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Published on May 10th, 2015 | by James Ayre


Wrightspeed Unveils Turbine Range Extender For Medium + Heavy-Duty Electric Powertrains

May 10th, 2015 by  

Originally published on EV Obsession.

A new turbine generator/range extender for medium-duty + heavy-duty electric powertrains that’s been dubbed the “Fulcrum” was recently unveiled by developer Wrightspeed.

The new 80 kW proprietary turbine generator is for use with the company’s “Route” family of electric powertrains (class 3 through 6). Some further details: the new design weighs in at about 250 lbs (roughly a tenth the weight of comparative piston generators), is claimed to possess a 10,000-hour lifespan, and is of a radial flow, axial design (with intercooler + recuperator).


Green Car Congress provides some more details:

The Route extended range electric powertrains incorporate a range-extending genset designed to recharge the high-power battery pack (currently from A123 Systems) and Wrightspeed’s own geared traction drive (GTD). Wrightspeed, founded by Ian Wright, one of the original co-founders of Tesla Motors, has used a 65 kW Capstone microturbine in earlier Route powertrains. The 65 kW Capstone unit weighs 300 lbs (136.1 kg), for a power-to-weight ratio of 478 W/kg; by comparison, Wrightspeed’s new Fulcrum microturbine offers a power-to-weight ratio of 750 W/kg. With Fulcrum, on which the company has been working for about 3 years, Wrightspeed now owns 100% of the Intellectual Property of its powertrain products.

A two-stage compression process and novel recuperation design make the Fulcrum 30% more efficient than existing turbine generators, while tripling usable power, Wrightspeed says. Its multi-fuel capabilities allow it to burn diesel, CNG, LNG, landfill gases, biodiesel, kerosene, propane, heating oil, and others. In addition, the Fulcrum will make for a smooth, comfortable ride for drivers and a quiet, clean experience for neighborhoods because of its ultra-low vibration.


Also worth noting here, is that the Fulcrum turbine generator manages to meet stringent emissions standards (such as those set by the California Air Resources Board) without the need for any add-ons — no catalytic converters are needed to meet these standards as is the case with piston generators.

Here’s an excerpt of some of founder Ian Wright’s recent comments on the Fulcrum:

“The automotive industry is in the midst of a fundamental disruption, with electric vehicles merely symbolizing the beginning of the movement. The Fulcrum, together with our range-extended EV architecture, is perfectly suited for achieving maximum efficiency in extremely high-power stop-and-go applications, such as garbage trucks. For many of the same reasons that aviation changed from piston engines to turbines decades ago, we believe turbines will begin to replace piston engines in range-extended electric vehicle applications.

“It doesn’t matter what the driver is doing, you operate the turbine only at its most efficient point. It’s only 250 lbs, incredibly clean and also multi-fuel. It has all those advantages.”

Image Credit: Wrightspeed

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About the Author

James Ayre's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy. You can follow his work on Google+.

  • sjc_1

    Good for buses, combine cycle with a stirling.

  • globi

    Due to their size, small gas-turbines have lower pressure ratios than big gas-turbines. For the same reasons, the internal leakage is also higher and the higher surface to volume ratio leads to more thermal and frictional losses in general. This all reduces the maximum efficiency which can reached with small gas-turbines. link.

    In addition, as opposed to a reciprocating engine, it requires more high quality parts as its internal parts are continuously exposed to very high temperatures and need to limit internal leakage at the same time and this all at very high rpms.

    Besides, a reciprocating with a turbo-charger is essentially a gas-turbine which simply uses pistons to reach high pressure ratios and high temperatures without having to use many compressor and turbine stages (costly stages).

    Smaller gas-turbines (below 10 MW) are being sold but they can usually not compete against reciprocating engines in that power range. link.

    65 kWp at 136 kg is not that impressive either, considering the fact that the Twinair engine from Fiat has 72 kWp at 85 kg – not that this engine would necessarily be suited as a range extender – but if this was necessary it could be provided with a simpler, lighter valve-train an a larger turbo-charger, such that it could be operated more efficiently at its nameplate power (keep in mind drive-ability including turbo-lag is not relevant in range extending applications). link.
    Yes, a given piston engine is limited to the types of fuels which it can be operated with. But this has little relevance in non-wartime applications.

  • spec9

    I think Dean Kamen also looked into Stirling turbines for PHEVs.

    But don’t they have pretty damn hot exhaust gas which could be pretty dangerous for for consumer vehicle?

    • Larmion

      Not per se. Like an ICE, a Stirling engine can work with any temperature differential from a couple of degrees all the way up to infinity. It’s all about striking a balance: efficiency increases in line with the temperature difference between inlet and exhaust (google Carnot cycle for an explanation), but of course your car has to survive the extremely hot exhaust gases.

      Since Stirlings are more robust and with fewer moving parts than conventional engines, I imagine they could safely run at higher temperatures than an ICE.

      The main reason why I don’t see them working in cars is their high upfront cost and their very complicated cooling requirements. The weight gain that comes with double heat exchangers as well as the need for strenghtening the engine’s walls could well eliminate any efficiency gains.

      I really don’t see Stirling working in confined, non-stationary applications. A shame, I really like the design.

  • JamesWimberley

    I assume there are technical reasons why turbines aren’t considered as range extenders for PHEVs like the Volt. The 100kw of the Wrightspeed turbine is the equivalent of a pretty powerful car ICE, the sort you would find on a midrange Audi. Is it that the weight does not scale down?

    • Larmion

      Weight should be okay, the article says 115-odd kg. From what I remember from my thermal engineering course, turbines are far superior in both size and weight to conventional ICEs of the same rated power.

      Turbines are more expensive than conventional ICEs though. Worse than that, they are very slow to respond to changing demand and are incredibly inefficient when running below rated capacity.

      That should be less of an issue in a series hybrid: the turbine can run at its optimum output at all times. As such, I’ve often wondered why we haven’t seen them in PHEV cars already. Especially in the pricier end of the market, they could do very well indeed.

      • JamesWimberley

        We have a design win for the next Batmobile!

      • Otis11

        I think it’s a matter of price – how much does a small one of these cost? Will it ever pay back in efficiency improvements?

        • Larmion

          Good question. I honestly don’t know, and frankly I don’t think anyone knows. There is no mass production of small turbines, whereas the market for small ICE is about as mature as any market can be.

          But even if the price difference is small, it’s still not clear it will pay for itself. A PHEV does most of its real world driving on its battery alone. That means you would need pretty spectacular efficiency improvements to recoup even a small added cost.

          My personal guess: turbines won’t break through in cars, but will go very far in long haul trucks.

          • Otis11

            So I threw that question out as a kind of lay response… I actually had this discussion with my father back in the 1999 after seeing the honda insight at a car show… (He was a design, and later a reliability engineer for small turbines used in auxiliary power units) actually contemplating a design very similar to the Volt except trying to utilize a small turbine for higher efficiency. (We chose a series hybrid to get by the turbine spin-up constraints, not the efficiency, but would have gotten both.) We came to a number of conclusions:

            First, the design of a serial hybrid was completely uneconomical at the time. (But this was largely due to the fact that battery prices were hugely expensive – sadly, we didn’t follow up as at the time, we didn’t see the trend in battery prices)

            Second, the turbines were something like $20-30K. We figured we could reasonably get them down to $15-20K since weight was less of an issue in cars, these would be smaller, and they’d be produced on a larger scale. However, the smaller size reduces the efficiency gains of going to a turbine in the first place. (This could be incorrect – just some back of the envelope calculations with my dad. I have no background on this material – I’m on the electrical side.)

            A typical small car engine, last time I checked, was between $3-5K for a reasonably high end one. That means we’re looking at adding $10k+ per car. That’s a TON of gas to make up on economically… even at $5/gallon, that’s 2k gallons. 40 mpg means you’re looking at 80K miles on the ice-series hybrid before they even start to compare. It would never pay back at those prices.

            Now, this company is claiming they can do it for $9k. I’d be suspicious of those claims, and the reliability of the turbines if they do deliver at this price point. That said, they are competing in a market with higher cost engines to start with, but also higher reliability. Overall, they might stand a decent chance here. I would be surprised to see the technology develop enough to make it economical in consumer vehicles though. We’ll see…

            Sorry for the rant… let me know your thoughts.

  • JamesWimberley

    Turbine engines are not new. The M1 Abrams battle tank (link), introduced in 1976, is powered by a Honeywell multifuel gas turbine. It checks the boxes on power-to-weight, fuel flexibility, and reliability. Fuel consumption, not so much. The Abrams gets about 2 mpg.

    • Jason hm

      Problem with the M1 is that its a direct drive turbine and the transmission is a monstrous apparatus. Because this most if not all piston tank engines outperform the M-1 turbine in fuel economy and reliability. Tanks like Germany Leopard 2 get over twice the mileage and much better maintenance profile. Canada used the Leopard 2 on patrols a unheard of role for the US M1. This turbine setup is different it’s set up as a generator something turbine excel at and leaves the torque and drive force to the electric motor.

    • Larmion

      And closer to home: almost all ICE cars have a turbocharger, which is a (very small) turbine running on hot exhaust gases.

    • spec9

      Well I’m gonna have to say that part of the Abrams tank MPG problem is its massive weight and use of tracks instead of wheels.

      • Joe Viocoe

        If you use wheels… instead of tracks… it isn’t a tank anymore… it is an wheeled armored vehicle. AFV, APC, Stryker, etc.

        There are still benefits to tracks.

      • JamesWimberley

        It’s a shame that Real Men aren’t allowed to drive them to the mall and defend themselves from Bad Guys with 120mm Rheinmetall smoothbore cannon and depleted uranium ammo. Under a proper reading of the Second Amendment …

        • MarTams

          Real wimps would need all that to fight an unarmed civilian.

  • Omega Centauri

    The Capstone turbines have always been pretty expensive.

  • Joffy Joefer

    Definitely a step in the right direction for turbines on this scale. Wonder what the pricing gain over the last iteration will be and whether they’ll be able to scale up and down well.
    Effiency gains, always good news.

  • lkruijsw

    I wonder what the efficiency difference is compared to a big utility turbine. It will probably less efficient, but if you place this near the houses, you have less conversion and transportation loss.

    • Joe Viocoe

      If you’re talking stationary power generation… might as well go for a SOFC like Bloom. Much better efficiency at 50%-60%… and even higher with CHP

      • Omega Centauri

        This seems to be an improved version of the Capstone turbine. The advantage of this class of turbine is it can burn just about anything (and supposedly cleanly). So if there is a source of low grade gas of some source, it can be used. I think the bigger problem is cost.

        • Steve Grinwis

          I think a part of the problem is that small turbines aren’t really all that efficient. Big turbines are relatively efficient sure, but big turbines are also many stages of expansion, run at very high temperatures, and then, often turn around and use the waste heat to boil water, to run another steam turbine again. These systems are also huge.

          I don’t think they have the efficiency for something like a volt. Might make a cute backup for something like a Leaf though, where it would pretty much never be used…

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