700 miles on LPG without needing to refuel

[LPGC]

As in the title, I've just done 700 miles on a single fill of LPG... 300 Miles local driving, plus a 200 mile round trip to Blackpool, plus a 200 mile round trip to Whitby.

Possible because I fitted a 2nd LPG tank behind the rear seats in my Nissan Elgrand people carrier. The original tank (fitted externally underslung where the spare wheel used to live) holds over 90 litres and the extra tank (fitted behind the rear seats) holds another 80 litres. The car only does around 20mpg but 170 litres is more than 37 gallons...

The additional tank can be fitted / removed at leisure because it is fitted with quick fit (snap on/off) LPG lines. When fitted it fills at the same time as the underslung tank (just the single LPG filling point on the car) and gas from it is used at the same time as gas from the underslung tank.

Filled both tanks at home from red bottles using one of the LPG pumps that I sell, the gas in red bottles costs me around 86p per litre.

[CNG]

Nah... sorry Simon. Compared to a mate of mine, - and I've got about 500 miles range - you or me? Nope, both of us play at it....




He gets roughly 1600 miles.

And if we're still struggling to concede defeat, he'll wheel-out this monster...

[LPGC]

You have 500 miles range on CNG?

My 700 miles range on LPG is with one additional tank in the luggage area, still space for luggage, still have all 7 seats in the car available, no need to tow a trailer for the fuel.

If I wished I could add another tank and still keep all 7 seats and still not need to tow a trailer, this would give me 1000 mile range on LPG (plus 350 miles range on petrol)... But I could stow the rearmost row of seats and carry another couple of (bigger) LPG tanks inside (for total of around 560 litres of LPG on board) and have around 2500 miles range with seating for 4 or 5 people without towing a trailer, with ease and with the only work I'd have to do being to add a couple of quick connect fittings to the extra additional tanks to make it possible. That's not even with tanks stacked on top of each other, that's with each tank sat on the floor with plenty space above them to carry loads of luggage. If I were to stack tanks I could carry a lot more gas in the car than the 560 litres I just mentioned. If I were to tow a trailer with an LPG tank on it I could fit a 2000kg (around 4000 litre) LPG tank on a trailer for total of around 4560 litres capacity and (with the reduced mpg due to towing a 2 ton trailer) have over 16000 miles range... But towing a large trailer just to carry (that much) fuel seems a bit OTT lol. I can see the point of fitting some additional tank(s)/fuel capacity in a trailer if it is necessary to tow a trailer to carry some equipment and there is spare room in the trailer to carry fuel (and I've done that in the past) but not really to tow a trailer just for the sake of carrying fuel.

I've converted pickup trucks in the past and fitted several tanks on the flatbed giving the owner well over 1000 miles range, come to think about it closer to 2000 miles range.

You''ll never beat LPG range with CNG, LPG gives more range per tank volume, the tanks are much lighter, cheaper and much more readily available. Just using some old but perfectly useable tanks I already have knocking around in the yard I could get several thousand miles range on LPG with my car... that would be using my current facility to add an extra tank, no need to modify the car (no need for any extra piping on the car itself etc), just fit a length of pipe with a quick fit connector to each tank I wanted to use. It would cost me around £50 per tank for the lengths of pipe and quick fit fittings to modify them for this purpose. If I so wished I could have 2500 miles range in my car today with parts I already have, no need to tow a trailer to carry the fuel it would all be carried in the car itself, it would still seat 4/5 people in comfort and not be overloaded.

[CNG]

Yes, of course I was joshing here. It was me in that thread that said this first.

I recall, no matter how hard I tried to say it's far more than 'simply' pressure.... weight in steel will top-out the heaps of scuba tanks, etc, this before volume is viable, thus you'll never run a high mpg luxobarge if you expect range even close to LPG etc etc.



Here’s some of the purest gems from that thread:

'The cylinder doesn't know or care what it carries as long as the pressure rating is appropriate it will suffice. Its a pressure vessel at the end of the day...

Yeah right...

"Yes, You're making it a challenge and really it's a simple fix".

Hence the pic of my mate’s er... ’simple fix’.

I gave up.

In all seriousness, it's much like pitting petrol vs LPG. We'll not match LPG fuel density with CNG, and the only way we'll come close is by cheating. And if with LPG, we pull the same stunts, LPG still wins. Hence [drum roll] the lunatic lengths a mate of mine goes to ensure within the realm of CNG these words become true.

"a cylinder doesn't know or care "

[hitman2]

Those purest gems are all FACTS whether you want to accept that or not is a different matter

[Gilbertd]

I wondered what CNG was on when he wrote that so wasn't going to bother replying, but as someone else has, I will. A pressure vessel is a pressure vessel, no matter what you put in it. I've got a cylinder in my garage that, when full, contains Oxygen Free Nitrogen at 290 bar. What goes in it is irrelevant, it can withstand a pressure of 290 bar (or probably considerably more than that depending on what the difference between safe working pressure and burst pressure is), so could fill it with liquid Propane at around 10 bar and it would be quite happy. Equally you could use your compressor and squeeze Methane up to 290 bar and it would still be quite happy. Unless you intend filling it with something that is corrosive to the material it is made of, then it would take it.

[LPGC]

CNG in a steel tank that had appropriate pressure rating would be fine, unlike say hydrogen which apparently can 'hydrogenise' (if that's the correct term) the steel turning it brittle and degrading the strength... but Gilbert covers that with 'corrosive to the tank'.

Maybe talking at cross purposes though because I think CNG's continued point is that a larger vessel will have greater internal volume versus vessel weight than a smaller vessel, so to get the big capacity if he can't get a single large capacity vessel he has to use several smaller vessels then it ends up being too heavy. But I thought we'd been through that, done the maths on it and everything lol.

[CNG]

Yes. Simon got it long since.

And yes, umpteen scuba cylinders could happen. Kinda’.

[Gilbertd]

to match LPG range, young Gilbert will want 7-8 of those white cylinders. Or a slightly less weighty and more viable 2 x 110L. ie no rear seating.

Unless CNG tanks are much bigger than LPG tanks, that wouldn't be a problem. I've recently fitted a 93 litre full toroidal tank in the spare wheel well of the second P38 I bought and could add one of these https://lpgautosupplies.co.uk/shop/lpg- ... 20-litres/ in the boot, giving me 217 litres capacity. I'd still have over 60% of the existing boot space available. But how long would it take to fill those tanks with your pump? CNG filling stations are relatively common in Germany and Italy at the larger filling stations but not here, France, Spain, the Netherlands, Belgium, Poland, Lithuania and Latvia, the countries I do most of my driving in. So nowhere to fill for the bulk of my driving either. Definitely not a practical option for me.

[LPGC]

How about using some oxygen / nitrogen / CO2 cylinders @CNG?

[CNG]

Yes two, not one of Mick's tanks sized as his 120L would get you something like 180, maybe as much 200 miles on a cold day.

[CNG]

How about using some oxygen / nitrogen / CO2 cylinders @CNG?

We're back to the same problem as scuba cylinders. We'll top out in weight or volume first

[Gilbertd]

Yes two, not one of Mick's tanks sized as his 120L would get you something like 180, maybe as much 200 miles on a cold day. In steel, maybe your Rooney would take the weight, not sure I would want to. Too heavy, certainly not both in the boot.

Why not? At present I've got a 100 litre petrol tank, the LPG tank, the spare wheel and tools in the boot and regularly tow a trailer with a nose weight of around 80-100kg. The petrol tank is above the rear axle and the rear axle can take an additional 840kg before the axle loading gets to the maximum weight allowed. EEC Kerb weight is 1100kg on the front axle and 1000kg on the rear, maximum axle weights are 1320k and 1840kg respectively. Seems like, due to your ignorance of the vehicle, you are underestimating its capabilities.

But it seems to me that CNG is even less practical than running a diesel on veg oil. Fine if you always fill up at home and never go beyond 50% of the range of a full tank so you can get back home to refuel, but totally useless for a journey any longer. At least with a diesel on veg oil you can stop at a supermarket and buy cheap cooking oil.....

[CNG]

Yes OK. I suppose space permitting, it 'could' work.

[Gilbertd]

Yes OK. I suppose space permitting, it 'could' work. We could run the equiv. in weight of two extra engine blocks in the back, the one that'd worry me is the lump forced to sit well beyond the rear axle. It would work, if you're fine with it, maybe I am underestimating its ability. But that's a lot of weight.

Depends what sort of engine blocks you are talking about. I can lift an alloy Land Rover V8 block on my own easily but the cast iron small block Chevy in my boat needs an engine crane. If you look at the design of the car, the rear axle is below the boot area so the weight wouldn't be beyond the rear axle, it would be above and slightly forward of it. What sort of weight would you envisage anyway? Don't forget I've also got self levelling air suspension so no matter how much weight I put in the back, it will always sit level, no drooping at the rear.

PS. Why do you keep referring to it as a Rooney? As well as Range Rover and P38, which are both correct, I've heard Range, Rangie, Rover (usually from owners in the US who aren't aware of Rover as a brand) and odd nicknames that people give their cars but never Rooney. Is this some sort of Northern thing I've not come across?

[CNG]

In steel, such tanks are heavy but possible.

[Gilbertd]

Not sure which Land Rover circles you inhabit but if it has anything to do with facebook, that might explain it. The home of those that think they know everything about everything when in actual fact they think they know a little about lots of things so know everything about nothing. I thought a Freelander was a Freeloader, a Discovery is simply shortened to Disco as it only has two syllables and not four so suits lazy people, and I can't see any top mum or footballer driving a 26 year old car with 524,000 miles on the clock, one of the later ones maybe. What would you call a 2 door Classic then?

[CNG]

Call it what you want, I'd love a two-door classic. My wallet won't let me.

[LPGC]

How about using some oxygen / nitrogen / CO2 cylinders @CNG?

Unless we're happy with minimal range, or using them as the pic above, before we even start, we're back to the same problem as scuba cylinders. We'll top out in weight or volume first. It's why I reckon whilst LPG flies fine, a long-range CNG Rooney would be expensive - and for it, one 'orrible beast.

I thought oxygen / nitrogen / CO2 bottles were available in a wide range of sizes? ...So if you went with a couple of the bigger sizes?

I only did a very quick check of pressure ratings and available sizes, but it seems worth asking if your home compressor can fill your CNG tank to the same pressure (what 300 bar?) that you could fill up to at say a forecourt? Since there are no forecourts where you can fill with CNG your setup only needs to have CNG containers that will withstand the pressure of your home CNG compressor. Also if (say) a CO2 cylinder is rated to a lower pressure than a CNG cylinder we'd expect it to be thinner walled and lighter?

[CNG]

Oxygen / nitrogen / CO2 bottles? Yes, I suppose so...