Lpg

[jabalv]

I tried to find information if someone using LPG to run petrol engine vans. Doesn't seems like a common practice. Why LPG can't be used? I know that torque is the problem comparing with diesel engines. But benefit would be same balloon can be used to power engine, heating, cooking etc.

What are your opinion of LPG in vans?

[carringb]

They never were popular in the US because gasoline/petrol is so cheap. Return on investment just never works out. Especially since most retail propane prices seem to trend with gasoline prices, even though market prices of LPG only loosely correlate. Plus bulk-filling stations have become more rare as BBQ propane-tank exchanges have proliferated.

They are semi-common in parts of Canada. I've read maintenance is better, since oil changes can go much further on LPG. Ford does offer a hardened valve seat package for running LPG, however it seams the conversions work find without the hardened valve seats too.

[deserteagle56]

The problem with a propane-powered van is locating a tank somewhere on the van of sufficient capacity to do you any good. Propane does not have the BTU energy of gasoline; your mpg will be less than on gasoline.
Back in the late 70s there was a real problem with gasoline availability so I converted my 1976 GMC Terravan to run dual fuel. With the flick of a switch and pull of a knob I could run either gasoline or propane. The propane tank was a 110 gallon water capacity (88 gallon propane capacity) unit mounted sideways up against the rear doors. Since it was actually inside the van I had to build a steel container around the propane tank, totally enclosing it, and have it vented to the outside. Drove this thing for 32+ years!

[arctictraveller]

A buddy in Cananda has his van set up for duel fuel. I think he runs propane as often as he can due to the lower price, but he can't always find it. Fuel prices in Canada are considerably higher than the US, I paid just over $5 US /gal a couple weeks ago, and last week they announced an additional 0.40 cent/gallon increase due to a shortage in B.C. Of course when converting from US currency to Canadian we get a 0.20 cent discount, but fuel is still nearly twice what I normally pay, so the investment in a propane conversion makes more sense there.

[86Scotty]

LPG vans and shuttle buses are fairly popular here in the Southeast. I've never understood the interest over gasoline but I do see them fairly often.

[MadScience]

In CA you can get a white carpool sticker with at least some LPG conversions. That's a big deal in some situations, though I'm not sure I understand why you'd want to drive a van alone in the carpool lane instead of leasing a loss leader electric.

Also: I dig that Terravan!

[TomH]

Originally Posted by 86Scotty

LPG vans and shuttle buses are fairly popular here in the Southeast. I've never understood the interest over gasoline but I do see them fairly often.

It's been around 35-40 years since I've seen liquified propane gas (LPG) vehicles anywhere. Here in the west, many shuttle busses and other fleet vehicles run on compressed natural gas (CNG), which is about 97% methane after 2% water is drained off. What we buy as propane and methane (aka natural gas) both have small amounts of other hydrocarbons mixed in. Methane can't be liquified at the same pressure propane is without cryogenic cooling. Liquid methane is what Elon Musk's next SpaceX rocket engine (named Raptor and to be used in the 2020s on a new Mars rocket) will use as fuel. Methane is CH4, so 1/3 of the exhaust gas is CO2 and 2/3 of it is H2O (water as steam). Propane burns cleaner than gasoline, but methane is even cleaner than propane, both in terms of exhaust to the atmosphere as well as deposits inside an engine. Propane is primarily distilled from liquid petroleum (along with gasoline, butane, diesel, fuel oil, asphalt, and small amounts of other hydrocarbons). Methane may exist above liquid petroleum in underground cavities, or may exist apart from liquid petroleum, but it is extracted by itself, not distilled from liquid petroleum as is propane. Even though the methane molecule is smaller than propane, methane has a higher energy density than propane. Fracking has driven natural gas prices down. The US was preparing to import liquified natural gas (LNG), but fracking has made it so that we are about to become a major exporter instead. NG is cheaper than propane.

Fitz works as a civil engineer at a petroleum distillery. Perhaps he can offer more advanced details than my knowledge level.

[86Scotty]

Your knowledge level certainly surpasses mine. I guess I'm seeing CNG vehicles. I haven't paid much attention, I just see the big tank hanging under the rear (mainly on shuttle buses around airports).

[TomH]

Correction to above: LPG is Liquified Petroleum Gas and is usually about 98% propane and 2% butane, with possibly trace amounts of other hydrocarbons.

Propane can't exist as a liquid unless you chill it to -44°F OR place it in a pressurized container at regular temperatures. If you open a propane bottle, the propane is under less pressure and will start boiling and vaporize to gas quite quickly. The pressure required to contain it at normal temperature isn't very high though, which means you can carry it around as a liquid as long as it's in a pressurized bottle.

The pressure required for methane to exist as a liquid at normal temperatures is way to high to carry it around in tanks, so the only way to transport it as a liquid is to cool it to < -270°F. When ships transport it from export countries to import countries, it is sent at those temperatures. The ships have to run active cooling systems to keep the stuff cold enough.

This is why a motor vehicle can carry a pressurized tank of liquid propane, but can only carry methane (natural gas) in the form of compressed gas. That means you usually get more range from propane. Extended range using CNG requires big tanks; that's why you mainly see it on things like public transport or school busses which make a circuit of 100 miles or less and can stop by the fueling station on each round.