying costs of both Kw-hr and gasoline.
>>
>> OHPerry
>> EEVC
>>
>> On Oct 14, 2010, at 7:44 PM, k9zeh wrote:
>>
>>> Am I missing something here? Why bother to describe an electric vehicle in terms of miles per gallon efficiency? There are so many factors to consider like heating and air conditioning, terrain, climate, day or night use, etc. There really is no way to equate an ICE vehicle to an EV. If you operate a Volt via the ICE, then you are comparing apples to apples. Otherwise, forget about it. It is what it is.
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