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From: Don Klipstein on 31 Jul 2010 14:29
In article <qll8569vm8foi514boug1nc2qfasb7gnkl(a)4ax.com>, Jim Thompson wrote
(and I edit for space somewhat):
>On 31 Jul '10 11:01:04 -0400, John Ferrell<jferrell13(a)triad.rr.com> wrote:
>
>>I smell a business opportunity for a younger Techie.
>>
>>In a few years there will be a supply of these things around that will
>>not have a market value that exceeds the cost of a new set of
>>batteries. A replacement power system that costs less than a battery
>>set may do well.
>>
>>Watch out for new laws that may restrict such things. A niche may
>>exist under all circumstances. Any one for Steam Power? After all the
>>Stanley Steamer held speed records for a long time!
>
>I suspect it costs more per mile to operate electrically than via
>gasoline. But I can't find anything on the Volt website other than
>obfuscated "specifications".

I would go with some figures for cost of energy and efficiency of
converting energy from one form to another.

Gasoline appears to me to cost lately $2.65 per gallon.

I plug into Google gasoline btu gallon and I see figures mentioned in
the hits to average-to-my-eyes around 120,000 BTU/gallon, and 115,000
BTU/gallon gives me the impression as reasonable for the modern stuff
diluted by ethanol and sometimes MTBE.

A BTU is 1055.9 joules
(http://msis.jsc.nasa.gov/volume2/appx_e_units.htm)

At this rate, gasoline has 121.43 megajoules per gallon, or 45.8
megajoules per dollar.

I do have the impression (no web work this minute to support it) that
car gasoline engines achieve around 25% efficiency of converting chemical
energy to mechanical energy into the car's transmission, and only at a
rate that high when "the going is better". Car engines have to do a lot
of work at RPM and mechanical loading far from their optimum, and they
often have to burn fuel when they re not moving the car at all. As a
result, I would like to think of 20% as an "average ballpark figure" for
car gasoline engine efficiency of converting chemical energy to mechanical
energy.

"At this rate", gasoline achieves 9.16 megajoules per dollar.

=============

Now, for the electric car alternative:

USA national-average residential electricity cost is nowadays probably
about 12 cents per KWH. A KWH is 3.6 megajoules. Divide that by .12,
and the result is 30 megajoules per dollar.

However, there are still the losses between one's electric meter and the
motor shaft of an electric car:

1: Household wiring downstream of the house's electric meter. I expect
a house with wiring to support an electric car to have a nice low
loss there around 1%, for 99% efficiency. However, many houses that
get electric cars will need wiring installations/upgrades whose cost
needs to be considered for return_on_investment.

2: Efficiency of the battery charging circuitry: My impression based on
my experience with a bewilderment of specific individual figures for
efficiencies for modern electronic fluorescent lamp ballasts and
modern line-powered lighting-grade LED drivers is that a reasonable
figure is 93%.

3: Efficiency of the battery storing and releasing the charge:

3a: Hysteresis between charging voltage and discharging voltage of
the battery: For sake of argument, I would take on a 12V lead-acid
battery. I seem to think that a lead-acid battery charged at a
mildly aggressive rate that appears to me necessary will have most
of its charge pushed in at a voltage of close to 14 volts, and the
average voltage per unit charge appears to me to be 13.6 volts (or
slightly more) to push the charge in.

The average discharge voltage of this battery appears to me to be
12.1 volts. At discharge current low enough to make IR drop
negligible and the battery being discharged and having discharged
at least half a percent of its charge since last recharge, it
appears to me that this is 12.7-12.75 volts at 90% charged and
12-12.1 volts at 10% charged. Average is probably 12.4-12.5, but
there is IR drop in the battery and wires connected to it, and a
motor to move a car appears to me to be a heavy load. I like to
think that 12.1 volts is "charatable in favor of an electric car".

Ratio of 12.1/13.6 is 89%, a figure that I consider to be somewhat
"charatable to electric cars". So, I now want to back that down to
88% for efficiency for the battery storing and releasing energy.

4: Efficiency of motor control circuitry: Such as likely-needed
PWM-based switching motor driver circuitry having simulated output
resistance. I am guesstimating efficiency of 96% on a good day, due
to lack of AC-DC conversion in electronic fluorescent lamp ballasts and
"lighting grade LED drivers", and to a lesser extent lack of fully
converting pulsed output to AC.

5: Efficiency of the electric motor: That one I have checked out less,
other than on the nameplates on a few motors in the near-one-HP
range (~~ ?? 80%). I would like to think that the electric motor in
an electric car is 85% efficient.

Total efficiency in an electric car:

.99 * .93 * .88 * .96 * .85, totalling 66.1%, probably optimistically,
for efficiency of converting billed electrical energy to mechanical energy
from the electric car's motor.

This appears to me to be 19.8 megajoules per dollar for cost of moving
an electric car, in comparison to 9.2 megajoules per dollar for cost of
moving a gasoline-powered one. "So far at this rate", the electric car
costs about half as much to drive as a gasoline-powered one does.

However, an electric car has further disadvantages:

1. Initial cost is higher, and initial cost of getting an electric car
also includes whatever cost of home wiring upgrade needed for
charging it.

2. A practical electric car nearly-enough-inherently requires a large
rechargeable battery, likely to need to be replaced more often than
"similarly-big-ticket" items in gasoline-powered cars need.

3. The amount of energy stored in a fully charged battery in an electric
car will not move it as far as can be achieved by the gasoline in a
typical gasoline-powered car.

4. Ratio of peak motor horsepower to loaded vehicle mass so far tends to
be less with electric cars than with gasoline-powered ones. That wil
impair an electric car's acceleration, especially acceleration after
achieving a speed around 30-35 or whatever MPH. That slightly
impacts ability to handle some somewhat-common emergency driving
situations, slightly impacts ability to accomplish merging operations
and lane changes on higher speed roads, and to many people greatly
impacts enjoyment of driving the vehicle in question.

Even if an electric car achieves as much acceleration at 60 MPH or
whatever as a fully-loaded 18-wheeler achieves, 18-wheelers are big
and have a higher rate of achievement of getting fellow motorists to
accomodate their movements than dinkier energy-efficient cars have.
(Although that becomes some argument in favor of mandating "usual
cars" to be "dinkified", but then-again that appears to me likely to
"not sell well" in USA anytime soon.)
--
- Don Klipstein (don(a)misty.com)
From: John Larkin on 31 Jul 2010 14:46
On Sat, 31 Jul 2010 11:01:04 -0400, John Ferrell
<jferrell13(a)triad.rr.com> wrote:

>I smell a business opportunity for a younger Techie.
>
>In a few years there will be a supply of these things around that will
>not have a market value that exceeds the cost of a new set of
>batteries. A replacement power system that costs less than a battery
>set may do well.
>
>Watch out for new laws that may restrict such things. A niche may
>exist under all circumstances. Any one for Steam Power? After all the
>Stanley Steamer held speed records for a long time!
>

As someone has noted, a boiler and a steam engine can be small and
very powerful, especially peak power. The problem is the condenser.

John

From: Paul Keinanen on 31 Jul 2010 15:35
On Sat, 31 Jul 2010 18:29:03 +0000 (UTC), don(a)manx.misty.com (Don
Klipstein) wrote:

>
> Now, for the electric car alternative:
>
> USA national-average residential electricity cost is nowadays probably
>about 12 cents per KWH. A KWH is 3.6 megajoules. Divide that by .12,
>and the result is 30 megajoules per dollar.

Electric vehicles can often be charged outside peak hours, which
reduces the production cost in power stations.

During peak demand, the peak power is typically produced with simple
gas turbines burning expensive fuels, such as gas or oil.

Extensive use of electric vehicles will reduce the peak/average ratio,
the need for peaking gas turbines is reduced and power plants using
cheaper fuels can be operated 24 hours each day.

The reduction of the production cost is not necessarily reflected into
end user prices (taxes, "Enrons" :-(

From: Nico Coesel on 31 Jul 2010 16:54
don(a)manx.misty.com (Don Klipstein) wrote:

>In article <qll8569vm8foi514boug1nc2qfasb7gnkl(a)4ax.com>, Jim Thompson wrote
>(and I edit for space somewhat):
>>On 31 Jul '10 11:01:04 -0400, John Ferrell<jferrell13(a)triad.rr.com> wrote:
>>
>>>I smell a business opportunity for a younger Techie.
>>>
>>>In a few years there will be a supply of these things around that will
>>>not have a market value that exceeds the cost of a new set of
>>>batteries. A replacement power system that costs less than a battery
>>>set may do well.
>>>
>>>Watch out for new laws that may restrict such things. A niche may
>>>exist under all circumstances. Any one for Steam Power? After all the
>>>Stanley Steamer held speed records for a long time!
>>
>>I suspect it costs more per mile to operate electrically than via
>>gasoline. But I can't find anything on the Volt website other than
>>obfuscated "specifications".
>
> I would go with some figures for cost of energy and efficiency of
>converting energy from one form to another.
>
> Gasoline appears to me to cost lately $2.65 per gallon.
>
>car gasoline engines achieve around 25% efficiency of converting chemical
>energy to mechanical energy into the car's transmission, and only at a
>rate that high when "the going is better". Car engines have to do a lot
>of work at RPM and mechanical loading far from their optimum, and they
>often have to burn fuel when they re not moving the car at all. As a
>result, I would like to think of 20% as an "average ballpark figure" for
>car gasoline engine efficiency of converting chemical energy to mechanical
>energy.
>
> "At this rate", gasoline achieves 9.16 megajoules per dollar.

Actually a diesel engine does much better. A good diesel like found in
a BMW will have a 50% efficiency.

> Now, for the electric car alternative:
>
> USA national-average residential electricity cost is nowadays probably
> other than on the nameplates on a few motors in the near-one-HP
> range (~~ ?? 80%). I would like to think that the electric motor in
> an electric car is 85% efficient.

You forget that the engine can also work as a generator to re-use
energy otherwise lost while braking.

>Total efficiency in an electric car:
>
> .99 * .93 * .88 * .96 * .85, totalling 66.1%, probably optimistically,
>for efficiency of converting billed electrical energy to mechanical energy
>from the electric car's motor.
>
> This appears to me to be 19.8 megajoules per dollar for cost of moving
>an electric car, in comparison to 9.2 megajoules per dollar for cost of
>moving a gasoline-powered one. "So far at this rate", the electric car
>costs about half as much to drive as a gasoline-powered one does.
>
> However, an electric car has further disadvantages:
>
>1. Initial cost is higher, and initial cost of getting an electric car
> also includes whatever cost of home wiring upgrade needed for
> charging it.

But these costs tend to go down.

>2. A practical electric car nearly-enough-inherently requires a large
> rechargeable battery, likely to need to be replaced more often than
> "similarly-big-ticket" items in gasoline-powered cars need.

Clutch and timing-belt replacements aren't cheap.

>3. The amount of energy stored in a fully charged battery in an electric
> car will not move it as far as can be achieved by the gasoline in a
> typical gasoline-powered car.
>
>4. Ratio of peak motor horsepower to loaded vehicle mass so far tends to
> be less with electric cars than with gasoline-powered ones. That wil
> impair an electric car's acceleration, especially acceleration after

Don't forget most combustion engines found in cars only achieve their
rated (peak) power output at unusable high RPM. Cars with an engine
which produce a flat power output graph over a wide RPM range are
rare. If you have a 100HP car you might actually use 50HP to 60HP max
or even less if you are a relaxed driver.

An electric engine with switchable poles ('electric' gearbox) can
output its full power at almost any RPM.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico(a)nctdevpuntnl (punt=.)
--------------------------------------------------------------
From: Spehro Pefhany on 31 Jul 2010 18:02
On Sat, 31 Jul 2010 22:35:40 +0300, the renowned Paul Keinanen
<keinanen(a)sci.fi> wrote:

>On Sat, 31 Jul 2010 18:29:03 +0000 (UTC), don(a)manx.misty.com (Don
>Klipstein) wrote:
>
>>
>> Now, for the electric car alternative:
>>
>> USA national-average residential electricity cost is nowadays probably
>>about 12 cents per KWH. A KWH is 3.6 megajoules. Divide that by .12,
>>and the result is 30 megajoules per dollar.
>
>Electric vehicles can often be charged outside peak hours, which
>reduces the production cost in power stations.
>
>During peak demand, the peak power is typically produced with simple
>gas turbines burning expensive fuels, such as gas or oil.
>
>Extensive use of electric vehicles will reduce the peak/average ratio,
>the need for peaking gas turbines is reduced and power plants using
>cheaper fuels can be operated 24 hours each day.
>
>The reduction of the production cost is not necessarily reflected into
>end user prices (taxes, "Enrons" :-(

Electric cars usually have the ability to use regenerative braking to
recharge their batteries so they should be particularly advantageous
in city driving. Gas cars need to add much of the overhead of a full
electric car (just a smaller battery) to get the same advantage.

I disagree with the article- I think GM made a reasonable choice for a
first offering in the US. Who would buy a car like the Nissan that
didn't have a backup gas engine? What if you forget or are unable to
charge it? What if you want to take it on a long drive? And it's silly
to try to connect the bail-out with the Volt. GM's problems are more
to do with their current unexciting and (in some cases)
award-winningly ugly product lineup.

As far as it being cheap to operate- watch out for laws that would
require separately monitored outlets, perhaps for off-peak charging or
some kind of bogus safety reason, so that extra road taxes can be
tacked on to the electrical rates at a later date.




Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff(a)interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
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Prev: OPERATIONS AND SUPPLY MANAGEMENT 13-E JACOBS Test Bank and solution manual is available for purchase at affordable prices. Contact me at alltestbanks11[at]gmail.com to buy it today. All emails will be answered ASAP.
Next: Frigidaire refrigerator temperature control ?