An Argument - diesel vs hybrids

"HammerheadFistpunch" (hammerheadfistpunch) 09/06/2013 at 13:19 • Filed to: None

3

47

Just wrote something up for an assignment on C&D, Thought you guys might want to take a read and tear it apart.

Obviously Im pro diesel vs hybrid...but I wanted to be fair sided and rational, and Im willing to take a little critique, oppo style. Assignment below:

The basic question, as it relates to the argument of diesel VS hybrid is; what is the bases of comparison? Is it Economic? Is it Environmental? Is it driving enjoyment? The facts support whichever side of the isle you lean to as it most often does but here are my experiences with said facts.

US diesels meet Tier II bin 5 and are as clean as modern gas engines.

US diesels consistently outperform their already stellar EPA numbers in real world testing.

US diesel price premiums are consistent with or less than Hybrid price premiums.

Diesels weigh less than hybrids

Diesels require much fewer highly controversial/political rare earth materials

Modern diesels are flexible, capable powertrains.

Diesels perform at capacity regardless of state of charge.

Diesel technology fits existing vehicle architecture and doesn’t require repackaging.

Hybrids on the other hand have the distinct advantage that they don’t use diesel fuel, which is often more costly, more volatile as well as being stinky, relatively rare in certain climates and sensitive to seasonal changes. There is also the debate as to whether the DPF systems are costly to replace and the question of their replacement intervals…but given that hybrids face a similar quandary with batteries, I’ll call it a wash.

What it boils down to, for me, is that I’ve never driven a hybrid I’ve enjoyed…and I likely won’t ever get to drive something as spectacular as a 918 or p1…so for me, with all other factors being equal, I choose fun.

Gamecat235 > HammerheadFistpunch 09/06/2013 at 13:23

3

why not both?

HammerheadFistpunch > Gamecat235 09/06/2013 at 13:25

2

If your going hybrid, I agree it should be a diesel hybrid, but the assignment was to debate the two...so I did.

RamblinRover Luxury-Yacht > HammerheadFistpunch 09/06/2013 at 13:25

0

Might be worth citing the reason for the EPA number balance difference between hybrids and diesels: a hybrid travelling in steady state or close to (constant speed, etc.) simply has far more dead weight. While that doesn't impact drag, it impacts rolling friction and minor acceleration/deceleration. The "free" pool of energy a hybrid offers is only useful for more significant acceleration, as from stop.

If you're in a city, the usually heavier rotating mass of a diesel engine soaks a bit of your energy and the balance shifts somewhat to the hybrid.

pdthedeuce > HammerheadFistpunch 09/06/2013 at 13:26

1

I think diesel is actually less volatile than gasoline .

HammerheadFistpunch > RamblinRover Luxury-Yacht 09/06/2013 at 13:26

0

didn't want to get too technical, and I only had 250 words.

HammerheadFistpunch > pdthedeuce 09/06/2013 at 13:27

0

depends on the region, but where I live it seems to change less, but more drastically.

Joe_Limon > HammerheadFistpunch 09/06/2013 at 13:28

2

I view hybrids as a necessary evil. I'll let all those pretentious smug hybrid drivers to purchase them in droves. This will help advance battery technology and eventually help bring in a range of "reasonable" full ev vehicles with comparable range/charge cycles.As to all them rare earth materials they use, this is only sustainable for so long, eventually the necessity for conventional materials (vs ever depleting rare earth materials) in our ev vehicles will drive technology to produce truly green vehicles.

HammerheadFistpunch > Joe_Limon 09/06/2013 at 13:30

0

given the choice between the two: current hybrids/current diesels...which would you choose?

pdthedeuce > HammerheadFistpunch 09/06/2013 at 13:30

0

are you referring to price ?

HammerheadFistpunch > pdthedeuce 09/06/2013 at 13:32

0

yes, and i just now realized that the way I worded it is not clear. Diesel is definitely less chemically volatile than gasoline.

pdthedeuce > HammerheadFistpunch 09/06/2013 at 13:33

0

gotcha .

Joe_Limon > HammerheadFistpunch 09/06/2013 at 13:34

0

Currently, Plug In>Diesel>Pure EV>Hybrid

Eventually with lighter weight/higher storage batteries.

Pure EV>Plug In>Hybrid>Diesel

dinobot666 > pdthedeuce 09/06/2013 at 13:34

1

You can throw a match into a tank of diesel and it won't ignite. I'm not sure if the OP understands what volatility is.

Also, as far as the whole rare earth metals thing is concerned, that whole myth has been debunked a few thousand times already. Don't be swayed by the junk science that CNW Marketing Research conducted fool you.

pdthedeuce > Gamecat235 09/06/2013 at 13:35

1

HammerheadFistpunch > Joe_Limon 09/06/2013 at 13:35

0

interesting. Care to try and persuade me regarding plug-ins over diesels?

doodon2whls > pdthedeuce 09/06/2013 at 13:35

0

I think the key discriminator between gasoline and diesel fuels shouldn't be volatility at this point - it should be Specific Energy (MJ/kg) or Energy Density (MJ/L).

Gasoline has a slight advantage over diesel w.r.t. Specific Energy, but Diesel has a noticeable advantage over gasoline w.r.t. Energy Density.

Battery technology is JUST not there yet... Until batteries (1-2.5 MJ/L) can rival the Energy Storage Density of HC fuels (30-37 MJ/L), we will be married to that smelly gasoline/diesel pump.

Party-vi > HammerheadFistpunch 09/06/2013 at 13:37

0

Given the (usual) increase in weight of a diesel engine over it's petrol counterpart there is repackaging that is required and the existing vehicle architecture does have to change in order to install the diesel engine, or I would imagine so for a non-diesel car. Audi didn't just slap in the TDI engine for the A4 - they had to redesign several components to make it work where the previous 2.0L and 3.0L were at.

pdthedeuce > doodon2whls 09/06/2013 at 13:38

0

he was referring to price volatility . I didn't realize that .

HammerheadFistpunch > Party-vi 09/06/2013 at 13:40

0

I'm not sure that's true regarding the tdi a4, given that the VAG is notoriously fastidious about component sharing. Obviously some things have to change, but compared to hybrids? its nothing.

BugEyedBimmer - back in the Saddle Dakota Leather > HammerheadFistpunch 09/06/2013 at 13:41

0

My biggest problem is that most hybrid systems use very underutilized engines. The hybrid setup should be efficient end to end, not use the battery as a band-aid.

Sethersm > HammerheadFistpunch 09/06/2013 at 13:41

0

The basic question, as it relates to the argument of diesel VS hybrid is; what is the bases of comparison?

I know this isn't the "tearing apart" you were looking for, but "basis" with an "i".

HammerheadFistpunch > BugEyedBimmer - back in the Saddle Dakota Leather 09/06/2013 at 13:44

0

care to elaborate....I don't quite understand what you mean...you mean the gas engine is underutilized or the electric motor is? and I'm not sure how either can be more efficient end to end.

HammerheadFistpunch > Sethersm 09/06/2013 at 13:45

0

Thanks, Dyslexics like myself are notoriously bad spellers and the C&D editor has a lousy spell check...though I guess bases it technically correct too.

and 100 more > dinobot666 09/06/2013 at 13:49

0

I seem to recall (or maybe I'm making it up) that during WWII the French Foreign Legion in N. Africa had a jeep-like vehicle that used extra diesel cans situated along it's sides as an early form of ablative armor.

Of course, people (like me, back when I read the article about said vehicle) think that using fuel cans as armor is basically asking to be blown up, but apparently it was quite effective against small arms fire, as long as the fuel cans were full.

Joe_Limon > HammerheadFistpunch 09/06/2013 at 13:53

0

Well, the plug in allows me to very rarely visit a gas station (I work 4.1km from home), not having to pay $50 in gas/diesel every few weeks is a great benefit, couple this to the ever abundance of block heater outlets, it's super simple to get "free" electricity. Plus, unlike pure EV vehicles, I am not limited to small trips.

Then when it comes to driving dynamics, diesels are great city cars due to all of their low end torque allowing the driver to have fun without revving the balls out of their vehicle. EV vehicles are similar, but have an even greater emphasis on low end (zero rpm) torque, which kicks in at every red light/stop sign. Going fast isn't fun, accelerating hard gives me my kicks.

Then when it comes to comfort, diesel simply can't live up to the smoothness/quietness of an electric motor, allowing me to play music without having to turn of the volume to drown out the ever persistent engine drone (which in all honestly, sounds pretty lame in a diesel city car).

HammerheadFistpunch > Joe_Limon 09/06/2013 at 13:57

0

having never been in a plug in, but having owned a tdi for 3 years...I can honestly say that aside from not having to buy fuel...almost all of what you said applies to my tdi. its quite, has massive kick in the pants grunt, and smooth as silk. Given that I only buy fuel once a month for that car and considering the high price of admission premium over diesel...I can't say I mind paying a little extra in fuel over the long run vs right up front. Don't get me wrong, I think electric motors are killer, but I don't like the batteries and you have to admit there is a cost there.

Party-vi > HammerheadFistpunch 09/06/2013 at 14:05

0

True - no big batteries or redesigned transmissions, but for your report it's something to think about :)

Joe_Limon > HammerheadFistpunch 09/06/2013 at 14:06

0

Personally, if I were worried about the environment/money I spend enough to make eco-cars a significant part of my selection, a new car is the last thing I would be buying period. Give me an old CRX and I'll laugh my way to the bank. Manufacturing a new car, regardless of drive type is a horrendous expense to the environment.

Mattbob > doodon2whls 09/06/2013 at 14:23

0

that is true about specific energy, but an electric motor is much more efficient at extracting energy from a battery and converting it to mechanical, than an ICE is at making chemical into mechanical, so while there is still a big difference, it isnt quite as bad as the raw energy density would lead you to believe.

doodon2whls > Mattbob 09/06/2013 at 14:50

0

It is not a great story for electric drive...

Most of the electric vehicle architectures leverage IC engine-based drivetrain configurations complete with energy robbing U-joints, CV joints, drive-axles, and drive-shafts. This approach is likely driven by the auto-industry's risk aversion to developing new drivetrain configurations optimized for electric drive - not to mention their love affair with parallel-hybrid powertrains which resemble typical IC engine powertrains. Tesla is the only one to make a leap but they still use halfshafts and centrally mounted motors. Therefore, the 90%(+) electric motor efficiency is diminished through this rotating machinery. Not to mention the motor controllers which 'leak' a lot of electric energy in the form of heat energy rejection. They need to move to wheelmotor-in-hat designs and put the conversion of electric energy into kinetic energy as close as possible to the point where it is needed (the contact patch).

At any rate, the energy storage density of Li-ion batteries is more than an order of magnitude worse than HC fuels (as shown above). The reason why we (society) have been accepting of a 30% efficient IC engine design for 130 years is because we could afford to simply add a few more liters of HC fuel capacity to our vehicles to make up for it. HC fuels are relatively cheap and convenient.

Sethersm > HammerheadFistpunch 09/06/2013 at 14:51

0

Bases would work if you change "is" to "are".

HammerheadFistpunch > Sethersm 09/06/2013 at 14:52

0

already changed it to basis on C&D, too lazy here.

doodon2whls > HammerheadFistpunch 09/06/2013 at 15:00

0

I think what he might be saying is that the IC engines are operated outside of their efficient operating speed (away from min BSFC). This is due to the dominance of parallel hybrid configurations in hybrid vehicles to this point where engine speed is matched to vehicle speed through a transmission and assisted with electric motors.

In a series-parallel hybrid arrangement, the IC engine could be run at min/best BSFC regardless of vehicle speed because the electric motor drives the wheels all the time. The IC engine is de-coupled from the drive wheels completely. It can be run at min BSFC (fixed RPM) when the battery requires charging or the power bus needs extra juice. The IC engine works solely as a generator in this configuration.

HammerheadFistpunch > doodon2whls 09/06/2013 at 15:01

0

BMEP? Also, this makes sense.

doodon2whls > HammerheadFistpunch 09/06/2013 at 15:09

0

Brake Mean Effective Pressure - A means of comparing the amount of work an engine can do regardless of displacement.

I need to correct my statement. It needs to read minimum BSFC.

min BSFC implies that the engine is producing the maximum power for the least amount of fuel consumed. BSFC = Fuel consumed / Power Produced for a given RPM.

HammerheadFistpunch > doodon2whls 09/06/2013 at 15:13

0

so a fancy way of saying torque peak?

doodon2whls > HammerheadFistpunch 09/06/2013 at 15:22

0

This wikipedia sourced image shows the relationship between RPM, BMEP and BSFC.

X axis is RPM, y axis is BMEP (proportional to torque output). The isobars (or islands) in blue represent regions within which the indicated BSFC is achieved.

If you operate an IC engine at low torque output (part throttle) and low RPM, the BSFC is poor (300-400 range).

In this case, the min BSFC is 206 and to achieve that min BSFC, you need to operate the engine at ~2200 rpm and ~15.3 BMEP. That is the rpm/torque output at which the engine is most efficient. High efficiency generators are tuned to run @ min BSFC to reduce fuel consumption and therefore lengthen resupply intervals.

doodon2whls > HammerheadFistpunch 09/06/2013 at 15:23

0

Uh, yeah.. I suppose so.. ;-)

HammerheadFistpunch > doodon2whls 09/06/2013 at 15:25

0

fascinating, thanks! It reminds me of turbo envelope maps.

doodon2whls > HammerheadFistpunch 09/06/2013 at 15:38

0

Yep. A similar graphical method is used to describe Turbomachinery compressor efficiency.

HammerheadFistpunch > doodon2whls 09/06/2013 at 15:40

0

exactly. Good ol science!

Mattbob > doodon2whls 09/06/2013 at 16:00

1

Oh, I totally agree with you, I was just pointing out that those numbers can be a bit misleading. The loss in drive controllers however, if they are good controllers is extremely small. If you optimize the switching times, there are very little losses due to the P-N junction voltage drop inside of the FETs.

BugEyedBimmer - back in the Saddle Dakota Leather > HammerheadFistpunch 09/06/2013 at 17:03

0

I mean that a lot of battery engines are not DI or high compression. Both of these are things being used in even the lowest of "MPG" engines for max efficiency. Instead, they're subpar engines, designed in the early-to-mid 2000s and recycled, just sandwiched with a battery.

HammerheadFistpunch > BugEyedBimmer - back in the Saddle Dakota Leather 09/06/2013 at 17:14

0

Most hybrids run Atkinson cycle and not Otto cycle so high power density isn't the goal, and high compression or direct injection are of little value.

Group B-raaaaaaaaaap! > HammerheadFistpunch 09/07/2013 at 13:28

1

I agree with your assertion that with the exception of the supercar hybrids (918, TheFerrari, P1), the basic concept behind and execution of your typical commuter-grade hybrid precludes it from any driving fulfillment.

As for the arguments of efficiency and economy, once again I feel that diesel lends more by way of availability, reduced dependency on rare-earth minerals for exotic battery systems, and it's natrual progression towards future alternative fuel innovation (biomass, anyone?) Despite there being no such thing as "Free Energy", most hybrids are promoted on the flawed concept of efficiency. Sure, the cars themselves reduce greenhouse gas emissions, but what of the powerplants which are generating the tremendous amount of electricity which power the BEVs and Plug-In Hybrids? Sure, you could potentially source wind, hydroelectric, or even solar power, but not yet on a scale which would be requisite to offset the emissions created by the coal-fired power plants which provide vast swaths of America's energy. I think hybrids were a great catalyst to addressing the developed and developing worlds' rampant thirst for petrol and a neat idea, but to me, the concept doesn't pan out longitudinally. As I had mentioned earlier, larger adoption diesel technology creates both the market and infrastructure for the development of future alternative fuels. There may never be "Free Energy", but at least we could burn things that are waste products already, and which will put a lower volume of greenhouse gasses into the atmosphere.

Two final thoughts about Hybrids, and why I don't see them playing a large role in the future of sustainable energy consumption. The first goes back to the hybrid's dependency on exotic battery systems. Not only are the rare earth metals and the process to mine them incredibly damaging to their environment, they also require copious volumes of processing and transportation, both of which work towards nullifying the goal of reduced overall emissions of hybrid cars. Furthermore, in the future the hybrid cars could create a large stockpile of dead, unusable batteries. Sure, parts of these massive packs could be recycled, but not most of the core. This will generate yet more e-waste. And America already has a big e-waste problem as it is. Except that instead of addressing it, we ship it to West Africa to let them deal with it. This is a pretty big story in and of itself , so I wont go into details here, but check out this video for a more in depth look. Yes, the argument can actually be made that the precious hybrids could literally kill African children.

And the second concern about hybrid cars. Perhaps the biggest hurdle which could ultimately deep-six the entire hybrid experiment are the drivers themselves. Care to guess what is the best way to kill a movement? Being a dick about it.

BJohnson11 > HammerheadFistpunch 09/07/2013 at 14:31

0

Now what needs to be more of a thing is diesel hybrids (I believe there is going to be a diesel-hybrid Chevy Cruze variant?). I'm a huge proponent of diesel engines, and I think they have a huge upside and there is a lot of room for innovation in the diesel engine world, but I also see hybrids as necessary for the further development of batteries and EV technology. In the mean time though, to cure range issues, running an electric powertrain with a diesel generator (what the Fisker Karma w anted to do) seems like a pretty bitchin alternative.

TheBloody, Oppositelock lives on in our shitposts. > Group B-raaaaaaaaaap! 09/08/2013 at 07:49

0

That video is probably the only time in my life I've actually seriously contemplated actively searching out a random stranger on the internet with the sole purpose of physically assaulting them.