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Westport Innovations Inc. Message Board

  • bslepicka bslepicka Oct 11, 2013 4:39 PM Flag

    Fill time dilemma for CNG and the possible solution.

    If CNG can only be filled at roughly 2 gallons a minute, how about using prefilled tanks and just transfering the tanks which will cut the fill time. You can have the cheap price of CNG and the fill tme closer to LNG.

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    • Doubt that CNG fill rates are that low now. They have been developing new technologies and methods of fill as the market matures.

      This is from CCJDigital website which discusses LNG vs CNG. Search : Letter: Clearing the air on CNG misconceptions

      Misconception No. 4 is that it takes too long to fill a Class 8 truck with CNG. Engineering advancements have made the best-in-class stations capable of fast-fill rates of 10-12 gallons per minute (while filling several trucks simultaneously). The standard 120 DGE tank system fills in 10 minutes. ---- The rest of the misconceptions are worth reading also!

      This is from Trillium's website: Remember, they have committed to build 101 CNG stations.

      HI-Flow: The Hydraulic Intensifier system uses the compressed gas in storage to provide faster fills than a typical CNG station design, with flow rates from 7 to 12 gallons per minute.

    • Westport Jumpstart - LNG
      Pump dispenses at 30–40 gallons per minute.
      Westport iCE Pack
      Faster fueling times & flexibility
      No loss of fuel back to station
      Unparalleled speed in fueling
      Can fuel at any LNG station
      Maximize payload
      Less system weight than equivalent CNG systems
      Increased range over saturated LNG tank systems
      Longer hold times than saturated LNG tank systems—up to 10 days
      Better residual value of assets
      Fuel flexibility allows end of life sale anywhere

      Sentiment: Strong Buy

    • A question
      Is the fill limited because it is set at a small tank rate
      So it may be just when we get larger tanks and more tanks they can adjust the fill rate faster for these

      • 1 Reply to rbtsherman
      • I really can't say, my information came from the clean energy article explaining why Piper was dead wrong.
        CNG just doesn't work for over the road trucking
        While CNG on a per-gallon equivalent basis is cheaper than its liquid counterpart, the cost of the fuel itself is just part of the equation. Without getting too "sciency," the simple challenge with compressing a gas, is tied to something called the ideal gas law. What this essentially means is when you start to cram all these gas molecules together at high pressure, the friction creates heat. When you're trying to cram a couple hundred gallon-equivalents into a 3,600 PSI space, it makes a lot of heat. So this means the tanks have to be filled at a relatively slow process, because:
        1.The heat is dangerous as it actually increases the pressure in the tank.
        2.Until the temperature drops, the tank can't actually be filled all the way up.

        How slow are we talking about? The fastest systems fill at about two or three gallons per minute. So a truck holding 200 gallons of fuel could take more than an hour to fill. It gets even better. The systems that can fill at that rate are expensive -- we are talking about $1 million per lane or more for a 4-lane setup. If you're the fifth truck in line, you're gonna be waiting for fuel for two hours. This is fine for "return to base" vehicles that can refuel overnight at low pressures. It doesn't work for truckers.

    • Good thinking. However, a prefilled tank with 100 Gallon (not say even 200 gallon for trucks) is too heavy to handle for drivers.

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