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ETV Motors Demonstrates Proof-of-Concept Microturbine-Based Range-Extended Electric Prius

Israeli startup ETV Motors Ltd. (ETVM) completed a proof-of-concept test of its Range-Extended Electric Vehicle (REEV) architecture using a gas microturbine for the range-extending generator. The company had closed a $12M Series A round in April. (Earlier post.)

For the test drive, the company modified a Toyota Prius using commercially available components. ETVM replaced the OEM NiMH pack with a large-format lithium-ion battery, and retrofitted a liquid-fueled, gas turbine generator to the car for the range extender.

The proof-of-concept demonstrator REEV will serve as a test vehicle for the company’s ongoing development work, which is focused on developing a new microturbine and a new Li-ion battery, in collaboration with the electrochemistry team at Bar Ilan University.

This milestone is a major pre-requisite for materializing our vision of plug-in EVs equipped with fuel-efficient, low-emission gas turbines for range extension.

—Dror Ben David, ETV Motors CEO

ETVM is developing its own microturbine, based on RQL (Rich-Quench-Lean) principles. The ETVM turbine will have the unique property of achieving optimum efficiency at two operating points. This “dual mode” property will provide a number of degrees of freedom when matching the microturbine to various drive cycles and vehicle categories.

ETVM expects that its first generation of the turbine, with an efficiency that outperforms the present state of the art by approximately 30%, will be fully functional in Q2 2010.

On the battery side, ETVM is working on two cell chemistries: lithium manganese nickel oxide (LMNS)/graphite to form a 4.7V cell; and LMNS/LiTiO to form a 3.2V cell.

Characteristics of the ETV 3.2V and 4.7V cells compared with the chemistries of selected commercial batteries
Battery chemistryNiMHLiCoO2LFPAdv. rapid chargeLMNSLMNS
Voltage 1.2V 3.7V 3.2V 2.4 3.2V 4.7V
Energy Density
Wh/kg (80-100% DOD)
50-70 180-200 65-110 50-70 120 240
Power Density W/kg 400-500 250-400 2,000-3,000 3,000-5,000 2,000-5,000 1,000-3,000
Cycle-life 300-500 300-500 >1,000 >3,000 >3,000 >3,000
Self-Discharge %/mo. 25% <0.3% <0.3% <0.5% <1% <1%
Projected $/kWh $500-700 $400-500 $200-300 $300-400 $200-$350 $200-$350



This turbine/hybrid reminds me of our helicopter operations. The turbine engine has fantastic power to weight, yet (generally) consumes fuel like crazy. However, in helo's, the weight savings is so important, it more than offsets the additional fuel burn. It's not easy to improve turbine fuel specifics. Tip clearance and compression ratio help. Heat exchangers using exhaust heat to supplement combustion heat also help (Think M1A1 tank turbines). Still, small turbines have never been efficient. Just effective. There is a difference. One interesting thing, Honeywell makes tiny APU's with integral shaft generators. The are very light and powerful.

In the case of a hybrid car, the weight savings of a small turbine (compared to a small diesel with conventional generator) could be many hundreds (maybe even 1000 pounds).


As PHEV e-range is extended over 100 miles, with high performance batteries (i.e 240+ Wh/Kg), genset operation will be reduced by as much as 90%, in most cases.

With greatly reduced operation time, genset weight becomes more important than consumption. Very low cost, low weight, replaceable (plug-in) genset may be a good worthwhile option for PHEV-100+ miles.

Also, reduced total vehicle weight will give increased e-range with smaller lower cost batteries. Why lug around an extra 1000 lbs if you dont need it.

Henry Gibson

A Capstone air bearing turbine was recently incorported into a regular vehicle and now this car continues the era of jet powered cars. The battery hybrid technology makes an efficient turbine powered car possible.

Regular automotive engines have such a low average efficiency that even low efficiency range extenders for plug-in-electric vehicles can compete. And for some users, the range extender will seldom or never be used, so the efficiency is much less important.

No plug in vehicle should be allowed to be sold or advertised for use on the streets that does not have a diesel or ethanol or gasoline fueled range extender built into it. The main reason for such a regulation is so that people can no longer be told or be allowed to believe that an electric car has a limited range.

The range extender can have very low horse-power and can be very cheap and small if it is seldom used like it would be in a TH!NK car. The OPOC engine might again reappear again as a range extender. It is usually forgotten that the range extender can be operating whilst the car is parked, so it can be even smaller than often thought.

AC Propulsion was one of the first to demonstrate a range extended electric vehicle, and they selected a standard motorcycle engine to do it with their TZERO. They also demonstrated that lead acid batteries were adequate for range extended plug-in-electric vehicles.

No new battery technology is necessary for plug-in-hybrid cars. If Lead batteries were adequate in the TZERO, ZEBRA batteries are more than adequate. Bipolar Lead batteries from EFFPOWER or others could replace the present Prius batteries at lower cost and be used in other hybrids and to replace complicated, high-power but low energy ultra-capacitors. CISRO invented a combination LEAD and Ultra-Capacitor unit that works well.

VOLKSWAGEN translates into "peoples car" and it and the Citroen and the Model-T were revolutionary at putting people into automobiles because they were designed for low-cost, utility and service. There is a similar experiment going on in India with the TATA NANO.

There needs to be a similar plug-in-electric hybrid car for the US. If people are forced by law to buy low flow shower-heads, toilets, energy efficient refrigerators and other appliances there is no logical reason that they cannot be forced by law to drive a low power plug-in-electric car with range extender especially if they own two or more cars.

It must be clear to most readers of the greencarcongress that many, if not most, automobiles are, even now, selected for reasons other than transportation. It is true, as mathematicians would state, that transportation is a necessary but not sufficient condition for buying a car.

Even the most well designed highly efficient automotive engines mentioned in greencarcongress articles mostly note the increase of horsepower over prior models. This horsepower is in excess of what a driver will ever get from the engine. The average horse-power produced by any car can be estimated by assuming an efficiency of 17 percent for the engine and calculating from the miles per gallon advertised. CALCARS and others estimate 200 watt hours per mile which gives a Prius an average 8 horsepower or less at thirty miles per hour in the city.

Many buyers want high horsepower, large mass and lots of pistons. Some of the largest, if not the largest, steam locomotives ever built had only four pistons, but this is not sufficient to impress most people so car buyers want, but do not need, more. Even many electric cars promote high horsepower and acceleration over efficiency and low cost of purchase and ownership such as the Tesla.

Jet engines may have a powerful enough image for most people, but some will want two jets or more. Perhaps RASER will build a three turbine HUMMER with their electric motor-generators.

Perhaps if there is enough demand, Capstone could be persuaded to build five and fifteen KW turbines for range extenders. Such machines could be modified for cogeneration at homes and commercial buildings.

Efficiency is also not as important in cogeneration units because the waste heat can be collected and used for heating cooling or other purposes, including the distillation of ethanol. Consider that whilst engines, including ordinary jet engines or gas turbines or steam turbines, waste a lot heat, ordinary boilers waste a lot of mechanical energy whilst producing heat.

Where natural gas is available, co-generation units can charge electric car batteries and heat or cool the home or business at the same time for an energy savings beyond that available from any engine or even the most efficient possible automotive fuel-cell.

Now GM might be forced to build a cheap PEOPLESCAR, a low power plug-in-hybrid. The US has invested enough money into the OPOC to make it the range extender. The process may well be subcontracted to TATA. ..HG..


A small SOFC running renewable methane stored as ANG with a gas turbine burning off the unused H2 from the stack and heat recovery with a rankine after that could be 70% efficient. This could easily get a true 100 mpge using only 8-10 kWh of batteries.



I am going to have to take issue with many of your comments. You are obviously very sharp, but I don't agree with the following.

"The range extender can have very low horse-power and can be very cheap and small" Meaning low output? Not so. The HP requirement of automotive use is not small. Try driving an old 50HP VW rabbit diesel for a while. You'll get it. 50HP is not enough for a 2000 pound car. A slight headwind can reduce speed beyond belief. So can a hill.

Nor can the government here in the USA "regulate" people into low powered, slow moving vehicles. You may have forgotten about the US constitution. The feds really don't have the authority to regulate where you go or to "force" you to do anything. They can only set guidelines manufactures must follow. There is a HUGE difference. I can drive a 'vette if I want, anywhere I want. However, the manufacturers (interstate commerce clause) may be required to produce to a standard (we see this today).

Having participated in some electric car testing for Car and Driver and a few electric car "races" I can tell you that even the best still fall short of the needs of the average driver. The Tzero was not that great and would not function for my commute.

Please don't get me wrong, I love the technology. I just don't see that small and slow is necessary in a world awash in energy.



A serial hybrid does not use the fuel combustion motor to push the car, and the HP of the range extender should not be confused with the HP of an ICE driven vehicle.

The range extender runs at it's most efficient RPM to charge the battery, and it at that speed it only needs to be able to "keep up" with the discharge rate of the battery.

It does not have to be nearly as big as you think: the Aptera 2h will likely use a 15HP engine, and the prototype Mini hybrid with the 160HP hub motor (on each of the four wheels -- so ~640HP pushing the car!) used a 2-cylinder 250cc engine to charge the batteries.

Sincerely, Neil


If the aim is to reduce cost and weight they're trying to re-inventing the wheel.

With a series hybrid it is easy enough to replace the current norm 100 Kw peak direct drive ICEs with a much smaller turbocharged Diesel ICE of approx 5 Kw constant.
As for energy efficiency, this Israel company says they can beat the current state of the art turbine by 30%... we'll take that claim to be BS until they prove otherwize!

To beat a gas turbine or turbo diesel ICE by 30% means they are claiming 75-80% energy efficiency from a micro turbine..... That's simply not possible without some kind of co-generation on the exhaust!!!!


The one case where a small power supply will not work is long mountain climbs. Out west we have highways that go for 50 miles and more up to 10,000 feet elevation. If you have 4 people in the car with luggage, the main source of energy must supply that, the batteries alone will not last.


Lot of myths here. 5 kW sustainer engines? A Prius needs 15 kW on a flat highway with a headwind, more with something on the roof. But as SJC notes, that won't handle long highway grades. You need 50 kW. Sorry, but math is math.

Aptera is grappling with this issue today and has backed away from the early 9-12 kW specs. Their ultra-light 2-seater trike can probably get away with 25-30 kW.

Harvey, we're a long way from 240+ Wh/kg EREV batteries. And we're even farther from 100+ mile EREV range. Batteries are the most expensive component and 40-100 mile days are not common. Why triple your battery cost just to take EV operation from 80% to 90% of miles driven? Doesn't make sense. If anything battery improvements will move us in the other direction -- e.g. EREV-20s designed to recharge at home, at work and at the mall. Cut battery cost in half and still run in EV mode 80% of the time.

Also, your 1000 pound engine weight is off by a factor of 10. The 50-ish kW engines found in tiny cars like the Smart and original Insight weigh about 70 lbs. GM initially spec'd a 3 cyl of this size. They only switched to a 4 cyl so they could cost-share with other models while Volt volume is low.

Henry, lead-acids are cheap upfront but expensive over the life of the vehicle. They are also too heavy. Perhaps Firefly can dramatically increase cycle life and double energy density to a barely acceptable 60 wh/kg. We'll see. ZEBRA needs to be kept hot all the time, inefficient for a typical car that's parked 23 hours per day. Might work for continuous-duty vehicles like city buses, though. NIMHs which people claim Chevron suppresses also lack the specs to handle the PHEV duty cycle. There's a reason every serious EV and EREV design uses lithium, and it's not because the engineers are all idiots.



I'd like to see the data that confirms your statement of a 70lb longblock 3 cylinder automotive engine. I'd be surprised if you could show me a shortblock that weighed 70 lbs (unless it were stripped of everything down to just the block and no internals at all).

The head alone on a 16 valve SOHC 4 cylinder engine is mighty close to 50 lbs (with camshafts and gears).

[but that 1000 lb wild number the other poster put up is way off the mark unless discussing a medium to heavy duty truck diesel]


ddw et al...

Taking 1000+ lbs off our current bulky, over powered, 4000+ lbs ICE, with future equivalent interior size vehicles, such as well disigned PHEV-100+ assumes that:

a) batteries used will produce 250+ Wh/Kg and be useable at 80+% on each full charge. (They will be available by 2015+). For a mid-size car, this could mean a 25 Kwh (Min) pack weighting about 100 Kg. Small, mass produced, in-wheel, very light e-motors could be an option to further reduce weight and offer more power flexibility.

b) the on-board range extender genset would be an ultra light, easily changed, ultra low cost 15 to 20 Kwh unit. It does not have to last much more than 1000 hours because it would seldom be used. Tata (and many others) could build a suitable unit within a few months. There is no very High-Tech involed.

c) for hilly areas, there are many solutions such as gear down e-motors, more in-wheel e-motors, larger battery pack and/or larger genset etc. However, not everybody require hill climbing vehicles. We do not all live in San Francisco or the Rockies. Those should be available as extra cost options.

This is not a dream car. It could easily be included into the 2015-2020 national Goals to reduce air pollution and imported Oil. If our New-GM, New-Chrysler and Agressive-Ford cannot or will not do it, many others in China (and in many other places) will build such vehicles. Tata may be one of the front runner.

Henry Gibson

Well thought out comments every one.



Regarding weight of range extenders, the recent Toyota 1-litre engine (as used in the Aygo etc) is the lightest in its class at 67 kg for 48 kW output.

A better option might be to use an engine from a Japanese Kei class car (660 cc, already optimised for weight, power and emissions etc).

Fred H

Nice to hear that you don't insist on being able to drive to the top of Mt. Everest within an hour anymore. ;-)
But even your reduced requirements are a bit extreme.
I am aware of only one highway in the entire United States that rises 10,000 feet (elevation difference) within 50 miles.

I did the math.
A 3,000 lb. car including a fully charged 20 kWh (usable) battery, loaded with an additional 800 lbs, would require only about a 15 kW range extender to drive 50 miles and 10,000 feet increase in elevation at 55 mph.
A 15 kW range extender is probably adequate for more than 99.9% of all trips.


Now that I have defended the validity of the mini-genset approach, I would like to say that in my personal opinion, the power-boost approach, as exemplified by the Fisker Karma, may be the better match for existing battery technology and consumer preferences in many instances.

Most likely, I think that both approaches, and variations in between, will coexist and compete in different areas of the market.



I never said anything about Mt. Everest, this is how lies get started with or without a smiley face. People do not want to have 40 hp VW beetle performance when going to the mountains for the weekend, that was my point.


Fred, the battery will generally be at minimum SOC when you reach the base of a long highway grade. And SJC's 10k feet in 50 miles is a benign, sub-4% grade. US Interstate max grade is 6%, and out west such grades can stretch for 20 miles. At 60 mph, your 3000 lb vehicle with 800 lb load needs 27 kw climbing power on these grades. Add 13 kW for aero, rolling resistance and accessories to get 40 kW total. This translates to 47 kW at the engine assuming 85% driveline efficiency. I rounded to 50. Furthermore, 60 mph is pretty weak, especially when the (much cheaper) competition is whizzing by at 70-80. Also note state highways and other roads often exceed 6% grade.

I've seen patents to integrate GPS data into the battery control logic so the battery will recharge whenever you're near the base of a long grade and be available to help with the climb, but let's get serious. Car magazine writers will always find a way to trick such schemes and write scathing reviews about being limited to a dangerous and illegal 35 mph goin up Interstate 80. Why risk a half-billion dollar product launch over this? Really small cylinders are inefficient due to volume-to-surface-area ratio, anyway. Also, peak efficiency occurs at high torque/low RPM which means a 15 kW engine will run far from optimum efficiency during highway cruising. Finally, it's no small trick to design a small engine which can run at 80% of rated power and high RPM for hours on end. You're giving up an awful lot to save a few pounds.

Patrick, I was wrong about engine weight. The old Insight 3 cyl weighed 124 pounds:

I couldn't find the Smart gas engine weight, though I have a note which says their TDI weighs 69 kg. I know some 50 kW motorcycle engines weigh below 100 lb but they are not efficient.


It may just be a trade off. If my four people scenario going from Sacramento to Reno over highway 80 above an 8000 foot elevation pass can put up with 60 mph worst case, then we have a winner.

I just don't want people to think that they can put a 20 hp engine in a range extended hybrid and everyone will love them. Once the word gets out that is is a slug when you go to Tahoe, the sales could drop no matter how good the mileage is.

Fred H

Sorry SJC, it was meant jokingly. I guess I shouldn't try humor.
Just in case you missed it, I was referring to this discussion:

A car with a 15 kW range extender and a 20 kWh battery using the above cell chemistry could have over 100 kW peak power. So Power is no problem, but the battery needs enough capacity to climb any existing hill that it would encounter. Since I-80 only goes up to an elevation of about 7,000 feet, with the range extender running it would have just enough capacity to drive from Sacramento to Tahoe at about 70 mph before the battery is depleted. Continuing downhill to Reno the battery would recharge.

For those who need to drive their commuter cars to Reno ten minutes faster, a 25 kW range extender would be enough.

For this particular trip, such a car would be just adequate. But for more than 99,9% of all other trips and commutes in the US, it would be more than enough.

There are already millions of consumers who buy cars that are just adequate. Such a car could fulfill the needs of this market segment.

There is also a market segment that wants overkill. As I already wrote in my first post, I think that for many consumers, the high power range extender approach would be better suited to their preferences.


Fred, you continue to erroneously assume full battery at the base of the mountain. Someone who starts in Vacaville and heads west on I-80 has exhausted their battery by the time they reach Sacramento's western edge. All energy for the climb from sea level to Donner Summit (7200 feet) must come from the range extender. Your 15 kW range extender will achieve 30 mph at most on the sections with 6% grade. That is not "adequate" and any new car with that level of performance will be laughed out of dealer showrooms.

Fred H

Hi doggydogworld,
I correctly assume that I would fully charge the battery and switch to charge sustain mode before starting a long drive.
I correctly assume that energy would be drawn from the battery for acceleration and many smaller hill climbs during the long drive to the base of the mountain and that the battery would be recharged during deceleration, downhill, and level driving by the range extender, so that it is still fully charged at the base of the mountain.

Using your figure of 50kW to drive 60mph up a 6% grade, the 20kWh (usable) battery by itself would have enough power and capacity to climb a 6% grade to Donner Summit at 60mph. With the range extender running additionally, it could be about 70mph.

BTW: You erroneously assume that the range extender must have really small cylinders, run far from optimum efficiency during highway cruising, and run at high RPM.

In my personal opinion, I think most people are smart enough to make sure their cellphones, digital cameras, ipods, laptops, and electric cars are charged up enough.
People who are too stupid to keep their electric cars charge up before driving up the mountain will get laughed off the road.

Like I wrote before, such a car is only just adequate for its intended purpose: as an all electric commuter that can also run on liquid fuel for the occasional longer trip.
And again: many consumers prefer a car with performance overkill, and in my opinion, a car with a cheaper battery and a high power (100+ kW) range extender would better suit their preferences.


It seems that many of us are still in the bigger-faster-more powerful than yours acquired mode.

Will it take another 1929 style long lasting depression to realize that most of us do not require a 4000+ lbs monster to commute to work, drive the kids to school and sport games, go shopping etc.

For real die hards, a limited number of Hummer like monsters (ICE, HEV, PHEV or BEV) could be built or imported. Of course, those people should be prepared to pay extra registration fees and extra road usage fees etc.

The rest of us could drive common sense, much smaller, lighter, more efficient electrified vehicles. Sure enough, PHEVs will come with various features and size to satisfy most drivers but they dont have to look and be like the current modified 4-ton International truck pick-up monster.


"Will it take another 1929 style long lasting depression..."

I do not think that it is THAT extreme. Car buying habits go in waves and form patterns, it was the station wagon, then the minivan and now the SUV going to crossovers. People know that we need good mileage, but they want room and good performance too. The car business is tough and only the strong survive, they are the ones that can read and shape the trends.

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