Surely Hank Hill isn’t the only one who thinks propane is the greatest thing ever made?
I know that propane and CNG vehicles exist.
Is there a reason why propane personal cars haven’t been pursued?
Surely Hank Hill isn’t the only one who thinks propane is the greatest thing ever made?
I know that propane and CNG vehicles exist.
Is there a reason why propane personal cars haven’t been pursued?
I suspect it’s the much lower energy density. To get the equivalent of one gallon of gasoline requires 5.75 gallons of compressed (at 2400 psi) natural gas. So you’d need a much bigger gas (literally) tank to give you the same range.
Then, of course, there’s the startup condition. No one wants a CNG car if there are few filling stations, and no one wants to supply CNG if there aren’t enough vehicles that will buy it.
Propane is better but is only about 75% as energy dense as gasoline.
CNG Civics made less power than their gasoline equivalents, had a shorter range (about 200-220 miles), and require a specialized filling station (since the gas is pressurized, the process is more involved). I’m sure there are benefits in terms of localized emissions and maybe NVH but it’s still a fossil fuel.
Both of these point to why CNG has been at least moderately successful with fleet vehicles, particularly trucks and buses. They have the space for larger fuel tanks, and they’re commonly fueled at a central fleet facility.
plus you have to have somewhere to put the tank.
gasoline tanks are under very little pressure so they can be designed with various shapes to nestle into place wherever they fit. Here’s one for a modern Ford Mustang. You aren’t going to get something that shape to hold the pressures you need for CNG, you basically need a cylindrical tank which is probably going to end up in the trunk.
Years ago I worked with a startup that retrofitted vehicles for CNG while trying to raise funds to launch its own line. There simply was no way around the energy density problem without (comparatively) huge fuel tanks.
Propane is basically somewhere between CNG and gasoline in almost every respect.
Propane is more energy dense than CNG, but still 28% less dense than gasoline, so there’s still a problem with fuel density. Propane burns cleaner than gasoline, but less clean than CNG. Propane is compressed to 120 psi (less than CNG) and still needs reinforced tanks.
There are vehicles outfitted for propane, but like CNG, they’re really only practical for short-range use and frequent refilling, like fleet vehicles.
I believe they’re a PITA in cold weather too.
The frosting issue? Or something else?
The frosting issue could be insulated against.
I knew a guy that had a truck that could be switched between gasoline or propane/CNG and he said in the winter you would have to start on gasoline first and let it warm up before switching.
There must be some because I know where a filling station is for them. IIRC they can produce less pollution per mile than gasoline but will cost more to operate. The pollution information is rather old and modern high mpg cars may be doing better than propane now. Even if you know where a filling station is you might have difficulty finding a mechanic who knows how to work on anything involving the fuel supply. I’d worry about a breached tank in an accident too. The gasoline will at least stay in one place. On a cold day a cloud of propane takes a while to dissipate and can be carried a distance away by any breeze.
Long ago much of the taxicab fleet in Winnipeg was propane powered. They were Crown Victoria or Caprices and a certain amount of their enormous trunk spaces were occupied with tanks. That didn’t really matter since nobody can fill a crown vic’s trunk with baggage that was or will be checked onto an airplane. They also smelled pretty bad. Don’t know if they all leaked a bit or if the scent just soaks into them over time. They’ve all been replaced with Toyota Priuses. On the plus side there are still lots of propane filling stations in the city so getting BBQ gas is easy.
Most taxis in Japan used to run on LPG (propane/butane mix). Mainly because LPG was cheaper than gasoline. Now the Prius seems to be most common - most of them are standard gasoline/electric, some have been converted to LPG.
Trunk space is an issue with LPG taxis, but it’s not horrible - you can see a picture halfway down this page.
As I understand it, for all pollutants other than carbon dioxide, propane actually fares worse than gasoline. At least, the last article I saw on the topic (decades ago, so might not be current) was hyping alternative fuels because they were cleaner than gasoline, and hyping propane because propane was an alternative fuel… but if you actually looked at the numbers in the table, propane was the only one that was worse than gasoline.
:dubious: Did he say why?
Winter gasoline blends include a larger proportion of butane to help with cold starting. The engine also deliberately runs a little rich during cold starts to compensate for gasoline’s reluctance to evaporate when it’s very cold; that bit of extra liquid ensures that enough evaporates to produce a combustible mixture.
Propane evaporates even more readily than butane, so I can’t fathom why it would be a problem for cold-starts.
And CNG…that’s a gas even before it gets injected into the engine, so zero evaporation problems.
How do CNG-only or propane-only vehicles manage their winter cold-starts?
I’ve owned and operated a propane powered van since 1999. It’s a Chevy G-10, converted right out of the factory when it had 21 miles on the odometer per the sticker on the inside of the door jamb. It is not a dual-fuel, it’s LPG only. I drove it for delivery, averaging 300 miles per day for quite a few years and I’ve put over 165K miles on the van since I bought it.
It does not have any sort of issue starting in the winter on the Left Coast. Propane comes out of a valve at about -109F and it has to be warmed up before it hits the fuel injectors–whatever chill is in the air is basically meaningless to the normal chill of the fuel as it comes into the engine.
The van gets about 10mpg these days, but it’s down some from when it was younger. I have two 18 gallon tanks on it and I just fill up every 300 miles because it doesn’t have any sort of a meaningful fuel gauge on it. Fuelling is not a big problem, because if nothing else most towns have a U-Haul and they all sell propane. Most filling stations have propane because they fill up RV tanks. Propane generally runs cheaper than gas, sometimes a LOT cheaper, depends. The further out in the boonies you go the cheaper the propane because lots of people rely on portable tanks to keep their homes going.
In every aspect aside from fuelling it up, it’s identical to a gasoline powered vehicle. Perhaps a touch less power, but then again for a 1989 full sized van with a 5 liter engine and a three speed transmission you’re not going to get much power no matter what fuel you use. It runs very clean, the fuel is clean and that safeguards the engine quite a bit and the van sails through DEQ no problem so it’s completely compliant with air quality standards. Doesn’t smell as gross as a gas powered vehicle though. That’s why you can run propane vehicles indoors (think forklifts) but not gas powered ones. Cleaner emissions, very little carbon monoxide.
Still on its original engine with good compression in all cylinders after at least 265K miles and it might have another 100K on top of that–I bought it when it was ten years old and it had been a fleet vehicle but it doesn’t go past 99999 on the odometer. It was at 91500 when I bought it, no idea if it was around the clock once before though.
It’s a conversation piece–people are always asking if I’m going to sell it but get cranky when I point out that the cheapest conversion kit is $3500 so they probably can’t afford it. I’m thinking of giving it to my nephew, though.
Everything I saw was decades old also. It’s not a popular technology now. Lower CO2 can be touted as reducing greenhouse gases but all of the data has to be examined on a per mile basis for actual driving conditions.
It’s very popular with fleets, especially considering the tax credits for conversion, the price differential between LPG and gasoline and the much easier requirements for onsite fuelling. You can pop a big LPG or CNG tank down with a pump on it almost anywhere, but try to do the same to install a new inground gasoline tank and pump. Friend of mine, the mechanic who’s always worked on my van, is now a dealer/installer for basically every CNG/LPG/dual fuel conversion kit on the market and no longer does basic mechanic work because he’s making so much money doing conversions instead. So no, it definitely IS a very popular technology now, just not so much in the passenger car sector.
My nephew has a CNG Civic.
He works for the local gas company, so he has access to fill it at work (they have a fleet of CNG vehicles, so he doesn’t have to hunt for a station, and, yes, he pays (you get nothing for nothing)), and he can drive in the carpool lanes.
It’s a gutless wonder and most of the trunk is given over to fuel tank. But it’s cheap to operate.
One improvement my friend the mechanic has been quite happy about is that there are new LPG/CNG torus shaped tanks that fit into the same volume as a standard gas tank and remove the need for a huge cylinder shaped tank that’s awkward to position. They’re very sexxay but also spendy–if I were to spend some money upgrading the van that would be the second thing I’d spend money on, after a new (four speed) transmission.
Propane is typically more expensive than natural gas, which is one reason why there has been more of a push for NGVs lately.
If you can find a link for that tank I’d like to see it. CNG is typically 3600 PSO (250 bar) in the US and while there are some noncylindrical solutions, I haven’t heard of this one.