I have feeling, that some people are bit misinformed about diesels. And as I live in eastern Europe where half of cars are diesel powered, here is some of my experience...
Emissions There is no black smoke from new diesel cars since EURO 4 emission standard (2005+). Yes, they still smells, but now the EURO 5 are coming so even the smell will probably be the history. Lots of cars are now equipped with DPF (diesel particulate filter) as standard, so there is no black smoke at any circumstances. Cars without DPF runs lean with lots of recirculated exhaust gases and it has some disadvantages. Mainly no torque off boost and slow reaction at throttle. DPF has problems too (regenerating conditions for the filter, and its plugging) There are only a few cars with NOx reduction system (MB, BMW, VW... cars sold in US) but with EURO5 coming there will be more. Some tests suggest, they have lower consumption than same car without deNOx system. The engine don't have to run near the stoichio. with huge amounts of recirculated exhaust gases, which spoils the efficiency. It just runs extremely lean.
Reliability Modern diesel engines are (to say it diplomatically) "fragile". It takes huge amount of technology to made modern diesels as good as they are, and modern technologies tends to break. And they are braking. Some European automakers has lots of problems with it. Modern Common Rail diesels (and as VW killed the PD, there is nothing else than CR) uses high pressure. And as "high pressure" I mean 1600 to 2000 bars. That is like 23'000 - 29'000 psi So the pumps producing this pressure are extremely sensitive to lubrication. And with low quality diesel fuel, it can ?grind? (sorry I don't know the right word) and produce microscopic metal particles. As the metal particles comes to the injectors, they brake them sooner or later too. The injectors alone are fragile too. They can break after around 120-150'000 miles. Still it hugely depends on quality of the diesel fuel. Lubrication, cleanness, amount of water and more... Next, we have turbocharger. Diesel engines has tiny turbochargers spinning at huge revolutions (usually 150-250'000 rpm) to reduce or eliminate lag. And of course they break from time to time. Turbos commonly have variable geometry turbine (vgt) and it tends to stop working too. Common effect are, that when driver require maximum acceleration, the turbo cant deliver required amount of air, ECU diagnostics it as a malfunction and falls into emergency mode with reduced power. And if this happen while overtaking, than you are screwed... (It can also happen because of broken injectors, and low pressure in common rail system) DPF filter. They require specific condition for regeneration. Something like constant speed and load (around 40-50mph), engine at working temperature, warm catalytic converter, working brakes and more. But in usual driving, it can be problematic to reach all required condition, DPF becomes plugged and you are on the way to the service station. This applies only for cars where the regeneration works trough later injection, where the unburned diesel fuel burns comes into the exhaust and burns the soot in DPF. It also requires more frequent oil changes. There are systems with independent injector in front of DPF and there could be fine. Next. Dual mass flywheel. It smoothen the power coming into tranny. But if you are driving at too low revs you can brake it. And as most of cars here has manual gearbox and most of people are not aware of it... Ok, that is probably everything important ( = expensive). Fuel pumps costs usualy 700 and more euros, at least 400 for one injector, 700 and more for turbocharger, and around the same for DPF or dual mass flywheel. Bigger, more expensive or luxury car, and the prices will double. Or tripe. Sulfur in diesel fuel are big problem. It will ruin the catalyst, and some diesel engines uses special cylinder coating (nikasil or similar), witch will be destroyed by sulfur.
It is no longer true, that diesel cars are more re
Do you live in the world, where no electricity is required in cloudy days and at night ? I don't. You just can't base any significant part of your energy production on uncontrollable sources like sun and wind.
And as far as I know, solar energy is far more expensive.
... is the reason why the solar (and wind) energy has to be supported in most of the Europe, and energy corporation has to buy it for twice the price as energy from other sources !
So, correct me if I don't have it right. 4Ah at 12V gives us 48Wh of energy for one battery. Tesla battery pack contains approx 50kWh of power, so we need thousand of these SCiB batteries if we want to replace. And as 1 piece weights 1kg, that makes 1 ton together. And as far as I know, tesla's li-ion pack weights about half a ton...
So this seems to be the catch. Same capacity, twice the weight.
I assume this is a language issue: hydrocarbons, not carbohydrates.:) Carbohydrates are what you consume when you eat bread, potatoes, pasta, etc.
My god, I have to read before I post something.
Citroen C3 1.4HDi diesel versus 1.4i petrol. 2001 models
Similar figures are common here. There are few even smaller diesel cars here, with bit better consumption.
Not "a lot" slower (at least compared to the model I was doing comparisons with, which is the only one that my above numbers are thus valid for).
Again, if you compare high speed performance, the prius is lot slower. Top speed of 320d ED is 228kmh, and that is much more than prius. So it is bit faster off the line, and lot faster at highway speeds.
"Out of juice"? Hybrids are designed specifically to prevent that from happening except in really exceptional conditions that most people never experience. Electrics are a different story, of course.
So if you are, I don't know, going to the vacation with full car, and floors it on highway, doesn't it drains the batteries ? If I remember right, the capacity of priuses battery pack was around 4-5kWh. It is not much when you are requiring full power.
It is. It's designed to help the coolant heat up faster.
Man, it is not EGR. EGR has to recirculate the exhaust gases back to the intake. It has to be near the exhaust, and intake manifold. Prius has to have EGR near the engine too, but what is on picture (pipes for hot and one for cold water going to the muffler/catalyst) is some heat recovery independent from egr.
I like it, although there are some deficiencies that most people aren't aware of -- specifically related to the battery pack. Most people think that EV costs are directly proportional to battery pack size, but that's not true at all.
I don't know if I remember it correctly, but doesn't battery pack for tesla costs around twenty thousand $$$ or even more? That is quite a lot. And what do you men by drivetrain ? Only electric motor, or all the power electronics ?
Another big advantage for PHEVs will come when some of the new crop of unconventional engines for running the generator, which offer higher power to weight (and to cost), hit the market.
But there is no such engine (I know of). Wankel offers high power output with low weight, but the efficiency is much worse than standard petrol engine. Expansion doesn't have enough time, compression ratio is low and there are lots of thermal losses due to the high surface area and low volume of combustion chamber. Stirling engine is hugely efficient, but really heavy with low power. And what more do we have ? Only thing that comes to my mind is "revolutionary" inventions where inventor claims 99.999% efficiency and all he need is lots of cash to make first prototype.
One thing. I read something about tinny gas turbines with lots and lots of efficiency for cars (as generators). And that could be really interesting. Too bad I don't remember where I read it.
I'm not convinced be EV from one reason. I can't imagine to plan my driving and recharging at all. With generator you are unlimited. But EV as only vehicle ? I can't imagine it. Not to mention problems of EV in cold conditions.
To avoid each person having a different metric, we use standardized drivecycles. The drivecycle that the EU uses to model how people typically drive for vehicle mpg ratings is called the NEDC -- the New European Drive Cycle.
That is how manufacturers measure their fuel consumption numbers, isn't it ? There is lots of critics here about it, because it doesn't reflects the reality. The numbers are really low, and most users gets their consumption quite higher. Read something about EPA cycle being much more accurate and real.
I'm pointing out that different sources give different numbers because there is no single correct number because they're not a single chemical mixture.
Ok, in US the situation is probably different. But you just can't sell diesel with density 950 (at 15 degrees) here. Maybe for some really heavy machinery, trains, ships or industrial generators. But not for cars. And yes, I know the density vary with temperature or "arctic" sort (800-840). Numbers I posted are for summer, at 15 degrees. And yes, I know that it is just a mixture of carbohydrates with very different characteristics. That is why the norm limits the density at 15 and 40 degrees, destilation figures, amount of sulfur, cetane number, CFPP and much more.
I cannot comment without you providing information on just what vehicles you're speaking of. Please be specific.
Citroen C3 1.4HDi diesel versus 1.4i petrol. 2001 models You can easily find them through carfolio. And you can check long time average for lots of cars here http://www.spritmonitor.de/en/ We have here lots of diesel superminis (or even small sedans) with similar consumption.
The BMW's tires are notably more expensive than the Prius's, for a reason.
Yes, that is probably true. And yes, rolling resistance is much more complicated to be figure out from like this.
No, they don't [bmw.com]. BMW 320d EfficientDynamics, 1495kg
I was using the numbers of standard 320d, not 320dED. ED is lot less powerful (aprox 20hp) and 10kg lighter
Unit power to unit power, yes, they are. Just look at the BMW 3-series. The gasoline straight 6 is slightly smaller and slightly lighter than the equivalent diesel, yet yields 306hp instead of 245hp.
335d with twin turbochargers has also 300hp. But it is bit heavier than standard 330d. Intercoolers, turbochargers.. you know. Yes, diesels are heavier and less powerful than petrol engines, no doubt about it. But the difference is by far not as big as it was few years ago. Diesel engines with steel engine block and steel head was much heavier. And they are almost completely gone now.
You forget something: the hybrid drivetrain allows for a significantly smaller engine, too. It's merely a 98hp 4-banger.
I'm not sure what do you think. Yes engine is smaller, but car is also lot slower. And I forgot another think. Prius don't have gearbox, just clever differential like planet gearing. And I assume this "gearbox" is much lighter then standard transmission.
I just showed you that it does. 109g/100km CO2 vs. 89g/100km (22% difference), for cars with roughly equivalent drag areas and mass differences little more than that attributable to the drivetrain type.
Yes 0-100 numbers are not that different. But in lower speeds the electric engine helps a lot. Once you are out of juice, it will not help anymore. And over a 100kmh the difference will be much different. Top speed is around 175 for prius and almost 230 for bmw. That suggest huge acceleration difference over aprox 140kmh.
I like much more the "second" difference. 19%:) And still. Heavier faster car, no brake energy recovery, higher overall efficiency for hybrid so the difference is not that bi
Wrong. Please pay attention to the wording that I highlighted: normal driving. See the highlighting? You're comparing *peak efficiency* to *normal driving*. Check out the graph [wikipedia.org] on the page that you linked. See how much efficiency varies? Beyond that, there's energy thrown away by braking and energy lost to idling. This (very roughly) halves the efficiency in non-hybrids from the peak.
So how do you think normal driving for truck looks like ? In europe it is highway driving at constant speed, more or less constant load for hundreds miles. They are designed to run most of the time near the peak. And I know the graph. That is why I'm using your averages for car efficiency.
If you had cited Wikipedia, you would have said that they're 18% different, giving a figure of 720kg/m^3 for gasoline and 850kg/m^3 for diesel. But the reality is that neither are right. There is no single density for gasoline or diesel because there is no single fuel called "gasoline" or "diesel". There are all different kinds of blends. They average about 15% difference.
No this is not from wiki. It is from book called "Automobile fuels" (translated) And as we have norms here for parameters of fuel, that is what our norm says. petrol : 720-775 kg/m3 at 15 degrees C diesel : 820-845 kg/m3 at 15 degrees C So it doesn't average about 15% Around 10%. And as far as I know, this is valid for whole EU with little differences.
Experience. To be less vague, when you've taken enough gasoline and diesel vehicles of the same model and same acceleration and compared their CO2 outputs and their density-adjusted fuel consumptions, you'll arrive at the same number (give or take ~5%).
Experience are important, that is no arguing about that. But did you tested great variety of cars? Where I live there are around 50% of diesels, and I had driven quite a lot a small diesel city car with average 4l/100km (~60mpg). Same car with equivalent petrol engine averaging about 6 liters (~40mpg). In CO2, it is 110 vs 160 Careful extra-urban close to 3 liters. Quite bigger difference than 5% for eff (in real driving, as you posted) and 10% fuel density (acording to our norm) And there are LOTS of cars with similar numbers here.
For all of the below, I will use this [gotbroken.com] and this [carfolio.com] for the BMW's stats. I will use this [priuschat.com] for the 2010 Prius's stats. I guess I have to explain this one as well. Drag area *includes* the drag coefficient (Cd) (what you refer to as "better aerodynamics"). Drag area is the cross sectional area times the drag coefficient.
Language barrier. My bad. I didn't know the exact terms in english. Using (maximum) vehicle dimensions for getting frontal area is wrong. I tried it few times myslef, and it differs significantly from actual numbers.
The Prius comes equipped with Yokohama AVID S33D tires. The BMW uses Michelin EnergySaver tires. Now, rolling drag coefficients are even harder to get than drag areas (and, FYI, are a grossly inaccurate measure anyway). But it's worth mentioning that the EnergySavers are the most efficient tire Michelin makes.
Yes that is true. But it changes nothing about a fact, that in all reviews and comparison test I read the conclusion was, that priuses tiers have little grip, and bmw is quite sporty with not a one complain about the grip. Latteral G forces 0.78-79 for prius, around 0.9 for bmw (can't find exact number rigt now) So not all eco tires are equal.
Prius: 3042 lbs BMW: 3296 lbs 200 pounds, perhaps, but not kg. Also note that part of the weight of the BMW is due to how heavy diesel engines are compared to gasoline, so this is, at least in part, something that should be credited as an advantage of hybrid tech over diesels, rather than a difference in the comparison vehicles themselves. Batteries are famously
You're pushing a common misconception -- that all fuels are equivalent. Yes, diesel engines are more efficient than gasoline engines, but only by about ~15%. The rest of the efficiency gain is that the fuel is denser -- there's more "oil" in that liter. Hence, the BMW 320d EfficientDynamics gets 109g/100km CO2, while the new Prius gets 89g/100km. Furthermore, not all cars are created equal; weight and drag areas being the big differing parameters.
The density of petrol varies around 750kg/m3 diesel around 820kg/m3. So yes, there is a difference, but it is around 10% And where the hell the 15% efficiency difference came from ? I'm quoting your post, using your numbers.
Non-hybrid gasoline ICEs average about 20% efficiency... Diesels average about 25%
And yes, drag areas differs. Prius is smaller. It has also better aerodynamics (0.26 vs 0.27), it has low RR eco tires, it is front wheel drive so there are (few %) less drive-train losses, it is almost 200 kg lighter than bmw (more than 10%), it has brake energy regeneration, it can move only on electricity, and it has some kind of waste heat recovery. ALL advantages (except fuel density) are on the side of prius. So again how the hell is it possible, if hybrids are 5-10% more efficient than diesels (again, your numbers. 25% vs 30-35%)
Another common misconception. 30-35% is *peak* efficiency, not *average*. Gasoline cars idle, they brake, they run in torque/rpm combinations that are far from optimal, etc. They average about 20% in normal driving.
No, peak efficiency of diesel engines are about 35-40%. I can take a picture of university scripts (in book version) if you like. Too bad they are not in english. And what is the difference ? Diesel cars don't idle, brake or run in different than optimal revs? I think they do. And even more then hybrids. Not to mention that all modern diesels are fuc*ed by NOx emissions limits.
People who know what they're talking about are welcome. People who rely on assumptions and ignorance aren't.
And you are the one, to tell which is which. Wow this is so arrogant, I don't know what to say.
Because I know a bit about genetic engineering, I should start telling genetic engineers what they can and can't do, right?
Again, what the hell are you talking about ? Where am I telling anyone what to do ? There is quite a difference between telling someone what to do and writing down an opinion. And do I understand it right, that you are TESLA chief engineer ?
Got a university around you? Heck, a lot of the papers on the topic are free. For example, the DOE/PNL's work.
Yeah. But no chance finding any new english papers.
btw are you from US ? I have tiny little feeling that you may be talking about bit different diesels than me.
So you're just going to A) magic all of these cars into existence in an instant, and B) run them *solely* on our existing generation infrastructure? How do you propose we do either of those? And, FYI, even if you build a car today -- the average car on the road is nearly 10 years old, implying an average lifespan of nearly 20 years. You think the grid is going to look the same decades from now as today?
Man, what the hell ? That is exactly what I'm talking about. About EXISTING cars and plants. About average of what we have NOW. No, super efficient cars will not magically pop-up, but nor your turbines will.
Or should I argue with some turbocharged turbo-compound diesel trucks with almost 50% efficiency ? No. Few trucks doesn't matter, and we are talking about average 20-25% for cars.
You mean things that EVs have automatically?
This is an argument ? So what if EVs have them automatically ? Doe's it change anything about the fact, that it will improve efficiency and reduce losses for ICE vehicles? And you don't need to improve efficiency of ICE to get far better mileage. You can make the car lighter, and reduce losses.
btw have you heard about bmw 320d ? 180 horses and 4.7l / 100km in combined cycle? Bit more interesting numbers (form me) than 135 hp 3.9l / 100 km from prius. Can you please explain it to me with your peer reviewed literature? Because diesel (25% eff) should be quite less effective than petrol hybrid cars (30-35%).
And sorry man, I didn't know that only expert in problematics are allowed to discuss here. I know a bit about the cars so I tough I can join the discussion, but I was probably wrong. And no, I'm not going to pay 30$ for some study just to discuss it with you.
Why did I said that? Because I tough we are talking about current situation. Yes, in 20 years we will have more efficient plants, but we will have also more efficient cars. We have numbers about car efficiency from 2007, so we have to talk about power plant (average) efficiency in 2007. Today, one super effective gas turbine doesn't matter. Thousands of old plants does.
And as car manufacturers are under huge pressure to limit CO2 emissions (fuel consumption), the efficiency of cars may go up even faster than efficiency of plants. Lots of new cars use some form of brake energy recovery, they are automatically turn off engine when you stop, they have low rolling resistant tires, improved aerodynamics, more efficient transmission, special cooling and waste heat management and more. In 5 years, all new cars will have this technologies. But it is included in the study you mentioned ? I'm not sure.
To be honest, I know nothing about tank-to-something studies. But as you have to produce petrol or diesel in refinery, you also have to "produce" gas and coal (I suppose it have to be cleaned, refined, transformed, milled) You have to move the petrol to the gas stations, but you also have to move millions tons of coal to the power plants. Is the difference that big ?
You seems to be an expert in battery problematics so, correct me if I'm wrong. Faster you charge (or discharge) less efficiency you get. right ? And the same for charger. Higher the power, means usually less efficiency. right ? I don't know much about batteries, but this is how it usually works in almost everything.
And in cars, what you need are deep discharge batteries, witch can be charged and discharged really really fast. right? So as I understand it. You can have battery good in almost everything, but at cost of efficiency. Or good batteries in each aspect (including efficiency), but with really high price tag.
All I want to say is, that it is hard for me to believe that all chargers are 92-93% efficient, and all batteries goes from 94-99. Standard home electronics battery could have different parameters than heavy duty ones, and standard chargers can by more efficient then some 8 kW heavy duty fast charger.
But latest plants doesn't really matter that much. Most of the plants are still old 40-45%. Yes in 30 years, we can talk about average 60%, but not now.
Second thing, around 50% of electricity in US are produced in less effective coal plants.
And if you put the numbers together (with 45-50% for power plant efficiency), you will get something around 30-35%
That is exactly same as hybrid.
btw any sources for the petrol / diesel efficiency numbers? thanks
man, I'm not an expert, but 99.8% of battery charge / discharge efficiency looks like a total BS to me.
1) that would mean, that only 0.2% of electricity used to charge the battery changes to heat. and that is not right, battery pack in hybrids and electric vehicles have cooling. and you don't need cooling for 4kW * 0.002 = 8W of heat produced.
it may work for charging with tiny little currents, but you don't wont to charge your car a whole week.
2) you are forgetting the efficiency of charger. and it would be around 80-90%.
Slashdot Mirror
page zooming and fit-to-width works in Opera also for images
images, flash content and probably everithng else.
I love, when I can zoom some little flash game to the fullscreen...
In supaplex, I got to level 104. :(
But none believed me
I have feeling, that some people are bit misinformed about diesels. And as I live in eastern Europe where half of cars are diesel powered, here is some of my experience...
Emissions
There is no black smoke from new diesel cars since EURO 4 emission standard (2005+). Yes, they still smells, but now the EURO 5 are coming so even the smell will probably be the history.
Lots of cars are now equipped with DPF (diesel particulate filter) as standard, so there is no black smoke at any circumstances. Cars without DPF runs lean with lots of recirculated exhaust gases and it has some disadvantages. Mainly no torque off boost and slow reaction at throttle. DPF has problems too (regenerating conditions for the filter, and its plugging)
There are only a few cars with NOx reduction system (MB, BMW, VW... cars sold in US) but with EURO5 coming there will be more. Some tests suggest, they have lower consumption than same car without deNOx system. The engine don't have to run near the stoichio. with huge amounts of recirculated exhaust gases, which spoils the efficiency. It just runs extremely lean.
Reliability
Modern diesel engines are (to say it diplomatically) "fragile". It takes huge amount of technology to made modern diesels as good as they are, and modern technologies tends to break. And they are braking. Some European automakers has lots of problems with it.
Modern Common Rail diesels (and as VW killed the PD, there is nothing else than CR) uses high pressure. And as "high pressure" I mean 1600 to 2000 bars. That is like 23'000 - 29'000 psi
So the pumps producing this pressure are extremely sensitive to lubrication. And with low quality diesel fuel, it can ?grind? (sorry I don't know the right word) and produce microscopic metal particles. As the metal particles comes to the injectors, they brake them sooner or later too.
The injectors alone are fragile too. They can break after around 120-150'000 miles.
Still it hugely depends on quality of the diesel fuel. Lubrication, cleanness, amount of water and more...
Next, we have turbocharger. Diesel engines has tiny turbochargers spinning at huge revolutions (usually 150-250'000 rpm) to reduce or eliminate lag. And of course they break from time to time. Turbos commonly have variable geometry turbine (vgt) and it tends to stop working too. Common effect are, that when driver require maximum acceleration, the turbo cant deliver required amount of air, ECU diagnostics it as a malfunction and falls into emergency mode with reduced power. And if this happen while overtaking, than you are screwed... (It can also happen because of broken injectors, and low pressure in common rail system)
DPF filter. They require specific condition for regeneration. Something like constant speed and load (around 40-50mph), engine at working temperature, warm catalytic converter, working brakes and more. But in usual driving, it can be problematic to reach all required condition, DPF becomes plugged and you are on the way to the service station. This applies only for cars where the regeneration works trough later injection, where the unburned diesel fuel burns comes into the exhaust and burns the soot in DPF. It also requires more frequent oil changes. There are systems with independent injector in front of DPF and there could be fine.
Next. Dual mass flywheel. It smoothen the power coming into tranny. But if you are driving at too low revs you can brake it. And as most of cars here has manual gearbox and most of people are not aware of it...
Ok, that is probably everything important ( = expensive). Fuel pumps costs usualy 700 and more euros, at least 400 for one injector, 700 and more for turbocharger, and around the same for DPF or dual mass flywheel. Bigger, more expensive or luxury car, and the prices will double. Or tripe.
Sulfur in diesel fuel are big problem. It will ruin the catalyst, and some diesel engines uses special cylinder coating (nikasil or similar), witch will be destroyed by sulfur.
It is no longer true, that diesel cars are more re
Do you live in the world, where no electricity is required in cloudy days and at night ?
I don't.
You just can't base any significant part of your energy production on uncontrollable sources like sun and wind.
And as far as I know, solar energy is far more expensive.
... is the reason why the solar (and wind) energy has to be supported in most of the Europe, and energy corporation has to buy it for twice the price as energy from other sources !
So, correct me if I don't have it right.
4Ah at 12V gives us 48Wh of energy for one battery.
Tesla battery pack contains approx 50kWh of power, so we need thousand of these SCiB batteries if we want to replace. And as 1 piece weights 1kg, that makes 1 ton together. And as far as I know, tesla's li-ion pack weights about half a ton...
So this seems to be the catch. Same capacity, twice the weight.
I assume this is a language issue: hydrocarbons, not carbohydrates. :) Carbohydrates are what you consume when you eat bread, potatoes, pasta, etc.
My god, I have to read before I post something.
Citroen C3 1.4HDi diesel versus 1.4i petrol. 2001 models
Similar figures are common here. There are few even smaller diesel cars here, with bit better consumption.
Not "a lot" slower (at least compared to the model I was doing comparisons with, which is the only one that my above numbers are thus valid for).
Again, if you compare high speed performance, the prius is lot slower.
Top speed of 320d ED is 228kmh, and that is much more than prius.
So it is bit faster off the line, and lot faster at highway speeds.
"Out of juice"? Hybrids are designed specifically to prevent that from happening except in really exceptional conditions that most people never experience. Electrics are a different story, of course.
So if you are, I don't know, going to the vacation with full car, and floors it on highway, doesn't it drains the batteries ?
If I remember right, the capacity of priuses battery pack was around 4-5kWh. It is not much when you are requiring full power.
It is. It's designed to help the coolant heat up faster.
Man, it is not EGR. EGR has to recirculate the exhaust gases back to the intake. It has to be near the exhaust, and intake manifold. Prius has to have EGR near the engine too, but what is on picture (pipes for hot and one for cold water going to the muffler/catalyst) is some heat recovery independent from egr.
I like it, although there are some deficiencies that most people aren't aware of -- specifically related to the battery pack. Most people think that EV costs are directly proportional to battery pack size, but that's not true at all.
I don't know if I remember it correctly, but doesn't battery pack for tesla costs around twenty thousand $$$ or even more? That is quite a lot.
And what do you men by drivetrain ? Only electric motor, or all the power electronics ?
Another big advantage for PHEVs will come when some of the new crop of unconventional engines for running the generator, which offer higher power to weight (and to cost), hit the market.
But there is no such engine (I know of). Wankel offers high power output with low weight, but the efficiency is much worse than standard petrol engine. Expansion doesn't have enough time, compression ratio is low and there are lots of thermal losses due to the high surface area and low volume of combustion chamber. Stirling engine is hugely efficient, but really heavy with low power.
And what more do we have ? Only thing that comes to my mind is "revolutionary" inventions where inventor claims 99.999% efficiency and all he need is lots of cash to make first prototype.
One thing. I read something about tinny gas turbines with lots and lots of efficiency for cars (as generators). And that could be really interesting. Too bad I don't remember where I read it.
I'm not convinced be EV from one reason. I can't imagine to plan my driving and recharging at all. With generator you are unlimited. But EV as only vehicle ? I can't imagine it.
Not to mention problems of EV in cold conditions.
To avoid each person having a different metric, we use standardized drivecycles. The drivecycle that the EU uses to model how people typically drive for vehicle mpg ratings is called the NEDC -- the New European Drive Cycle.
That is how manufacturers measure their fuel consumption numbers, isn't it ?
There is lots of critics here about it, because it doesn't reflects the reality. The numbers are really low, and most users gets their consumption quite higher. Read something about EPA cycle being much more accurate and real.
I'm pointing out that different sources give different numbers because there is no single correct number because they're not a single chemical mixture.
Ok, in US the situation is probably different. But you just can't sell diesel with density 950 (at 15 degrees) here. Maybe for some really heavy machinery, trains, ships or industrial generators. But not for cars.
And yes, I know the density vary with temperature or "arctic" sort (800-840). Numbers I posted are for summer, at 15 degrees.
And yes, I know that it is just a mixture of carbohydrates with very different characteristics. That is why the norm limits the density at 15 and 40 degrees, destilation figures, amount of sulfur, cetane number, CFPP and much more.
I cannot comment without you providing information on just what vehicles you're speaking of. Please be specific.
Citroen C3 1.4HDi diesel versus 1.4i petrol. 2001 models
You can easily find them through carfolio.
And you can check long time average for lots of cars here http://www.spritmonitor.de/en/
We have here lots of diesel superminis (or even small sedans) with similar consumption.
The BMW's tires are notably more expensive than the Prius's, for a reason.
Yes, that is probably true. And yes, rolling resistance is much more complicated to be figure out from like this.
No, they don't [bmw.com]. BMW 320d EfficientDynamics, 1495kg
I was using the numbers of standard 320d, not 320dED. ED is lot less powerful (aprox 20hp) and 10kg lighter
Unit power to unit power, yes, they are. Just look at the BMW 3-series. The gasoline straight 6 is slightly smaller and slightly lighter than the equivalent diesel, yet yields 306hp instead of 245hp.
335d with twin turbochargers has also 300hp. But it is bit heavier than standard 330d. Intercoolers, turbochargers.. you know. Yes, diesels are heavier and less powerful than petrol engines, no doubt about it. But the difference is by far not as big as it was few years ago. Diesel engines with steel engine block and steel head was much heavier. And they are almost completely gone now.
You forget something: the hybrid drivetrain allows for a significantly smaller engine, too. It's merely a 98hp 4-banger.
I'm not sure what do you think. Yes engine is smaller, but car is also lot slower. And I forgot another think. Prius don't have gearbox, just clever differential like planet gearing. And I assume this "gearbox" is much lighter then standard transmission.
I just showed you that it does. 109g/100km CO2 vs. 89g/100km (22% difference), for cars with roughly equivalent drag areas and mass differences little more than that attributable to the drivetrain type.
Yes 0-100 numbers are not that different. But in lower speeds the electric engine helps a lot. Once you are out of juice, it will not help anymore. And over a 100kmh the difference will be much different. Top speed is around 175 for prius and almost 230 for bmw. That suggest huge acceleration difference over aprox 140kmh.
I like much more the "second" difference. 19% :)
And still. Heavier faster car, no brake energy recovery, higher overall efficiency for hybrid so the difference is not that bi
Wrong. Please pay attention to the wording that I highlighted: normal driving. See the highlighting? You're comparing *peak efficiency* to *normal driving*. Check out the graph [wikipedia.org] on the page that you linked. See how much efficiency varies? Beyond that, there's energy thrown away by braking and energy lost to idling. This (very roughly) halves the efficiency in non-hybrids from the peak.
So how do you think normal driving for truck looks like ? In europe it is highway driving at constant speed, more or less constant load for hundreds miles. They are designed to run most of the time near the peak.
And I know the graph. That is why I'm using your averages for car efficiency.
If you had cited Wikipedia, you would have said that they're 18% different, giving a figure of 720kg/m^3 for gasoline and 850kg/m^3 for diesel. But the reality is that neither are right. There is no single density for gasoline or diesel because there is no single fuel called "gasoline" or "diesel". There are all different kinds of blends. They average about 15% difference.
No this is not from wiki. It is from book called "Automobile fuels" (translated)
And as we have norms here for parameters of fuel, that is what our norm says.
petrol : 720-775 kg/m3 at 15 degrees C
diesel : 820-845 kg/m3 at 15 degrees C
So it doesn't average about 15%
Around 10%. And as far as I know, this is valid for whole EU with little differences.
Experience. To be less vague, when you've taken enough gasoline and diesel vehicles of the same model and same acceleration and compared their CO2 outputs and their density-adjusted fuel consumptions, you'll arrive at the same number (give or take ~5%).
Experience are important, that is no arguing about that.
But did you tested great variety of cars? Where I live there are around 50% of diesels, and I had driven quite a lot a small diesel city car with average 4l/100km (~60mpg). Same car with equivalent petrol engine averaging about 6 liters (~40mpg). In CO2, it is 110 vs 160
Careful extra-urban close to 3 liters.
Quite bigger difference than 5% for eff (in real driving, as you posted) and 10% fuel density (acording to our norm)
And there are LOTS of cars with similar numbers here.
For all of the below, I will use this [gotbroken.com] and this [carfolio.com] for the BMW's stats. I will use this [priuschat.com] for the 2010 Prius's stats.
I guess I have to explain this one as well. Drag area *includes* the drag coefficient (Cd) (what you refer to as "better aerodynamics"). Drag area is the cross sectional area times the drag coefficient.
Language barrier. My bad. I didn't know the exact terms in english.
Using (maximum) vehicle dimensions for getting frontal area is wrong. I tried it few times myslef, and it differs significantly from actual numbers.
The Prius comes equipped with Yokohama AVID S33D tires. The BMW uses Michelin EnergySaver tires. Now, rolling drag coefficients are even harder to get than drag areas (and, FYI, are a grossly inaccurate measure anyway). But it's worth mentioning that the EnergySavers are the most efficient tire Michelin makes.
Yes that is true. But it changes nothing about a fact, that in all reviews and comparison test I read the conclusion was, that priuses tiers have little grip, and bmw is quite sporty with not a one complain about the grip. Latteral G forces 0.78-79 for prius, around 0.9 for bmw (can't find exact number rigt now)
So not all eco tires are equal.
Prius: 3042 lbs
BMW: 3296 lbs
200 pounds, perhaps, but not kg. Also note that part of the weight of the BMW is due to how heavy diesel engines are compared to gasoline, so this is, at least in part, something that should be credited as an advantage of hybrid tech over diesels, rather than a difference in the comparison vehicles themselves. Batteries are famously
They're already being built. Diesels which average 50% in normal driving don't even exist in the lab.
My bad, it is only 44.8%
http://tinyurl.com/39mgjwt
You're pushing a common misconception -- that all fuels are equivalent. Yes, diesel engines are more efficient than gasoline engines, but only by about ~15%. The rest of the efficiency gain is that the fuel is denser -- there's more "oil" in that liter. Hence, the BMW 320d EfficientDynamics gets 109g/100km CO2, while the new Prius gets 89g/100km. Furthermore, not all cars are created equal; weight and drag areas being the big differing parameters.
The density of petrol varies around 750kg/m3 diesel around 820kg/m3.
So yes, there is a difference, but it is around 10%
And where the hell the 15% efficiency difference came from ?
I'm quoting your post, using your numbers.
Non-hybrid gasoline ICEs average about 20% efficiency ... Diesels average about 25%
And yes, drag areas differs. Prius is smaller. It has also better aerodynamics (0.26 vs 0.27), it has low RR eco tires, it is front wheel drive so there are (few %) less drive-train losses, it is almost 200 kg lighter than bmw (more than 10%), it has brake energy regeneration, it can move only on electricity, and it has some kind of waste heat recovery. ALL advantages (except fuel density) are on the side of prius.
So again how the hell is it possible, if hybrids are 5-10% more efficient than diesels (again, your numbers. 25% vs 30-35%)
Another common misconception. 30-35% is *peak* efficiency, not *average*. Gasoline cars idle, they brake, they run in torque/rpm combinations that are far from optimal, etc. They average about 20% in normal driving.
No, peak efficiency of diesel engines are about 35-40%. I can take a picture of university scripts (in book version) if you like. Too bad they are not in english.
And what is the difference ? Diesel cars don't idle, brake or run in different than optimal revs? I think they do. And even more then hybrids.
Not to mention that all modern diesels are fuc*ed by NOx emissions limits.
People who know what they're talking about are welcome. People who rely on assumptions and ignorance aren't.
And you are the one, to tell which is which. Wow this is so arrogant, I don't know what to say.
Because I know a bit about genetic engineering, I should start telling genetic engineers what they can and can't do, right?
Again, what the hell are you talking about ? Where am I telling anyone what to do ? There is quite a difference between telling someone what to do and writing down an opinion.
And do I understand it right, that you are TESLA chief engineer ?
Got a university around you? Heck, a lot of the papers on the topic are free. For example, the DOE/PNL's work.
Yeah. But no chance finding any new english papers.
btw are you from US ? I have tiny little feeling that you may be talking about bit different diesels than me.
So you're just going to A) magic all of these cars into existence in an instant, and B) run them *solely* on our existing generation infrastructure? How do you propose we do either of those? And, FYI, even if you build a car today -- the average car on the road is nearly 10 years old, implying an average lifespan of nearly 20 years. You think the grid is going to look the same decades from now as today?
Man, what the hell ?
That is exactly what I'm talking about. About EXISTING cars and plants. About average of what we have NOW.
No, super efficient cars will not magically pop-up, but nor your turbines will.
Or should I argue with some turbocharged turbo-compound diesel trucks with almost 50% efficiency ? No. Few trucks doesn't matter, and we are talking about average 20-25% for cars.
You mean things that EVs have automatically?
This is an argument ?
So what if EVs have them automatically ? Doe's it change anything about the fact, that it will improve efficiency and reduce losses for ICE vehicles?
And you don't need to improve efficiency of ICE to get far better mileage. You can make the car lighter, and reduce losses.
btw have you heard about bmw 320d ? 180 horses and 4.7l / 100km in combined cycle?
Bit more interesting numbers (form me) than 135 hp 3.9l / 100 km from prius.
Can you please explain it to me with your peer reviewed literature? Because diesel (25% eff) should be quite less effective than petrol hybrid cars (30-35%).
And sorry man, I didn't know that only expert in problematics are allowed to discuss here. I know a bit about the cars so I tough I can join the discussion, but I was probably wrong.
And no, I'm not going to pay 30$ for some study just to discuss it with you.
Why did I said that?
Because I tough we are talking about current situation. Yes, in 20 years we will have more efficient plants, but we will have also more efficient cars.
We have numbers about car efficiency from 2007, so we have to talk about power plant (average) efficiency in 2007. Today, one super effective gas turbine doesn't matter. Thousands of old plants does.
And as car manufacturers are under huge pressure to limit CO2 emissions (fuel consumption), the efficiency of cars may go up even faster than efficiency of plants.
Lots of new cars use some form of brake energy recovery, they are automatically turn off engine when you stop, they have low rolling resistant tires, improved aerodynamics, more efficient transmission, special cooling and waste heat management and more.
In 5 years, all new cars will have this technologies. But it is included in the study you mentioned ? I'm not sure.
To be honest, I know nothing about tank-to-something studies.
But as you have to produce petrol or diesel in refinery, you also have to "produce" gas and coal (I suppose it have to be cleaned, refined, transformed, milled)
You have to move the petrol to the gas stations, but you also have to move millions tons of coal to the power plants. Is the difference that big ?
You seems to be an expert in battery problematics so, correct me if I'm wrong.
Faster you charge (or discharge) less efficiency you get. right ?
And the same for charger. Higher the power, means usually less efficiency. right ?
I don't know much about batteries, but this is how it usually works in almost everything.
And in cars, what you need are deep discharge batteries, witch can be charged and discharged really really fast. right?
So as I understand it. You can have battery good in almost everything, but at cost of efficiency. Or good batteries in each aspect (including efficiency), but with really high price tag.
All I want to say is, that it is hard for me to believe that all chargers are 92-93% efficient, and all batteries goes from 94-99.
Standard home electronics battery could have different parameters than heavy duty ones, and standard chargers can by more efficient then some 8 kW heavy duty fast charger.
But latest plants doesn't really matter that much. Most of the plants are still old 40-45%. Yes in 30 years, we can talk about average 60%, but not now. Second thing, around 50% of electricity in US are produced in less effective coal plants. And if you put the numbers together (with 45-50% for power plant efficiency), you will get something around 30-35% That is exactly same as hybrid. btw any sources for the petrol / diesel efficiency numbers? thanks
man, I'm not an expert, but 99.8% of battery charge / discharge efficiency looks like a total BS to me. 1) that would mean, that only 0.2% of electricity used to charge the battery changes to heat. and that is not right, battery pack in hybrids and electric vehicles have cooling. and you don't need cooling for 4kW * 0.002 = 8W of heat produced. it may work for charging with tiny little currents, but you don't wont to charge your car a whole week. 2) you are forgetting the efficiency of charger. and it would be around 80-90%.