Hybrid w/turbine engine

Turbine engines are very expensive to make.

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...

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!

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.

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.

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?

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.

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.

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. :)

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

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.

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.

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.

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.

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?

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.

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

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.

capstone turbines
http://www.microturbine.com/

You have almost no knowledge of turbines. Please do some research (like the turbine-powered Chrysler from the 70's) before you make any more comments

I kind put my money where my mouth was.

http://www.factoryfive.com/whatsnew.html
http://www.youtube.com/watch?v=Bvg6a0F2tVs

The Capstone C30 is designed to be used in HEV applications. My unit was originally in a bus. Let's be clear, it is a turbine generator set, not direct drive. It produces between 8 and 28 kW at between 1 and 3 Gallons of Diesel (or biodiesel) per hour. In my case, that power is dumped into a 24kWh LiPoly Battery Pack, and drawn from (and charged by a AC150 Drive system (at about 165kW). This is a serial hybrid.

The Capstone at a constant RPM is VERY efficient, better than any ICE (30%). It is fully recuperated, recovering more than 50% of the combustion heat. Aircraft, and all but the Volvo turbines previously used we open systems, writing off energy. The turbine is CARB 03 emissions certified, and probably would meet the Carb 09 standards. The car cruises at 80MPH at under 200 watts per mile. That means with the Turbine on, it gets about 40MPG at speed. Being a plug in Hybrid with an 85 mile Pure EV range, it is a pretty good match. Use the battery system around town and the turbine on the open highway. It will also power your house in a pinch.

BTW, if you don't punish batteries and keep them better than 80% depth of discharge, they will last a long time. Prius batteries, used under similar circumstances, are lasting 2X or more longer than Toyota calculated (and warranted). I expect to get 10 years from my current pack.

Oh yeah, it sounds pretty good and is a 4 second 0-60. Remember, cars are mostly sold as entertainment, and George Lucas says that Sound is 51% of the experience...

the advantage to a gas turbine electric hybrid car would be that you would be able to burn any combustible liquid and not be bound to petroleum products, ie corn oil, alcohol exct

I like Rosens idea of a solid core generator and the "flywheel". Couple that with either electric or hydrolic energy generation with the brakes and release upon acceleration, and conventional ICE technology could bridge untill turbine becomes even more advanced.

Check out:
http://www.turbo-electric.com/Impulse-EV.html

I'm working on this too.

The 'serial hybrid' concept with a gas turbine for automotive use has been an interest of mine for a while. A fairly small gas turbine turboshaft motor could be used as a generator

Here's another turbine hybrid:
http://www.capstoneturbine.com/news/story.asp?id=536