As a new Prius owner living in Vermont I was reminded the other minus 20deg F day of an overlooked ( by me ) fact about batteries: the AH storage capacity goes down drastically as a function of temperature. At -20C we can use only ~50% of the battery's design capacity of Ampere-Hours of storage ..... oops.... there goes the useful range per charge, which OBTW seems to be one of the most difficult design criteria to satisfy.

Put the model in the pix in furs and maybe some muckluks, for a more-to-the-point illustration of a practical vehicle.

http://www.bdbatteries.com/peukert.php

"The efficiency of an electric motor is a curve"

True for induction machines but not for modern permanent magnet machines, these exhibit a very high part-load efficiency.

EDIT: Of course a PM machine will be more expensive!

Let me disagree on a few points.

"I doubt a battery charger is more than 90% efficient."

Cheap charges aren't efficient, but when you start talking about several kWh spent every day, an expensive charger starts making sense. One could make a more than 90% efficient charger, it would just be expensive.

"Industrial drives are about 95% at rated output, but this falls to zero as output frequency tends to zero."

That is a quite good reason to use some reduction gear between the motor and the wheels. Ok, a normal car motor operates on a much lower frequency than a normal electrical motor, but there is a very big body of knowledge on how to reduce the electrical motor's rotation into something useful.

"There is no infrastructure to support electric cars, despite what those in fantasy land claim."

Now, I agree with that. But I also think that no sane person will construct the needed infrastructure before there is demand. That is one of the reasons plug-in hybrids look so good.

"It has been regularly quoted that compressing hydrogen to 200 bar that is consumes one third of the energy contained, so you are being generous here."

I agree, and also think that he is quite generous with the ICE. To make it short, the graph seems generous with all the analyzed alternatives...

I hate to poop on your party Partypooper, but based on current offerings, which are few and far between, charger efficiency varies from about 50% at low power/voltage to 95+% at higher voltage/power ratings, so it can be pretty crappy but is would probably be at 90+% for most apps. At the kind of voltage/power output needed for air conditioners (barring the kind you put in a window) and electric dryers, the efficiency is somewhere around 95%. The efficiency of an electric motor is also relatively low at low speed/high torque like you mentioned, at ~75% (same source as above) and goes up to 91% at high speed/lowish torque, w/ an average of around eighty something percent.

Course, in the spirit of pooping on parties, a conventional vehicle will only see 40% efficiency very rarely, and will in fact spend most of the time around ~10-20% efficiency, so there are definitely greater losses there as well. The Prius for instance, has a peak efficiency of 230g/kWh. With a gallon of gas at ~6.25lbs/2834g, this means the Prius can at best get 12.3kWh of mechanical energy out of a gallon of gas. A gallon of gas has about 36.6kWh of energy, so that means that a the engine in the Prius, one of the most efficient cars out there, operates at ~34% efficiency. Course, since gasoline engines are so lossy at low load, going from ~230g/kWh or 34% efficiency, to 400-600g/kWh, which is ~13-20%, we can see that if even one of the most efficient cars seen today, which actually cycles the engine on and off and saves that energy in a battery pack for later use because it's more efficient todo that than run at low load, can barely hit 34%, then the average car is probably somewhere around 10-20%. City driving is pretty close to a 10-15% average for most vehicles, and highway is probably around 15-20+%, with an average of around 15-20% give or take.

Since the only way to significantly improve fuel efficiency *given consumer attitudes is via hybridization, and even then we're only going to see something less than ~35%, since the emissions systems still has to be lit off and the engine warmed up, from the POV of efficiency there's no point not to stick a larger battery pack in and have a PHEV or pure electric.

*Arguably, if we could convince everyone to drive cars with 6-8 speed manual transmissions (maybe CVTs ala the 3L Lupo) ,1-2L engines w/ idle shut-off, no A/C, and so on, regardless of vehicle size, then we could see ~30+% average efficiency but I think it's more likely people would accept limited range from electrics before they accepted all that.

By 2031 I imagine the whole of the worlds fleet of cars will have been replaced. This is likely to happen whether you like it or not.

lATER ...

Well unless the economy tanks completely (which it may well do and this may deliver your mythical paradise) then the global car fleet will be replaced whether you like it or not.

Are you really sure????

I have questions:

Who will make all these cars? General Motors? British Leyland? Fiat?

Where will the 'car owners' drive these millions of automobiles to and from? Suburbia? Back and forth to work in offices? Will they drive to the mall? Will they drive out to the country- side to scavenge for something to eat?

How will these millions of cars be made? In factories or by blacksmiths? What is the EROEI for an auto factory? Do you know how much it costs to build an auto factory? How much it costs to build - and fix - a medium sized road? Where is that money going to come from?

Where will these cars be made? Will they be made in Japan? How will they arrive in the US or Europe, how will American cars arrive in other countries? On sailing ships? What is the EROEI for a clipper ship? What about the wind turbines and grid and backup power for the humans? Do we get some precious power or is it set aside for the autos?

Most people think about the economy as a discrete thing, like a grand piano or a cuckoo clock. The economy is too complex for such analogies. You can only look at the economy a little at a time; a point here, a point there. Add the points together and you have something like a cloud. A cloud is comples and interconnected. However, if one part of a cloud is disturbed, the rest of the cloud continues as before. A cloud is unresponsive. The economy is very sensitive.

A better analogy is an organism, a bear or a chipmunk. Nobody can see an entire chipmunk or all the parts of it, only a bit here and another bit there. An organism is responsive. If a bee stings the bear on the foot, the entire bear reacts. Tiny bee, giant bear. Cut the foot off the bear, and something must be done or the bear will die. Now, the bear has gotten incredibly large, from devouring everyting within reach. At this point, it is eating itself! Not necessarily by swallowing its tail, but by digesting itself from within. For years and years it has been doing this aelf- digesting and for a long time it has been; '... so far, so good!'

Now, the digestion process is advanced. People say, "The eocnomy is collapsing!", or, "the economy is broken!", or it is "tanking". It's considered sick or ill or needing a jump- start or some other 'treatment'. Rather, the massive, all engulfing economic bear is manifesting advanced self- digestion. There is nothing really 'wrong' with the bear, in fact it is exactly as it should as it desperately tries to save itself.

The economic bear must either stop the digesting or it will die. It will completely devour itself.

This is what 'sustainability' is all about. Some action proceeds - like beating a family member with a baseball bat - until it cannot anymore; the action morphs into something else that may be sustainable or it stops, completely.

Period. There are no exceptions. There is no such thing as 'more sustainable' or 'less sustainable'; there is sustainable and there is everything else. Being 'more sustainable' is like being 'more pregnant'. Sustainability can be considered a natural law, one of the few metaphyxical principals that reaches into the world of the 'REAL'!

I call thes 'THE IRON LAW OF SUSTAINABILITY'. It is the mainspring that drives markets; PRICING by supply and demand. Markets attach values to actions and when these become manifestly unsustainable, the market reacts. The market has declared that the auto industry is unsustainable and this declaration has been made bu the market pricing the industry into the toilet.

Like the bear digesting itself ... the car business has succeeded to the point of failure. In light of this 'market pricing', the issue of what kind of motive power is 'under the hoods' of the different cars is irrelevant.

The only way the auto industry can possibly survive at this stage of the digestion cycle is to stop making cars. It can make something else - streetcars) or military vehicles (In very limited numbers) or sailing ships. Otherwise, it will make fewer and fewer more and more costly (to itself) autos... and will eventually disappear.

This sounds ironic, but we live in ironic times and have a wickedly ironic economy. GRRRRLL!

I tend to agree with the kilted green. Euan has shown a distinct aversion to sustainable economics or societies, in the past, even though he understands the limits of nature.

But it is optimistic in the extreme to suppose that the worlds car fleet will be all electric by 2031. That is barely 22 years away and it takes, I think, something like 15 years to replace the fleet, with extra cars being added all the time. So each iteration might make some inroads into electric car utopia, but it would take a lot longer than 22 years for a significant portion of the fleet to be all electric. And that is assuming similar kinds of societies and economies to now. People need to sell their car (usually) in order to buy another, but will that even be possible for many people?

The kind of societies envisioned by having all electric cars for a billion people are probably pie in the sky societies.

This earth is limited. The energy and resources available for us to use without damaging the environment is limited, even if we damage the environment, they are limited. Unless authors understand this, we won't get any useful articles from them, about how we should plan future societies or prepare for a more resource limited future. Quotes such as, "It seems you favor some version of a mythical paradise where all the houses, shops and places of work are somehow just magiced into one place so that folks can walk or cycle everywhere." are not helpful. The implication is that any kind of society that requires reduced consumption just ain't gonna happen. If it doesn't happen, bye by civilisation.

As Steve from Virginia mentioned, "more sustainable" is meaningless. Something is either sustainable or it is not. Current lifestyles, using 1.2 earths and rising, are not sustainable. Even if we all drive electric cars.

Dear Euan.
Interesting points for discussion, but where will we get the electricity from? - Not just for hybrids or all electric vehicles but for basic living? (I speak not just of Scotland, but also the UK as a whole). As you are most certainly aware, the recent cold spell has punished our meagre gas storage reserves. Nuclear power at least in Scotland is still off the agenda and wind is at a very immature stage. Tidal is still on the drawing board and of course Coal is now unacceptable to the pro AGW people. Add to this that we now no longer have any money after the bailouts and less tax revenue and increasing numbers of people becoming a charge on the state: In the summer, about half of this years new graduates will not find employment That alone will add 200,000 to the newly disposessed. I would hate to go into a decadal cooling phase in our present parlous state! - Which IMO we are, looking at our idling Sun.

I suggest our proposed solutions are in fact now entirely hypothetical: We do not have the money, will power or resources to reverse our course. With luck, we will occasionally have some electricity to watch Top Gear (I hope so - he is an antidote to the remorsless droning on AGW).
Rgds and Good Luck
Dropstone

By 2031 I imagine the whole of the worlds fleet of cars will have been replaced. This is likely to happen whether you like it or not. In my opinion, its best to replace the existing car fleet with the most energy efficient vehicles that can be designed and built, and that will include cars that last 15 to 20 years and which can be largely recycled, running on renewable energy. Too bad that you don't agree with me.

Given the ways things are financially, let alone in terms of energy, that's a moot point I'd say and simply speculation. I am in complete agreement with you that if cars ARE to be manufactured then they should be recycled and be as efficient as possible. Where we seem to differ is that you are of the opinion that those cars SHOULD be replaced whereas I'm generally of the opinion that there's better things for us to do with our resources, namely, to satisfy our transport needs in the future with something other than cars. I imagine that there will be car pools, taxis, car clubs and so on, but that the idea of 1 household = 1 (or 2 or 3) cars is over in my view.

It seems you favor some version of a mythical paradise where all the houses, shops and places of work are somehow just magiced into one place so that folks can walk or cycle everywhere.

The future is local and the idea (prevalent only over the last 50, or fewer years), that you just drive 50 miles at the drop of a hat to buy a TV or something, is simply a fossil-fuelled blip in the way humans live and is not sustainable. You seem to imply that the opposite - hypermarket and retail theme park 4 miles out of town and work 30 miles away is something that is destined to continue. I did not say walk & cycle OR private car. What I'm saying is that the current presumption that we all have our own car, or aspire to that ideal, is an idea with no future. Given that we're already using the equivalent of 3 planets to support the current human experiment then we must reduce demand for everything, including travel, and what travel needs do remain should be satisfied by walking, cycling, public transport and probably several types of shared car use.

the global car fleet will be replaced whether you like it or not.

Such certainty! And presumably by extension, the global domestic fridge fleet, global CH boiler fleet, global TV fleet, global computer fleet, global washing machine fleet, global cooker fleet and so on and so on. And it logically follows from that, that all of those in their time must also be replaced by newer, more efficient models. You are obviously in support of the current market paradigm:

Our enormously productive economy demands that we make consumption our way of life...that we convert the buying and use of goods into rituals...that we seek our spiritual satisfaction, or ego satisfaction, in consumption. We need things burned up, worn out, replaced and discarded at an ever-increasing rate.'
Victor Lebow, US Retail Analyst, 1950

This is the same thinking that tells us that we must have a 3rd runway at Heathrow because air travel expansion is such that we will run out of capacity if we don't. Do you support that analysis? Is there a moment of reflection to ask if these scenarios are actually desirable? It's a bit like the 'sexy' attraction of building Zero carbon homes to address our domestic energy use so that's where that attention goes. However, even before the finance/house building crash, the government's own figures say that 70% of 2050's houses have already been built. So, what we need is to reduce energy demand in our existing buildings, not knock them down and replace them with Zero-carbon homes (whatever that means!).

My OND was in automobile engineering and I was obsessed with cars for many years before I realised that we had to find alternatives. I don't watch Top Gear. I haven't had a TV since 2003 and even when I did I only watched about 2 or 3 programs around the time when it started. I've seen a minute or two here or there on the web or at friends' homes. JC's mindset is exactly the kind of world view that has to be ditched if we're to have a real chance of a future. His unbounded arrogance and dismissal of anyone who wants to spoil his fun exemplifies the way of thinking that is sending us down the toilet.

I'm not quite sure what you are trying to say in your comment on cycle lanes, but it is as true in 2009 as it was back (I think) in the time of Thatcher when someone commented that "The UK does not have a transport policy, it has a roads policy". We could probably also insert 'and air travel' before 'policy'. Considering the benefits in personal health, reduction of pollution, emissions and noise engendered by a widespread adoption of the most efficient transport system on the planet, cycling provision is still given almost less than lip service by the government. Just look at the abysmal state of cycle carriage on trains for only one example of the total lack of joined-up (or indeed any) kind of thinking at all for an alternative to the car. Walking and cycling are my main way of getting around, and I'm reminded every single time I use my bike how atrociously I'm treated as a cyclist compared to car users. This is something that absolutely has to change so that people's first thoughts of options on how to get to where they want to go is walk, then cycle, then public transport and then car. Not just car.

Thanks for your replies Euan.