Prototype Natural-Gas Vehicles Use Gasoline As Range Extender

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To date, natural-gas vehicles have come with significant compromises.

The high-pressure tanks that hold enough compressed natural gas to run 200 miles or more take up many cubic feet of space in the trunk, load bay, or pickup bed.

But what if you could design a vehicle that had just enough natural gas to run 50 to 75 miles--without any change to its cargo space?

That's just what vehicle-development consultant Carlab designed--four of them, in fact--and we drove the prototypes last month.

The concept is identical to that of a Chevrolet Volt range-extended electric car: Run the vehicle's first miles on a cheaper energy source that can be provided at home, then switch to gasoline for those occasions where longer continuous range is needed.

Overnight home fueling

In this case, though, the primary fuel is natural gas rather than electricity, and it powers the combustion engine--meaning no electric motors, battery packs, or electronics are needed.

These cars are best suited, Carlab said, to those regions where natural gas is plentiful, cheap, and already installed in a large numbers of homes for heating or hot water.

For home fueling, the vision is that a small compressor fills the natural-gas tank to its maximum pressure of 3600 psi overnight.

Major appliance makers, including some who attended the drive event, view such a compressor as an opportunity to launch a new category of home appliance sales.

Whirlpool concept for home natural-gas refueling appliance

Whirlpool concept for home natural-gas refueling appliance

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No gasoline for weeks?

Almost four-fifths of U.S. vehicles travel 40 miles or less each day--as Chevy Volt advocates repeatedly note--so conceivably a driver could run for weeks by filling up on natural gas at home each night.

Visits to gas stations might stretch to weeks apart, a popular selling point.

But the biggest incentives are cost--natural gas costs less than $2 per gallon-equivalent in most markets--and the opportunity to drive using a domestically-produced fuel, rather than on gasoline refined from imported oil.

Mainstream vehicles

The four prototype vehicles--we're tempted to call them Range-Extended Natural Gas Vehicles, or RENG-Vs--are being unveiled today at the Alternative Clean Transportation (ACT) Expo in Washington, D.C.

On one level, they're simply traditional bi-fuel conversions--but with much smaller CNG tanks, and no requirement that the driver select which fuel is used.

But on another level, they're the first vehicle aside from the low-volume Honda Civic Natural Gas to show how natural gas can be used for everyday passenger vehicles--and they're designed to avoid that car's drawbacks of limited range and minimal trunk space.

At a preview drive event, held May 21 in Los Angeles, journalists drove four vehicles that covered popular market segments, from four different automakers.

Natural-gas vehicle prototypes, Los Angeles, May 2013 - BMW X3 added instrumentation

Natural-gas vehicle prototypes, Los Angeles, May 2013 - BMW X3 added instrumentation

Enlarge Photo

They were a BMW X3 compact crossover utility vehicle, a Ford Mustang GT sports coupe, a GMC Acadia large crossover, and a Hyundai Sonata mid-size sedan.

Their engines varied from a 2.4-liter four-cylinder in the Sonata to sixes in the BMW X3 and GMC Acadia and a 5.0-liter V-8 in the Mustang GT, to show that natural gas could be used in vehicles with a variety of engines and power ratings.

All were engineered to start up and run on their CNG supplies, giving them rated ranges of 55 to 77 miles on natural gas.

Ranges of 375 to 574 miles

When the natural gas supply was exhausted, each vehicle switched seamlessly to its gasoline for the remainder of its range--an additional 320 to 518 miles.

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Comments (22)
  1. So, it has the disadvantages of an range-extended electric vehicle (more complex drive drain, long alt fuel refill time, limited alt fuel refill points and range) and none of the advantages (zero local emissions on alt fuel, ability to run off solar power, superior performance of electric). It's only supposed advantage is upfront cost, but that's not worth speculating on until compressor costs are known.

    And they will look mighty silly in a few years when natural gas prices rise and battery costs continue to fall. I would be very surprised if they sold 20,000 units.

  2. Α simple but novel idea… using alt. fuel tank just big enough for average daily use!

    Obviously a second fuel injector is needed for NG in addition to gasoline. The ability to home (or fleet) fill the NG is significant as reduces time at gasoline pump. Time saved is added value, in addition to avoiding seasonal gas pump price volatility!

    What would a home NG compressor cost to install? Under $1500 would keep vehicle payback period reasonable, making it a desirable option.

  3. Far easier to put in a 30A charger than a natgas compressor, especially if your house doesn't get gas service.

  4. I have been wondering when any one would take CNG seriously as a vehicle fuel. A good boat cost 40-50 bux to fill up and uses all of it in a hour or so of running around. Natural Gas is suppose to be clean burning so there is that. for a boat which would be very much tied to a "Home Base" I think it will work out just fine. Much better than the electric ski boats that cost another 10,000 just for the battery and its only Lithium Ion battery tech.

  5. Home fueling is great. But how much electricity is used to run the compressor? How does that compare to just using that electricity to charge a PHEV?

  6. The article acts like this is new technology. I did a trip to Lima, Peru this spring and I estimate 40% of the vehicles in Lima run on NG. Half of the pumps in the service stations are NG. As a Taxi Driver told me its cheaper, cleaner and Peru has a surplus, why wouldn't we use it. The government offerred incentives and the consumers converted their cars. What is stopping the USA. I did not see one Hybrid. I have an Old Porsche 914 I would love to convert if the compressor becomes affordable.

  7. The oil industry is a powerful lobby in the District of Corruption. Money makes the difference, not logic or good intentions.

  8. @Victor: As the article clearly states, the difference here is that the natural-gas tanks are sized so they can be incorporated into the existing vehicle structure without compromising load space.

    I suspect those Lima taxis had most or all of their trunks filled with natural-gas tanks. That's a compromise that most U.S. buyers are unlikely to accept.

  9. if you are at the Expo, look around for me. i will try and swing by in the afternoon

  10. Here in the Netherlands we have two companies that make most of the CNG pumps here. These companies are CNGnet and OrangeGas (which provides only bio-CNG). There about 100-130 CNG pumps here, which make a pretty dense network. I think this is a much better solution than refueling at home, because it's fast-filled (about 5 minutes). This also takes away the upfront cost of installing a compressor at home and makes long trips feasible.

    I believe the best way to short-term green transport, especially transport by trucks or vans, is to use bio-CNG provided by landfills, sewer sludge, manure and compost.

    Even better; costs are about 40% less than diesel and specially gas. One KG of CNG costs about €1,00. And can travel as far as 1.5l diesel!

  11. How does the cost of running such a hybrid on natural gas compare to a EV hybrid like the Volt?

  12. This is a great idea as long as it doesn't use up too much space. How about going one step further and having hybrid-gas-natural gas. That would really cover all the bases but probably fill too much space.

  13. 1. Way late to the party.
    2. Still pollutes.
    3. Uses more overall energy than a EV or PHEV.
    4. Have to rely on a costly to maintain ICE.
    5. Car market is growing with OEM made EVs and PHEVs.
    6. Seem to be some sort of desperate distraction from well established EVs and PHEV technology mean to fool non-tech consumers.

  14. BRC FuelMaker has marketed a home Phill unit for several years and with the $1000.00 federal tax credit, purchase price is getting closer to $2800.00 plus installation. So the price is coming down on a unit that's been in production since 2005.

  15. Sure, it cost less upfront. But its so called "mpg" for NG based vehicles are in the low 20s. Even if the cost of NG is about 60%, but its mpg is about also 2/3 of what a comparable vehicle is. So, what are you really gaining in effiency?

    Isn't a hybrid better and cost less? Sure, emission is less and the fuel can be domestic sourced.

    I think a PHEV/EREV running on NG is even better.

  16. Your MPG comparison may not be correct.


    "In EPA fuel-economy terms, the CNG achieves 27 and 38 mpg (in gasoline-gallon equivalence) compared with 28/39 for the Civic LX with the five-speed..."

    Personally, I'd rather have a full CNG rather than a hybrid anything (be it CNG or electric hybrid). I have been thinking about getting a Civic GX for a while to commute with, but not anymore, thanks to the Focus Electric. BEV is the way to go for small commuter cars.

  17. The measurement of CNG fuel in the tank is by Gasoline Gallon Equivalent (GGE), which means 1.0 GGE puts out the same MPG as 1.0 gallon of gasoline.

    On these 4 vehicles we proved this point with dyno testing to show no significant reduction in MPG.

  18. So this car will be filled up with natural gas, then needs to be filled up with gasoline, then in the future another hybrid EV system included...?

  19. All in all, it still is a clever idea..

  20. Nice idea, but I'd prefer full CNG for vehicles that are too heavy to make full-electric a viable option (i.e. full-sized pickups).

  21. The Michigan automotive engineering technical team that was contracted by CARLAB to design, engineer and build these 4 CNG prototype vehicles has embarked on another project to shatter another paradigm.

    We are proving the point that using CNG does not decrease horsepower by modifying a 2003 Mustang GT Street Muscle Car that currently puts out 470 HP at the rear wheels with alcohol injection.

    We will unveil this CNG Muscle Car at our beloved Dream Cruise event in August, see to track our progress and how to help by various sponsoring opportunities.

    Are you interested in helping us with this project?

  22. We completed the Mustang GT running on CNG in a high performance modified muscle car that puts out 470 HP at the rear wheels. See our website of a video of this car making "Skid Marks" on both fuels, gasoline and CNG. There is no difference!

    We will be on the dyno in the coming weeks to calibrate the engine for more HP using CNG as the fuel.

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