SF Yellow Cabs Adds 10 Escape Hybrids
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“Extreme” Plug-In Flywheel Hybrid Promises a Possible 250 MPG


AFS Trinity Power Corporation has unveiled a flywheel-supported hybrid technology that the company anticipates will enable fuel economy in the 200–250 mpg range.

The Extreme Hybrid drivetrain—under development for light duty and heavy duty vehicles—is a plug-in hybrid that gets most of its power from the grid. The flywheel system provides greater efficiency in energy capture and release from regenerative braking, thereby extending the operational range of the vehicle in all-electric mode.

The hybrid drivetrain system consists of five primary elements:

  • Advanced lithium batteries that are recharged at night with off-peak power from the power grid

  • An advanced flywheel for improved energy capture (up to 80%) and storage from regenerative braking

  • Advanced power-conversion and management electronics

  • A high efficiency steady-state Internal Combustion Engine

  • An electric powertrain

A flywheel is a rotating, kinetic store of energy. As energy is drawn from the system, the rotating components slow down, and as the system is charged, they speed up. Flywheel energy storage grows in proportion to the flywheel mass and the square of its rotational velocity.

The trick for a vehicle flywheel system is optimizing size and weight, durability of materials, rotational speed, speed of energy capture and discharge, and cost.

AFS Trinity’s approach is to use a flywheel within a flywheel. Its ARC (Active Rotating Containment) flywheel—for which it received a patent in 2002—uses a slower, heavier rotating outer flywheel to contain a much faster, lighter inner flywheel.

The result is more power per pound, more efficient energy transfer and a neutral gyroscopic effect which will allow vehicular operation without having to use counter-rotating pairs of separate flywheel systems.

When the flywheel hybrid vehicle runs on electricity alone it will not rely solely on its batteries; the flywheel and ultracapacitors will do the heavy lifting, providing high power over a short duration for acceleration or for quickly capturing regenerative braking energy.

This capability addresses one the limitations of the current chemical batteries used in plug-ins: the difficulty in absorbing or releasing high currents when they are in a deeply discharged state.

The flywheel thus buffers and protect the batteries, leaving them to do only what they do best: provide low-current longer running time in electric-only mode.

Power from the batteries will be “sipped” by the vehicle, not “gulped”. Although all of the subsystems are important, the high performance energy storage system is the critical part of a plug-in hybrid drive train.

—AFS Trinity CEO Edward W. Furia

AFS Trinity expects that a driver will be able to operate the vehicle in electric-only mode for 40 miles, and at any time may flip a switch to run the vehicle as a conventional hybrid with a 500-mile range.

If Trinity can meet the 40 mile range mark with acceptable speed and performance, then it will be able to satisfy the daily driving needs of many drivers solely on electricity and thus deliver that extreme fuel efficiency.

We need to cure our addiction to oil. Our current 20 mpg national average vehicle fuel efficiency is embarrassing. While 50 miles per gallon in cars like the Toyota Prius is great for today, to address our transportation energy needs in the near future our national average fuel economy should be more than 200 miles per gallon.

—Edward W. Furia

An Extreme Hybrid drivetrain for passenger cars is expected to begin development this year, be demonstrated in a prototype vehicle in two years and be ready for licensing to U.S. and foreign carmakers in three.

AFS Trinity Power Corporation is a flywheel energy company, created in 2000 through the combination of two pioneers: American Flywheel Systems (AFS)—the recipient of the first patent ever given for a flywheel battery (1992)—and Trinity Flywheel Power (Trinity). The company has devoted more than $45 million, 75% of it from private sources, to the development of kinetic energy storage, power management and UPS power backup technologies.

AFS Trinity is currently engaged in or has participated in development programs with a number of private and government organizations including DARPA, NASA, the U.S. Navy, U.S. Army, U.S. DOT, California Energy Commission, Oak Ridge National Laboratories, Lawrence Livermore National Labs, Lockheed and Honeywell.



Mikhail Capone

That sounds incredibly promising!


Can someone explain how using flywheels, a vehicle is suppose to get 200-250 mpg. Will cars/trucks still be using gas?


Liquid fuel is still part of the mix, but the combination of the flywheel and the plug-in battery is designed to allow the vehicle to operate mostly electrically—at least within an average 40-mile range during the day. The huge projected savings in fuel MPG mainly comes from not having to use the combustion engine much.

Current batteries are good at prolonged discharge and are slow to recharge; the flywheels are good at rapid energy capture (“recharge”) and discharge. Looked at another way, the flywheel supports the extended operation of the battery by handling spikes in need for power (acceleration, inclines), and also presumably does a better job at capturing more of the kinetic energy from braking (regenerative braking).

On a long trip at high speed, the fuel consumption would increase.

As a comparison, you can look at the work that CalCars is doing in converting a Prius to a plug-in. (Earlier post). The end concept is similar—a plug-in hybrid. But the Prius+ team figures their maximum range in all-electric mode is 15–20 miles at a maximum 35 mph.

The proposed concept flywheel hybrid doubles the range and increases the maximum speed—again, due to the capabilities of the flywheel to augment the battery.

With better battery technology, would you need a flywheel to have the same sort of result? Maybe not.


The flywheel sits between supercapacitors and batteries in its power/energy capability:  it can handle more power/weight but stores less energy/weight than the battery, and probably less power but more energy than the capacitor.

Improve either capacitors or batteries enough, and the flywheel's niche disappears.  I wouldn't mourn them; they are neat devices, but only means to an end.

I am going to have to revisit an old blog post of mine to see how the new Altair li-ion electrode material will affect the details of a car.


I need disign of girbox of car


I need disign of girbox of car and the engin of car

Travis Spier

A flywheel's efficiency is also dependant on its radius squared, not just it's mass and angular velocity. Inertia is what stores the energy. I=(1/2)mr^2. So, getting the mass as far away from the center of the flywheel is important. I have put some thought into this; glad to see someone is doing it.


As for how it stores electrical energy, well, if you put some permanent magnets in the actual flywheel, then put some electromagnets in the casing, you can pulse electricity through the electromagnets to speed up or slow down the flywheel. When you're speeding it up, you're charging it (more energy goes in than out, and the flywheel accelerates). When you're slowing it down, it will induce current back into the electromagnets, discharging the system (more energy coming out than in, flywheel decelerating). The result? Put the flywheel in a vacuum in its casing, pulse the electromagnets just right so that the flywheel actually levitates within the casing, and you have a nearly frictionless system. There is no gearbox; there's no mechanical connection between the flywheel and anything outside of the casing. It's just a nifty way of storing electrical energy, which can handle serious surges in input and output.

IIRC, most designs use something more like a rotating drum. That way, the inertia is maximized for the amount of materials involved. Also, the energy is relative to the SQUARE of the speed, i.e. 4x the energy = 2x the rotational speed.


It seems to me that this flywheel design would work best in a vehicle that is engaged in a lot of stop and go such as a city bus. I remember reading about this being tried on buses in England back in the 70's Here in my hometown I've read that the buses get around 1 to 2 mpg.

The fly in the ointment is the mpd (miles per dollar) figure which is really the number any good business man must look at. If the cost of adding these fuel saving devices is more than the cost of the fuel saved then it will be a very tough sell.

We've all seen the price of fuel go up and then sooner or later it goes back down again. Your investment in fuel savings doesn't look good if the price is going down.

The free market is a wonderful thing, but it makes knowing what you should do about high fuel price spikes as mysterious as quantum mechanics

Mark Earnest

I'm perplexed. The idea of using the kinetic energy from a flywheel in a hybrid vehicle is brilliant. Makes perfect sense. Then why is this technology -- and the obvious commercial potential -- on the technical "lunatic fringe"?

Sorry for the invective, but wouldn't all the transportation visionaries in the world latch onto this and translate it into products that could earn them millions? There must be some sort of commercialization "gotcha" that is relegating this to science fiction. What am I missing?

Mark Earnest


There is an idea which may possible work.

Imagine the roads in city are modified such that it can passed EM energy to the bottom of the car. So that the car can recharge through EM waves. Sinec the moment of time it can charge maybe short. So we need a flywheel to store these peaky energy bursts. Since there are so many of these on the roads, the batteries are not large.


if this technology would include a E85 engine, the theoretical 'gasoline' consumption would be 1250 mpg!!!!!! or a biodiesel, no petroleum used at all!


I would like to know more about car.


Very interested in purchasing and making suggestions for the Extreme Hybrid(TM). Please call me back at (808) 346-1895.




And new low cost solar panels can recharges the flywheel. The solar panels would be the roof and hood of the car. Recharging will occur as long as you don't put your car under a shade. I can see this working out really well in the tropics... Go to work, park outside, the car would be recharged when it's time to go home. Wow!

kenneth johnstone

No one has mentioned compressed air technology. I believe the French or one of it's neighbors has a model that is going to be marketed shortly. Of course they get most of there power from nuclear powerplants.
I woild like to see a motor scooter model first to tell if flywheel and ultracapacitor is really viable.


Hi my name is A.K. I live in dallas TX. I am working on this new idea which is a car can run 200 to 250 MPG with out plug-in over night. And i like to work with your guys please let me know if you guys interasting?

My early morning (lazy-day) Saturday was abruptly jolted by CNN when Edward Furia broke the news of his XH-150 Hybrid vehicle. As I shook my head in amazement I couldn’t help, but remembered not so long ago, when another American inventor named Kamen made a similar announcement about "It" which turned out to be the revolutionary Segway.
Unlimited miles per gallon of gasoline with a vehicle that will travel 40 miles without charging is the announcement we’ve all been awaiting. Now let’s see how long it will be before BIG Oil buys up the plans, and scraps this idea.


I'm still looking for an affordable solar car, or info on how to convert my 20 year old subaru wagon into one. Everything I've been reading about is TOO FAR OFF. I need something now, live in the foothills of Northern NM, drive alot.


i'm glad to see someone has finally understood a concept that i've also been working on for years. my ideas are very much the same except i concentrated on savings in production and ease of production to help get this out to the consumer faster and more affordable. but i'm not complaining, that will follow now anyway. good jobs folks!

Henry Gibson

Mass production is the only reason that cars can be bought at a low price. Diesel electric locomotives are hybrids. Present hybrids are both too complicated and too expensive to actually save money. There are no mass production flywheels so they are more expensive than ultracapacitors, but flywheels could be cheaper than ultra capacitors. Lead-acid-batteries from EFFPOWER combined with the technology from Firefly and Atraverda could be far more useful than ultracapacitors for vehicles. Put firefly batteries in a TATA NANO car and a resistor speed controller with a brushed DC motor and not a single transistor for a cheap electric car. Make it into a hybrid with a model airplane engine from RCV with a cheap alternator.....hg....

Henry Gibson

Hydraulic hybrids may cost the least in mass production and be more cost effective in the long run for most short run vehicles. The UPS truck and Parry People movers are good examples to look at. Hydraulics can be designed to have relatively high efficiency. The low efficiency of modern large engines at low speeds makes the efficiency of hydraulics interestingly usefull. The efficiency and horsepower of French steam locomotives was almost doubled by proper design of steam paths. This means that careful design of hydraulic paths could give performance improvements to hydraulic hybrids as well....hg...

warren currier

So this car has a 500 mile range, correct?

500 minus the 40 miles it gets from the grid... equals four-hundred and sixty miles. Right?

Let assume that the ICE gets 30 mpg... so that 460 divided by 30 will give us 'how many gallons of fuel we'll need to travel 500 miles... ie 15.33

Now let say that the grid power is free, and we go 500 miles on 15.33 gallons... that dictates 32.61 mpg. Right?

warren currier

Another way to look at it:

Say that you are going to travel 41 miles per day, and you will charge the vehicle every night from the grid.

In one year you will use 12.16 gallons of fuel (excluding whatever may be used to produce your grid power)

41 X 365 = 14,965 total miles traveled in one year!!

divide 14,965 by 12.16 gallons of fuel used.. and it looks to me like you get 1230.67 miles per gallon. Right?

warren currier

Help me out here!!

So when people say 'WOW' and wonder why the Big Three are NOT interested in it any more than to walk over to have a peek at what these guys have come up with (as they did in Detroit)... I'm confused.

This AFS Trinity system is NOT the answer. It is clever.

I sure that there are some MUCH better systems soon to come into public view.

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