CNG compressor?

[BioHazard]

I've really, really become interested in natural gas, and I blame you guys completely. The first thing I like to consider is that the more gas I use, the less it costs. I can't get natural gas service at my shop, and as I work on plans for building a new one I don't think I'm going to get natural gas out there either.

The only supply of natural gas I have is at my house, so that makes me really interested in the possibilities of CNG. I could bring tanks of it to my shop, and most likely run my truck on it. Having the ability to bottle and use NG like propane has some serious cost advantages. It has only been recently that home CNG compressors have started showing up in the DIY price range:
Examples:
http://cgi.ebay.com/CNG-Refueling-Compressor-DMC-3-200-3-0Nm3-h-/260719833144?pt=LH_DefaultDomain_2&hash=item3cb41cf038
http://cgi.ebay.com/ebaymotors/Compressed-Natural-Gas-smart-CNG-Compressor-_W0QQcmdZViewItemQQhashZitem41563cb45fQQitemZ280619693151QQptZMotorsQ5fAutomotiveQ5fTools
http://cgi.ebay.com/ebaymotors/Compressed-Natural-Gas-CNG-Compressor-_W0QQcmdZViewItemQQhashZitem415598c32fQQitemZ280608949039QQptZMotorsQ5fAutomotiveQ5fTools

Something I notice about them is that they all put out approximately "1 Gas Gallon Equivalent" per hour, give or take.

What I wonder, is how long a super high pressure compressor like that might last? Especially a cheap chinese unit? At only 1 gallon/hour equivalent I'd have to be running it most of the time. They also of course sell larger, more commercial type units, but most of them are $10,000+.

I've also noticed that "expired" CNG automotive tanks often sell on craigslist/ebay for low prices. Is it possible to get these tanks recertified again?

[billswan]

Bio

Got to give you credit you sure are thinking about lots of different stuff.

In looking at the 3 different machines you linked to, I did notice 2 things cost and don't forget to factor in the cost of the electricity that it takes 2 and 3 hp motors running lots of hours on your high priced grid might add up unless you can time it to run only during off peak.

You mentioned plans for a new shop! Hope you are making plans for a sound proof enclosure for you chp unit some day if I ever reach a point I am comfortable with the performance of my unit I plan to build it it,s special place and sound proofing is definitely on the list of needs. But for now the hurtle of increased wear from WMO is looking huge.

Billswan

[deeiche]

rm /

[TimSR2]

 The fuel makes total sense when it comes out of a pipe and can be used in a stationary engine. Even though the power density of the fuel is low the engine can be sized larger for it, and transportation and storage is no problem.

But I've never been a fan of auto cng systems -- The system pressures are just incredible, and the range so poor! Because of the extreme weight and size of the tanks getting a hundred mile range on cng was always about the limit.   If you are going to need to transport the fuel, or drive the truck,    the advantages of propane are pretty obvious.  The fact that it can be liquefied at reasonable pressures makes it the hands on winner. And there is lots more BTU content to propane.

Regarding getting a recert on an ng cyl you can forget about the fiberglass units. Nobody will recert those. The steel ones should be able to be done at any welding supply store. Count on them selling you all new valves for sure .

[BioHazard]

If you are going to need to transport the fuel, or drive the truck,    the advantages of propane are pretty obvious.  The fact that it can be liquefied at reasonable pressures makes it the hands on winner. And there is lots more BTU content to propane.

The problem is of course propane is about double, maybe triple the cost of NG. I've done the math for converting my truck to propane - I already have really high compression so I have to buy premium - and if my numbers are right propane and gasoline cost about the same per mile. With CNG we're talking 100,000 BTUs for about $1 vs $3.50+++ for gas. It wouldn't take a lot of miles to recoup the cost. Right now it cost me more than 30 cents/mile just in fuel for my truck. I could also possibly convert some other family members vehicles.

The other thing is it would likely remain a dual fuel vehicle, so I can still get as much gas as I want and drive where ever I need to. My normal commute isn't far so I'd be happy with a ~30 mile range on CNG. Additionally, if I'm sucking all this gas out of one meter at home - for transportation, generators, heating, and even fuel for my shop - it all starts getting cheaper per therm.

I just worry about those relatively low cost chinese compressors doing their work for maybe 18 hours/day...how long would that last? Does anybody know of any reasonably priced (say less than 5 grand) CNG compressors that come with a warranty from an american company? I wonder if I could buy just the compressor pump from a reputable company and build my own - add a motor, some gauges and some plumbing. I don't need a fancy stainless steel box with a bunch of cool gauges on it like the ones on ebay....

I gotta keep a real close lookout on craigslist, about a year ago I almost bought a late model crown vic that ran on CNG and came with a compressor. It was only $3000 and I probably could have sold the car for that much alone. A lot of people who end up with surplus CNG equipment/cars don't have a clue about it.

[TimSR2]

If you get a car that is certified you are good for the life of the car, as there  is no recert interval (in Canada). Unless you get ordered to do it by the authorities because of some unsafe condition in your vehicle you are good for life.

[BioHazard]

If you get a car that is certified you are good for the life of the car, as there  is no recert interval (in Canada). Unless you get ordered to do it by the authorities because of some unsafe condition in your vehicle you are good for life.

I don't know how that works legally here, but I'll be instituting mostly a don't ask don't tell policy.  There are no vehicle inspections of any kind here.

One thing I think expired or near expired tanks could be used for is non portable storage, like in my shop, or possibly if I can change to a NG plan where the price fluctuates and take advantage of cheaper gas.

Does anybody know if any of the CNG compressors I linked, or any others, are rebuildable? My FOURTH harbor freight air compressor blew up tonight, doesn't really make me want to buy any kind of chinese compressor without a good warranty.

[Tom Reed]

Don't forget the electric costs. That 2hp motor running for 9 hours to fill a tank to drive 30 miles would be around .04 per mile.

[BioHazard]

Don't forget the electric costs. That 2hp motor running for 9 hours to fill a tank to drive 30 miles would be around .04 per mile.

Yeah, I would definately have to set it up so that it only runs at night and all day on sunday's when my electric rate drops to about 4 cents.

Seems like it would also create quite a bit of waste heat compressing that high, for that long. Even my little 120v air compressor can heat up a room....

[slowspeed]

http://ventura.craigslist.org/pts/2188912232.html
Cng compressor for sale
I like the idea,Power it with your lister free wvo
phoenix list has a few used tanks
Good luck
Jeff

[cognos]

Lots of private Natural gas wells around here. I think you could drill anywhere and get a well up and running - but the cost is becoming prohibitive, and there are onerous inspections and service to be done. The old, low-tech wells that were drilled years ago are grandfathered, require little service,, and were drilled by inventive farmers.


I have a friend who has a good producer on his property. He heats his house and fuels his cars with it. Cars get around 200 miles/fill.

He has two of the small compressors in the large garage/shop. He plugs both cars in every night and fills them. The compressors shut off automatically. The cars were converted and the compressors installed by a certified technician - a requirement here for it to be legal, and be able to insure your home and vehicles.

The compressors do get warm, they just vent the heat into the shop, keeps the chill off - but the garage is heated with an NG radiant tube heater.

He was looking into a 20 KW NG generator, but the well doesn't produce enough gas for it and everthing else. Others in the area have them, and more...

[rcavictim]

How about using a scuba tank/paintball compressor?  Here is a powerful 15 CFM used, 4-stage unit for just $350 BIN.  One would have to check that NG won't deteriorate the seals used.

http://cgi.ebay.com/Paintball-Scuba-Compressor-High-Pressure-Pump-4-Stage-/280624855529?pt=LH_DefaultDomain_0&hash=item41568b79e9

[BioHazard]

How about using a scuba tank/paintball compressor?  Here is a powerful 15 CFM used, 4-stage unit for just $350 BIN.  One would have to check that NG won't deteriorate the seals used.

http://cgi.ebay.com/Paintball-Scuba-Compressor-High-Pressure-Pump-4-Stage-/280624855529?pt=LH_DefaultDomain_0&hash=item41568b79e9

I vaguely thought about that...though I have no idea how "safe" it is. I would think a scuba compressor would be easier to rebuild in the future.

cognos - you have no idea how happy I would be if I had my own gas well!  Seems like the earth is pretty worthless around here, no oil, no gas, no metals. The most valuable thing you can dig up is gravel. 

[cognos]

I'd be pretty happy myself! Unfortunately, the days when a private landowner could economically drill his own well are long over.
There are plenty of properties for sale locally that have private gas wells. You would think they would be woth more! However, in most cases, they actually decrease the value of the property, because sometimes you can't get insurance on the place until the well is modernized or safely cemented shut, and once the original owner or his family moves off the property, the new owners are subject to all the modern regulations and controls. Which really isn't a bad thing, some of these wells and their systems are really old, poorly maintained, and badly designed to begin with. We have an explosion in a residence or outbuilding every few years... And many of them are really small producers, barely able to run a furnace.

[BioHazard]

Does the gas have any scent at all as it comes out of the ground? That seems like it could be quite dangerous compared to the stinky stuff the gas company sends me...

The thought of sticking a pipe in the dirt out back and running an engine off of it without a meter gives me goosebumps...