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Any one using this type of CNG tank set up?

8K views 18 replies 7 participants last post by  oil pan 4 
#1 ·
I have been wanting to harnes CNG for years but cant get around the $3,500 boost compressor needed to bring the gas pressure up to the extreme pressure needed to get a good volume of gas crammed in the small space of the cylinder.

http://www.gas-tec.com/products_5.html
For get about the cylinder charger price ($4,700+), I can build my own.

Is any one running these types of cylinders?
 
#2 ·
I've also been looking into this for some time and the size and cost of the tanks have been the primary reason for not pulling the trigger. Looks like the largest tank they offer is 49"L x 12"D and holds 19GGE (if the volume capacity they claim is @275psi). That's approximately double the fuel capacity of a comparably sized 3600psi CNG tank.

I guess the space issue may have been solved for me. Now there is the question of cost. Do you have any info on price?
 
#3 ·
The tanks weren't too bad.
http://www.gas-tec.com/purchase.html#BuyCylinder
The big tank, roughly the size of a 100 gallon propane cylinder is $600.
The refueler is very expensive, $4500. But since the gas only needs to be pressureized to 275psi I could build my own compressor using a high quality R-22 compressor and off the shelf parts.
It has been done before.

When I add up the volume times BTUs, 130 cubic feet times 1,000BTUs for each cubic foot I only get 130,000 BTU. Almost as much energy found in 1 gallon of diesel fuel.

I am not sure what the price of natural gas is now but if its $4/therm (1millionBTU) then it would cost 52 cents to fill that 130 cubic foot tank, if gas prices are real high say $10/therm then it will cost $1.30 to fill that tank.

This natural gas stuff is so expensive because they know the buyer can save a ton of money over time going with natural gas Vs. propane or Acetlyene.
That is, if you are a high volume user.
 
#4 ·
1000 BTUs per cubic foot is at atmospheric pressure. I would think they are reporting their capacity with the gas compressed at 275psi - as it would be in the tank. That would be 19 Gas Gallon Equivalents(GGE) @ 114,000 btu/GGE or 2,166,000 btu in a tank.

If it is only 130,000 btu per tank (barely more than 1GGE) you won't get too far down the road.

I wouldn't have to compress my own as I have numerous CNG fill stations in every direction from my home @ only $1.20 a GGE, but I would build my own if it could be done cheaply. I will have to see if these tanks could be filled safely from the fill stations 3600psi storage tanks.
 
#5 ·
Capacity - 130 cubic feet

Height (with cap) - 48.5”

Diameter - 12”

Weight - 130 LB

CGA 510 female valve
http://www.gas-tec.com/cylinders.html
That is too bad, I believe it means it can hold 130 cubic feet of gas total. Internal volume is only a few cubic feet.
That is too bad I had hoped this would give allow for cheap gas compression and easy storage of a lot of gas.
 
#6 · (Edited)
Capacity - 130 cubic feet
Height (with cap) - 48.5”
Diameter - 12”
Weight - 130 LB
CGA 510 female valve
http://www.gas-tec.com/cylinders.html
That is too bad, I believe it means it can hold 130 cubic feet of gas total. Internal volume is only a few cubic feet.
That is too bad I had hoped this would give allow for cheap gas compression and easy storage of a lot of gas.
Right, the volume of that NG-130 tank itself is a little over 3 cubic feet, or about 22.5 US gallons.
It holds 130CF of natural gas, about 130,000 Btu, about the same as a gallon of diesel fuel. That's a mighty heavy tank to hold so little energy.

Natural gas compressed to 3,600psi is about 39,000 Btu per gallon of tank capacity, requiring about 3.4 gallons to roughly equal a gallon of diesel fuel.
Natural gas compressed to 3,600psi is a little over 50,000 Btu per gallon of tank capacity, requiring about 2.6 gallons to roughly equal a gallon of diesel fuel.

So those adsorbed tanks hold 15% (1/6.6) as much energy as a similar sized 3600psi CNG tank.

Given that the pressure ratio between 3600psi and 275psi is 13:1, they are about twice as space efficient as a straight compressed tank.
In other words, an 1800psi adsorbed tank might hold about the same as a 3600psi straight compressed tank.

Maybe somebody else makes higher pressure adsorbed tanks?
 
#7 ·
Well I made it to newmexico and natural gas is very cheap but diesel is pretty expensive usually over $4 a gallon.

Unfortunatly I have not seen any higher pressure absorbed tanks. These canadians are the only ones I could find offering anything like this.

Is there any possibility of converting a high pressure empty volume tank to a high pressure gas absorbing tank?
 
#8 ·
The adsorbant saturates at 500 psi. The tank will not hold any more gas if you go higher in pressure. The advantage is that it will hold the same amount of gas at 500 psi as a tank without adsorbant will hold at 3500 psi. It's all about low pressure, not increased storage. It also requires very pure gas. The adsorbant will retain propane, butane, and other components which reduce refill capacity. The tank has to be heated to drive out the heavier components.
 
#10 ·
Yeah DIY CNG is looking like a bust. If you can get the tanks, compressing the gas is a crap shoot unless you have a ton of cash or happen to have a rare public CNG filling station near by.
 
#11 ·
CNG is like hydrogen. On paper it sounds a GREAT idea, but as soon as you start hitting the numbers, You get hit by reality.

the infrastructure is just not out there for regular use by everyone

The equipment is bloody expensive on top of that
 
#14 ·
CNG is like hydrogen. On paper it sounds a GREAT idea, but as soon as you start hitting the numbers, You get hit by reality.

the infrastructure is just not out there for regular use by everyone

The equipment is bloody expensive on top of that
Just because everyone doesn't have it means no one should?

First of all hydrogen fuel is just a stupid idea, I will agree to that. Second the best source of feed stock to make hydrogen is natural gas. Plus the fact that natural gas is an all around better motor fuel than hydrogen makes the concept of hydrogen fuel pointless.

If any of that other stuff directly pertaining to CNG is true then why do I see 18 wheelers filling up with it?

You say the infrastructure isn't there. In texas there are CNG stations far enough apart to where dual fuel vehicles can use them. They have multiple stations around the DFW area, Amarillo, in a small town half way between DFW and Amarillo and Lubbock.

The trucks that use CNG take up to 40gge.
 
#12 ·
Well first off, CNG is nothing like hydrogen, CNG actually contains a good amount of energy, and high octane too :thumb:

Didn't mean to dig up an old thread, but it caught my eye. I tuned a kids truck (I work with his dad), he has an 07 lbz with a CNG kit from Marc Deluca (sp?). I tweaked the tune for him, had to cut fuel because he's drawing in a bunch of CNG it would start smoking. Anyhoo, he's netting 50-55mpg on diesel hwy. Think he's got a 16gal CNG tank, and it'll take almost a tank of diesel to burn off the natural gas.

Yes, in the short run the costs are overwhelming compared to fuel savings, but he has 3 cars, and his race car that run on CNG so he saves big time. He actually hooked me up with a factory CNG cavalier! Much better short term solution compared to converting my truck over. It does help that we have 4 CNG stations on the east side of Columbus here, all within 30min drive, and one in Mt Vernon, 5min from work :coolnana:
 
#13 ·
You didn't get what I was saying. CNG is just like hydrogen, electric, LPG or any other alternative fuel source. The infrastructure is not out there across the country like normal gas stations. Gas stations won't gear up for these alternatives because there is no call for them and the cost to set up is no good for the one or two that may come by.

If you have it close at hand, that's good. But if you haven't, you have crapped it or you got to have some seriously big tanks for long journeys.
 
#17 ·
I know precisely how many alternative fuel stations there are. The list is few months out of date.
In the US when a vehicle is registered you have to specify fuel type so its tracked some where.
Last I saw in the US alternative fuel vehicles (not including E85) are increasing 20% to 30% per year. They are the fastest growing vehicle market in the US.
 
#18 ·
percentages don't mean dick.

if we start with 100 vehicle and increase it by 20% that's only 20 vehicles. it's still not the storming change over to alternative fuels your talking about.

I know 5 gas stations within 20 mile of my house used to stock LPG for road use because they fell into the trap of the " alternative fuel " avalanche. They put the pumps and tanks in ready and guess what. 4 out of the 5 got rid of the LPG within a year.
 
#19 ·
Ever hear of compounding percentage rates?

100, then 120 the next year, 144 the next, then 173, after that 207.

So in 4 years they doubled their numbers and will continue to double every 4 years.
Plus they started out with around 10,000 electric vehicles and up to 20,000 alternative fuel vehicles, so the starting number back in 2008 is more like 30,000 not 100.

I agree there is no rapid change over. If you don't consider 20% year growth rapid.
 
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