Demonstration and validation of direct injection CNG

Discussion in 'Fuel' started by Carcus, Sep 19, 2019.

  1. Carcus

    Carcus Well-Known Member

    Report released in May, 2019. Basically what I've been saying for a while, ...

    - dedicated CNG (vs gasoline) engines can be built that will increase efficiency (about 15%) and cost about the same (additional $2,200) as modern diesel engines
    - efficient cars can have a decent range without sacrificing room for cng fuel storage
    - emisssions are way less compared to gas or diesel
    - running costs are substantially less

    At least where hauling/ long distance is concerned, ... dedicated (i.e. turbocharged DI ) cng makes way more sense than BEV/PHEV to me (unless there is some sort of pending battery break through (huge breakthrough) we don't know about

    /look at the graphs on Ford's 1.0T gasoline vs single and dual turbocharged cng (figure 5-10) impressive improvements in efficiency (up 12%) AND power (120 vs 160 hp)
    //rumormill has it that Ford is working on a CNG 3.5 (dual turbocharged) F150 [Bobcat 2.0?? -- pure speculation]

    //// the way I sees it -- batteries will have their place in urban environments, .. but once you get out on the open road (especially if you are hauling a load) -- dedicated cng is the more likely future
    Last edited: Sep 20, 2019
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  2. Trollbait

    Trollbait Well-Known Member

    Makes more sense than hydrogen. Though the tank improvements may have come out of FCEV research. The 370 mile range for a car isn't much better than a FCEV though.

    Should work well for trucks and trains. It is also easier installing stations to get adoption started than for personal cars.
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  3. Carcus

    Carcus Well-Known Member

    compared to a BEV ... 370 miles with a sub 5 minute re-fuel time is outstanding. ... and then their is durability, hot/cold massive range change concerns, safety, .. etc... And the very big one that a CNG vehicle isn't carrying around an $18,000-ish (optimistic) single point of failure (battery).
    Last edited: Sep 19, 2019
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  4. Carcus

    Carcus Well-Known Member

    I would encourage anyone interested to read pgs 24 - 28 of this report.

    Gasoline performance, diesel efficiency, low emissions AND particulate filters/ exhaust treatment/ etc. ---- NOT required.

    /not that much of an additional investment , .. and the payback operating on cheaper CNG should happen in short order.

    // This is what I have been talking about for years! -- Where are the dedicated CNG engines?
    Last edited: Sep 19, 2019
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  5. Trollbait

    Trollbait Well-Known Member

    I wasn't aware CNG refuel times had come down. I brought up hydrogen FCEV, because CNG is like them in that refueling at home isn't possible. The Phil station cost more than a 40amp Level 2 charger. The annual maintenance might cost more than a Level 2 charger. More importantly, Honda had stopped supporting home refueling near the end of CNG Civic's life because such systems didn't clean the natural gas, and cars' fuel systems were rusting out. Those Civics had a sub 200 mile range(maybe closer to 100), and took 10 hours to fill at home.

    The 600km range mentioned in the report for CNG was an 'up to' statement. For many cars on the road, that's a distance easily reached before the low tank light comes on. So a CNG car will have to visit a station more often. CNG runs into the same problem as hydrogen. The physics of storing compressed gases means bulky, potentially heavy, tanks, which can be a problem in the frame of a car. More so when it comes to hybrids.

    Your battery estimate is high.

    For a Model S long range pack to reach $18,000, the assembly and case would would have to be nearly $7000. Besides, the way most traction packs are arranged, only the bad part of the pack would have to be replaced.

    The range drop in cold is an issue to be aware of, but I'm not sure what safety and durability concerns there are for BEV. Except the Leaf, their battery cooling sucks. For those in which Supercharging is too slow, there are PHEVs.
    Just converting a gas or diesel to NG greatly improves emissions. This has been known for years. Think you'll still need a 3-way cat, because some NOx will be made.

    I think it can be a great fuel for trucking. The tanks could be an issue for cars in space loss, though. It was likely a problem for past CNG cars. There are many private fleets using it. For consumer cars, the issue is refueling infrastructure. I expect the equipment for fast filling(private fleets likely use overnight filling) has higher cost than for gasoline and diesel. Which is hard to justify if there aren't any CNG cars to use it.

    Maybe the time is right for the Pickens' plan.
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  6. Carcus

    Carcus Well-Known Member

    oh my, ...

    Elon just a few months ago said the modules (not the pack) would cost $5,000 to $7,000 to replace in a model 3 (4 modules per pack). Of course, .. he says the batteries will last 500,000 miles ... Elon says lots of things.

    I've owned a cng vehicle , .. refueled in 5 minutes, that's it... believe it or not.

    Audi A3,4,5s are pressing 500km. VW has small vans that are 600 to 800 km.
    (and the Audis are also carrying a petrol tank, ... and these are still 'early days')

    yah, maybe ol' Boone was ahead of his time, ... RIP.
    Last edited: Sep 20, 2019
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  7. Carcus

    Carcus Well-Known Member

    2019 VW Golf TGI

    -130 hp
    -304 miles CNG + 93 miles gasoline
    -no compromise in interior space
    - mpgge -- mid 40s

    If this were sold in the states when I was car shopping, I would have bought one. But like the song says --- you can't always get what you want.
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  8. Trollbait

    Trollbait Well-Known Member

    The article was about the price of cells, so excludes management circuits and casing. A tweet from Musk doesn't give us details; it could be an out the door price including labor for all we know. Used modules for the Model 3 LR are listed for $2250 on Ebay.

    The most driven Model S is already over 550k miles. A Model X that did 300k in two years, lost only 12.5% of battery capacity, and owner reports the loss plateaued after 9 months. Data for the Model S is showing that capacity loss will average under 15% at 150k miles. It should be less with the newer cells now used in the Model 3.

    I think I read an article years ago in which it took longer to fill a CNG vehicle. Looking into it, they might have been doing a quick fill from a time fill station. Which means directly compressing the gas into the vehicle tank. A fast fill station has a pre-filled reservoir tank that is at a higher pressure than the vehicle's for filling. Or they were filling a commercial truck from a fast-fill designed for cars. So my impression was outdated or wrong or I conflated it with hydrogen.

    Had to go back to 2016 to find a CNG car on, and it was just the bi-fuel Impala.
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  9. Carcus

    Carcus Well-Known Member

    So you think you could just take that ebay module and slap it in as a replacement? Nope. They have to be matched to the other modules that are in the pack.

    So this module replacement (i.e. refurbished pack) would need to be done where they have a lot of modules to pick from. And then I suspect they will restrict the overall capacity (and possibly the charge/discharge rates) of the pack so as not to push the likely still not perfectly balanced refurb pack. I think this would need to be done at a centralized location (Gigafactory?) and would involve substantial shipping costs.

    The cells in the high mileage Tesloop cars are getting what I think Jeffry Dahn (Tesla battery guru) would call "beat the clock" cycles. You have to factor in age with normal battery use. (300k in 2 years is NOT normal).

    /and BTW, a simple-cheap (no thermal management) 24 kWh Leaf battery is now $8,500 to get replaced from Nissan (Nissan prices have gone UP ,.. not down).
    // .. there have been a few posts in the Tesla forums on quotes to get a model S battery replaced .... If I remember correctly, in the $20ks --don't know if that was new or refurbished pack (and new vs refurbished -- BIG difference).
    Last edited: Sep 20, 2019
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  10. Carcus

    Carcus Well-Known Member

    Ran through the tesla forums ...

    Looks like a Model 3 battery pack is $15,000 plus labor (4.5 hours -- could be as high as $195/hour rate (I've seen $110, $175, $195..) and you have to turn your core (old battery) in. (more than one source -- people with damaged cars -- they are quoting the same number from the SCs)

    /maybe the refurb model 3 pack cost ends up (eventually) in that $7,000 price range --- I do wonder what the warranty will be (1 year, 2 years? ...)
    Last edited: Sep 20, 2019
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  11. Trollbait

    Trollbait Well-Known Member

    Not at all. I just mentioned it as a guide for what just the module would cost alone. New would be more of course, but I don't think it would be triple, as I take the $7000 in Musk's tweet refers to one for a long range model.

    A brand new module would need to be balanced with the rest. All that is absolutely needed is a decent multimeter and a proper charger. Enterprising individuals and businesses have been doing this for years now with refurbishing hybrid packs. Despite its size, the Model 3 pack looks easier to work on, but hybrid packs were designed more for pull and replace by the manufacturer.

    Americans drive an average 13,476 miles a year. The average age for registered vehicles is 11.8 years. With those averages, a car will see just over 159k miles in that time.
    Here is the blog post cited in the second article I linked,, updated last December.
    "On average the batteries have 91% remaining at 270.000 km (170,000 miles). If the linear behavior would continue, then the ‘lifetime’ (still 80% capacity left) can be calculated as follows: 91-80 = 11% times 50.000 km = 550.000 km, plus 270.000 km, gives 820.000 km (510,000 miles)."

    The Model S isn't even ten years old, so total age in real life might prove detrimental. So can climate and charge rates, but data from driven cars is showing that for most Tesla owners, the battery will be good for the life of the car.

    Yeah, I wouldn't own a hybrid or plug in with a passively cooled battery. Even my gen2 Prius had a fan for it.

    Heat tolerant battery chemistries are more expensive, and Nissan gambled on getting by with less expensive. Then there are other factors determining price. The 24kWh pack was just in the first gen Leaf; smallest in the current is 40kWh, and likely a different chemistry. I think Nissan even changed cell providers at some point during that time. So the 24kWh pack now costing more maybe due to simple economics. One of the reasons manuals are dying in the US is that it costs the company more to simply offer it as a low volume option. Or Nissan was simply subsidizing more of the price earlier on.
  12. Jay

    Jay Well-Known Member

    CNG makes more sense to me too. BEV proponents tend to overlook the multi-trillion dollar electrical build out that would be necessary to make BEVs somewhat competitive with gasoline/diesel. They also tend to forget that it's not just a range and cost problem that makes BEVs uncompetitive. It's a range, cost, and recharge time problem. CNG solves all three. CNG is already being built out to long-haul truckers via existing diesel stations without subsidy because CNG just makes sense economically. The main achilles heel of CNG is volatile prices, I think. Right now, it's abundant and fairly cheap but supplies can dry up in a hurry and prices spike making it uncompetitive again with gasoline/diesel. That's what happened with LP gas. Infrastructure for LP gas was being built out and many conversion kits available that really saved folks money. Then prices spiked and the momentum slammed to a halt. The LP gas infrastructure is still available at many gas stations.
  13. Carcus

    Carcus Well-Known Member

    AFAIK, .. all the Model S refurbished packs had to be sent from California (i.e. no modules were replaced in the Tesla Service Centers -- loaner packs installed for months on end while the SC awaits the refurbed pack arrival) ... do you know something different?
  14. Carcus

    Carcus Well-Known Member

    The pricing is a valid argument. Once all the LNG export terminals get into operation, .. it could have an effect.
    Last edited: Sep 21, 2019
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  15. Trollbait

    Trollbait Well-Known Member

    How much would hydrogen infrastructure cost? With cars, plug ins don't have the chicken or egg issue, so infrastructure build out can be taken in steps.

    But I acknowledge BEVs aren't suitable for all tasks. CNG could be great for trucks and shipping. Injection systems on diesels can improve overall emissions and economy. It is easier to make renewable methane than diesel or gasoline. I wouldn't want it for a car, as it would double the times I have to visit a station in a week, but methane to methanol is also an easy process.

    Another issue for the fuel pricing to consider is fuel taxes. Some states still don't tax natural gas or propane for road use, and others charge less for it than gasoline and diesel.
    You have a source for that? I only came across something mentioned in a message board. The car got a loaner pack as Tesla refurbished the original pack. This is no longer the policy. It was probably put in place when there was no supply of refurbished packs or modules on hand. It is possible Tesla was also tearing apart individual modules, and balancing individual cells takes more time. Much of it is sitting around waiting on charging and discharging.

    In the beginning, only Toyota had replacement batteries for the Prius. Now independent mechanics are refurbishing them in their garages. The same will happen as plug in numbers grow.
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  16. Carcus

    Carcus Well-Known Member


    Still waiting(5 mo) for replacement battery pack....

    Again, as far as I can tell, ... it is not the Service centers that are "refurbing" packs. It looks to me like all that work is getting done in Freemont. If you've got a source that shows Service Centers replacing modules --- then let me know.

    Will that change with the Model 3? Who knows? . .. But my guess would be they'll have to set up some regional refurb divisions at some point do to the sheer numbers and logistics.

    Independent rebuilds: The Prius until recently has exclusively used NIMH batteries -- which are much less susceptible to thermal runaway. These are (obviously) much smaller packs that were run in a fairly conservative (small) SOC window. Big difference!

    /I would be quite surprised if Tesla would tear into modules except at the end of life --- but I guess with enough robots , .. anything is possible.
    // Also, .. there may be a way with the model 3 to balance new modules into an old pack --- I would be interested in knowing how they would manage that. I think self discharge and internal resistance would need to be close across all the modules -- so maybe there is an electronic way to change these variables in a module (i.e. make a new module act like it is an aged module --'tune' the module) -- I don't know.
    Last edited: Sep 21, 2019
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  17. Carcus

    Carcus Well-Known Member

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  18. Carcus

    Carcus Well-Known Member

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  19. Trollbait

    Trollbait Well-Known Member

    I named Prius because it is the hybrid. There are third party companies refurbishing the Li-ion packs for Fusion hybrids.

    In time will see the same happen for plug in cars.
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  20. Carcus

    Carcus Well-Known Member

    ... so there's been a second trailer full of Teslas mysteriously go up in flames on I-80 in Nevada (in the last couple months). And hydrogen is still not gaining any ground -- primarily because the hydrogen facilities keep blowing up. Not to mention, nobody has come up with a good (efficient) way to produce the hydrogen.

    Seems like it might be a good time for plan B, .... or C or D ....... -- call it CNG. **

    /btw -- I think the lithium-ion safety issues will get worked out, hydrogen -- I'm not so sure.

    ** be more like Egypt? --

    Egypt Plans Major Drive for Vehicle Conversions to CNG
    "The agreed plan calls for the establishment of 54 natural gas refuelling installations across 15 governorates, including a number of car-conversion centers, by 30 primary and 24 secondary phase stations divided between the two companies. Furthermore, it is intended that 350 new stations be completed in 6 years after the study and selection of suitable sites.

    Just weeks earlier, the Minister announced an integrated plan of action to expand the use of natural gas as fuel for vehicles and to motivate citizens to convert their cars to a bi-fuel system (natural gas – gasoline) through facilities and payment facilities. He stated that the Oil Ministry’s plan aims at converting 50 thousand cars annually, a significant increase compared to last year which witnessed the conversion of 33 thousand cars. About 14 thousand cars were converted in the previous year and 7 thousand cars annually over the prior three years."
    Last edited: Sep 26, 2019
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