DU Geeks: Let's hypothetically design the most efficient car

[Taverner]

Let's not bog ourselves down and get all Larry Niven, but just throw out ideas.

For example how about a car that uses:

- the heat generated from the engine and friction to make steam for overdrive
- solar panels on the roof (just like the new Prius)
- a self driving car that automatically locks on to the speed limit, and drives in the most efficient way

Any other ideas?

[Inchworm]

1. I always wondered

If there would be a way to harness the forward motion somehow. You know, kind of like gravity + tapered hoses can make water come out with high enough pressure to strip mine.

A big air scoop? :shrug:

Who knows. I've always wondered though.

:hi:

[Taverner]

2. Well the Prius always charges the battery, even when accelerating

Does that count?

[flvegan]

3. Yeah, but a BMW M3 is more efficient than a Prius.

Thus sayeth Top Gear.

[kentauros]

6. Only, it isn't.

http://www.treehugger.com/files/2008/07/top-gear-prius-hybrid-bmw-m3-video-wrong.php

:P

[flvegan]

7. Meh, they're just angry

that the Prius got exposed as a gas hog compared to the brilliant BMW M3. 420 horsepower, 0-60 in 4.5 seconds, gas sipper.

:P

[Pierre.Suave]

12. You know

I saw that episode of top gear and while I laughed at the result, I dont think it can be taken as true, real world, evidence.

I have first hand experience with the M3 and it is by no means a gas sipper...

[flvegan]

14. Ah, but as Clarkson pointed out

it's how you drive the car. I saw a guy in a Prius the other day, and I swear he thought he was Michael Schumacher. Completely insane. He would get less mpg than a fellow driving an M3 responsibly. However, yes, the Prius and BMW being both driven comparatively in proportion to their ability, the Prius is much better, boring as it may be.

[Pierre.Suave]

16. I agree

it IS in the way the car is driven.

I saw a Prius driver just a few days ago go speeding by me on the snow covered road and then slide right on through the intersection, luckily for him he was not hit but it sure was awfully close.

I think the prius may be boring, but they are kind of neat anyway.

[kentauros]

19. uh huh

Let's put the M3 at the other end of the spectrum for driving conditions in comparison to the Prius: true gridlock stop-and-go traffic. They could do another London Race, only to see who uses the least amount of fuel to get across London at peak traffic hours.

:P

[flvegan]

23. The M3 would still win.

I'd have it trucked across on a lorry. The M3 would use nary a bit of gas to get onto and off of the truck. It's mpg would be epic.

[kentauros]

29. Until the lorry gets pulled over for too much pollution and not paying the smog fee

:P

[Pierre.Suave]

39. rofl

good thinking.

[Inchworm]

5. Yup!

Same concept. That just seemed silly all along that this wasn't done.

:)

[kentauros]

4. First off, you can generate steam mechanically:

Karl SCHAEFFER - Steam Generator
James L. GRIGGS - Hydrosonic Pump

Add ammonia to improve efficiency:
Alexander KALINA - Steam Cycle


If you want to recapture the waste heat from an ICE (internal combustion engine) use Sterling engines.

Of course, if you're not using an ICE, then go electric with low-unspring weight wheel motors, like the latest from Michelin. That lowers weight considerably, allowing for more room for batteries, flywheel-power, gas turbine or even a deisel-electric-generator power source. If you go with the deisel, you can then do the waste-heat-recovery with the sterling engines and generate that much more power :)

Fully "automated" cars are a dream I hope to see in my lifetime. It would eliminate so many road hazards... :D

[Schema Thing]

8. I think wheel motors are the future

from scooters to motorcycles to cars to trucks to 18 wheelers to big earth moving equipment...

that and better energy storage: batteries, super capacitors, flywheels(?).


and infrastructure that provides quick (like a fill-up) repower. It's really not hard to imagine pulling into a station after driving 250 miles and sliding out your used batteries to be quickly replaced by sliding in a fully charged set.


I love thinking about the most efficient way to use ICE (probably just as a generator), but I wonder if that whole concept may just be leapfrogged over... and go straight to all electric with kickass storage/charging capacities?

[kentauros]

10. I agree on replacing the ICE entirely, and on the use of wheel-motors.

The big advantage of generating electricity at a central source is that you can better control the pollution problems, at least for those systems that burn something just to boil water (nuclear is just an expensive way to boil water.)

I know supercapacitors exist, but I really need to learn more about them. Aren't there ultracapacitors and ultraconductors, too? Do you have some links on supercapacitors? :)

[JCMach1]

9. Braking recharge... this tech has been available for years...

Every time you hit the brakes you recharge your batteries.

Also, why not dual wind turbines on the side that spin as you drive to make energy... Hell, you could also tune the frequency to scare animals out of your path! How green is that?

[Orsino]

11. You can't make the Most Efficient Car in isolation, I'd say.

Petroleum distillates are great "free" energy for as long as the supply lasts, but I'd say that we'd have to consider sustainable sources that aren't planet-killers. Solar, wind and geothermal ought to be tapped to power vehicles, and this probably means electric-only capability.

[Pierre.Suave]

13. I think the most efficient car we could make now

would have to be a true Diesel/Electric. not a hybrid, but a true, honest to goodness Diesel/Electric drivetrain where the diesel acts as simply an electric generator and can therefore be ran at its most efficient all the time/would not need to run all the time if we made it capable of running on pure electric as well.

then, add in all the other technologies such as solar, lightweight materials, etc...

and we might be onto something.

[Taverner]

17. I agree - we have to eliminate the ICE

At least in terms of powering the drive train

[pokerfan]

30. The original hybrid

[Pierre.Suave]

38. Exactly

trains are super efficient

[flvegan]

15. Put wheels on a sailboat.

With a small 50cc engine for windless days.

Watch out for low bridges!

[Fire Walk With Me]

18. Sure.

Ask Larry Niven.

[mainegreen]

20. No safety features. Just a chair in a thin foil shell.

Much more efficient.

You drive it first!

:7

[kentauros]

21. Another use for Sterling engines:

Since roadways made from either concrete or asphalt are huge heat sinks, lets use that heat-island energy to make electricity. You could then run the power generated to roadside generation stations to "fill-up" your batteries.

It could probably only be used as a supplement. I don't know what the generating capacity of such a system would be...

[Taverner]

22. Wow - hadn't thought of that

It's one big black heat sink though...that's for sure

[kentauros]

28. Of course, it would only work in the summer or places with lots of daylight

unless Sterling (or is that Stirling) engines could work with differences in temps in cold climates.

So, I guess this is one form of "alternative supplement" that you agree with? :P

[Taverner]

31. LOL

[LaydeeBug]

24. as a non conformist, I am not altogether sure "self driving" is the way to go...

sometimes I will take a less travelled route in order to avoid traffic.

[Taverner]

34. But that's the beauty of self driving cars

A central database routes and re routes all the cars to different highways to reduce load. So in the bayarea, if 101 is packed, the database will automatically reassign your car to 280.

[krispos42]

25. The biggest thing to get rid of is weight

Not so much good for highway fuel economy but critical for city (stop-and-go) economy.

Replacing steel with, say, titanium or carbon-fiber would dramatically cut weight while maintaining structural strength and rigidity. If we evern find a way to mass-produce carbon-fiber, cheap, it would be both a boon to the auto industry AND part of a carbon-capture plan.

If the internal-combustion engine is to be retained, we need the highest compression ratio possible to maximize energy gained from each gallon of fuel. Ideally an ethanal engine; the high natural octane of ethanl would allow it to have the high compressio and burn cleanly. We already have very good direct-injection fuel systems that do an excellent job of quickly spraying a fine mist of precisely-metered fuel into the engine, so there probably isn't much improvement that could be made on that score.

We could replace the mechanically-actuated intake and exhaust valves and replace them with solenoid-driven ones. This would meant that engine timing would be easily and infinately variable with less mechanical drag on the engine, and the valves would open and close faster. I believe that Formula 1 cars already do this.

Solenoid-actuated valves would also allow the car to cut cylinders out as needed to save fuel, Simply turn off the spark and fuel for an unwanted cylinder bank and leave the valves closed. The air locked in the unused cylinders would act as an air spring.

Utilizing waste heat to drive a steam turbine would also result in significant fuel savings on highway drives. A heat exchanger around the exhaust manifold can capture the heat otherwise lost in combustion and generate steam to power a turbine that helps drive the engine's crankshaft. Volkswagon is experimenting with this and got a 30% fuel savings in highway MPG. They call it the "TurboSteamer"; it's in my Journal if you want to look at it. Towards the bottom.


If the ethanol is made from otherwise-wasted biomass and distilled via wind-turbine-powered heating coils, the fuel would be very earth-friendly.




If we go with all-electric cars, then the power sources would best be an ultra-capacitor. An ultra-capacitor can be quickly charged and discharged; none of this having to wait overnight to get a full charge. Ultracaps hold their charges via physical, not chemical, means, so there are no chemicical reactions to wait on. A 10-minute recharge time is possible if the charging station has enough amperage behind it and the ultracaps have a sufficient cooling system.

It doesn't have the energy density of a regular battery so you might have to recharge every 100 miles or so, but I think for most people that would not be much of an issue, especially if it only cost you $2 to get your car charged up.

How the electricity is generated is an issue; however the cars could be part of the electric grid. Parked at home and plugged in, they could pump power into the grid during high demand, then suck it back out later on when the rates are cheaper and supplies are up. This would be especially useful if your house had a small wind turbine or rooftop solar array.

Supposedly the Danes are working on this as a serious national policy.

If the car was covered with solar cells, it could also trickle-charge itself from daylight.

[LaydeeBug]

26. krispos, that was very informative. Is there a way to use solar power for

actual fuel? I know the prius 2010 should have solar panels in their premium package, but doesn't that go to things like the heat or ac?

And, when are you starting your own car company?

[krispos42]

27. Thank you

We can't use solar power directly; there's not enough power being transmitted per square yard. IIRC the Sun puts about 1,400 watts per square yard of earth. Our best solar cells can convert about 40% of that into electricity, so you're getting less than 600 watts. A horsepower is 746 watts, so you're basically getting the power output of a weedwhacker for a square yard of solar cells.

Now, it's free power, which is nice and pays in the long term, but covering the roof of a Prius with solar cells would make enough power to run only a couple of accessories. Stereo, HVAC blower, instrumentation, etc. Now, obviously, if you left the Prius outside it would add charge to the batteries, saving you from burning gas later on. And it would ease the electrical load on the engine-powered generator. But it's not enough to run big things continuously.



And starting my own car company? Ha! :-)

[Taverner]

33. Thing is there is energy all around us

Tesla, if anything, made this abundantly clear

And not using as much as we can is killing us

[Taverner]

32. "...boon to the auto industry AND part of a carbon-capture plan"

AND not to mention a safer car

[krispos42]

35. The mass-production of carbon nanotubes...

...I think would enable us to replace huge quanties of steel with carbon nanotube composites. It is also possible that we could weave cloth from carbon nanotube fibers, generating clothing that is much stronger than conventional fabrics.


The only problem is that carbon nanotube fibers might be a cancer risk on the same order asbestos, if inhaled. The long, thin strings can penetrate cell walls.

But in a solid form, like fiberglass, it should be okay.

[Taverner]

36. My thing is what kills most people in a car crash is the mass

the mass of the impact can throw you out of your seatbelt and through the window

If the car only weighs 100 lbs, different story

[krispos42]

37. It's the sudden stop...

:-)

[kentauros]

41. However,

if it only weighs 100 pounds, a good wind will blow you off the road. Hell, getting passed by a standard tractor-trailer rig would blow you off the road!

Either we have to have relatively heavy cars, or not only must they be "self-driving" but linked together so that wind is either no longer an issue, or not as bad.

Of course, the truly best option is more trains with non-personal cars for public use at all stops, kind of like public-use bicycles, which we should also implement. It may require the de-commissioning of roads to bicycle-only traffic, like one lane at a time until there's more bike traffic. Then do the same for the remaining lanes as needed.

I don't see this happening for a long while, though. I remember years back reading in the NYT about how the big car-makers are totally against self-driving vehicles because, get this, "it would take the fun out of driving." Methinks none of these upper-level people ever have to drive in stop'n'go traffic

[Taverner]

47. Well I would hate that universe

Self driving cars are the great comprimise, that way people like me who like control can use them, but we get a nice logical machine driving, not crazy ol' me.

I hate the idea of taking trains everywhere - it was one of the things that bothered me about Europe. You have to schedule around them, not the other way around.

[Rabrrrrrr]

40. Simply make the thermodynamic system of the car the entire universe. Then there's no loss of energy.

It's you small-box thinkers that are fucking up the system.

[kentauros]

42. Don't you need a piece of fairy cake to make that?

Just beware of the lynchmob from the scientists that have worked their whole careers trying to invent it when all you do is reverse-engineer it out of a piece of fairy cake :P



(paraphrasing from memory the invention of the Infinite Improbability Drive.)

[Rabrrrrrr]

44. No, it's merely a matter of boundary setting.

If instead of setting the thermodynamic boundary at, say, the outside edge of the car, make the boundary the entire universe.

[kentauros]

45. So-o, how does one go about "setting" a boundary like that?

Sounds like magic to me...


:P

[Rabrrrrrr]

46. It's not magic at all, it's just a math problem. It's not a physical boundary.

Did you not study thermodynamics?

[Pierre.Suave]

43. FYI to everyone in this thread...

I was watching some show on Discovery a few days ago and they were highlighting some guy here in the US that is planning on manufacturing a car that is not only hyper efficient, but almost made entirely out of Carbon Fibre because he had developed some way to manufacture it in quantity, cheaply, and then form it to the desired shape.

Oh, and he had a piece of the carbon fibre frame of the car, and when he rapped on it, it sounded just like metal, but weighed next to nothing.

[Taverner]

48. I just want to know: if I hit another carbon fiber car at 60 mph

Will it smash up instead of me?