Stirling Engine based hybrid car

I'm not the only one to have thought of this, but as yet no real work has been done. How about a hybrid car powered with a Stirling Engine? (Not spelled Sterling, btw.)

The Stirling is more efficient than the internal combustion or diesel engine, and it's also a lot quieter. Sounds great, but it's not good for cars because it can't rev up quickly and it takes about 5 minutes to get the engine hot enough to run well. We want our cars to start the minute we put the key in.

A hybrid design (with enough batteries for 10-20 miles) solves this. You can get all the acceleration you need from the electric motors, and you can start driving right away, while heating up the Stirling "boiler". Then it kicks in to provide the power to run the car for the long haul. If you know the trip is short, no need to fire up the Stirling until the battery gets low.

The Stirling can burn anything. Gasoline, kerosene, diesel, vegetable oil, hydrogen, even wood! Yes, you could, in theory, be stuck by the side of the road out of gas, then go out with an axe to chop trees and refuel your car.

Well, almost. You want high-temperature burning for the best efficiency, and this would pollute and probably dirty your nice clean boiler. Right now the engines are expensive to machine but I suspect that could change.


Patience. The sterling has a place in the hybrid scheme. But first the hybrid has to be accepted, and it's a brand new baby.
Sterlings lack flexibilty - that's the technical term for 0-60 acceleration followed by a quick shutdown when the cops spot you. By hitching the sterling to a generator/motor for final drive you put the flexibility back in - the electric motor can smoke an IC engine off the line. And it can be a very effective brake on the other end. Meanwhile the sterling putt-putt-putts along (not!) under the load of its generator. Surplus energy can be stored in a battery or capacitor.
More efficient? no. The laws of thermodynamics dictate that your lose power every time you change states. So in theory an IC engine directly using the energy of burning gas is going to be more efficient than burning fuel and then using it to expand a gas, then using that to swing a magnet, then using the resulting energy to swing another magnet.
On the other hand, given the choice of a 427 hemi or a 97HP wheezomatic, the consumer buys the hemi -- way more engine than she needs. That's where, when the engineer designs a hybrid, he may make better choices. Or not. But a compact car _only_ needs a 20 hp electric motor to feel peppy, due to the inherent flexibility of the power plant.
Cheaper fuels are another good cause to get behind. Because they burn in a steady state, furnace burners are more efficient than an IC engine. They can also be optimized for the kerosene/bunker oil/soy oil family instead of demanding complex high-octane gasoline.
Good design would keep the air fresher, and since the low-grades are virtually interchangable, offers more choices for filling the tank. My point? A sterling uses an external burner, just like your house. It's a fun model to think about - especially since some vans now have a refrigerator and closet space. How many MPG does your house get?
Last thought. My flight of fancy leads me to a sterling hybrid that runs 24/7 in the yard (not in the house - whose idea was it to give the car in its own room, next to the kitchen?) where it charges the family electric cars and heats water for your morning shower. The electrics are for the short errands, the hybrid for the long or heavy hauling. Hot water keeps, sort of, so the car can contribute to the overall heating capacity of the house. (Now there's a car that deserves to live in my house!) Live in the woods? Let your car power the evening TV time.
Now isn't that worth waiting for?

We can take a conversion step out if we have the output shaft of the Stirling engine coupled to the shaft of the IC engine to provide power more directly. No electric motor or battery back needed. You would need some kind of electronically controlled linkage (a planetary gearset, perhaps?) to allow them to work together efficiently at whatever speed each engine is currently running at.

As someone else suggested, the Stirling should run off of the waste heat that the IC produces. This can be done by putting the Stirling inline with the IC's cooling system, so to speak. Instead a coolant loop between the IC engine block and the radiator, there would be two loops: one between the IC block and the Stirling's hot side, and one between the Stirling's cold side and the radiator. If you REALLY want to get creative, perhaps a block could be designed that contains both IC cylinders and Stirling cylinders.

Good luck getting a sterling to run happily at 6000+ rpm and still produce any useful torque.

Apparently this is not all that far fetched. I caught this article posted on Slashdot. It describes a prototype Stirling hybrid electric car.

You don't directly turn the wheels with one. Torque is immaterial - you run the armature of a generator at the speed where you get maximum rpm. The generator either drives electric motors directly (you want torque?) or charges batteries that drive electric motors. You don't whack a clutch on it and drive it like a conventional car.

First off, no one has addressed the primary problem with this concept which is that
Stirling engines are not efficient at all!! Anyone who has done their homework knows
that the IC engine is no less than THREE TIMES as efficient as the current crop of
hot-air engines in regards to fuel burnt vs. watts of power generated: 7-15% claimed
efficiency for Stirling power and 25-39% demonstrated efficiency for IC power. At the
end of this post are some addresses that you should check out detailing this.

Now then, the otto-cycle engine took off largely because it worked, and the others
didn’t. Even Stirling advocates will admit that a Stirling engine has to be quite large to
produce a given amount of power. I don't think that anyone who has posted yet
actually realizes exactly how big these things are!! They are not a little bigger, they are
ten times as big!! A ½ hp Stirling weighs about as much as a 6hp Briggs and Stratton,
which is not exactly a power dense IC engine–and that’s not including the burner,
shrouding, and chimney. Let us remember that the otto-cycle engines that won out
over steam and Stirling power were enormous contraptions that produced little power,
operated over a very limited rpm range, and used a then-scarce and expensive fuel.
Let us also recall that most of these engines were used in stationary applications,
where you would expect a Stirling engine to have a chance at competing and the
otto-cycle engine still won out!! And it wasn’t because of big oil companies–there
weren’t any!

But let’s just say that someone has built a Stirling engine that approaches the
“theoretical” possible efficiency (no one has come anywhere near yet by the way, not
even Kohemms of Sweden.) Beyond “theoretical efficiency” of an engine we must
consider power to weight ratios if we expect this engine to move its self down the road,
and further some useful payload (That‘s you.) Also true is that to power a motor vehicle
in traffic this engine must be able to cope with the demands of traffic: It must be able to
start and stop somewhat quickly, though in reality no where nearly as quickly as we
seem to believe or demand. The generally low power density of the Stirling engine will
provide serious problems with a machine that must move itself down the road. I
suggest that you look at the ST-5 5 hp Stirling engine, which is the highest hp output
Stirling that is commercially available. Look at the pictures. This thing is the size of
two 55 gallon oil drums. And the low power density is something that won’t be easy to
overcome, chiefly because of issues regarding how fast the working gas can be heated
and cooled through the conduction of the cylinder walls without applying ludicrous
amounts of heat to it (and therefore losing much of it- the very problem we are trying to
solve here.) But this post is not about the Stirling engine per sei, but rather the sterling
hybrid, so I digress. An average small car doesn’t need that much power to maintain
speed, usually 10-20 hp. One could reason that the Stirling hybrid could average this
much power and use a battery-electric motor setup to smooth out the lumps in traffic.
The problem here is that unlike the otto-cycle hybrid, in which the car is capable of
being powered directly by the otto cycle engine, with a “boost” from an electric motor,
(meaning that the motor/battery could be smaller,) the Stirling hybrid would require a
motor/battery combination that was capable of 100% of the vehicles power needs,
which would mean that they both would have to be very large and HEAVY. Which
leads us to the next problem. Inefficiency. As stated, the Stirling engines that are
available today, even those being used by NASA and the military, are much less
efficient than an IC engine. I guess if your car were running on trash or cow dung, you
wouldn’t care how much of the stuff that it burned, but neither of these fuels is very btu
dense, like diesel or gasoline. And because diesel and gasoline are so easy to store
and dispense, it’s highly unlikely that anyone would be willing to give up their fuel tanks
in favor of a “coal car” that trailed behind holding the solid fuel. Also, fuel prices are
high enough right now that I don’t think that you would ever be able to convince anyone
that it was good to drive a car that burned three times as much of it.

Which takes us back to the problem with hybrid car in the first place: The electric part.
Electric cars are a bad idea. They are heavy and slow. In order to have any
performance at all the chassis must be kept as light as possible, which makes them
unsafe in accidents, considering all the weight that is tied up in batteries. When the
vehicle stops, the batteries are going to keep right on going. And while there is no
emission at the vehicle, that electricity had to come from somewhere, and that means
fossil fuels and so forth. It boggles my mind that “environmentalists” think that driving
around in cars that have over half their weight tied up in expensive, fragile, plastic
boxes that are filled with toxic chemicals and heavy metals is a good idea!! Or that
people concerned with efficiency would think that it was a good idea to add weight or
changes of energy states to a moving vehicle.

For going down the highway, nothing that you add in the way of electric motors and
batteries will help squat. They will hurt, actually. For highway driving, the most
efficient arrangement that you could imagine would be to have the driving wheel bolted
to the crankshaft without even a transmission (this is impossible for a number of
reasons...) Where the hybrid cars make up is in the possibility of having regenerative
braking. I knew a person who was considering a hybrid and I asked them, "How often
do you push on the brakes?" For this person, hardly ever, as most of their mileage was
commuting to town from the suburbs. "Do your self a favor, get a VW diesel Jetta- it's
bigger, more comfortable, and will turn in better highway mileage."

I would like to see what kind of performance one of these hybrid cars would turn in with
the same engine, a standard 6 speed transmission, and all the weight from the hybrid
garbage stripped off. They would definitely get better highway mileage, and my guess
is that the around town figure wouldn't be hit too bad, since they are only marginally
better anyway.

As far as the devices used by NASA and the military go, a submarine and a spaceship
have far different operating requirements than an auto. For one, weight is not an issue.
Also, in the case of the submarine, it is surrounded by water that is FREEZING cold,
which helps with the power density. And as a stealth weapon, silent running is more
important than efficiency. The sub in question, by the way, is powered by IC diesel
engines whenever that is possible, with the Stirling gen-set only kicking in when silent
running submerged is needed, and then only at very low sustained speeds.

There is much work to do in the area of efficience, and sadly there are many real world
solutions that we could implement today but simply won't. For one, most of us drive
cars that are MUCH bigger than they need to be, and we drive them places that would
be reached more quickly on foot or with a bicycle. We keep our houses lit up like the
day when we are not at home. We heat the house to 80 Fahrenheit in the winter and
run around in our underwear to keep from sweating, and then we cool them to 60 in the
summer, and curl up on the couch in blankets to keep from freezing. This is madness!!
If I see another person driving down the road in a 10,000lb. off-road commando-wagon
that gets 8mpg by themselves I think that I am going to vomit!

My shop is less than 100 meters from the corner store. When I need to go over there, I
walk. Everyone that works for me drives!! Of course, I can't make them walk, by I do
make fun of them for driving across the street.

One last thing. Everything that I’ve said might make it seem like I don’t, but the fact is
that I LOVE Stirling engines (Though I hate calling them that, since Stirling did not
invent them, but rather patented the “economizer” a device that improves their
efficiency). I think that there is real potential for waste heat recovery and for total
house energy provision. A number of the sites that I’ve listed are companies that are
doing just that. Also I like the fact that the big, low-power, slow turning Stirlings, like
the ST-5 are perfect for application in third-world environments, where maintenance
and clean fuel are unheard of.

These first sights talk about REAL engines that are in production today:

This next one is for the Stirling Engine Society USA, and it has a number of links to
other sites.

One thing that you need to look out for when doing research are words like “promises”
and “will deliver.” These are sure signs of a quack. They can “Promise” and “Will
Deliver” ‘till they are blue in the face, but with out the numbers it means nothing. Any of
the honest sites that actually have products don’t include “efficiency” as a quality of the
Stirling engine. “Clean running” “Multi-fuel” “low-vibration” “low maintenance” are real
honest claims. Most of the Stirling products available today are either gen-sets or
whole house co-generation/heating. All the gen-set manufacturers that provide data
about fuel burn per. watt of electricity show that they burn on average three times as
much fuel as an IC engine to deliver the same electrical output. If they can’t back up
their claims of efficiency with a number based on the btu/h input per kilowatt of
mechanical or electrical energy output then their claim means nothing.

This next site is an off-shoot of the American Stirling company. In the opening
paragraph they speak a bunch of double-talk, then quote some meaningless numbers,
and then never answer the question posed at the beginning of the paragraph: “Is the
Stirling engine the most efficient heat engine?” They don’t answer the question,
because the answer is a resounding “NO.”

They also mention the 1979 AMC spirit Stirling experiment, again with double-talk like
“promised to deliver.” Well what did it actually do? My thought is that no numbers
were posted because it was an absolute failure. And anyone who believes that it’s all
government coverup funded by big oil companies needs to do their homework and see
for themselves that so far, even companies with BIG military budgets like Kockums of
Sweden haven’t made a fuel efficient Stirling engine yet.


Also check out the California DER site. There are links to other sites and also
strengths and weakness of the various power generation systems. Note that under
“Stirling weaknesses” is “Low efficiencies”

I think that the hot air engine has yet to discover it’s real potential. And on that front,
I’m working out a design for a small external combustion engine that I hope might
address some of the inefficiency of the Stirling, though I’ve only gotten as far as
working out the volumes and locating a few of the source components. Maybe
someday...I’m not betting my pension on it, though!!

Hope this has all helped out,


You seem like a knowlegible person with experiance in this field. What are some the problems you've run into with your design. I am also an engineer I might have some sugestions that would help you along. Alternately, I might be notify that your idea has been tryed before unsucessfully. In which case we could brainstorm on line online that could result in a better idea. Heck, may be could start an R&D operation together. I believe sterling engines are not the only answer too.


"I would like to see what kind of performance one of these hybrid cars would turn in with the same engine, a standard 6 speed transmission, and all the weight from the hybrid garbage stripped off. They would definitely get better highway mileage, and my guess is that the around town figure wouldn't be hit too bad, since they are only marginally better anyway."

FYI: Several weeks ago a small group of enthusiasts filled the gas tank of a Prius and ran it to empty to see how good they could get their mileage. They got over 110 MPG. That's marginally better?

Sorry, but that's definitely bull. I am a Prius owner, and I love my car, but you're not going to get > 50MPG in any reasonable mix of realistic driving. Sure, I can drive it down from the top of Mt. Diablo in California and get >100MPG, but on normal streets, stop and go or highway, driving carefully, I've never seen a whole take average over 48MPG and I've been doing this for three years now.

Still, the Prius is a great car, and I'd say it gets about 20% better milage than any other car of it's size with similar performance charicteristics. That's not utopia, but it's not bad at all.

(And no, it's not about saving money, it's about using less oil, polluting less, and voting with my dollars for using technology to solve our oil/pollution problems)


Not bull at all. I get 60+ miles per gallon in "regular" driving. So just because you don't, doesn't mean it's not possible. I'll be happy to send you a picture of my consumption screen if you don't believe me. Right now it's reading 61.8 mpg with over 300 miles on this tankful.

In the 1990's I drove a Metro, which had a 1.0 litre 3 cylinder engine. I drove the hell out of it as is my habit. For th most part I got from 45 to 52 miles per gallon, based on a tank of gass used. Like I said I drove the hell out of it. The motor lasted 65,000 miles. The A/C compressor went out about the same time. I lived in Iowa at the time and the body did last the 100,000 miles promised. I bought it in 1990 and got rid of it in 2004. The second engine was still operating O'K. The body was still in terrific condition as I had never had an accident in this car. Well that is not entirely true as there was that time I was trying to cross a street and I was hit on the rear corner and I spun like a top. But still, the car was in great shape when I got rid of it in 2004.

Now here is my point, I'm sure the engine would have lasted much longer, if it had been combined in a hybrid scenario. The fuel economy would have been greater, but the cost of operation would not have been low enough to justify a hybrid scenario. If I were to use it in Southern California, It would have to have the A/C compressor replaced. Since I drive a lot in Southern California I see a lot of hybrids with thei windows down. If the air conditioner in on I have to believe the engine is running. This now defearts some of the benefits of the hybrid. So, Green has to be the major issue in building and using a hybrid at this time. It certainly is not one of efficiency. As someone suggest earlier the added cost of the car and my issue of the air conditioning, I can't see the benefit. Toyota suggests that their batteries will last 150,000 miles and they seldom say what the cost to replace is. This must be added to the cost of operation. Further, it was suggested on the Radio on Tuesday, November 6, 2007 that the real cost of gas is $15 dollars per gallon. This calculated in medical costs, taxes, artifically high price through the emotion of war. The cost of getting the oil out of the ground has stayed around 3-4 dollars per gallon. So what is the real problem here? Is it the managed cartel price of oil today? When the Democrats last left office the price of a gallon of gas was about $1.25 dollars per gallon. Forcast are for over $4.00 per gallon next year.

If you all want a soap box to get on why not get on this one. Predictions are that the war will now cost over 2.4 Trillion dollars. I know its hard to imagine, but do we have our priorities right?

In my first reply I said that the cost to get a gallon of oil out of the ground was 3-4 dollars per gallon...what I meant to say is that a 55 gallon barrel of oil cost 3-4 dollars at the well head. This means that a gallon of oil at the well head is about 0.07 cents based on 4 dollars to get it from the ground. Refining adds to the cost of gasoline as well as distribution.

So, when you hear any oil company executive or Republican defend the current administration, remember as George Carlin the comedian would say, "Bend over and spread your Cheeks." Be carelul if you are in the restroom at the airport in Minneapolis, though.

The cost to the oil company to get a barrel of oil out of the ground depends on several factors. In certain places, like Saudi Arabia, oil is fairly cheap to get out of the ground. The technology there is mature and the formations are easily accessible. However, easy oil is getting harder to find and more challenging fields will need to be developed in order to meet demand. Some of these fields require market prices at $60 a barrel or higher in order to be profitable. The point being that as oil reserves deplete (according to most of the accepted theories on oil formation) oil will get more expensive over time.

The current price for oil is inflated to a degree for many factors. However, the main reason oil is at a high price is because we and the rest of the world like to go places in our car that use diesel or gasoline. The only real way to decrease the cost of gasoline is to either increase supply, i.e. more drilling, or decrease demand through conservation. Likely both are necessary to prevent hardships. Exxon Mobil or Chevron cannot produce enough oil on American soil to meet American demands. Even if it could, supply and demand would determine the cost and not necessarily what it costs to get it out of the ground. When arguments are suggested that the price of gasoline should be based on the price of production without regard to market principals, then a national or state-owned oil company is what I hear. Venezuela for example offers gasoline to its people at $0.22 a gallon (or thereabout). Maybe socialism is a solution to this problem, but its one that I think the American people will find hard to accept.

The final report for this project is:

Ernst, William D. and Shaltens, Richard K. (1993), "Automotive Stirling Engine Development Project", Final Report, NASA Contractor Report 190780, MTI Report 91TR15

The Abstract, part of the Summary, the main headings from the Table of Contents and the Conclusions from this report are reproduced below.

The development and verification of automotive Stirling engine (ASE) component and system technology is described as it evolved through two experimental engine designs: the Mod I and the Mod II.

Engine operation and performance and endurance test results for the Mod I are summarized. Mod II engine and component development progress is traced from the original design through hardware development, laboratory test, and vehicle installation. More than 21,000 hr. of testing were accomplished, including 4800 hr. with vehicles that were driven more than 59,000 miles. Mod II engine dynamometer tests demonstrated that the engine system configuration had accomplished its performance goals for power (60 kW) and efficiency (38.5%) to within a few percent. Tests with the Mod II engine installed in a delivery van demonstrated combined metro-highway fuel economy improvements consistent with engine performance goals and the potential for low emission levels. A modified version of the Mod II has been identified as a manufacturable design for an ASE.

As part of the ASE project, the Industry Test and Evaluation Program (ITEP), NASA Technology Utilization (TU) project, and the industry-funded Stirling Natural Gas Engine program were undertaken to transfer ASE technology to end users. The results of these technology transfer efforts are also summarized.

SUMMARY (partial)
The objectives of the Automotive Stirling Engine (ASE) Development project were to transfer European Stirling engine technology to the United States and develop an ASE that would demonstrate 30% improvement in combined metro-highway fuel economy over a comparable spark ignition (SI) engine in the same production vehicle. In addition, the ASE should demonstrate the potential for reduced emissions levels while maintaining the performance characteristics of SI engines.

Mechanical Technology Incorporated (MTI) developed the ASE in an evolutionary manner, starting with the test and evaluation of an existing stationary Stirling engine and proceeding through two experimental engine designs: the Mod I and the Mod II. Engine technology development resulted in elimination of strategic materials, increased power density, higher temperature and efficiency operation, reduced system complexity, long-life seals, and low-cost manufacturing designs. ..........................

(The remaining part of the summary contains essentially the same material that is contained in the abstract)


This final report has summarized work performed in the ASE project. The project's success can be determined by comparing accomplishments to the defined project goals and contract requirements. In so doing, the following conclusions can be made:

The potential for improvement in fuel economy for Stirling engines over SI engines has been demonstrated. A 10 to 13% improvement in fuel economy for the Mod II over the SI engine has been demonstrated for the USPS LLV in the EPA driving cycle. Based on test data obtained with the LLV, if the original Mod II Celebrity vehicle had been retained for fuel economy demonstration, the project goal of a 30% improvement could have been achieved. The Mod II engine had been sized and optimized for the Celebrity. Component optimization would also provide further improvements for USPS LLV fuel economy.
The potential for low emissions has been demonstrated in the Mod II engine: CO=<2.2 g/mi, NOx=<0.9 g/mi, and HC=<0.4 g/mi with gasoline. The 1985 Federal emission limits were easily met without using a catalyst.
The ability to operate on a broad range of liquid fuels was demonstrated. This evaluation was achieved not only in an engine test cell but also in vehicle operation.
Measured Mod II SES [Stirling Engine System] power and efficiency performance was in excellent agreement with analytical projections, i.e., the differences were less than 4% in power and less than 1% in efficiency.
Vehicle performance of a Stirling engine can be predicted from engine dynamometer test results. The Mod II-powered USPS LLV prediction of a 10% fuel economy improvement in the EPA driving cycle over the comparable SI-powered vehicle was verified by experiment.
A manufacturable Stirling engine automotive design has been identified under the project. The engine is the Mod II (V-block design with annular heater head) concept modified per the Deere & Co. VA/VE study. Manufacturing costs of $3500 to $4000 were projected by Deere & Co. for commercial production of 15,000 units per year.
In accomplishing the objective of transferring European Stirling engine technology to the United States, the ASE project succeeded in establishing an extensive U.S. technology and vendor base capable of designing, developing, and commmercializing Stirling engines. As a further indication of successful technology transfer, MTI, along with a gas industry consortium (GRI, NYGAS, and others) and Hercules Engines, Inc. of Canton, Ohio, is developing a commercial Stirling engine based on ASE technology developed in the Stirling Natural Gas Engine Program.
The NASA TU project demonstrated the ability of a Stirling-powered vehicle to be operated over the road by non-Stirling personnel; it demonstrated adequate availability and drivability.

The above report is for sale by the National Technical Information Service, Springfield, Virginia 22161

Last updated: Wednesday, May 3, 1995

"Which takes us back to the problem with hybrid car in the first place: The electric part.
Electric cars are a bad idea. They are heavy and slow. In order to have any
performance at all the chassis must be kept as light as possible, which makes them
unsafe in accidents, considering all the weight that is tied up in batteries"

This is a common misunderstanding. But completely wrong! Hybrids aren't necessarely slow. On the contrary. Combining the huge zero rpm torque of electromotors with the excellent high rpm performance of ICE's can give really quick cars. As proven by Dr Frank of the University of California in Davis. (see or various other internet sources)
The latest vehicle, Yosemite, a Ford Explorer converted to a 1.9L ICE with electromotors, outperformes a BMW X5 4.4 V8, on speed AND on fuel economy!!!

Removing the heavy ICE and replacing it by a smaller, lighter one helps a lot. Electromotors and battery packs can be made small and light as well nowadays. Don't base your judgement on hybrids on biasses, but on facts please.
As for crash safety, you can see that the weight gain isn't that high at all, and if a bigbucks car manufacturer would invest in this technology you would see the mass going down real quick as well. Besides, mounting bigger brake discs and calipers solved that for the UCD vehicles.

Q: If Stirling engines are so efficient, why don't I have one in my car?

A: The best answer for that is to pick the MM-1 engine up after it gets up to speed. Notice that it keeps running for a minute or so. While it's very easy to build a Stirling engine that will stop instantly, there is not one thing in the world anyone can do to make one start instantly. When I get in my car I want it to start immediately (if not sooner) and be able to burn rubber off the tires as I leave the parking lot! Stirling engines can't do that. In spite of these limitations, Ford, GM, and 1979 AMC SpiritAmerican Motors Corp. spent millions of dollars developing Stirling engines for cars, back in the 1970's. Ford even built a Stirling that could drive away from the curb (with relatively low power) twenty seconds after you turned the start key! Many prototypes were built and tested. Then oil prices came down in the 1980's, and people started to buy bigger cars. Suddenly there was no compelling reason to build an engine that was substantially more efficient than internal combustion engines, but wouldn't start instantly. Here is a picture of a 1979 AMC Spirit. It was equipped with an experimental Stirling engine powerplant called the "P-40". The Spirit was capable of burning gasoline, diesel, or gasohol. The P-40 Stirling engine promised less pollution, 30% better mileage, and the same level of performance as the car's standard internal combustion engine. [From "An Introduction to Stirling Engines"] The French Research Sub Saga is Stirling engine powered. Stirling engines also work exceptionally well as auxiliary power generators/heaters on yachts (see Victron Energy.), where their silence is valued and good cooling water is available. They would also work very well in airplanes where the air gets colder as the plane climbs to altitude. There is no aircraft power plant (jets included) that gets any improvement in any operating conditions from climbing. Stirling engines won't lose as much power as they climb as do either piston engines or jets. Also wouldn't you like to have silent airplanes with very efficient engines that also have exceedingly low vibration levels?

"Do your self a favor, get a VW diesel Jetta- it's
bigger, more comfortable, and will turn in better highway mileage."

The Prius runs on gasoline. You are comparing apples and oranges. Diesel is a more compact fuel than gasoline. It weighs more per litre, pollutes more per litre (CO2) and contains more energy per litre. In each case around 10-15%. You should therefore NEVER compare diesel and gasoline mileages without applying this correction. I'm sure the Prius wins after multiplying the Jetta's consumption by 1.12.

However it won't beat the VW Lupo 3l or Audi A2, though. Reality is that diesel engines are much more efficient than gasoline engines. It's just not as much as it seems when you simply compare mileages. You should always take the basic properties of different types of fuel into account.

It should, the jetta is twice its size with 3x as many luxuries and will bomb down the freeway at 100+ mph without breaking a sweat. If the prius didn't beat a gasoline powered jetta in MPG, something would be seriously wrong.

FWIW, even disregarding differences in fuel, the diesel cycle has inherently higher thermal efficiency then otto / gasoline cycle. Combine that with higher energy fuel and of course the MPG is better. Plus, the VW tdi is actually quite a good diesel.

We don't have any of the smaller VW / Audi cars available to us here in america though, the Jetta / Gti is as small as it gets. I agree though, if city driving is not a priority, the jetta / gti will kill the prius in every category except for what comes out of the tailpipe.

On the other hand, one could easily make the same arguement, because the jetta doesn't have (lots) of li-ion or lead acid batteries to deal with when it's junk. Lithium mining is not exactly "green"....

See here for two diesel hybrids.
Hybrids fundamentally make sense, and diesel hybrids make even more sense.
So reiterating what others have already stated.

Petrol vs diesel is a valid comparison.
Hybrid vs non hybrid also.
But Hybrid vs diesel doesn't make sense when you can have diesel hybrids.

Sometimes the comparison is valid: if you're comparing cost. Especially since in many countries
diesel costs about 10--15% less per litre than petrol (the road tax is higher, but it is a net savings
if one drives as much as the typical diesel owner) and also biodiesel is available which is even cheaper.

So is it not even possible for a stirling to drive a generator with enough power to run an electric motor at car-friendly levels? The 37" Wide Solar Dishes from SES are boasting an electrical output to power a house for a year. Wouldn't this be good enough?

I keep wanting to research this or at least do a mathmatical model but I don't really have the time or resources to devote to it.

I think it is obvious that an engine has to be designed to capture the explosion and the heat, both. everyone can stop comparing heat and otto. Both must be utilized and one engine can do it. By the way I worked for a time at the largest small engine manufacturer in the US. I have a design that acomplishes this by the way. I need to find backing. andy

"For going down the highway, nothing that you add in the way of electric motors and
batteries will help squat. They will hurt, actually. For highway driving, the most
efficient arrangement that you could imagine would be to have the driving wheel bolted
to the crankshaft without even a transmission (this is impossible for a number of
reasons...) Where the hybrid cars make up is in the possibility of having regenerative
braking. I knew a person who was considering a hybrid and I asked them, "How often
do you push on the brakes?" For this person, hardly ever, as most of their mileage was
commuting to town from the suburbs. "Do your self a favor, get a VW diesel Jetta- it's
bigger, more comfortable, and will turn in better highway mileage.""

My father has a prius which I have driven on the occasion. I am not an engineer, but I would be suprised if the hybrid system did'nt at least pull it's own weight (so to speak) even on the highway. What you are saying might apply driving on a perfectly flat stretch of highway at constant speed, but those conditions are rare in the real world. Even going down a sligh incline at 70 mph, the engine will cut out and regenerative braking kicks in. I burned a couple of tanks of gas cummuting between Denver and boulder this december with snow tires and got between 47 and 50 mpg overall, and usually between 45 and 75 on the highway.

The diesel vs. hybrid argument is a red herring; one is a kind of fuel, and the other is a kind of powertrain. You can but the two together and get even better mpg than either one alone. But switching en masse from gas to diesel isn't going to solve our oil dependency. When we refine oil we don't get to choose whether we turn 100% of it into diesel or 100% to gasoline; the ratio is pretty much fixed. And if we ever have to depend on biodiesel, it will probably all be going to trucking, public transit, and the military, not vw jettas.

"Which takes us back to the problem with hybrid car in the first place: The electric part.
Electric cars are a bad idea. They are heavy and slow. In order to have any
performance at all the chassis must be kept as light as possible, which makes them
unsafe in accidents, considering all the weight that is tied up in batteries. When the
vehicle stops, the batteries are going to keep right on going. And while there is no
emission at the vehicle, that electricity had to come from somewhere, and that means
fossil fuels and so forth. It boggles my mind that �environmentalists� think that driving
around in cars that have over half their weight tied up in expensive, fragile, plastic
boxes that are filled with toxic chemicals and heavy metals is a good idea!! Or that
people concerned with efficiency would think that it was a good idea to add weight or
changes of energy states to a moving vehicle."

The prius and other hybrids aren't really electric cars; they are gasoline cars with motor generator or two built into the transmission. They do add some weight but not an astronomical amaount. The batteries in the Prius are small enough to fit under the back seat and still allow the back seat to fold down flat. In hybrid cars the batteries are really just big enough to act as a buffer to store energy from braking and allow the internal combustion engine to run at it's most efficient output.

> First off, no one has addressed the primary problem with this concept which is that
Stirling engines are not efficient at all!

This is positively false, and provably so.

What you MEANT to say is:

"No one has addressed the power density problem. While Stirling engines are more power efficient than other engines, they are larger, heavier, and generally more bulky than their internal combustion equivalents, for any equal amount of power. For use as a prime mover in an automotive application, these factors weigh against customer satisfaction."

This is why Stirlings excel at charging batteries, rather than running the drive train. Let the batteries handle the peak power moments. That's why they're there.

Batteries don't care about power (energy delivered per unit of time) -- they only care about the amount of energy you deposit in them. Hence, a Stirling engine can be spec'ed out to be MUCH SMALLER than the internal combustion engine of your choice, because you really only want it to supply the AVERAGE power needed to actually drive the car. The engine *CAN* still run while you're sitting at a red light, or when you're parking the car, to recharge the batteries for your future peak-draw needs.

No one seems to have mentioned the Whispergen unit yet...

Whispertech, a New Zealand company has signed a huge contract with Powergen in the U.K. to bring the units into homes in large numbers this year (2005).

Trials in the U.K. have gone well with an average of 20% saving on C02 emissions, and 20% off the power bill for the home owner too. This is compared to the running costs an average gas boiler.

Whispertech's DC unit, intended for use on boats or remote locations, is being used in antarctica now and seems to be a great improvement from their old generator.

Whispergen in Antarctica:

Here's Whispertech's website:


Yes, Yes. The Whispergen is a cool unit no doubt. And in a co-generation setup, where you can use the ample waste heat, it makes sense.

The dc unit (like one would use in a yacht) burns .75 liter/hour to make 800 watts.

A yanmar marine 2200 watt generator burns .79 liter/hour at a full load of 1900 watts.

The 800 watt figure that Whispergen quotes is "modulated watts" whatever that is supposed to mean. Sounds like its surge output to me. But even if it is its continuous output that still means it burns TWICE the fuel per watt output.

These things definitely have a place in the energy scheme, but only where the horrible thermal efficiency can be offset by using the waste heat for something else. I would LOVE to have a heater in my house that had the by-product of producing a couple hundred watts of electricity!!


A heater doesn't produce waste heat. You would just be decreasing the efficiency of your heater.

There's High-end Heat, and there's Low-end heat. The High-end heat should be put to work making energy-intensive electricity, and the remaining "warm" heat could then be used to heat the home. This is an excellent method of using energy, as it puts valuable fuel to work making valuable electricity, and then uses the waste heat for home/office/business heating needs. considering that electric is only about 10% efficient (from coal to outlet), and all the waste heat down at the power plant has to be "spilled" into the environment (heating the air or water around the plant), it makes much more sense to generate electricity right where it's needed, and put the waste heat to good use as well. Sure, the heater then is slightly less efficient, but the gain overall from these types of systems is enormous! I am considering creating a producer gas run system along these lines - one of the possibilities would be using a heat engine genset to extract valuable electricity for home use.

I have driven a Stirling engine car built by MTI technologies. It was a nice drive an had about the same output as an IC engine. I also managed an army project to build a stirling generator. The big problem with Stirling engines is NOT power but rather sealing of the unit and to a lesser degree hydorgen embrittlement. I doubt the sealing issue will ever really be resolved. The power efficiencies mentioned above are overcome by pressurizing the gas inside the engine. The gas used in most cases is hydrogen or helium, the low molecular weight makes these gasses very insideous. that is, they can penetrate just about anything very easily. That makes it hard to seal a pressurized charge inside the engine. Further, the gas infuses into the surrounding metals and changes their characteristics. This can be overcome, but the sealing issue....

For those who may have thought the sealing problems of Stirling engines would never be solved, I have solved it! along with the few remaining critical problems with these engines. The simplicity of my device is deafening and my intention is to give all Stirling engines a huge kick in the ass. On a much humbler note I need to figure out who needs to see it first and how to get their attention before the deadline on my provisional patent app. comes due.

How about putting the engine in a chamber and pressurizing this chamber to the higher possible pressure in the cylinders? I think the chamber along with a small compressor to compensate pressure leaks could solve the problem.


Do you have any references or links? More info please! So was the Stirling engine in
this car able to rev up and down quickly? If not, what sort of transmission was used to
accommodate the constant engine speed? Was it based on any production car? What
fuel did it burn, and how much of it per mile? Also how did the army project work out?

All of the production engines that I referenced ARE pressurized. Some with helium and
some with air, all around 100-150psi, and none make that much power per pound.
How much pressure is required to get this power density that rivals IC engines?
Certainly not more than the 2500 psi that the helium cylinder that the local Pizza Joint
uses to blow up balloons for kids. These cylinders reliably hold a lot of helium for a
long time at IMMENSE pressure. The biggest sealing issue with an engine is the
output shaft, even if air is the working gas. The engines that use air as the working gas
generally have a built in air compressor to maintain the working pressure. Many of the
engines that use helium are used for generating electricity (check out
and have the alternator hermetically sealed within the engine, eliminating sealing
issues; no output shaft.

Early refrigerators had the same sealing issues. If you have ever looked at your fridge
“inside” you will notice that the compressor is hermetically sealed. A very simple and
effective solution to holding a light gas for a long time.

If anyone has any tangible reference to an auto that has been powered with a Stirling
engine I would greatly appreciate this information. I have searched long, far, and wide,
in libraries, book stores, on the internet, and my in giant cache of engineering
textbooks with publishing dates from the 1900's to the present, and have found no
tangible information.

Thanks in advance for any info. Also I’d like to give my mantra, “Think for yourself.”
Don’t take anyone’s word for it, especially not mine--for all you know I’m as big a quack
as the next guy! Do the research, and draw your own conclusions.


I read about "hydrogen migration" many years ago from a reort at Brookhaven National Lab. It is one of the problems in storing hydrogen, and was investigated when one of the Brooklyn Bridge cables snapped (thought perhaps made brittle by hydrogen from pigeon droppings). I enjoyed this discussion, and found a link to a report of the Swedish Sterling sub being used by the US (which only has one non-nuclear sub "Dolphin" in a terrible accident in 2002) in San Diego sometime this year in detection training ( I used to drive a rotary (Mazda RX4) which had a "thermal reactor" rather than a catalytic convertor, a heat chamber that created fewer emissions by burning them (again). Perhaps, there's something there for a Stirling device, after a turbo (which compresses intake air w/ exhaust pressure) that could provide additional energy in say in a colder clime like Antarctica? New snow tractor maybe.

I have two points. 1: Competition involving wealthy (powerful?)corporate and industry factions love central control and counting beans for determined policy. Alternative energy tends to be de-centralizing. 2:I've read reference in these posts to heat sources in an auto system ie; radiator, exhaust etc. I haven't seen the mention of the Catalytic Converter... Doesn't a converter produce viable heat for a source?

I had a thought about the use of a stirling engine as either a power source or suplimental power source in a hybrid or fuel cell vehicle, it plays to the strengths while minimizing the weaknesses.

Most the hydrogen vehicle prototype I've read about use liquid hydrogen or compressed hydrogen gas (which comes out very very cold).

Now, side note: "cryogenic engine" running on liquid nitrogen has been proposed and one was even built (on shoestring budget, but it did work)

Now, apply this concept to hydrogen and surplus heat from a fuel cell or IC or even from a hydrogen burner. No bulky cooling system required, free cooling from the fuel! A combination stirling / steam engine could be built to use the recoup the energy required to compress the hydrogen in the first place.

Could someone give me feedback on this?

Why did no-one mention the linear stirlings, completely sealed, using air-bearings? They have rated efficiencies around 30%, and are very compact, is there something I am missing about them?


Theoreticaly speaking it is the best idea proposed on this blog. A cryogenic heat sink could use heat from a source at 220F very efficiently. However, it would require two high pressure, cryogenic fluid conducting circuits with some fairly serious heat exchangers. I am sure it can be done, but at what cost and how much extra wieght would it add. I would love to work with you on some ideas for implementation.


I agree that this is a very clever idea and it could be combined with the ideas behind the liquid air powered vehicle you mention.

You start of with liquid hydrogen. The liquid Hydrogen is used to cool a stirling engine, which boils it and turns it into gas. ~The heated hydrogen is then run through a cyro motor of the type described as running on liquid air. It is then burned to heat the hot end of the sterling engine. The stirling engine is of the free piston linear type and charges the battery. Very difficult to vary the power out put from this type of sterling engine so it is a good candidate for a hybrid. The temperature difference between liquid hydrogen and burning hydrogen is enough to allow the Stirling engine to be compact. The gas pressure engine output would be easier to vary and this could be an advantage. So by burning the hydrogen one would be drawing on the stored energy consequent on making the Hydrogen, and by boiling it one would be drawing on the stored energy consequent on liquifying it.

I do not see a problem with using stirling engines in hybrids. granted my knowledge of real life sterlings is very limited, but I dont see why a sterling engine couldnt be retro fitted to gasoline/electric hybrids to reclaim heat produced by the gas engine, electric motor, and bateries. Perhaps via the conventional cooling systems. would 160-190 degrees F be sufficient?
that would make for a 65F-210F difference (here in wisconsin). I think it would be both practical and efficient to harness lost heat to RE-CHARGE the batteries, but not to drive the car.

Here's the challenge... Stirling engines are wonderful, and very efficient and all that, but they are BIG, so they have a very poor power/weight ratio. You would need an engine almost as big as your car to power your car. ;o)

First in a response to Sean Lynch at June 3, 2004 04:45 PM "It uses a Miller cycle engine"
The engine cycle is actually called a Atkinson cycle the turbo-charged/super-charged version is a Miller cycle.
These new power sources are still in their infancy when compared to the Otto cycle while similar in actual age the research done on them is limited.
But the Sterling engine is not suited for transportation power simply because of it’s bulk and expense.

a link to info about General motors electric sterling hybrid

In 1969 GM introduced to the world through its Opel division the Stirlec1, an experimental prototype conversion of its most popular European vehicle. It was equipped with a Stirling engine and an electric drive train, what we now call a series hybrid. It was said to be able to get 84 miles to the gallon and produce minimal emissions. You don’t have to believe me you can see it for yourself.See

a link to info about General motors electric sterling hybrid

"But the Stirlingengine is not suited"

I need to address some of the people pointing to agro-fuels/biomass conversion as the energy source of the future and aid them in understanding the amount of land needed to produce the amount of fuel required for the transportation sector. Even with our most efficient crops, producing 10 percent of the nation’s energy through biomass would require doubling the amount of our land being farmed. Total biomass reliance would mandate at least a 20-fold increase in farmland. Where are we going to find the topsoil, water, fertilizer, and human labor to grow that much crop? I'm not saying that some of our vehicles couldn’t use biofuels but not any substantial amount.

Our best hope for our future is to have a wide range of fuel efficient options and places to refill these at a reasonable cost.

According to the USDA 19% of U.S. land mass is currently in use for crop production and 41% is used for farming in total including grazing. Large areas of the rest go to cities, housing, arid southwest and frozen Alaskan tundra unsuitable for growing crops. It is not possible to simply replace current oil consumption by growing crops for biofuels. Solar and unfortunately nuclear will be used more. Changing our design of buildings and methods of transportation so that we stop being energy hogs must also be part of the answer. Passive solar building design is a big part of the solution.

I have enjoyed reading the comments here about Sterling engines. You might be interested in another hot air engine: The Afterburning Ericsson Cycle Engine, developed by Proe Power Systems.

In response to Brenton's post about biomass fuels. Biodiesel made from algae could be the answer. There is a type of saltwater algae that is 50% oil that grows well in saltwater ponds.

If aqueducts were built to supply ocean water from the Pacific Ocean to the deserts of the Southwestern USA, then millions of acres of unused land in the deserts could be "farmed" to produce biodiesel on a large scale.

You can read about this on the American Energy Independence website:

Overlooked in mnay discussions about efficiency is the cost of efficiency- it sounds a little backwards, but suppose you could devise a new engine design, I don't care what- IC, Stirling, Biodiesel with or without coupling to electric drives, only to find that in order to achieve the fantastic efficiency, a by product of the process was the need to use large quantites of Dioxin, or lead, or some other contaminant. Or we required the use of strategic metals that are avaialable only from hostile countries. What is the MTBF of the complete life cycle for each system? Cost of repair?
What if instead, we recognize that the cost of using internal combustion for commuting purposes isn't just the cost at the pump, it includes the cost of insurance, both automotive and medical, the cost of maintenance, both of the vehicle and the road infrastructure and the cost of lost working hours in gridlock.
What if I proposed that for those of us who daily commute to an office, wherein we sit at a computer in whatever capacity for the duration of the workday, we work from home? We have broadband capability now that never existed so cheaply before and it is improving. We can videoconference and conduct transactions, do research and report results with unprecedented capacity. It would reduce the demand for any form of automotive fuel, it would create savings in all the categories I mentioned above and have the added dimension of putting our homes to work, keeping kids with parents instead of daycare and doubtless other savings I can't enumerate here.

Trackback from The Underground Economist:I think not. My comment started out as a short mention that Stirling engines have low power density and don't have boilers, but one thing led to another and it ended up larger than Brad's post. Brad has some good ideas on his site. I particularly like ...

I am planning to do a science fair project on Stirling Engines and needed some input on the Stirling on a hybrid format. What people said was that there was a pickup problem for a Stirling in cars. Somebody suggested that the battery be used until the Stirling be warmed up and then fire the Stirling. I've researched on that a little bit and I realized that there was a problem: the Stirling is a constant speed machine, it isn't easy to alter the RPM without adding complexity that makes a normal gasoline four-stroke engine more practical. How about this: the when you start your car, the battery is already charged to some extent. You use the power from it to run the car until the Stirling heats up, but here's the catch: once the Stirling warms up, you can use it to recharge the battery while it is still running on optimum RPM, and the battery is the thing still being used to run the car. Now people said that fuel requirements/HP also are a problem in an automotive application. I don't really understand. Can somebody help me out? Thanks.

People thinking about stirling engines should be careful to differentiate between crank type stirlings and free piston stirlings. They are very different. For example, the free piston can go from zero power to full power in a few cycles, say 1/20 of a second. And back again just as fast. Free pistons have live times between overhaul of many tens of thousands of hours, and cranks are still trying to get a few thousand hours. To learn more, go to

Clipped from a recent news article ( )

University of California, Davis engineering professor Andy Frank built a plug-in hybrid from the ground up in 1972 and has since built seven others, one of which gets up to 250 mpg. They were converted from non-hybrids, including a Ford Taurus and Chevrolet Suburban.

Frank has spent $150,000 to $250,000 in research costs on each car, but believes automakers could mass-produce them by adding just $6,000 to each vehicle's price tag.

Several individuals/companys are able to create cars that can travel 250 miles on a gallon of gas, but are required to be plugged in at the end of the day. Couldn't we keep this capability, but add Stirling technogy to assist in the charging of the batteries when the car is at rest? By this, collect the heat from as many sources as possible during rest; turn the roof and trunk into solar collectors, use the raditor and exhaust pipe heat. If you go to mall and stay an hour or two, you car is fully charged when you leave. Drive to work on a sunny day, charged. If the heat sources are not available, plug in.

Funny that you mention Dr Frank and his work. I've been working as a student for him this spring and have to admit I was impressed by his work. Plugging in your hybrid has so much benefits above the 'common' hybrid yet available. All the electricity in the Prius is still generated by burning good 'ol gasoline. That isn't the most efficient way. Besides, the plug-in's made by the UCD are also outperfoming the vehicles they're based on. The Ford Explorer (Yosimite) is actually faster then the stock 5.0 V8 AND is more fuel efficient then a midsize saloon. Go figure.
The only thing that I would suggest as an improvement is replacing the ICE used now by a hydrogen/gasoline hybrid ICE as built by BMW for example. That would mean you could drive electrical from the grid, have the ICE if extra performance or charging is needed, and this ICE could run on either hydrogen or gasoline. And actually Davis has one of the hydrogen refuelling stations as part of the californian hydrogen highway.
So okay, sorry, no Stirling, but I just couldn't resist this opportunity to give my suggestion for the optimal solution to our little 'running-out-of-gasoline' problem.

Remember, all this technology is available already, it only has to be combined into one vehicle.
The Stirling has to be improved largely before you will be able to make a realistic prototype vehicle, and for what? Even if you get to make it work efficient on bio-fuels, where does all the biomass come from? I mean even ICE's can be make to work on bio-fuel (saab is already selling cars running on bio-ethanol, with factory warranty) but if all cars and trucks in this world would run on biomass, you'll need enormuous amounts of woods or fields to get all the biomass from. At this point we aren't even able to feed Africa, and you think we will be able to feed our cars?
Hydrogen on the other end can be produced from electricity, which can be generated by all kinds of renewable energy sources. (or even nuclear power) If we start investing big time in renewable energy, i guess that huge technological improvements can be made. If you see what an ingenuity we can come up with to suck the last remainders of oil out of this planet....

Don't normally comment on wep pages etc. But would like to pose an aparently new direction for Stirling threads. Solutions come from thinking outside the box. I.E. yes Steriling engines are cumbersome
if your attempting direct replacement for 6.0 liter V8. The purpose of this comment is to add that in order for Stirling to be effective ALL of it's positive attributes need to be exploited. Here is one scenereo.
The NASA stirling engine project produced a successful "power plant".
It consists of inline pistons shuttling back and forth with Stator
of Electric generator placed between pistons. (one moving mass) The entire unit is then hemerically sealed. Therefore heat energy goes in and electrtical power comes out. NASA's intent was thier Stirling keep going in Space for months/years. Such a device in miniture could be gathering power off waste heat of IC engine. For Automotive Hybred the I.C. engine or Diesel may be downsized, All the electrical power could be run off batteries charged by Stirling. All of the IC power robbed by Alternator, Water pump and A/C which are best operated at constant
speed run off battery/Sterling generator. How does this help? Think
of small Kerosene burner (Secondary fuel?) keeping stirling running
while automoble sat in garage (vented) or parking place. A small unit
run over long periods could generate barrey charge PLUS. Toss in an
AC inverter and one could light your home or run your PC. No warm up just get in and go. Just some thoughts.

One possibility is to use a phase change material to store some of the thermal "power" for the engine. One could even build a collector on the vehicle for situations where you need more thermal difference to make it work better.

As a phase change material stores energy in the chemical bonds as well as the material temperature, you wind up with far more time at the temperature that you can use to propel the vehicle. A side benefit is that you can construct a passive collector on roadsides, eliminating the running out of gas problem up to a point. You can also make a smaller variant of the same passive system, using the roof and possibly included reflector panels to store the heat. Although charging would be slower in the winter, it could be designed to operate like a trickle charger.

In theory, you could even have something like a solar closet with a nook for the canisters, providing a means of quick charge on days with lots of sunshine, or a limited amount of extra "fuel" on cloudy days.

In addition, the worst that paraffin does if it leaks is annoy people. And paraffin is an example of a phase change material.

I imagine if extreme efficiency was possible to achieve in a cost effective, short time frame it would help the oil debacle some, but I recently read, that if everyone in the us bought a hybred today that in 6 years we would be back to where we are today, considering the spiral in fossel fuel use worldwide. That is also considering the current mpg of the hybred vehicles. Although Hydrogen is some years off, I suspect someone will develop a cost effective method of in situ separation and eliminate the need for mass storage. If this ever happens , it won't matter much what engine we use.

Someone mentioned that on a network news clip just a short time ago a pickup was running on the gasification of wood pellets. Did anyone see that? I missed it, dang....JB

The old Mother Earth Magazines have articles on burnig wood to run cars and trucks. It's old technology us in wartime Europe when gas was extremely scarce


I just came across an article that talks about Vortex Tubes. Since a Vortex Tube generates Hot and Cold are from Compress air, and a Sterling Engine need hot and cold to operate. I was wondering if anyone has ever tried to combine both of the technologies.

Many of you have probably seen the Air powered car available in Europe. Nice idea, but seems pretty limiting. Here is a slight variation I came up with...

Use an air tank to store pressurized air in a car equiped with an undersized (but toughly built) engine... say a 80hp motor in a small car typical equiped for 120Hp. When we need that extra acceleration the air is fed into the intake creating a "temporary blower" effect allowing the engine to produce significantly more Hp for its size.

Why do this - Batteries are expensive and wear out. Depending on how this is designed (with a small controlled compressor) it may also be possible to create a "regenerative braking" effect by running the compressor while slowing down. You could also likely improve normal Hp efficiency by using the pressure to limit into manifold suction (of course fuel mixture control needs to be compensated along the way... a solvable problem). Incremental costs of this Hybrid would be low compared to the $6-8K battery packs currently in use.

Why Not - I suspect the biggest draw back is polution when running your "blower". Engines are less efficient near peak outputs, but if considering the lower emissions normally from a smaller engine this may play out to be a savings.

Seems like a cheap way to get us from 30 up to 40+ miles per gallon...

There exists research on this.
Check out these links:

Sorry if this is a bit off subject for Stirling engines, but many other posts have also wandered.
Around 10 years ago on British TV, a science programme (Tomorrow's World) featured a new layout for a piston ic engine which was vastly more efficient than our regular car engines. I have searched for details since, but without success.
The inventor stated that a conventional petrol (gasoline) engine is an explosion engine, as compared to a diesel, which is a slow burn expansion engine. (Please do not take me to task on these descriptions, the logic will fall into place.) With the gasoline engine, most of the power of the explosion is wasted attempting to compress the solid piston/con rod/crankshaft assembly and only after a considerable amount of crankshaft rotation, the expanding gases exert a turning force on the crankshaft.
The proposed engine (which had been built and tested) used a different layout, the exact details of which I cannot recollect, but I will attempt to describe here. The intention was to have the explosion take place as usual, with the piston at the top of it's stroke, but with the crankshaft already at 90 degrees, thus using the force of the explosion at the greatest mechanical advantage. The engine was mounted in a British compact car which would normally do around 38/40 miles per Imperial gallon. The test car gave 135mpg!
The engine layout was a conventional piston in a cylinder, but instead of the con rod linking to the crank, it was connected to a crosshead slide. This crosshead contained an internal gear ring (similar to the gear inside a Wankel rotor) and then the crux of the engine, which I cannot recollect in detail, was the drive from this crosshead gear, to an otherwise conventional crankshaft. The resultant effect was somewhat similar to that of the Scotch yoke of the Bourke engine, except that with the piston at "TDC" the crankpin was definitely at 90 degrees.
Assuming that someone can visualise the principle from my description, does anyone have any information on this engine? I would not be surprised if the patent has been bought up, simply to keep the engine out of production, as it would not be in the interest of Big Oil to cut our fuel consumption by so much. The inventor was negotiating to build a plant in Northern Ireland for the production of a car with this engine and composite bodywork that reforms it's shape after minor accidents.
The bodywork came to light again on a Leyland or MG Rover concept car after a few years, but the engine has not been heard of since.
Food for thought, surely, using the explosion rather than only the expansion of the combustion gases. In a turbine, the impulse (high pressure) stages are more efficient than the expansion stages.
Please note: I am not a mechanical engineer, so please do not crucify me on details!
Hope someone somewhere knows something.

I am not sure, but it sounds like you are talking about an Atkinson engine cycle.
You can see an animated version of that engine at:

Maybe it is a good idea to try to contact the BBC with your question. I don't know if anybody ever built a working prototype car with this engine type.
Toyota is claiming their Prius II has an Atkinson type engine, but that engine is just an normal Yaris/Echo Ottotype engine, but with altered valve opening times. The exhaust valve is still open when the intake valve opens, making the fresh fuel mixture push out the last bits of burned fumes. That's just a small part of the Atkinson principle.
Anyway, I think the engine concept you are discussing above is an Atkinson engine.
Anybody else?

once i found this site on the net about a quatro turbine engine that was very good, it was rotary (like the wankel) and ran on anything.But i havent found it again.

Did you mean this?

I was a partner with MTI of Albany and H-Power of ? New Jersey and I
worked with Dr. Bill Ernst and Joe Maceda of H-Power on a proposal to NYSERDA to package an H-Power proton exchange fuel cell with my Hydristor in a 10 passenger Chevy Lumina. The Hydristor was to provide the infinitely variable drive train using counter turning, pitch and roll gimballed flywheels spinning in the yaw axis. MTI's Stirling was not involved in this package. Nyserda approved the proposal but ultimately there was no state money. MTI had developed
an automotive Stirling running on a half dozen, switchable fuels and
I got to drive that truck once. It was not very quick, but it was quiet. My approach is to feed low grade makeup energy such as from a Stirling into a combination of flywheel kinetic storage and hydraulic
accumulator energy storage. That way, the Hydristor can directly handle several thousand road horsepower to/from the flywheels, and the Hydristor can very efficiently mix the longer and somewhat less
peaky hydraulic stored energy to give blazing performance and very high mileage on the road. Check out the word 'Hydristor' on Google.
ps: there would be no warmup issue with my system. If anybody wants to call me, my number is 607-7631607 USA-EST
Tom Kasmer

Hydrogen powered stirling hybrid
Submitted by David Barry (not verified) on Thu, 2006-05-04 03:12.
I agree that this is a very clever idea and it could be combined with the ideas behind the liquid air powered vehicle you mention.

You start of with liquid hydrogen. The liquid Hydrogen is used to cool a stirling engine, which boils it and turns it into gas. ~The heated hydrogen is then run through a cyro motor of the type described as running on liquid air. It is then burned to heat the hot end of the sterling engine. The stirling engine is of the free piston linear type and charges the battery. Very difficult to vary the power out put from this type of sterling engine so it is a good candidate for a hybrid. The temperature difference between liquid hydrogen and burning hydrogen is enough to allow the Stirling engine to be compact. The gas pressure engine output would be easier to vary and this could be an advantage. So by burning the hydrogen one would be drawing on the stored energy consequent on making the Hydrogen, and by boiling it one would be drawing on the stored energy consequent on liquifying it.

If these get combined in a single vehicle we gwt a fast excelerating sterling hydrogen powered car with no polution. posibly powered by a home solar/geothermial powered sterling powerplant/hydrogen compresser.

I was a partner with MTI of Albany and H-Power of ? New Jersey and I
worked with Dr. Bill Ernst and Joe Maceda of H-Power on a proposal to NYSERDA to package an H-Power proton exchange fuel cell with my Hydristor in a 10 passenger Chevy Lumina. The Hydristor was to provide the infinitely variable drive train using counter turning, pitch and roll gomballed flywheels spinning in the yaw axis. MTI's Stirling was not involved in this package. Nyserda approved the proposal but ultimately there was no state money. MTI had developed
an automotive Stirling running on a half dozen, switchable fuels and
I got to drive that truck once. It was not very quick, but it was quiet. My approach is to feed low grade makeup energy such as from a Stirling into a combination of flywheel kinetic storage and hydraulic
accumulator energy storage. That way, the Hydristor can directly handle several thousand road horsepower to/from the flywheels, and the Hydristor can very efficiently mix the longer and somewhat less
peaky hydraulic stored energy to give blazing performance and very high mileage on the road. Check out the word 'Hydristor' on Google.
My system would use a Stirling sized for the highest steady speed on level ground and would not have any warmup time.
Tom Kasmer 607-7631607

Try using a sterling engine with you internal combustion engine. Use waisted heat from engine to run the sterling for a hybird. Heat from cooling system and exhaust gas can be recovered to run the sterling engine. It would only need to be about 5 HP.

Stirling could make a proper addition to an IC engine. The IC should be a diesel burner and be turbocharged. A good exampe of an engine is the Three cylinder turbo-charged unit in Smart's fortwo model.

The sterling's heat needs should be supplied only by the exhaust gasses from the IC engine AFTER they have passed through the turbo. The turbo is very hot. This makes the exhaust gas coming out of it very hot. (especially being a diesel engine.)

There are no suitable stirlings on the market that are small enough to fit under the hood. They need to be small. Isn't the point of a hybrid to utilize all (most) of the energy in your fuel? A big heavy engine would ruin any gains by increasing the weight of the vehicle. Exhaust gas is wasted currently anyway, so doesn't it make sense to build a purpose-built stirling engine, capable of using this source of heat, even if its output were under ten HP? I think so.

The stirling should just run contiuously. Charging batteries at red lights, and electric motor(s) flying down the interstate.

If the public won't buy diesel go with gasoline, but the catalytic converter should be designed into the stirling, therefore making one of the hottest parts of the exhaust system (the source of fuel for the stirling) as close said engine as possible.

Cars do not need more the one hudred horses. Period. You want to go fast? Build a race car. You need to comute? Grow up and buy a shit box.

Not many know theres a Stirling motor that generates 55kW (70+ horsepower) and can be picked up under one arm?

Its power for size comes from the working gas being at 3,000psi.
There ARE further tricks to increase its efficiency. i.e. compound style. Pressurising the burner etc. etc. Whether its worth the extra effort and cash, I haven't calculated.

What this engine is sorely in need of is a fully variable, efficient gearing system. Especially for the reason of low initial power and removing the clutch etc. A motor like this is with a burner will quickly warm your cabin on that frosty winter morning. Any comments about needing huge radiators is silly as the car shifts through huge amounts of air compared to a static engine anyway. And of course, higher efficiency means less heat is expelled in total for a given amount of work.

Nuclear submarines use a Stirling cycle engine because they are extremely quiet, efficient and no giveaway exhaust.

However, someone kept parping on about nuclear power. Having/obtaining nuclear material is moot. To be reasonably small one needs plutonium, the most poisonous substance known to man. A terrorists delight. So lets not talk stupid eh?

I am considering converting a 4 cyl motorcycle or v-6 automobile engine into a stirling generator for the home, and a hybrid auto which should get about 300-400 miles to the gallon. I note on the internet that there alot of expensive toy and model stirling motors being built but nothing about conversion of used auto engines. The only conversion I came across is being done in Wales. There they converted a four cylinder engine into a 7Kwe power plant, and a V8 into a 35Kwe generator. I am looking for something a little more partical for everyday use. Is there anyone out there trying out an auto conversion?

I am new here, but I have noticed no one talking about using the waste heat from any engine or motor to power a stirling heat pump to cool the interior of said vehicle. Modern refrigerants are terrible pollutants.....this one could use air. A simple fix that should, in theory, frustrate DuPont to no end.
The main reason for not going bigger with this is marketability. Make it in a kit form and sell it. Get a toe hold first, then more people will pay attention (money) to your stirling engine ideas. But making it practical is the key. Piggyback the driver stirling to the catalytic converter (550+ deg. F) and use it to drive the "heat pump" stirling to cool the interior.
What I fall short on is the performance of the heat pump in question. There is not much info on stirling heat pump design tips or specs. Will the stroke have to be longer or shorter? I know surface area always will help, but I have difficulty in seeing how well it would cool the interior of the car below ambient air temp.
I work as a (modern)certified master mechanic and I am accustomed to fighting bad engineers and limited life let the attack on me begin.....I can take it.
BTW...I have seen a thesis with this idea in mind.....but no specific advice was given. (without the weakness)

All this talk about heat makes me wonder why we dont just use the geothermal the earth has to offer. just plant a huge sterling engine harnessing the volcanos heat sources like yellowstone park. Create the electricity and run your cars with batteries or run the trains buses etc. then the price for fuel will drop and all will be happy in both camps.


Forget all that heat ,noise and now expensive fossil fuels .
Try running on fresh air ,compressed that is.
MDI have developed over many years and many prototypes a piston engine
that runs on compressed air.They claim that the storage tanks can be refilled in your own garage or in about 3 minutes fom a road side service station.Also for the greens a Windmill Pump.Like electric motors no energy is being wasted in traffic jams and other stationery situations.Also a great option for marine engines where the reverse action by outgoing tides turn the propellers into pumps to refill air tanks.Read about it for yourself

Interesting stuff. Glad I came across the site. I think one of the issues with Stirling engines that others have pointed out quite well is the size of those normally contemplated for running an automobile.

I have done some thinking about the issue. Why not utilise every available resource of opportunity to power the car? There are smaller Stirling engines which do not require any liquids whatsoeve to run. Simple differences created by holding them in the palm of your hand will cause them to run. Why not integrate multiple systems theories/resources into a more conducive whole?

Say for instance, I have a car. It is powered by an electric motor that runs of batteries, which I normally plug in to charge. Now, how about on the car I have two of these small Stirling engines that work as follows:

On the outside of the car, built into the lightweight fiberglass body, are two Fresnel lenses which focus sunlight (much like solar lensing but without the mirrors) onto the bases of the two small Stirling engines. They are both connected to the same cam turning the generator that produces electricity that charges the batteris the car runs on. Further, the bases of the Stirling engines are set so that some of the generator's current is fed to create spark across the base like in arc welding...thus generating heat to keep them going.

Not only do we use those systems, but in the body of the car, you also have to small induction rams...two forward facing cones small turbines that will also serve as mini wind turbines to generate some charging of the electric batteries as well? Thus, you use solar, wind (from the forward movement of the vehicle), temperature differences all to power the batteries. If one system won't work on its own, make it work with other systems. Seems to me it could be down, and rather low tech...but I confess my major was eBusiness and not Electrical Engineering.

Anyway, love the site. I'll be visiting here a lot I imagine.

Sean Wilson

Stirling engines prbably never will be practical for passenger cars, but a hybrid powertrain with a stirling or steam engine might work for semi trucks. The trucks could be run on coal on the highway (with some sort of automatic hopper/feeder system), and diesel, gas, or some other clean-burning fuel in town.

There really are no evironmental problems, no fuel shortage, no shortage of electricity, or global warming crisis. You see we are all approaching the problem from the wrong end. We are looking at the symptoms of the problem, but not seeing the true problem. If we can't see the true problem we can never come to a solution. If we double efficiency of cars, what have we done. It is called a band aid. Do you know what the real problem is. Overpopulation. A one word sentence that speaks volumes. There is more than enough oil, more than enough food, more than enough air, more than enough energy. The problem is not one of resources, rather one of resource consumers. 500 mile per gallon cars, 99% efficient solar panels, and genetic engineered crops can band aid the problem, but if you don't fix the problem, eventually you run out of band aids. The worlds overpopulation problem is like a sucking chest wound. Its a warning to all of us that we need step back and think about our reproductive habits. The sad fact is all our problems may be solveable by one simple word. Contraception.

The overpopulation of this planet by us can be solved nicely (by realizing what we are doing and fixing it, the intelligent solution. Or it can be solved the hard way, AIDS, famine, war, poverty, crime, etc.

Can anyone say I am wrong?

Your right, wait for WWW3 it will take care of that problem.

It is great to here people discussing this. I am an engineer working in the power industry and thought I'd make some comments.

1) Nuclear power is cheaper over the life cycle of the plant. If the civilian sector had the same regultations as the military sector, it would even be cheaper. There is a false debate in the media concerning the nuclear waste. I ask, why does this debate not cover military nuclear waste which is the majority of nuclear waste produced and is not regulated. Besides, we pull the uranium from the ground, and put it back in when we are done with it; whats the big deal? It's better than pumping our waste to the atmosphere where it can be inhailed by our children and taken directly into the blood stream (no filtration or breakdown as in the stomach). I'm going from memory, but coal emissions are typically as follows:
70% CO2
10% SO2
10% NOX
10% volital organic compounds (cancer causing and other unknown affects)
.004% mercury (this is larger than you think considering the affects of mercury on life. to give an example, if a pregnat women were to eat fish every day of her pregnacy, statistically speaking, both the women and the child would experience mental difficiencies if not death. This is a big problem, as the fish eat fish and mercury cannot be excreted by life, so the process is cumulative. Fish is a staple food of humans as well as anaimals. An interesting fact is that when the tests were completed and determined that mercury levels have been tripled in every fish in the sea, they raised the legal limit for mercury and kept in quite.)
% Others

2) Wind power is getting better and better and will continue in this manner. Currently there are 5 MW wind turbines and 50MW wind turbines on the horizon. To give you an idea, coal power plants usually produce between 200-1000MW per turbine. Nuclear is between 900-2000 MW per turbine. The nuclear fuel cost is negligable since tens of thousands of tons of coal are not needed (fuel only needed to be changed every 2 years)

3) Wave power is really comming along and, in my opinion, is just another extention of wind power which uses the entire planet as a wind tunnel.

4) Geo thermal is great.

We have more inportant concerns at this point than money. cancer rates have risen from (historically) 25% to 35% of the population dieing of cancer in just 50 years. Imagin what will happen to the human race in 100 years if we "maintain the course". Additional affects of coal exhaut that can be seen in every city around the world include sperm count reduction, increase in asma, smog, dirty residues, posioned oceans, global warming, learning difficiencies, global water acidity and temperature changes (currently responsible for the disappearance of corral refs, which are expected to be completely extinct within 100 years), cancer, ozone reduction, increase in automospheric particulate count (possibly causing global dimming), possible sea level rise and melted ice caps (the full affects of this are unkown, but probably extensive), and the list goes on.

Hydrogen is a fix to our problems. yes, it's not extremely efficient, but it is better than gasoline in terms of efficiencies. hydrogen from coal power plants is just an absolutely rediculus concept do to similar reason. Hydrogen will always be the best fuel source for our vehicles because our planet is covered by 2/3rds water and all our emissions can be condensed or vented to atmosphere as water only. Zero harm will come from our emissions and no loss of performance of our vehicles is required (though the range is less, typically half the range of gas engines, though still 200 or more miles).

At this point, money (or should I say profit) is not an issue. I suspect all people of the planet will realize this in 10 to 50 years. The problem is, it may already be to late, as the evidence is mounting that the process we have started is a positive feedback system that can't be stopped. We have already doubled the amount of CO2 present in our atmosphere in just 50 years and our emissions have been rising exponentially.

How about a hybrid that incorporates a gas or diesel engine combined with an electric engine and a stirling engine? All three could be used to power the wheels. The gas and electric engines could be used the same way an ordinary hybrid normally uses both of them, but the stirling engine runs off of the waste heat from the internal combustion engine, the electric engine, the batteries, etc., or anything in the car that produces heat. This way, you are recapturing the energy in an engine that 70% of is normally lost through heat. The stirling engine can be used for either charging the atteries or for directly powering the wheels.

This is a new interesting technology, please keep reading.

There are currently three potent ways to store the ultra large amount of lightning energy, just a matter of initiatives and funds to start it about. A lightning storm can power the whole USA for 20 minutes. In every second, there are currently 2000 bolts of lightning flashing in the skies.

1. Use high heat capacity metals to store current-induced heat. Current of the lightning will pass through metals like tungsten(don't think tungsten is rare and expensive, it's cheap in fact) or silicon to produce large amount of heat. The heat is gradually tapped.

2. Store through electrolysis, yielding hydrogen. Electrolysis is definitely cheaper - water is free, metals are not free.

3. Supercapacitors, there is a variety of supercapacitor (must be instantaneous rechargeable) like superconductor magnetic energy storage (SMES), carbon nanotube ultracapacitor, highly porous ceramic supercapacitor. Some of my examples are yet under research and development. These supercapacitors are connected in series and a Bang could replete them with full of current.

Lightning can be induced in three ways:

1. Place lightning bolts in highlands.

2. Fly mini rockets with copper wire attached.

3. Flashes very high power lasers into the clouds, to ionise the air. Ionisation causes the atom to release electrons, and ultimately reduces resistance. Thus, pulsing beams of laser is like pulling the clouds with a copper wire.

You probably heard of hydrogen economy and nitrogen economy, but mine is Lightning Economy. Since lightning produces an ultra large amount of energy, it can replace fossil fuel instead if researches are done exhaustibly. Run trucks and cars with battery, run Industries with ultra low electric bills, produce very cheap products, increase exports, free energy for mining resources, no more home electric bills..... Readers, please further think about this and keep this idea in your memory.

Most of the contributions to this subject are limited to rather feeble minded reasoning. I, for my part, do not favor nuclear - nor combustible (coal,oil) power generation; there are many other means that are far too less exploited.
For the past six years, I've heated my home with a heat pump and produce electric power(15 kWp)with a photovoltaic system. More than half of the produced power is distributed to the grid; the minor portion I use for myself. There certainly is room for improvement of efficiency of currently available systems but I can't afford to wait for the non-plus-ultra until my life expectancy has expired; for that matter, nor can anyone else. Don't wait until tomorrow, ACT NOW. Pollution isn't waiting, it's steadily progressing from day to day.

Ok after reading about 2/3 of these comments, I wanted to add my own. I am currently working for a solar testing lab where we test and certify modules to US(UL) and international (IEC) standards. I also graduated with a degree in Alternative Energy.
Nuclear power is useful. It has issues, but it is cleaner than coal and oil powerplants. Just as hybrid vehicles are a stepping stone to society driving cleaner vehicles, nuclear cannot be overlooked as an important stepping stone.

Solar plants are feasible. Solar plants running sterling engines can be feasible. The biggest problem is energy storage. Energy storage and distribution is viable, but that is the weakest point of solar currently, that power demand doesn't meet power production with solar energy. Sterling engines paired with concentrated solar modules create a very efficient power source.

Wind power is a huge success story, for alternative energy. The biggest problem with wind power is it's random availability. Putting up wind farms will not destroy the environment by slowing down winds...they do slow down wind, but keep it in perspective. Buildings, trees, anything that raises above ground level will block the wind. Wind is created by the solar irradiation that strikes the earth, and wind won't run out. The noise...well I've worked around wind farms and the noise was not oppressive if the turbines are maintained. And as far as the life of birds...well how many animals have died by being hit by cars? How detrimental is the air and water pollution to every living being? Any moving object will have the possibility of killing living beings. I have never heard that people should stop driving or should only drive at 15 miles an hour to save the countless animals that are killed on our roadways.

Tidal can be completely predictable, and is no more dangerous than the countless boats that are used everywhere...I don't see us stopping to use prop driven boats and they kill marine life at a level that isn't even close to what creatures will die to turbines running off of wave power.

As far as electric motors and electric powered vehicles...they are better than gasoline and diesel engines purely do to the fact that they offset the carbon imprint to concentrated areas. Instead of pollution everywhere in a city, it is localized to power plants. Those power plants are much cleaner than the exhaust from vehicles, and always will be. And it is capable of making the exhaust from these plants even cleaner. And electric motors can be much more efficient. Electric motors can be placed in wheel wells to run the axle directly. They would also be closer to brakes for a regenerative breaking current regenerative braking systems are very inefficient due to how large the cables would have to be made to handle the amount of power we can reclaim. I don't have the exact percentages unfortunately at hand. And also don't neglect the added cost of keeping gas stations everywhere...the cost of delivering fuel to remote gas stations everywhere, the cost of materials to make these storage areas. Gas stations and fuel delivery and storage must be included in these costs.

One final note, fuel cells are still not currently the answer. The problems they have had in the past are the same problems they still have. How do you store hydrogen? How do you "create" hydrogen? Current hydrogen production sources still use fossil fuels to create them, unless you use electrolysis which is only viable if paired with a renewable such as solar or wind. And the materials current fuel cells use are rare. Current calculations if all cars were switch to using a PEM fuel cell, there wouldn't even be enough platinum in the world to replace all of the cars in Los Angeles. And switching to a hydrogen economy means that we would have to completely swap out the current fossil fuel distribution system for a hydrogen distribution system...there is no economic viability for this to happen in the next fifty years.

I personally would like to see a biomass powered stirling hybrid. size the batteries for commuters (less than 125 miles or so per charge). use biomass fuel (gasifiers?) hooked up to a small stirling (1hp or less) to recharge the batteries while its parked at work. I would guess an enclosed bicycle type vehicle would probably work. (I've calculated my average speed to work at 35mph- even though a large part is 65mph speed limit- damn traffic...). My assumption here is that 10 to 30lbs of sawdust (corn, garbage, etc...-dry biomass...) would sufficiently recharge the batteries for commuting. The gasifier and stirling would need to be electronically controlled(charging cycle), because burning biomass is typically considered a stationary rather than mobile task. a 1hp stirling is still rather large... anyway my .02$.

I think a Stirling engine would work fine in a car, but in an electric drive car as a generator. I don't know how well one would do driving the wheels directly. They seem to be an engine that likes running at a steady RPM.

Why not have a combustion engine and use the acess (I know it's wrong) heat for the stirling engine.

Gearturbine - Atypical Thermodynamic Technology Submission

YouTube Video; Atypical New * GEARTURBINE / Retrodynamic = DextroRPM VS LevoInFlow + Ying Yang Thrust Way Type - Non Waste Looses

GEARTURBINE -Atypical Combustion Turbine Engine, -State of the Art, -New Thermodynamic Technology, -With Retrodynamic "Dextrogiro vs Levogiro" Effect, is when the inflow direction moves is against [VS] of the circular rotary dynamic, When the inflow have more velocity the rotor have more RPM / because push the single turbine with the planetary gear, (an a example is like to move the head to the side of the strike hit) / RPM Rotor Move VS Inflow Conduits Way /ACTION VS REACTION / Front to Front / Velocity vs Velocity, making in a simple way a very strong concept of power thrust, a unique technical quality. -Wide cylindrical shape dynamic mass (continue Inertia cinetic positive tendens motion / all the motor weight is goin with the power thrust direction), -Non Waste, parasitic losses form-function engine system for; cooling, lubrication & combustion; -Lubrication & Combustion inside a conduit radial position, out way direction, activated by centrifugal force Fueled Injected, -Cooling in & out; In by Thermomix flow & Out by air Thermo transference, activated by the dynamic rotary move, -Increase the first compression by going of reduction of one big circumference fan blades going to, -2two very long distance captive compression inflow propulsion conduits (like a digestive system) (long interaction) in perfect equilibrium well balanced start were end like a snake bite his own tale, -Inside active rotor with 4 pairs of retrodynamic turbos (complete regeneration power system), -Mechanical direct "Planetary Gear" power thrust like a Ying Yang (very strong torque) (friendly loose friction) 2two small gears in polar position inside a bigger shell gear, wide out the rotor circumference were have much more lever power thrust, lower RPM in a simple way solution, to make possible for a some innovative work application (cars/land). -3 Stages of inflow turbo compression before the combustion. -3 points united of power thrust; 1- Rocket Flames, 2-Planetary Gear & 3-Exhaust Propulsion, all in one system. -2two continuous circular moving inside combustion (rocket flames) like two dragons trying to bite the tail of the opposite other. -Hybrid flow system different kind of aerolasticity thermoplastic inflow propulsion types; single, action & reaction turbines applied in one same system, -Military benefits, No blade erosion by sand & very low heat target profile. -Power thrust by barr (tube); air sea land & generation application, -A pretender of very high % porcent efficient power plant engine. -Patent; Dic 1991 IMPI Mexico #197187

Why do advocates of nuclear power as a "green" energy source almost never discuss the thorium fuel cycle? Many experts believe that the problem of waste management can be contained within a humanly manageable time span using variations of this technology. Thorium is more abundant than uranium. Thorium-based reactors cannot be used to breed plutonium. There is essentially no risk of a Chernobyl-style disaster.

It's true that thorium can't sustain a chain reaction without help--some "seed" quantity of conventional nuclear fuel is required for known practical designs, although Carlo Rubbia's "energy amplifier" concept, if made practical, would eliminate that need. But this feature, advocates say, makes thorium-based systems far safer and more controllable then their uranium-based counterparts.

Speaking as a practical, non-religious advocate of high technology and a scientific view of everyday life, I can say that if the reality of the thorium cycle lived up to the claims that are made for it, my own environmental objections to nuclear fission as a source of electricity (in and of itself and pending an analysis of the costs and benefits of other "green" alternatives) might well be removed entirely.

It makes you wonder what the true motives of the "uranium or die" nuclear advocates really are. And why does advanced capitalism, that professedly infallible guarantor, via the "invisible hand," of the greatest possible good for the greatest number, seem to be ignoring this technology, which would be extremely popular and marketable if its benefits could be realized?

Petro-electric hybrids are not there yet with battery technology
still a long way to go, although supercapacitors are promising.

The problem with urban diesel trains is that they are just too
slow. The acceleration and speed is pathetic to electric urban
trains. Upgrading lines to electric is very expensive, and ugly,
with overhead wires, and in many cases not viable.

Diesel-hydraulic hybrid urban trains are being R&D's in Germany.
They toss the engine, the transmission, the brakes, and all that
goes with them and replace them with hydraulic cylinders and motors
and a tuned constant speed engine to charge pressure cylinders.
They are stripping modern trains of all of their complex systems
and replacing them with pure simplicity. A petro-hydraulic train is
simple, with fewer control electronics required.

A hydraulic motor drives the train not the internal combustion
engine. The engines is for charging only. The hydraulic motor has
reversing valves. These motors propel the train forward or are
reversed to act as brakes. When braking, they return hydraulic
pressure to the hydraulic accumulator tanks for future use.

That's right, the hydraulic fluids compress nitrogen gas in an accumulator
tank, store braking and slowing down energy and provide propulsion.

This technology is being used in large construction and commercial vehicles.
...and has been for decades. The larger the accumulator the more energy
stored. Trains tend to have space under the floorboards for such devices.
Some of the largest construction vehicles in the world use this setup.
90% plus of brake energy can be reclaimed while in cars this is currently
about 25%.

Chrysler and the US govmt EPA dept are both partners in a people carrier
project. But they are still using the oversized standard 2.4 liter engine.
This will be far too large and will return poorer mpg than a smaller matched
to average use engine. The minivan body is also not designed for
petro-hydraulic applications. This project can only be a compromise to prove
it will work in small passenger vehicles, which we all know it will as it is
not new technology. The skills around to service are there as millions of
back-hoes, etc are around.

Ingocar Valentin in the USA is buildings prototype car to run for 15 minutes
before the engine cuts in and recharges. The engine can supply fluid to
the hydraulic motors, which are also brake reclaim and the brakes, all
in one small unit in the wheel hubs, smaller and lighter than a disk brake
setup. .. No stepped transmission is needed. Valentin is designing the
accumulator as the structural part of the chassis of a vehicle
to maximize space. The suspension will recharge the accumulator as well, as
the suspension will be on the hydraulic setup.

But R&D'ing is in hand. Petro-hydraulic at the this time is far more
efficient that using batteries and electric motors. The Germans have
used petro-hydraulic trains since 1935 and still do. Preferring them
to petro-electric setups. But not exactly in the accumulator brake-regen
setups, more hydraulic transmissions. For urban trains the setup is perfect
enabling a Diesel Multiple Unit to compete with an Electric Multiple Unit
in many aspects. The engines can be off at stations, so not emissions at
platforms, and accelerates fast using the hydraulic motors. These will
transform some services.

The energy consumed in producing nuclear fuel rods and the materials needed for the generation of electricity in a nuclear power plant (the building/structure/plant, upkeep, etc. are greater than the energy produced by the nuclear plant.
Also, nuclear power is only cost effective because of government subsidies.