Gives overall efficiency of EVs at 28% compared to 14% for ICE engined
vehicles. Do you have better figures? If not EVs are twice as efficient

The site above is very misleading though

Of course. Best I could find in a hurry. If you find some better facts
please let me know. I think we can manage to see the valuable facts
behind the sales talk.

- Table 5, "comparison of fuel efficiency" which is your figures' source,
is a masterpiece of obfustication.

My figures come from table 4. Table 5 is poor science at best with lots
of cludges. Table 4 however it rather more useful. Lets stick to that
shall we?

David

--
****** David Round - EMail Tel (01248) 382416 *****
*****These are my own views, I represent nobody (Well maybe myself)*****
***********I guarantee nothing - Particularly the spelling**************

Apparently on date Thu, 1 Apr 2004 10:20:20 +0000 (UTC),
(D.P.Round) said:

Gives overall efficiency of EVs at 28% compared to 14% for ICE engined
vehicles. Do you have better figures? If not EVs are twice as efficient

The site above is very misleading though

Of course. Best I could find in a hurry. If you find some better facts
please let me know. I think we can manage to see the valuable facts
behind the sales talk.

- Table 5, "comparison of fuel efficiency" which is your figures' source,
is a masterpiece of obfustication.

My figures come from table 4. Table 5 is poor science at best with lots
of cludges. Table 4 however it rather more useful. Lets stick to that
shall we?

Table four merely plucks the two figures out of the air. It doesn't derive them
or explain how it came to these figures, it just says "88%" versus "15%".

One of the issues I have with the comparison is it ignores things like vehicle
range and carrying capacity.

Petrol, as a fuel, carries around 30 MJ / kilogram, might be 40 MJ. Somewhere
around twice the energy capacity of wood, and in this I'm assuming the fuels
are used for combustion, in terms of the energy you can get from them. A car
fuel tank contains about thirty kilos / litres of petrol, which means it has
something of the order of 1000 MJ of energy contained within it, and weighs
about 30 kilograms with the engine adding another 70 kilograms, just for the
same of comparison. That is, 1000 MJ of energy costs about 100 Kg of payload
for a 1000 Kg car to manage about 400 miles of travelling.

Now consider a battery, with the same energy capacity as a car fuel tank.

Batteries also use chemical reactions to derive their energy output, but in far
less explosive and exothermic ways, and that means they deliver far less
energy, put plain and simple. A lead acid battery contains about 0.2 MJ of
energy per kilogram.

You can get more from nicads, if you don't mind the fact that you are utilising
a fairly expensive and polluting metal Cadmium, you can bump this up to maybe 1
MJ, and if lithium polymers work out in practice, this type may reach 2 MJ per
kilogram, not counting the containment chamber, which has to be much heavier
and more durable than a petrol tank, partly because the energy conversion is
going on inside the fuel chamber. Note that these types of battery require
considerable investment of energy to manufacture them, and they have to be
replaced quite often. This means serious expense to the owner of a vehicle
using them, e.g. 5,000 quid a year for replacement batteries as a ballpark
estimate.

For an equivalent range to the car above, with a 30 Kg fuel capacity, you will
need about 500 kilograms of the expensive, lithium polymer type of battery and
you haven't yet included a motor to convert the energy into motion. Using lead
acid, you have about 2.5 tonnes of batteries to cart about in a 1 tonne
vehicle, which isn't in the right ballpark. You can propose electric motors
that are more efficient in terms of energy conversion - although these will not
generally be true when the comparison is for a constant speed - but you are
still only halving the requirement, and that means a battery with a car
attached and low power, lightweight motors in all but the most ideal
theoretical examples.

So, battery powered, electric vehicles have lower range, and / or greatly
reduced sustainable power output, simply because there is no way to build
batteries which can liberate the sort of chemical energies that combustion of
highly reactive flammable fuels can liberate. This is, and always will be,
fact.

Sometimes people trot out the notion that future technologies will mean
batteries with higher and higher energy capacity and power outputs, and this
has some relevance as this is what development tends to do. However, people
*have* been developing battery power for mobile phones, laptops and PDAs for
some time and there are no easy leaps in technology to come due to the fact
that a battery must be capable of not exploding / melting / thermal runaway
release of the energy in it.

The conclusion I have come to long since, is petrol cannot be replaced by
battery powered vehicles without some seriously inconvenient changes in what a
vehicle is used for, e.g. we have single person vehicles with short ranges,
rather than cars able to carry shopping, passengers, etc along the motorways.

This is why, I do not tend to accept the websites / people who push or promote
a technology that I already can see will never be able to compete with the
existing technology on equal terms. It's an expensive, out of date concept that
is only popular among those who do not understand the situation and is intended
to solve a problem that no longer exists in any serious extent, which is the
emission of nitrous oxides and incomplete combustion products by passenger
vehicles in city environments, i.e. the reduction of smog. Modern cars in
roadworthy condition produce almost no smog even in cities.

The idea we have to use mains power instead of a diminishing petrol resource
fuels is conjoined with the notion that nuclear power is inherently clean and
inexhaustible, which can only be convincing when mains power is primarily clean
and inexhaustible, not when it is a less efficient way to burn the same
carboniferous resources

And the fear of releasing fossil carbon into the biosphere is as yet
unconvincing and is a gradual issue which can be reversed quite easily by a
reversionary economic model, e.g. fuel processing where the carbon and hydrogen
used to produce the fuel is extracted from the air by what may be a nuclear or
solar (or wind, or tidal) plant which is clean and inexhaustible, and produces
petrol which can then be used in passenger vehicles which release harmless
natural chemicals back into the atmosphere from where they were extracted.
Which is more or less what plant / animal life does at the moment.

Personally, I would adopt the final model using hydrogen as a fuel, because
hydrogen fuel contains far more chemical energy per kilogram* and converts into
clean water when used in a fuel cell. And it is much easier to liberate
hydrogen than to build petrol hydrocarbons. Course, this model only becomes
economical when there isn't an easily exploited source of hydrocarbon fuel
lying about ready to be used with less investment in processing.

Either way, battery powered vehicles are an expensive dead end for all but the
most radical and people-unfriendly transport models, mad in a democracy, not
very convincing even in a dictatorship like the socialist states which gave up
on battery vehicles even quicker.

(* - this is why space rockets use hydrogen fuel, it's pretty much the best
combustion fuel available for calorific capacity, and that is even when you
have to carry the oxygen to burn with it, which is 80% of your fuel load in a
space rocket, and a passenger vehicle burns it much slower so will take oxygen
from the atmosphere instead, which means a quarter of the weight that can take
you into orbit.)

Table four merely plucks the two figures out of the air. It doesn't derive them
or explain how it came to these figures, it just says "88%" versus "15%".

Fair comment but it is the best data I could find in a hurry. We since
have a figure of 34% for a 'Prius engine so I suspect that they have
not tried hard to present ICE in the best possible light. Still the
*efficiency* of the EV concept is similar as the losses are not large.

One of the issues I have with the comparison is it ignores things like vehicle
range and carrying capacity.

A point that cannot be argued with and the true reason that EVs are not
practical. Efficiency is not the issue. Batteries are very poor compared
to petrol and are not getting better that quickly.

You can get more from nicads, if you don't mind the fact that you are utilising
a fairly expensive and polluting metal Cadmium, you can bump this up to maybe 1
MJ

Why no NiMH? No Cadmium and a higher energy density again. Currently based
on AA size (which may not be a useful comparison for a great many reasons)
the achievable energy density seems to be something like four times that
on NiCads. Again for small batteries Li poly do much better than NiMH and
far more than twice NiCads. This doesn't tally with your data. Do you
know why? Regardless it will not get close to petrol anytime soon.

80% of my annual milage is done in stop-start slow driving with total
journey length of around 20 miles. This is achievable for an EV.
Add an engine for long trips (hybrid) and the result should be really
useful. I guess there must be snags or we would all have one since
I am sure that my requirements are not unusual.

It's an expensive, out of date concept that
is only popular among those who do not understand the situation and is intended
to solve a problem that no longer exists in any serious extent, which is the
emission of nitrous oxides and incomplete combustion products by passenger
vehicles in city environments, i.e. the reduction of smog. Modern cars in
roadworthy condition produce almost no smog even in cities.

Perhaps though it doesn't seem that was in a traffic jam.

David

--
****** David Round - EMail Tel (01248) 382416 *****
*****These are my own views, I represent nobody (Well maybe myself)*****
***********I guarantee nothing - Particularly the spelling**************

Apparently on date Fri, 2 Apr 2004 14:20:07 +0000 (UTC),
(D.P.Round) said:

Table four merely plucks the two figures out of the air. It doesn't derive them
or explain how it came to these figures, it just says "88%" versus "15%".

Fair comment but it is the best data I could find in a hurry. We since
have a figure of 34% for a 'Prius engine so I suspect that they have
not tried hard to present ICE in the best possible light. Still the
*efficiency* of the EV concept is similar as the losses are not large.

Efficiency in this case is very misleading. An electric motor has few losses,
primarily because the energy loss has already been paid converting the fuel,
(mostly oil or coal) into electrical energy in the first place. Petrol is not
an energy source that you can use to run a computer or power light bulbs, it is
a combustible fuel that you can burn to produce heat, firelight, or drive an
internal combustion engine that can then make a car go forward. The
"efficiency" in that case, is obviously not as meaningful when converting the
"fuel" into intrinsic "contained energy value" and talking about which engine
converts it into motion with fewer losses.

There are hidden factors, an ICE engine produces heat that is used to keep the
passenger compartment warm while the engine is running. Try keeping the car
warm, dry or for that matter cool in summer, using your battery power source
instead of the combustion engine's mechanical or heat energy and suddenly
there's a whole extra load on the alternative power source that is not at all
easy to incorporate.

I might say how much motion does the electric motor manage to produce per litre
of petrol. To be more efficient, it has to use the same fuel. To use an
inherently more useful energy source is cheating, like comparing a steam
engine, with lower calorific wood fuel with a petrol engine.

To take an extreme example, an electric motor runs almost forever on a
kilogramme of electricity, mainly because it weighs almost nothing. That's
obviously not a sound basis for comparison.

One of the issues I have with the comparison is it ignores things like vehicle
range and carrying capacity.

A point that cannot be argued with and the true reason that EVs are not
practical. Efficiency is not the issue. Batteries are very poor compared
to petrol and are not getting better that quickly.

I don't think they can become equivalent, based on the nature of "a battery".
Of course, an energy cell may be invented, e.g. something with a core fissile
energy supply, that can have a lot more energy in it than petrol, kilo for
kilo. But, that's not what I mean by a rechargeable battery.

You can get more from nicads, if you don't mind the fact that you are utilising
a fairly expensive and polluting metal Cadmium, you can bump this up to maybe 1
MJ

Why no NiMH? No Cadmium and a higher energy density again. Currently based

AFAIK they're much the same, maybe 35% more energy but less power output, if
that matters and it probably doesn't. Either way, the same situation applies to
both sorts, and also to anything under development to the best of my knowledge,
which isn't catholic.

on AA size (which may not be a useful comparison for a great many reasons)
the achievable energy density seems to be something like four times that
on NiCads. Again for small batteries Li poly do much better than NiMH and
far more than twice NiCads. This doesn't tally with your data. Do you
know why? Regardless it will not get close to petrol anytime soon.

I didn't study the figures, just got some examples off the web, Duracell as I
recall. They ought to be in favour of battery use, though, so I feel they are
reliable enough.

80% of my annual milage is done in stop-start slow driving with total
journey length of around 20 miles. This is achievable for an EV.

I couldn't travel 16 miles in stop-start driving. As the average speed in stop
start driving is supposed to be approximately 4 mph, that is a four hour
journey, I'd buy a bicycle. Alternatively, 80% of your *time* is stop start,
and it is probably more correct to say you do 2 miles of stop start and 18 at a
moderately constant speed. But, I don't know. And there are journeys where
electric motors would make more sense, no doubt about that, just they are the
exception, not the rule.

Add an engine for long trips (hybrid) and the result should be really
useful. I guess there must be snags or we would all have one since
I am sure that my requirements are not unusual.

Hybrid is a good technology for certain types of driving. On a steady journey
you can see why running an engine to make power that you convert into
electricity and then use to drive the wheels, is inherently inefficient when
you could drive the wheels using the power output directly. The hybrid scheme
really comes into its own when you couple a fuel cell or portable nuclear plant
with electric motors, these power sources can constantly produce power to
charge the batteries, which can then carry only what is needed for driving the
car at that moment. Thus, the car has plenty of power to accelerate, and can
cruise at a steady rate with modest required power output, retaining some
energy for overtaking in bursts. When you park it, the batteries recharge from
the nuclear plant so it is ready to use again when you want to go home.

If you drive it all day, the car loses power and slows down, until you are
using the output power directly, which means you never get stranded, but you
can't always dash about flat out.

It's an expensive, out of date concept that
is only popular among those who do not understand the situation and is intended
to solve a problem that no longer exists in any serious extent, which is the
emission of nitrous oxides and incomplete combustion products by passenger
vehicles in city environments, i.e. the reduction of smog. Modern cars in
roadworthy condition produce almost no smog even in cities.

Perhaps though it doesn't seem that was in a traffic jam.

Ten years ago, motorways began to smell bad when you were parked in a huge
traffic jam. I have to say, that this is no longer the case and I recall
sitting in a jam near Heathrow last year with outside temperature over 40
centigrade, the air conditioning was managing to keep the car cool and dry, and
there was no smell of smog or smoke from the other vehicles. It is the case
that diesel buses still pump out fairly sizable clouds of smoke, I have noticed
that. An old "Atlantean" double decker pointed this out to me a year or two
back, reminded me what things used to be like, in fact.

You can monitor the air quality, people have done this and the old smog issues
have basically gone away. You're free to do your own study.

In article ,
Sales! wrote:

snip
Either way, battery powered vehicles are an expensive dead end for all
but the most radical and people-unfriendly transport models, mad in a
democracy, not very convincing even in a dictatorship like the socialist
states which gave up on battery vehicles even quicker.

Excellent post - thanks.

--
*Welcome to **** Creek - sorry, we're out of paddles*

Dave Plowman London SW 12
RIP Acorn

In article ,
D.P.Round wrote:
80% of my annual milage is done in stop-start slow driving with total
journey length of around 20 miles. This is achievable for an EV.
Add an engine for long trips (hybrid) and the result should be really
useful. I guess there must be snags or we would all have one since
I am sure that my requirements are not unusual.

All EV or hybrid vehicles use advanced weight and friction saving methods
- combined with restricted performance. Apply these parameters to a small,
say diesel, vehicle and the quoted differences might well disappear. In
other words, the comparisons given by makers don't use an even playing
field.

--
*Why are a wise man and a wise guy opposites?

Dave Plowman London SW 12
RIP Acorn

In article ,
D.P.Round wrote:
Why no NiMH? No Cadmium and a higher energy density again. Currently
based on AA size (which may not be a useful comparison for a great many
reasons) the achievable energy density seems to be something like four
times that on NiCads. Again for small batteries Li poly do much better
than NiMH and far more than twice NiCads. This doesn't tally with your
data. Do you know why? Regardless it will not get close to petrol
anytime soon.

It's as well to note that none of the rechargeable cells approach the
capacity of an alkaline type like Duracell...

--
*If one synchronized swimmer drowns, do the rest have to drown too?

Dave Plowman London SW 12
RIP Acorn

In message , Sales!
writes

There are hidden factors, an ICE engine produces heat that is used to
keep the passenger compartment warm while the engine is running. Try
keeping the car warm, dry or for that matter cool in summer, using your
battery power source instead of the combustion engine's mechanical or
heat energy and suddenly there's a whole extra load on the alternative
power source that is not at all easy to incorporate.
Showing just how inefficient a petrol engine is.
--
Clive

In article ,
Clive wrote:
There are hidden factors, an ICE engine produces heat that is used to
keep the passenger compartment warm while the engine is running. Try
keeping the car warm, dry or for that matter cool in summer, using your
battery power source instead of the combustion engine's mechanical or
heat energy and suddenly there's a whole extra load on the alternative
power source that is not at all easy to incorporate.

Showing just how inefficient a petrol engine is.

Perhaps you'd better set about a more efficient way of converting a high
density fuel like petrol to mechanical energy, then. Electric vehicles
driven off storage batteries have been around for nearly as long. If they
were capable of being developed into a viable competitor, it would have
been done years ago.

--
*Puritanism: The haunting fear that someone, somewhere may be happy.

Dave Plowman London SW 12
RIP Acorn

In message , Dave Plowman
writes

Showing just how inefficient a petrol engine is.

Perhaps you'd better set about a more efficient way of converting a
high density fuel like petrol to mechanical energy, then. Electric
vehicles driven off storage batteries have been around for nearly as
long. If they were capable of being developed into a viable competitor,
it would have been done years ago.
Try diesel. Or indeed any compression ignition engine.
--
Clive