To Darell-80 mpg diesel hybrid-real or not?

rodfran

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I read an article the other day about the car companies making 80mpg diesel hybrids as prototypes in the late 90's, but supposedly abandoning the idea because of costs involved. Do these prototypes really exist or is this pure fantasy?Anybody have any pictures or articles on this subject? Thanks!
 

gadget_lover

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Re: To Darryl-80 mpg diesel hybrid-real or not?

I heard that the German manufacturers were making those.

As always, the devil is in the details. You can pair ANY power source in an electric hybrid design, but you have to take into account the strengths and weaknesses of each part.

Example; Toyota Prius (which I know well) uses a gas engine (an ICE) that is designed to be very efficient and clean at the cost of almost no low end torque. It also uses an electric motor that provides gobs of torque from 0 RPM and up. The battery pack will only store enough energy to run the car for a few miles by itself. They created a CVT (Continuously varaible transmission) that allows the power to be provided by the electric, the ICE or both. The result is a package that has lots of torque at any speed that can run the ICE at higher than normal RPM regardless of the speed of the tire rotation. The ICE runs only when it's needed to provide power.

Now bring this back to the Diesel hybrid. The diesel already has lots of torque. It's weakness (in the past) is that it's noisey and creates a lot of particulates. The high sulfer in fuel oil makes it a pretty bad polluter. The addition of a turbo, direct fuel injection and a particulate trap largely solves those problems. But at that point what does the hybrid add? Mainly the ability to stop the engine at traffic signals without having to wait for the engine to start up when the light turns green. I've heard that using a heavy duty starter aleady does that. There is a volkswagin in Europe (golf TDI??) that has most of these attributes, but not the hybrid parts.

There was a small (real small) desiel car that was shown in europe last year. It got 100mpg on open roads. It's 0-60 MPH time was around a minute and it had no storage and was cramped and noisy. It did not have a particulate trap. It's milage in stop and go was no where near it's freeway milage.

Most fuel cell designs are actually hybrids. The current fuel cells do not provide enough energy to accelerate briskly, so power generated when at a stop or coasting is stored for use when needed.

We could make a 80 MPG hybrid using the Toyota design, but you end up with a car that's slower to accellerate and smaller. Mine gets an honest 45 to 55 MPG depending on the driving conditions. It makes no compromises in drivability or comfort. It handles mountain ranges and wide open roads with the same ease as stop and go commuter traffic.

The Honda hybrid uses an electric motor like a supercharger, allowing lower output engines than would otherwise be practical.

Just my opinion, but the best hybrids uses power sources that are not perfect and combine their strengths. I wonder if a steam/electric hybrid would work. Or a sterling / electric. Or a turbine/electric. At some point it becomes an electric car with portable generator, but that might work with better and better battery management.

Daniel
 

Darell

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Re: To Darryl-80 mpg diesel hybrid-real or not?

Hey rodfan -

I have nothing specific on automotive diesel/electric hybrids, but as Daniel points out - there is NO reason to think that it isn't possible. Diesel has been a sticky wicket for a while because of the bad rap in the past as far as particulate pollution. And since CA is the world's biggest car market... and isn't allowed to sell diesel passenger cars for another couple of years... it probably makes no economic sense to market something like that yet. When "clean" diesel becomes widely available, I can easily envision some of the big players (VW!) coming up with a diesel hybrid. It makes sense in many ways, though there are some considerable obstacles (keeping the diesel ICE hot enough to instantly fire, keeping the weight down, etc).

One of the best applications for diesel/hybrid is in locomotives. Switching engines most specifically. Instead of a 2500HP diesel running at idle for the better part of the day, they can use a 100HP generator running at full capacity all day to charge batteries - and use the batteries when great torque is needed.

There, I don't think that'll scare Turbodog all that much.
 

jtr1962

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Re: To Darryl-80 mpg diesel hybrid-real or not?

The best design is one where the engine (when it's running) runs at one speed (the speed at which it gets the best efficiency). Connecting the engine to the wheels directly was never a good idea. Doing so in the Prius was a bad idea even with the high-tech transmission. From day one when cars were first built we should have had the engine running a generator which in turn powered electric motors, as is done with diesel locomotives. This would have done away with cumbersome multispeed mechanical transmissions and resulted in better acceleration for a given engine power. When you have a 200 HP engine accelerating a car through a regular transmission, on average about 60% of the power actually ends up being used for acceleration. The reasons are several. First, because the RPM varies, the engine spends a good deal of time out of its peak power RPM. Second, energy is spent speeding up the engine with each gear change. Third, the gear changes cost time. If you do it the other way, when you floor it the engine goes right to its peak power RPM, the generator puts out full power, and the electric motors convert most of that power into acceleration. The same car might only require 120 HP instead of 200 HP for the same performance. By storing energy, you lower the peak power requirements even more. Ideally, you only need an engine which supplies the average power used by the vehicle. This might be less than 25 HP for most driving. In fact, in a properly designed car, 25 HP should be good to maintain a speed of 125 mph, more than adequate for any sensible driving. Energy storage will take care of the power bursts for acceleration. In regular driving the 25 HP engine might be running less than half the time.

Using only electric motors to drive the car has many advantages. Regenerative braking for one. The ability to electronically control speed to a very high precision for another. And the ability to control torque for different driving conditions if you use a motor on each wheel. All cars should, regardless of power source, be designed with 4-wheel electric motor drive, energy storage for acceleration, regenerative braking, and solar cells to supplement the power plant (these can generate a good portion of the vehicle's energy needs when it is parked). Ideally, in light use, the solar cells can supply 100% of the power, making recharging and refueling unnecessary. Powering the vehicle directly off the power grid via inductive pickup from high-frequency AC power cables embedded in the roadway is another possibility. This gives all the advantages of a straight electric without the range or recharging problems.

As for the technical limits on fuel economy, I've heard that 100 mpg @ 100 mph is very feasible. 200 mpg might represent an upper limit for a 4-passenger driveable vehicle. I'd like to see fossil fuels done away with in the near future, but in the mean time we can do a lot better than most people think.
 

Eugene

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I always understood the same. Modern engines are a tradeoff between maximizing efficiency and having a wide range of rpm's. Trains use a big engine to run a generator which then turns the motors that run the wheels. I would love to have the chance to put this design into practice, put a small engine under the hood that runs at one rpm connected to a generator, a few batteries and electric at the wheels. I always wanted to buy one of those fiberglass Jeep bodies from the jc whitney catalogs to build it on. Put 4 small motors in the wheels for a super efficient 4x4 that would have true 4x4 (run all 4 wheel motors at the same time) and not loss due to the transmission, transfer case, drive shafts, etc.
 

Frangible

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Re: To Darryl-80 mpg diesel hybrid-real or not?

[ QUOTE ]
I'd like to see fossil fuels done away with in the near future

[/ QUOTE ]

Not possible unless we can come up with new power generation technologies, unfortunately. It'll happen in the future, but probably the far future I think.
 

jtr1962

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Re: To Darryl-80 mpg diesel hybrid-real or not?

[ QUOTE ]
Frangible said:
Not possible unless we can come up with new power generation technologies, unfortunately. It'll happen in the future, but probably the far future I think.

[/ QUOTE ]
How about running cars off the grid as I suggested and generating all the power via solar, hydroelectric, wind, and nuclear? And once fusion is commercially viable (within a decade if we threw enough R&D at it), we can kiss fossil fuels good-bye. The stink alone is enough reason to accelerate fusion research even without the geopolitical problems.
 

gadget_lover

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There are a few problems with the concept of a constant speed engine driving a generator. This is known, by the way, as a series hybrid. Besides the losses involved in generating and storing the electricty, there is the tricky part of trying to determine what is big enough to handle the worst case scenario while still remaining more efficient than a conventional car.

The Prius (as an example) has a continuously variable transmission (CVT) that allows the engine, when it's running, to run at it's most effcicient RPM. When more power is needed (such as climbing long and steep hills) it will rev even higher at the cost of efficiency. Don't forget, fuel effeciency and peak power are NOT usually at the same RPM.

The Prius gas engine is NOT directly connected to the wheels. The CVT means that there are no gear changes. Did you know that the 2002 Prius uses a 79 peak horsepower engine? The system is also designed so that it can use (for instance) 50 HP to drive the wheels while using another 20 hp to drive a generator to charge the battery. Or it can use all 79 to drive the wheels and add the full power of the electric motor. This is what happens when you merge onto a freeway on an uphill stretch in the mountains.

The series hybrid will need an engine big enough that it can supply the power directly when the battery is exhausted. Imagine driving to Lake Tahoe. You climb 7,000 feet over the course of a few hours. The series hybrid will need a big battery pack or a large engine. Of course, it could also just crap aout and require that you park for an hour to build up reserves again. That's actually a viable option. The Honda Insight does that when the battery is exhausted. The Prius is sized (and designed) such that the battery never runs down, even when driving through mountain ranges or at high speed.

The Locomotives use huge diesel engines running huge generators that run huge electric motors. Last I heard, they have no storage. They use the motors as a sort of transmission, converting the huge horsepower of the diesel to the huge low speed torque of the electic motors.

I read that a standard car like a Ford Taurus requires about 150 HP to maintain 125 mph, but only 40 at 55mph. I've not done the math, but it sounds about right. As jtr said, the biggest peak power requirement is accelleration from a stop.

Just as a point of interest, the Prius is most efficeint at 40 MPH. It consistantly gets 65 - 75 mpg at that speed due to reduced aerodynamic drag and optimum conditions for it's engine. The milage fluctuations are due to slight inclines that are hard to notice.

Daniel
 

Frangible

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Re: To Darryl-80 mpg diesel hybrid-real or not?

[ QUOTE ]

How about running cars off the grid as I suggested

[/ QUOTE ]

In order to do that you'd need one of two things:

-- better batteries than today's technology
-- hydrogen fuel cells

The problem with the latter is you can't mine hydrogen, you have to split it from water, probably seawater. Doing this on a massive scale would lead to a lot of nasty byproducts (all the other stuff in the seawater, increased salinization around the processing plants detrimental to local marine life, etc).

As I'm sure you know the hydrogen process is one of net energy loss. It's more of a battery than anything else.

Making a closed system in cars where external power was applied to generate hydrogen from the water byproduct would be a lot cleaner, but probably not economical or space effecient.

[ QUOTE ]
and generating all the power via solar, hydroelectric, wind, and nuclear?

[/ QUOTE ]

The bulk of our power today comes from coal, for good reason. People are deathly afraid of nuclear power, they will go hide in the corner if you even say the word. It will never fly. Hydro, geothermal are all tapped out. Wind is coming down a lot in price but it's a very sporadic energy source that consumes a ton of sq miles to equal one coal/nuke plant. The problems are even worse for solar, which sees less energy generation time than wind, and at a higher cost. I believe good progress will continue to be made with solar and wind but neither are quite "there" yet.

[ QUOTE ]
And once fusion is commercially viable (within a decade if we threw enough R&D at it), we can kiss fossil fuels good-bye. The stink alone is enough reason to accelerate fusion research even without the geopolitical problems.

[/ QUOTE ]

I do not believe fusion is so close. Despite the promises of "perfectly clean energy too cheap to meter", the fact is fusion research has been going on since the 1960s and there have been no major breakthroughs lately. Of the competing possible designs for fusion power, all produce some nuclear waste and all are costly and not effecient. Especially those that use deuterium and/or tritium. All current research in fusion centers around exotic H2/H3 fuel, the irony being tritium is only made in nuclear fission reactors from the transmutation of lithium. (there also isn't a whole lot of lithium out there to begin with... seawater for deuterium, yes... lithium, no)

I am not saying that fusion power won't happen eventually... but we've got a lot more work to do with it.

I think another avenue that also has to be pursued is conservation... which isn't too popular in these days of city skyglows and V8 hemis.
 

cobb

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I had a 1979 diesel vw dasher that seated 4, had a batch back, 4 doors, and got 49mpg.

I too have heard those rumors that VW and other American companies have diesel cars, 3 wheel cars, etc that get unbelievable mpg and they are production cars that do not meet the US standards.

I too have heard the prototype cars that get 1000 mpg and what not, but know they are way out there.
 

jtr1962

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Re: To Darryl-80 mpg diesel hybrid-real or not?

[ QUOTE ]
Frangible said:
[ QUOTE ]

How about running cars off the grid as I suggested

[/ QUOTE ]

In order to do that you'd need one of two things:

-- better batteries than today's technology
-- hydrogen fuel cells


[/ QUOTE ]
No, you misunderstood me. I'm talking about cars picking up their power directly from the road in much the same way that an electric train gets its power from the third rail or the catenery. Instead of using dangerous, exposed high voltages we would bury a high frequency AC cable in the road, and an inductive pickup would be able to tap power from the cable. The cars would only need enough energy storage to carry them over a few miles of back roads where installing cables wouldn't be cost effective, and also to take the car over any "dead spots". No good reason cars need to generate their own power, whether through engines, fuel cells, or whatnot, unless they're going off road. Consider that even if you generate 100% of grid power with fossil fuels, which you don't, large power plants convert 50% or more of the fuel's energy into power versus 20% for typical car engines. Even with transmission losses of 25% you're way ahead. Furthermore, because the emissions are in one place rather than distributed, they are easier to control. Indeed, many modern fossil fuel plants emit very little except CO2, and some are even planning to capture that as well. Cars powered directly off the grid wouldn't suffer the noise problems that current vehicles do, nor would they carry dangerous, explosive fuels like gasoline or hydrogen. Lots of good reasons why we should switch over to this method. It really wouldn't even cost that much either once you discount the costs of pollution. I'm surprised I'm the only one here who thought of it.
 

gadget_lover

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[ QUOTE ]
cobb said:
I had a 1979 diesel vw dasher that seated 4, had a batch back, 4 doors, and got 49mpg.

I too have heard those rumors that VW and other American companies have diesel cars, 3 wheel cars, etc that get unbelievable mpg and they are production cars that do not meet the US standards.

I too have heard the prototype cars that get 1000 mpg and what not, but know they are way out there.

[/ QUOTE ]

Think you meant prototype "vehicles", not cars. A car has connotations of multiple passengers, freeway speeds and cargo capacity. The 1000 mpg vehicles have been essentailly fairings wrapped around reclining people with miniscule motors.

The 1979 diesel vw dasher was a great little car, but suffered from the problems of all diesels of the time. Noisier than gas, smellier than gas and more poluting than gas.

My buddy got great milage in her VW diesel (about the same time) but she almost always drove on the freeway. We commuted 30 miles a day each way, often at night. About the same time I was driving a Dodge Colt that got 40mpg on the freeway at 55 MPH. It sat 4 adults, if they were trim, supple and good friends. It held 3 grocery bags in it's cargo area. A great little car.

Some of the cars that don't meet american standards get great milage because they are superlight, having shed safety devices and such. They don't meet minimum safety standards. No crumple zones, air bags, reinforced doors, 5 mph bumpers, etc.

I think what's amazing about the hybrid is it's ability to get great milage when driving around town as well as when on the freeway. The energy required to climb hills is recaptured on the down hill side, so hills don't relly effect the milage much.

Daniel
 

Frangible

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[ QUOTE ]
Even with transmission losses of 25% you're way ahead.

[/ QUOTE ]

Problem is, as I understand it, inductive power means you'd have to radiate a *lot* of power to all the roads simultaneously. Especially the kW needed to run a car. I don't see how you could be specific with the power radiation, unless I'm missing something here.
 

jtr1962

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[ QUOTE ]
gadget_lover said:
The Locomotives use huge diesel engines running huge generators that run huge electric motors. Last I heard, they have no storage.


[/ QUOTE ]
It wouldn't make sense for trains to store energy. Cars accelerate to cruising speed in maybe 10 to 20 seconds, and are much lighter than trains. It's easy to store the kinetic energy in a very small package. Trains, especially freight trains, can take many minutes to come up to speed. It would be impossible to store the kinetic energy of a 70 mph freight train without dragging along hundreds of tons of batteries, and it would make no sense anyay. If you tried to use the stored power to supplement the diesel engine, wheelslip would prevent you from using it for a good portion of the speed range anyway. As it is, wheelslip is an issue which limits power to the rail for most diesel locomotives at speeds much under 20 mph. You could make the locomotive heavier to transmit more power, but then you need to add axles to distribute the weight, and you'll burn more fuel dragging the extra weight along. When it's all said and done, there is little to be gained storing energy but there are other ways to make use of the train's kinetic energy. Busy mass transit systems can capture the train's kinetic energy when braking and either dissipate it in a resistor grid, or if other trains in the system need power feed it back into the grid through the third rail or pantograph. This actually works well if one train is stopping while others are accelerating.

[ QUOTE ]

Just as a point of interest, the Prius is most efficeint at 40 MPH. It consistantly gets 65 - 75 mpg at that speed due to reduced aerodynamic drag and optimum conditions for it's engine.

[/ QUOTE ]
I've heard that 40 to 45 mph is the optimum efficiency speed for the majority of cars out there, not just the Prius. Under a certain speed, the engine is close to idle and doesn't burn much less fuel than running at the very low power needed to maintain 40 mph or so. Of course, as speeds increase, the power needed to maintain them increases dramatically, mostly due to air drag. That's the reason 40 mph or thereabouts is optimal. If we ever went to cars with batteries or fuel cells, then there is no energy use when idling, so the most efficient speed would be far slower, perhaps around 5 mph. Below that, the bearings tighten up a bit because the grease isn't flowing freely. Above that, and you have greater losses from tire and aero drag.
 

jtr1962

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[ QUOTE ]
Frangible said:
Problem is, as I understand it, inductive power means you'd have to radiate a *lot* of power to all the roads simultaneously. Especially the kW needed to run a car. I don't see how you could be specific with the power radiation, unless I'm missing something here.

[/ QUOTE ]
I never looked into the physics of it. I mentioned it because I heard that this method of power transmission is what is proposed for maglevs because a third rail or catenery wouldn't work at maglev speeds. There weren't any problems mentioned with high transmission losses. I believe the principle here is that the cable acts as an antenna with very high impedance unless there is a car picking up electricity. The inductive pickup running close (i.e. a foot or less) above the cable decreases the impedence of the "antenna" and the resulting power is mostly transmitted to the load. When there is no load, there are few losses. Remember that the power grid is essentially high-voltage, lower frequency AC. The main losses are I²R, not radiative. Higher frequency is needed for my proposed car system to keep the components to a reasonable size. You could probably get "free" power now if you lived under a high tension power line but the "pickup" would be the size of a house due to the low (60 Hz) frequency. As I said, I'm not completely familiar with the physics, but that's the gest (spelling?) of it.
 

Minjin

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How about we take all the research effort and money used in developing the stuff talked about above and just put it into making teleporters like on Star Trek and The Fly? /ubbthreads/images/graemlins/wink.gif

Mark
 

gadget_lover

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That type of power transmission is usually not used due to low efficiency. In the case of the maglev they have ruled out the more efficient methods (third rail and catenery).

That's why no one else mentioned it. /ubbthreads/images/graemlins/smile.gif

Daniel
 

Minjin

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Alright, Darryl ( /ubbthreads/images/graemlins/wink.gif ), I'm curious. What are some good sites where people (maybe a forum) talk about building electric cars? Haven't had much luck googling a good one yet.

Mark
 
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