Hybrid w/turbine engine
Created November 4, 2004, at 4:12 pm by Anonymous
Does anyone know if any automakers are working on a hybrid vehicle with a turbine engine? These would be more fuel efficent, lighter and simpler than an internal combustion engine. I also believe you could use a variety of fuels. Then the electric engine would alleviate the problem of sluggish accelleration with the turbine engine.
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Turbine engines are very expensive to make.
Turbine engines are only efficient if they are powering very heavy equipment (like a dump truck) or very fast equipment (like a military jet) because of the extreme RPM's they generate. Automobiles are neither as heavy as a dump truck, nor as fast as a military jet. If a turbine engine were placed into a car, not only would it be many orders less efficient (fuel would be consumed based on weight, not by volume), but every free square inch of the car's internal storage space would have to be filled with fuel.
This question is also debated in experimental aircraft circles. Turbines are better suited to aircraft (no need for very low speed, rather constant power once airborne), but even there they are not as efficient as a well-tuned ICE. The main reasons they are considered is their simple construction (well, relatively), high reliability, and superior power-to-weight ratio. Emissions and noise have never been high on pilots' list of priorities...
Rather than a turbine, the optimum engine is more likely a diesel engine as in the hybrid HMMWV (Humvee) shown in 1998 (!) - see http://evworld.com/archives/conferences/evs14/humvee.html (among others).
VW has a Rabbit diesel that gets great mileage - imagine coupling that engine in a hybrid platform. Is VW working on a hybrid?
There are some similarities in operating conditions that would suit putting a turbine engine into a hybrid. The main thing would be that turbines like to operate at constant speeds, which is how the Prius engine would like to run. However, since turbines operate at high temperatures and high rpms, they require exotic metals and metal-ceramic composite materials to keep from melting and would require an "extreme" transmission to gear down from 10-30,000 rpm at the shaft, to typical axle rpms. So they are probably too costly for automobile use.
I think a diesel-electric hybrid would be a good choice, although I don't know the relative efficiencies between the Atkinson cycle gasoline engine and the diesel engine. I would suspect that the reason we haven't seen them yet is because the auto companies think most consumers wouldn't want a diesel. Whether or not that's true, I don't know. Diesels also put out a lot more particulate matter than gasoline engines, which is costly in health care costs.
Scientific American Frontiers (a show on PBS) had a special a month or two ago on future automobiles, highlighting manufacturers from Europe and the USA. There are going to be a lot of really interesting cars (and trucks) coming out in the next decade!
Volvo did a gas-turbine hybrid concept in the 1990s. It was called the "Environmental Concept Car" or some such (they tend to have very bland names for their concept cars). It was a serial hybrid, as I recall, not a parallel like the Prius and Escape. The turbine was used to drive a generator that produced the electricity.
Volvo's aero-engine subsidiary was responsible for producing the power plant.
I may have more info buried somewhere on this concept car if others are interested.
VW recently demonstrated a hybrid Golf diesel with an average 57 mpg, but has not yet taken a decision about massproduction.
Since dieselcars already have a better fuel economy than gasoline cars, benefits from a hybrid version are not that spectacular. That's probably the reason why diesel-hybrids are not yet on the market.
A Stirling engine might be a good alternative too. It's in fact a external combustion engine.
Like a turbine, it get's great efficiency at stationary load, but is not suited for variable speed. Combined with a electrical motor it could do much better than four-stroke hybrids, especially on highways. I'm not sure that it would beat a four-stroke hybrid in city driving
There's also the issue of particulate emissions with Diesel, especially in North America where our Diesel fuel is rather dirty.
Diesel cars are still hard to market in the US after GM turned out some real citrus fruit types in the late '70s.
The comment on Volvo's Environmental Concept Car seems to be correct; unfortunately, I'm also having a tough time finding information on it. It was back from 1992/1993, so I'm sure we could do better these days, what with new research being done on micro power turbines (often used for onsite cogeneration of electricity for buildings, etc.). I think that a properly outfitted turbine (with regenerator and possibly intercooling and reheat) would be much more efficient than an Otto or Diesel cycle engine, and would certainly be more reliable. Cost, however, is another story. Maybe this is another case where the "law" of supply and demand would apply, though. For more on turbine efficiency, see: http://www.qrg.northwestern.edu/thermo/design-library/airstd/brayton.html
What about using the "rotary" style engine like the RX-8? Anyone got any numbers on how these engines are with respect to fuel efficiency and reliability?
Hyundai was experimenting with a gas turbine hybrid in their Santa Fe SUV back in 2000/2001 and promised that they would go into production with a similar system in their light commercial utility vehicles in 2002. Obviously, this never happened and the world is still waiting.
GM also had a gas turbine hybrid version of their EV1 around the same time. Nothing came of it either.
As to turbine engines, they have a lower BSFC than 4-stroke piston engines, even at their most efficient ranges. As someone else already posted, even in aircraft, turbine engines are generally avoided for anything under 350 horsepower because you'll get better gas mileage from a piston engine.
Where turbine engines shine is when you need to make huge power or desire extremely high reliability. I read one study that compared turbine and piston engines in aircraft and showed that turbine engines fail only 2% as often as piston engines. Granted, a lot of that is probably because most guys are only buying $15-30k piston engines and turbines are $75-500k and maintained better anyway, but still, the fact remains that turbine engines have lower BSFC even at peak, and their efficiency at low power percentages is horrible. A turbine engine at idle will use something like 20 times as much fuel as a piston engine at idle.
As for Mazda's rotary engine, the easiest comparison there is between Mazda's 220hp RX8 and Honda's 240hp S2000. They both produce almost the same torque, power, and have nearly the same weight, but the S2000 gets dramatically better gas mileage. Rotary engines have much lower BSFC than piston engines. Why do you think piston engines are so common? Because they're extremely efficient, especially at light load.
In the middle of 2006, new regulations will be in effect with regards to ULSD, aka Ultra-Low Sulpher Diesel. That will all but entirely eliminate the nasty smell from diesel and will pave the way for far better particulate traps on diesel powered vehicles making it possible to pass even California emissions with a diesel engine. Diesel has greater thermal content per gallon than gasoline (about 130,000 BTU versus 115,000 BTU for gasoline) and because diesel engines don't use a throttlebody, they have lower pumping losses and overall far higher total energy efficiency. Once the new regs are in effect, we'll see greater willingness for manufacturers to introduce non-smelly high tech diesels in America.
I would like to see a manufacturer use a small, and efficient, constant speed diesel engine coupled only to a generator which would charge a battery bank which powers a traction motor. It seems to me that the overall complexity of such a system would be far less than that of a hybrid since you would be dealing strictly with one propulsion system than two.
Some common systems would have to reengineered to be run electrically: brake booster pump, power steering pump, etc. Heating and cooling could be done via a heat pump setup with an electric heater for extremely cold temps.
The owner of such a car would also be able to plug the vehicle in at night (and perhaps at work) to supplement the charge thus reducing the need for the diesel alternator to run.
All wheel drive (AWD) versions of this vehicle could easily be created by adding a second electric motor to the rear.
In the event of a blackout, emergency power (and utility power by backs?) could come off of the battery bank via an inverter.
It is my understanding that turbines run in their optimal rpm efficiency constantly (like in hydrid applications) have a more effcient cycle than even diesel engines; especially with a regenerator. The proper sizing of a smaller turbine might be ideal for a hybrid, but two obstacles exist in their current manufacturing. Exotic metals may ultimately be replaced by gel-cast micro-fiber reinforced ceramics that can be mass produced to solve the first manufacturing/cost problems. The second problem is building a simple, efficient, and reliable small turbine. When you shrink the dimensions.. the reynolds numbers stay proportionally the same - therefore your tolerances have to be even tighter to maintain efficiency. Ask Dr. Williams of Williams Internationsl - he'll tell you the real problems.
The problems with making small turbines is one issue, the other problem is with fast rotating devices such as the turbine, in automobiles. That is the gyroscopic effect. Cars move around a lot and the gyroscope of the turbine rotor wants to remain at a fixed orientation in space, therefore the mounting has to fight to turn the turbine.
Capstone is working very hard on both these problems but I don't know where they are with something suitable for the automobile environment yet.
Flywheels also have this same kind of flywheel problem in vehicular applications.
Why not mount the turbine generator in a freely rotating way, so that the car does not have to "fight" the gyroscopic effects. Compare with cyroscopic compasses. It "only" need some clever design for cabels, fuel in and waste out though. But that can probably be solved by some smart guys.
Maybe Turbine Hybrids are not a good idea, maybe they are. However the principle of choosing the most fuel efficient engine for generating electricity and then using the electricity (possibly via buffert batteries) to power electrical motors is sound IMO. Also, it should always be possible to plug in a hybrid, if the owner chooses to. In some countries there are 100% environmentally friendly power (nuclear + hydro) and users in those countries might prefer "fueling" with clean electricity.
Cars like that would become "electric cars with internal powerplats for optional use", which is my dream car. :)
Magnus,
Gimbals only handle the rotational problem, not bumping and motion -- but I'm sure they will help a lot.
I agree that a plug-in hybrid is the answer for now.
see
www.pluginamerica.com
www.calcars.org
www.edrive.com
There are many who share your vision.
Below are a couple of to the most recent use of a gas turbine in a car by a major auto manufacturer. The microturbine in this modified EV1 "series electric hybrid" runs at a constant optimal speed. It is a single-stage, single-shaft, recuperated gas turbine with a high-speed permanent magnet AC generator. Only the electric motor is connected to the drive train.
http://www.evworld.com/archives/testdrives/gmshev.html
http://www.evworld.com/archives/testdrives/carpicts/gmshev-dia.gif
Small single-stage turbines are less efficient than the multi-stage versions used in most jets. However, multi-stage turbines are very expensive to build. When using a recuperator, and running at a constant speed micro turbines DO have better efficiency than a reciprocating ICE. In a series hybrid configuration the car could get up to 100 mpg using gasoline. It would also be able to run on any other fuel like alcohol, hydrogen, diesel or methane. The ability to use multiple fuels is a good reason alone to reconsider the use of the turbine in autos.
Because the gasses in turbines reach such high temperatures most of the toxic compounds found in gas and diesel fuel are more thouroughly combusted and broken down. The turbine engine in the 65 Chrysler experimental turbine car was touted as a clean air engine. This was 5 years before the EPA was formed.
http://www.allpar.com/mopar/turbine.html
http://www.turbinecar.com/sia/sia57.htm
approx 4 yrs ago i read an article about a constant speed gas turbine attached to a generator running an automobile. of special interest about this auto was that it was being developed by the man that founded compaq computer. he claimed their hybrid was getting 150 to a gallon of gas. he also said he had patented an air bearing that allowed the shaft of the turbine to ride on a cushion of air, friction free. also at this time he was storing electricity on two shafts constantly rotating ( verticle ) in front of the firewall, wound with a carbon fiber composition. at the time of the article he felt the system was refined enough to place in commercial vehicles in different parts of the country to test durablity and to further improve the system in a five yr test. ? has anybody else heard of this.
It sounds like you're referring to Ben Rosen, former Chairman of Compaq. He and his brother Harold (founder of Hughes Space and Communications and 'father of the geostationary satellite') founded Rosen Motors. Their main goal was to store energy in a flywheel. This would allow them to create either a flywheel-hybrid vehicle or a pure flywheel driven vehicle.
Unfortunately, Rosen Motors went broke in about 2001.
Among the reasons I heard for their failure were that it was hard to get people to trust something spinning very rapidly in an automobile.
There was a mention of the wenkel rotary engine somewhere up there, but i dont think it was discussed as a genset capability but rather as the drivetrain. Is a micro gas rotary engine a more suitable direction for serial hybrid genset than a turbine ? Thks !
Complexity of a turbine engine; Tesla had one 100 years ago that used PDE combustion. Combined with Siemens motor/generator a Tesla gas turbine today (SEE: Phoenix Navigation, Inc.) would provide 140 mpg on ethanol with water injection at zero emissions. Why are fuel efficient solutions not provided to the public? Corporate Greed! The Tesla gas turbine is so simple a person with a machine shop could build their own. Simple solutions for a foolishly complex world.
I don't think a turbined coupled with an electric generator is efficient enough (in producing electricity) to be worth it. Electric motors are allready not that effecient, couple that with a generator and you get a lot of wasted energy.
And also the problem with purely electric car (with or without onboard powerplant) is the weight of the battery packs! Thats why the new hybrids have DC-DC converters to boost voltage from fewer battery packs.
I think all we really need is cleaner fuels, not new engines.
Robert,
I'm not sure where you get the information about motor efficiency. Modern electric motors exceed 90% efficiency while internal combustion ones in vehicles are around 20% efficient.
Well if you look at just the motor yes indeed an electric motor is effecient... just like a turbine when well tuned and used at the optimal setting. And it'd be much more efficient to just run the turbine straight to a "hybrid synergy drive" so full power can be applied to the drive train. What my point though is that there's no point in creating this complex system under your hood when all you could do is switch to a cleaner fuel such as hydrogen or else. When creating electricity can be done cleanly and cheaply then why not run on full electric. But I don't believe we've reached that point. The best solution short term is a better fuel IMO.
Thanks Robert,
I see your sources of confusion.
1. the electric motor, unlike any combustion engine, is efficient throughout it's performance range. Max torque is at zero RPM but it remains pretty much flat up to a point where it starts to roll off (magnetic eddy currents start to hold it back). Efficiency remains pretty much constant up to the point where it starts to fall off.
2. ICE's do not lend themselves to easy fuel swapping. The injectors, sensors, compression ratios, ignition, and fuel handling systems (tanks, fillers, filters, fuel lines, etc) all need to be radically changed to handle fuels with different properties. A good example of this is the difference between a diesel and a gasoline engine. Fundamentally, they are very similiar but practically they are totally incompatible. Hydrogen modifications are even more severe.
This places great burdens on coming up with fuels that mirror the properties the engines are designed for. While theoretically and practically possible, it is very expensive and inefficient. Coupled with the inefficiency of the ICE, this isn't a very economical system.
The beauty of the plug-in electric is that many energy sources readily lend themselves to conversion to electricity and we have a very efficient, nearly ubiquitous grid to deliver it nearly anywhere we need it.
The trick, of course, is getting someone to make plug-in vehicles in sufficient quantities to be affordable.
The really exotic ideas are for aircraft. There is a new small jet in the works called the Elclipse. It is a 6 passenger aircraft that gets about 1300 miles with a 45 minute safety reserve on 249 gallons. It can cruise between 250-370 mph.
The more far out ideas are to use a turbo prop with electric assist for take off with high efficiency batteries. In other words, a hybrid electric airplane.
Electrics now are taking over model airplanes. Some people think hybrids for big planes are next.
Thanks for all that info ex-EV1 driver!
Maybe you can clear up another issue I have with full electric cars:
Arent batteries toxic and need replacement every 5 years or so?
I thought we were no where near having green batteries.
And I thought that was the reason hybrids are using so little batteires (that and the weight... but weight is getting better with litium and the like)
And would you agree that if not using batteries, using a gas motor to generate electricity is kind of not efficient or dare I say... pointless for the future?
(cost of research, engeneering, etc... for such a temporary solution)
Also, I think converting natural gas engines to hydrogen or other gaseous fuel has been done without much modification. That could be a cheap alternative to reengeneer complete engines (be it electric or other)
Oh.. one last point I'd like to debate is the ruggedness of electric motors compared to ICE with winters or sandy / dusty places. I think ICE would produce less landfill garbage in the long run, what do you guys think?
Robert,
I opened a new discussion topic "Electric car issues" to address these electric car things since I feel this topic should stick with the turbine concept - another very cool possibility.
This is the most sensible solution. I've looked at these pages for months and no one is working on this.
What about using a Hatz one cylinder diesel engine to power the generator.
A lot of the comments on this page refer to using turbines as a sole power source, not as part of an turbine/electric hybrid. The "too fast, too slow" and "too much fuel" arguments relate to this as does the "gearing down" argument. You don't have to gear down when you're powering an electric motor, nor will you use as much gas. Also, the smaller the engine, the easier it would be to keep it insulated and cooled. I think the biggest problem is still mass production of the more exotic materials -- although I would suppose that this could be dealt with given the right motivation (political will?).
I was wondering if anyone knows of a company that makes small turboshaft motors or generators?
I'm in a college competion to make a hybrid oneseater race car. I would love to test these engines to see what king of efficiency can be obtained with a series setup.
For my application I propably need something with less than 100 hp if you know of anything let me know.
thanks
M-DOT makes mirco turbines for DARPA of 1kw in size. What school are you in?
Volvo did make a diesel powered turbine hybrid in the 1990's. The turbine would power a generator, that in turn would supply power to the electric motors. Looked just like a normal volvo car, turbine was small, and fit in the engine bay. If I remember correct, it had a range of 800 miles on a full tank of diesel. US would not allow it into the country from what I remember. An American company later came out with a similar car concept, but they had no intentions to do anything with it. Hence Toyota took the same concept and applied a piston engine to it, now they have the gas electric hybrid.
Does anybody know what the emissions out put would be for using one possilbly two micro turbines to power generators, say in the 1-2 Kw/hr range? I am also curious to know how efficient the new class of microturbines, such as those made by Capstone and Honeywell, are? It seems that the weight savings alone would make this promising. Finally, why has it taken so long to make minivans, full size vans, trucks and SUVs effective hybrids. With better low end torque for towing and off road, and a chasis better suite to take the weight of batteries, it seems like a no brainer, am I missing something?
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