Other hydrocarbon fuels like gasoline, diesel, and kerosene have limited shelf lives but propane will seemingly last forever. What’s different about it?
Not an expert, but for one, it’s not exposed to oxygen. Most fuel degradation is oxidation plus loss of volatiles to the atmosphere. Diesel/Jet A is much less volatile than gasoline and much much more stable.
Yeah, no oxidation is the big reason. It’s kept under high pressure in a tank that’s up for the job. I have a propane powered van that sits for years undriven sometimes and people never believe me when I tell them it will fire right up as soon as I attach the battery cables. Every time, starts first try. Because of very stable fuel.
A bit off track, but when I was in High School back in the dark ages (the early 70s) my Ecology teacher’s car was modified to run on propane. I assume he did it because it burned cleaner than gasoline does. The propane tank was welded into his trunk. Why didn’t this ever catch on? You can buy propane at every hardware store where I live and it’s not that expensive…
Because gasoline is (was?) cheaper, and propane tanks have to be heavier because they’re under pressure.
So you’re saying I should throw away the plastic bags I filled with propane from a leaky gas plant pipe ten years ago that I’ve been keeping in my basement??
Plus bulkier. I drove a CNG Honda Civic for eighteen years. It had a 6gge* capacity with a 220-mile range. It was in six pressure bottles, three underneath taking up the space where the gasoline tank would have been, and three more standing vertically in the trunk taking up about half the space there. Half the capacity in double the volume.
*Gasoline Gallon Equivalent
Actually, propane is a volatile. As noted, because it is stored under pressure in a tank, there is no opportunity for it to react with oxygen or any other oxidizer unless there is contamination in the tank (hence why it is necessary to keep the tanks dry, and why you should never fully exhaust a refillable propane tank unless you are preparing it for inspection). Chemically, propane is a pretty simple alkane with only three carbon atoms; the only alkanes that are more simple are ethane (two carbons) and methane (a single carbon), and thus it is very stable under terrestrial temperatures in the absence of an oxidizer. Gasoline, diesel, and kerosene are complex liquid hydrocarbon fuels that contain a large number of different hydrocarbon compounds that are typically produced by fractional distillation of petroleum with additives to control stability, volatility, denotability, et cetera. Although these fuels are liquid, they have to be vaporized or aerosolized in order to actually function, so they are formulated to be near a threshold of evaporation, and thus over time the lighter constituents and polycyclic aromatic hydrocarbons will volatize and evaporate, leaving the thick, viscous residue often referred to as “varnish”.
Natural gas at 2,400 psi (the normal pressure for NG vehicles) has about 1/6 of the volumetric energy density of liquid gasoline. That means that for the equivalent of a 20 gallon gasoline tank would require a 450 liter tank. By comparison, your typical scuba tank is about 11 liters in real volume, so you’d need the equivalent of over 40 scuba tanks to obtain the same range as a gasoline car, and unlike conformal liquid fuel tanks that can be fitted into any open volume, the propane tank has to be cylindrical with domed ends to retain pressure. For a fleet vehicle that doesn’t travel long distances or a piece of construction equipment that is always near a fuel source this isn’t a big problem but it’s not really workable for a typical passenger vehicle.
No, you should start a YouTube.com channel called “Prepper Failz!!!” devoted to humorous ways of inadvisable hoarding and preparing for the end of civilization. And remember, I get a “Idea By” credit.
Stranger
Not to confuse natural gas (methane) which can only practically be liquified at cryogenic temperatures with propane which is liquid at room temperature when under modest pressure.
Kerosene goes bad?
Does this mean that my ancient plastic bottles of lamp oil are a) hazardous to use b) not hazardous but won’t burn well c) probably OK, since the bottles are tightly closed?
Inquiring mind thinks she’d probably better find out, preferably before I or somebody else decides to light a lamp.
It’s supposed to be stored in a cool dark place but I don’t know if it will ever get to where it won’t light a lamp.
Kerosene does go bad, apparently mostly because of condensation of water.
It’s in a cool dark place, inside a closed cabinet next to the basement stairs. It’s in the plastic containers it came in, most of them never opened (there’s several of them, one might be open.)
The article reads as if I should look at it and, if it looks odd, pour off the top portion (leaving any water in the bottom) through coffee filters in order to filter out any particulates or moldy bits, and could then most likely use it. It doesn’t seem to have any dire warnings about hazards; but I suspect I’d light the lamp the first time outdoors, just in case.
I’m not sure what they mean by “old”. Mine is, I’m pretty sure, somewhere between 20 and 30 years old. I’m also pretty sure some of it was used about 10 years ago, without any messing around first except the light-it-outdoors-first-to-check technique, and it worked fine; but I might be remembering wrong how long ago that was.
This article indicates that, yeah, 20+ years old would be “old,” though it might well still burn.
Thanks, kenobi; that looks useful.
My mechanic, who’s the only certified dealer/installer for basically every alt fuel system on the market in the PNW, showed me a very cool new torus tank that makes retrofitting a lot of vehicles super simple since it fits into the footprint of a lot of large sized gas tanks. My van has two 18 gallon tanks, old school cylindrical DOT certified ones, one is mounted transversely in the rear of the van with the filler routed to the existing gas cap and the second is mounted in line on the driver’s side underneath and is filled right there at the cap. It’s a bit of a PITA to fuel but I’m so used to it now (I’ve owned the van since 1999 and have put about 175K miles on it) I don’t even give it a thought. I do rather lust after the torus tank though, it’s very sexxay.
Linamar’s Flexform tank is designed to fit into all your car’s nooks and crannies:
The current product (if they’re even selling it) is small and marketed for hydrogen, but the startup they bought it from was focused on natural gas back when prices were very low.
2 years ago I bought a used travel trailer. The previous owner had not used it since 2014 and that was the last time the propane tanks were filled. My wife and I used that trailer for 5 camping trips throughout the state of Washington and never had to buy propane. I bought 2 new 30 gallon tanks and had them filled just in case, they are both in my shed and will be installed on my new trailer before we leave on a month long journey this May.
The two services offered at public stations when I had my CNG vehicle in post #7 were 3,000 and 3,600 psi. You could plug a 3,000 psi probe into a vehicle with 3,600 psi tank but not vice-versa for obvious reasons.
Yes. There are LNG vehicles around, mostly busses, but you need to cool the natural gas in order to liquify it and the vehicle’s tanks are insulated. Plus, if you fill a vehicle and let it sit, it will start to vent after a day or so as the fuel warms up. This is not practical for home use but it does get the energy density up.
As a side note, natural gas is just that, gas out of a well with only contaminants like sulfur compounds removed. It is typically 95% methane and 5% heavier fractions. LNG approaches 100% methane as the heavier stuff liquifies first as the temperature drops and is easily drained off before the methane is liquid.
We have a few buses here that run on pressurised natural gas. Until the advent of commodity trading in LNG it was cheap fuel. Pressurisation is a net energy loss, which is enough that one needs to factor it in to the cost. The buses used to sit being slowly filled overnight.
The simple answer for the OP about any of the four economically important gasses - methane, ethane, butane and propane is: they have sat undisturbed for many millions of years underground. They didn’t degrade then, and there is no reason for them to degrade now. The fact that there are not many options for messing up the geometry of the small number of atoms in these gasses also helps greatly.
The liquid fuels we use are OTOH an evil mix of junk. Refining crude oil is a matter of removing the worst of the stuff that makes it not fit for whatever purpose, to the point it just meets the requirement. What is left can still contain stuff that will engage in all manner of horrible reactions, all the way up to polymerisation. If you had a nice pure mix of medium sized straight chain alkanes things would be much nicer. But you don’t. The liquid petroleum sources have not spent the eons hanging around doing nothing. Over time, they undergo all manner of interesting reactions forming a whole mess of large and cyclic horrors in addition to the simple alkanes. The gaseous alkanes (our four economic gasses) tend to rise up out of the morass and are remain close to what we want right out of the well. Unless there was sufficient sulphur around to sour the well. That makes things less happy. Nowadays there are pretty strict regulations of sulphur, so that gets scrubbed out before we consumers see it.