Posted on 10/11/2010 12:10:12 PM PDT by dangerdoc
Interesting news from General Motors today that's resulted in some puzzled expressions at Engadget HQ. We've learned that the Volt, which Chevrolet has been making quite a fuss about calling an "extended range electric vehicle," is actually just a traditional hybrid with some... potentially misleading marketing behind it. Since the concept stage the company has been saying how the onboard internal combustion engine was just to charge the batteries, that only the electric motors (there are two) are actually connected to the drivetrain. Indeed that's what we were told in person when we test drove the thing back in March. We're now learning that is not the case, that the Volt's gasoline engine can directly provide power to the wheels in concert with the electric motors.
Is that a problem? In terms of efficiency the answer is "apparently not," as we're guessing the car would not have been designed this way if it weren't the most frugal way to go. So, why all the deception? Why insist this isn't just a hybrid when it apparently is? When the company went looking for a government bailout it was in part awarded one because of the innovation shown in the Volt. Now that we're learning the Volt is basically just a plug-in hybrid with a bigger than average battery pack (Popular Mechanics is finding 30-odd miles of purely electric range), we're left wondering: where's the innovation?
'Green' is 100% deception.
The biggest hope is moving away from heat engines and the inherent ineffiencies of the Carnot cycle.
What energy source do you envision?
Most electrical power is generated from a thermal power plant?
Direct chemical to electricity conversion.
Examples?
Solid Oxide Fuel Cells
SOFC is the one to watch.
Solid Oxide fuel cells run rather hot for a passenger automobile, don’t you think? The beauty of hydrogen fuel cells is that they operate at around 80°C.
Hydrogen fuel cells have thier own problems. Fuel storage being the biggest, Hydration management for the membrane is another stumbling block.
Newer tech has SOFCs running much cooler and more efficient. But it is the heat that allows them to digest fossil fuels and allows the potential of using the current fuel infrastructure.
That is true.
The trouble in doing this are the costs involved in possible replacements. When we look at possible replacements, we realize that:
1. The internal combustion engine sucks...
2. But everything else sucks at least as hard, if not harder. So far.
Yes, it is. However, the execs and PR flaks for GM made a big hoopla about it being an “all electric!” drivetrain, that it was NOT a hybrid (as tho that were a bad thing) and made sure that we taxpayers (who paid to bail their incompetence out of bankruptcy) heard all about how the car was always powered by the electric motors.
Most people can’t read that patent app that I just sent you and make heads or tails of it. They wouldn’t know a planetary gear from a spur gear if you shoved both types of gears up their noses.
What people do know is that they HATE GM. With a flaming passion. There are the people have been burned by GM’s quality back in the 70’s and 80’s. Then there are the people that hate goldbricking UAW workers. Recently, there are the people like my mother in law, who was burned by how were SECURED GM bonds were wiped out by how the government gave the assets of GM to the UAW and shafted the bondholders.
GM has made a lot of enemies among the US public over the last three decades. A big portion of the US public now has no patience for ANY lie, no matter how small, no matter how technical, from GM. A pretty good size chunk of the US public thinks it was wrong to bail out GM and that they’d be better off dead.
GM is truly living on borrowed time - purchased with money “borrowed” from the US taxpayers.
And GM, once again, has put their foot in their mouth.
This is an example of ICE technology but illustrates that there is better technology coming.
http://www.autoevolution.com/news/opoc-engine-explained-22609.html
At the beginning of last century, it you wanted to get real work done you used steam power because everything else sucked worse. The internal combustion engine has made a good run but it will be supplanted by better technology, and I think sooner than many suspect.
OK, 50% better efficiency than a gas engine gets us to 45%, which is where we are with today’s diesel engines, a computerized fuel rack and a turbo. It doesn’t exceed Carnot limits, and I don’t see how that engine design could exceed Carnot limits either. It’s still a suck-squeeze-bang-blow engine when you get down to it. Cleverly done in many fewer parts, much lighter in weight, but still a SSBB engine.
If we make some use of Seebeck effect units plastered on the engine block, radiator and in the exhaust stream, we could capture some useful work out of the rejected heat on a diesel and go yet higher. There were some ag engineering students in the midwest who had a bright idea of using Seebeck effect modules in the exhaust stream of a diesel tractor engine to power Peltier effect units to run the cab cooling, which would then eliminate the need to an A/C compressor on a tractor. And there’s a lot less to go wrong than a typical freon A/C compressor system - no moving parts.
In general, most internal combustion engines use a third of the available thermal power in their fuel, they reject about a third of the thermal energy into the radiator/heat off the block, and about a third goes out the tailpipe.
A turbo captures some of the energy that had been going down the tailpipe. If we could use the heat rejected into the coolant and exhaust stream to do something useful, we’d be getting a good deal further down the road with existing engines or even new engine designs.
Getting better efficiency than a Otto-cycle gas engine is easy. Miller cycles or Atkinson cycles get us there, going to direct injection compression ignition with gasoline (ie, a diesel engine without the diesel fuel) gets us there.
Getting better efficiency than a theoretical best possible Carnot cycle at our current ambient temps (which would be in the low 60’s of percent)... not quite as easy.
You forgot to mention Rush.
What about him? Since I’ve heard Rush only sporadically in the last, oh, five years I sorta need to rent a clue here...
I linked that engine because I just read about it last night and found it interesting. It should get better efficiency with much less weight.
How much of the time does the best designed engine spend in it’s peek torque band? Not much, which means that the engine will not provide advertised efficiency. Fuel cells are about 60% efficient now, absolute, not Carnot, and the energy not converted into electricity is rejected as high quality heat. Perfect for thermoelectric conversion since you brought it up.
“How much of the time does the best designed engine spend in it’s peek torque band?”
Depends on the application.
For a diesel in stationary applications, almost all the time. For diesels in train applications, most all of the time. For diesels in a direct-coupled automotive application, at highway speeds with the cruise control on, it will spend quite a lot of time at or near peak torque if we have a transmission that wasn’t designed by morons. eg, my Ford Navistar engine is quite efficient at 65MPH, which is just about 1900 RPM. That’s about 100RPM above the peak torque hump. The most efficient internal combustion engine in the world extant is a maritime two-stroke diesel with about 52% thermal efficiency. It burns bunker C fuel.
Assumptions of proper transmission technology obviously excludes GM immediately from discussion, so let’s not worry about them right now, but I digress.
The European diesel sedans are adding more gear ratios to their transmissions all the time. Benz is supposed to have a nine speed transmission under development for their new diesels. Audi has a eight speed. Ag tractors have increasingly gone to IVT/CVT’s, which allow them to run the engine at just above peak torque RPM’s all the time, maximizing efficiency. The same could easily be done in automotive applications.
However, if we assume the existence of a series hybrid drivetrain, then a diesel can be run at the best point on the fuel/torque curve all the time. Let the electrical half of the drivetrain worry about varying the drivetrain speed, then the diesel gets to operate at its most efficient.
The truth is this: the most efficient internal combustion engine technology we have at our disposal right now is a turbocharged diesel with a computerized fuel rack. Most all the other ideas extant either cannot develop their ideas in an economically feasible package (eg, Stirling engines), or they’re just not competitive (eg, Miller, Atkinson cycle engines). I could whip out a design for a hybrid diesel auto on several sheets of paper right now, with existing technology, for a car that would get 80MPG on the highway and I would not need to get into bleeding-edge aerodynamic design or ultra-technical body/frame materials (eg, carbon fiber). We’d just be talking about steel and aluminum body/frame components, a hybrid setup, a modest battery, regen braking, etc. In other words, rip the engine out of a Prius, dump in a diesel and call it good.
Distractions with all electric cars, or “zero emissions” and other such nonsense has been preventing us from getting to a point where a good, but not perfect, design doubles the US fleet mileage ratings.
The perfect is the mortal enemy of the good. And far too many non-engineers have been polluting this issue with their goofy goddamn ideas for the last 20+ years, along with telling us of all the conspiracy theories of “300 MPG carburetors” and other technology that the oil companies have “bought and buried.” I would dearly love to see the US simply put a stake in the ground and say “We want to achieve a fleet efficiency of X MPG by year T and deliver it at the average auto sales price +/- 10%” and then give the problem to engineers and tell everyone else to shut up and quit pretending that they know anything. Don’t tell us that it needs to be or can’t be “zero emission” or “hydrogen” or “natural gas” or any other such BS. Just tell us mileage and delivery date. Then tell everyone else (environmentalists, politicians, auto writers and all manner of dreamers and fools) to STFU.
Then we could finally make some progress.
BTW, in case you think I’m full of crap in my 80MPG estimates, check out the latest Audi effort which is similar in idea. I didn’t know this had been unwrapped until after I posted the previous message:
http://www.greencarcongress.com/2010/10/etronspyder-20101001.html
107 MPG (US gallons). And it will blow the doors off most sports cars. And it doesn’t look like some boring Detroit sedan or some idiotic Japanese econo-box.
It looks fast, it IS fast, and it is efficient.
Meanwhile, we’re listening to a bunch of patchouli-oil soaked morons who carp and whine endlessly about “zero emissions” who inspire such nonsense as the GM Volt, which was the original topic of this thread. The GM Volt will probably get over 40MPG on the highway. Let’s say it gets 50MPG.
Whoopti-freakin’-do.
Compared to this Audi, GM has labored mightily and brought forth.... boredom.
I know the idea of a diesel hybrid would work. Now. Today.
The Germans are proving me right.
And GM continues to deliver absolutely boring shite. At my expense, because I’m paying taxes.
I’d by a European turbo diesel sedan today for my commute if the EPA would let me.
That being said, when fuel cells hit the market, they will come out of the gate about 30% more efficient than the best diesel. A SOFC would also be more flexible regarding fuel. It would run on diesel as easily as gasoline or kerosene, or fuel oil or methanol or what ever is cheapest per joule of energy.
I’m not philosophically opposed to the internal combustion engine. It has done a great job and will probably continue to so in some form for the next 100 years but there is room for better technology.
I’m not holding my breath on fuel cells. On paper, fuel cells are super-sexy technology. No moving parts, high efficiencies, quiet, etc. Oh, they look so sexy.
Why wouldn’t anyone want them? You put in a little hydrocarbon fuel (or pure H2) and out the back end comes gobs of electrical power.
We’ve been hearing about them in engineering for the last 40 years, just like solar cells are going to be so cheap that we’ll be able to do away with coal-fireed power plants “next year.”
There’s always room for new technology. The problem with some of these technologies is that researchers put out these wonderful prototypes, people get their hopes up, not understanding in the slightest what the economics of the widget they’ve seen are. Many times, the economics are horrible. Sure, we have solar cells with over 40% conversion efficiency. You couldn’t afford them on the roof of your house unless you’re Bill Gates.
Same deal for the SOFC cells. There’s fundamental materials engineering issues that have to be addressed, and we’re not making a whole bunch of progress on that issue.
Meanwhile, we could have made substantial strides with known and proven technology we have now.
As I said before: “The perfect is the mortal enemy of the good enough.” Diesels, batteries and motors are good enough to get over 80MPG. Now, today. And that 80MPG could have been delivered last year, or the year before, or the year before that... going all the way back to, oh, 1995 or so.
Yet here we are, 15 years later, with nothing but distractions to show for the time wasted.
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