"Why also is the prime mover a petrol engine rather than a diesel?"

As you say, 659, the US market is surely the answer to that. But I'm sure I read that Peugeiot / Citroen were developing a diesel-electric hybrid. Anyone know about progress, if any?

But, can the Auris hybrid be charged from National Grid energy which does not carry in the UK such a high rate of taxation as does vehicle fuel? Elsewhere, significant proportions of grid energy can be generated from renewable sources. Clearly, this option does not exist if all you can do with this particular vehicle is to tip petrol into it.

659.

In practice very very little national grid energy is generated from renewable sources, and when you take into account transmission losses, and losses in the battery, and imperfect conversion of battery energy into motion, and the environmental cost of mining all the elements needed for the battery and motor, an electric vehicle might well end up being less green than a petrol car. The only real advantage is moving emissions from the car exhaust to the power station.

Why also is the prime mover a petrol engine rather than a diesel? I'm afraid that cynically, I think this is due to the non acceptability of most diesels in the US and Toyota naturally want a world saleable product. A petrol engine is not a thermally optimum solution.

I think a big part of why diesel isn't used is cost - a plugin hybrid needs two power trains, so the Volt/Ampera gets (I think) what is fundamentally a very cheap 1.4 petrol engine from the Corsa. A similar size/weight diesel engine will have a turbo charger plus a common rail injection system, plus EGR & DPF. The last two might be omitted in a series hybrid because you've completely isolated the engine from the wheels, meaning you can always run the engine at its cleanest and most efficient speed.

But what about us (fairly) green people who need transport, but normally spend about as much on a car as others do on lunch at a Michelin* restaurant ? We won't be buying battery toys or hybrids for years yet .... bangernomics don't come into this yet ... (elderly Saab 2.2TID estate plus a Toyota Yaris fyi)

I sometimes think about a situation where all the cars on the road were electric, and how quiet it would be, but actually, apart from the bigger commercial vehicles and the odd boy racer, it would probably be much the same, as most of the noise on the road currently is from the tyres. And unless the cars can be made lighter (not much chance yet with the batteries they need) and the tyres made more narrow, the road noise may well increase.

Some cars produce a lot more road noise than others, and it seems dependent on engine location. A Golf Tdi with a heavy diesel engine in the front, for example, is much noisier than a Toyota MR2 with it's engine in the middle. So if the electric motor/ motors were lighter and the batteries placed in the centre, road noise could be reduced. One of the advantages of electric motors is that they can be placed near the wheel hubs, so that car packaging could be more versatile, and designs made more exciting, as you're not constricted by leaving a large space at the front of the car for a conventional engine. But I agree that battery technology has yet to be further developed for them to be successful. At some point we will turn a corner. I'm sure that many people scoffed at the idea of an internal combustion engine. But look where we are now, and look how long that concept has lasted.

I know it's a small point but these hybrid cars already have stored energy that has been paid for, the top gear economy test pitted a Toyota Pious against two small cars, one petrol and one diesel, they put a certain amount of fuel into each car and then drove them on the same route to determine which one could get furthest before it conked out - did they flatten the drive batteries on the Pious prior to the test? No they did not, so the comparison simply was not a comparison. The conventional cars were competing against another car which had more "fuel" in it to begin with.

Yes I know I misspelled the name of the ubersmugwagon.

That may be so to an extent, but the peak availability of any non-renewable resource does not occur when 50% of it has been extracted. Rather it is related to the net energy available from the source.

To use the example of oil, in the early 20th century producing 100 barrels of oil 'cost' 2-3 barrels in extraction and refining; now it may cost 20-30 barrels and in deep water drilling may be considerably higher. Producing a barrel of oil in 2010 gives much less net energy at a given cost - if the global economy cannot work with oil at $147 per barrel but the costs associated with producing a barrel of oil mean that the cost cannot be lower then it is likely that the oil will not be extracted. This would be so for any resource.

There is an interesting article in this weeks New Scientist magazine. Bio-ethanol has a bad rap as it takes away land from food growing, increasing food costs, and potentially hunger. More recent methods of producing bio-ethanol use low grade vegetable matter and are much more efficient at producing ethanol. There are also methods based on algae. It might turn out that electric cars do not take off, as liquid fuel is such a convenient and dense energy source.

Actually, I would like to expand on that last remark about over population, if I may (!). Most of the fuel consumed is by the developed nations, whose populations have stabilised, but already the rapidly expanding countries with huge populations like China and India are demanding the same living standards as the rest of us, which means more cars. So a more sustainable means of powering cars will have to be produced in the long term. Or go back to riding horses!

>> Acually, those little Honda 50cc engined bikes are enough to get by aren't they?

I don't understand why the Government are discouraging the use of motorbikes by making it harder for people to take their motorbike test, and getting stricter on emissions for bikes. OK their emissions are worse than cars at the moment but they use less materials to build, they take up less space on the road, they use (on average) less fuel, and there are far less on the road. I don't own a motorbike, but I occasionally read the odd bike mag out of interest. I was disappointed to see that the dutch built tilting carver was axed, presumably down to it being economically unviable. But something small and light based on the carver with a proper cabin and heater would be ideal for commuting. There will be the usual response of ' Yeah, thats all well and good, but where do my 2.4 kids and paraphenalia go?'. But when do you take all that with you when you go to work?

http://www.youtube.com/watch?v=PgbbkzZSK-Q&feature=related

>>We may become the next supply of oil

According to my geology course, if the entire 4600 million years of geological time is compressed into a single calendar year, human-like primates appeared in the late evening of 31st December and the last ice age ended around 1 minute and 15 seconds before midnight on that day. So yes, you're probably right!

>> I don't see why we can't have small vehicles that do no more than 70 mph, and have lightweight body panels, providing a shield against the elements, and a basic heater.

It's a Lotus Exige isn't it?(apart from the 70mph bit) :-)

Edited by corax on 29/05/2010 at 19:19

>> There are also methods based on algae

It would be nice if this worked, but would we be able to produce enough bio-ethanol to feed the demands of every vehicle on the planet?

...

The real problem is over population, not very popular subject, but that is the hard fact.

At present no, because there is not enough land, but the new method being more efficient and using low grade plant matter might do the job. I suspect it is too new and experimental to know. But bear in mind American/Western technology, and I would not be surprised were it to be totally viable for present needs. Advances in biotechnology, and dare I say, genetic engineering, could work minor miracles.

Yes, over population is a real issue. Our country is densely populated, and relies on imports for most food etc. It is interesting to look at the difference between India (democratic, massive population growth, poor infrastructure, huge poverty and inequality) and China (dictatorship, stable population, improving infrastructure, less poverty/slums).