Just returned from a tour through the Questar facility in Salt Lake. I'm interested in converting a vehicle to cng (compressed natural gas) and then having my own compressor that fills it overnight. It will cost me the equivelant of $1.06/ gallon of gas once I buy the conversion and equipment. The circles I've been hanging out in to learn about this stuff are slanted to the positive side for sure but I can't find a downside. I drove one of the 6.0 Sierra Questar pickups around SLC for about an hour and could tell no difference when I switched to gasoline. Oil is still clean at 10,000 miles, some of their older trucks had 800,000 miles on them. Engines don't wear when there's no residue running down the cylinder walls. I asked the engineer about the realities of running it in my supercharged 500 horse pickup and he said "it's 130 octane, loves high compression applications and the only problem you might have is at the regulator, you might have to install a higher flow-rate regulator." So... that got me thinking about aircraft engines, would it work? Would it freeze? I'd love to put dollar gas in my plane at 5.6 pounds per gallon.

It's not a new idea. I don't remember all the details anymore, but back in the late 70's someone had a private strip near Stevensville Montana with a few planes on it, one of them was a biplane (possibly a steerman) that had been converted to run on propane. He flew it from the rear seat, the front seat had a fuel tank in it, and it flew quite a bit until it caught fire on the ground when he was doing some work on it one day and there wasn't enough left to tell it had been a plane.

There are a few downsides to consider, but if they don't apply to a particular situation, the cng route could be pretty attractive.

Refill time is significant. You already pointed that out. This can be minimized with fixed storage tanks, but adds significantly to the facility costs.

Because of the weight of the tanks, range is much less than a similar performing gas powered setup. Not much to be done about this. CNG is not very energy dense. Gasoline and diesel are much better. But, you can trade payload for range in many applications.

There is no infrastructure to support cross country flying. A company with a fixed route could install compressor stations along the route. They might even make money sell it to others.

But, there are some applications that might make a lot of sense. For example a flight school would be just about perfect. Lots of short flights based at a particular location. Crop dusters might economically use it, too.

Back in the seventies I looked into this for a commuter car. It was very attractive for that application, but as an individual I just couldn't justify the fixed costs for the distance I was commuting. I had lots of fun thinking about the concept then, and it would be great if you could make it work for you.

tom

the downside is range, saskenergy has some of there trucks on it but only the in town ones. I asked them about it and they said because natural gas does not become liquid when compressed like propane it is not possible to have a big enough tank to get any significant range.

NG can be compressed into a liquid. About 600 to 1 in LNG form. That's how it's transported across the ocean. Our Fire Dept had a training film about possible LNG vehicles. The tanks are very high pressure & had 4 relief protection devices for over pressure. If I remember as you use the gas off it naturally cools the remaining liquid & keeps it in a chryo state. The film showed bypassing the valves & exposing the vehicle to a fire. When it let loose..... Wow! Was not much left of the SUV to pick up.

L-19 wrote:NG can be compressed into a liquid. About 600 to 1 in LNG form. That's how it's transported across the ocean. Our Fire Dept had a training film about possible LNG vehicles. The tanks are very high pressure & had 4 relief protection devices for over pressure. If I remember as you use the gas off it naturally cools the remaining liquid & keeps it in a chryo state. The film showed bypassing the valves & exposing the vehicle to a fire. When it let loose..... Wow! Was not much left of the SUV to pick up.

I has to be compressed and super cooled. More weight. More expense. I haven't run the numbers, but I bet you won't see serious use of that in the next ten years of aviation.

tom

LNG would be easier to haul but then would have to be gassified. CNG takes space but wings are big. The 30 gallon tank I was looking at in the back of the pickup took up most of the width of the bed and left room for a shallow toolbox. Float planes could easily haul 100 gallons in the floats. As Tom mentioned, the pig in the python is really where to refuel. I'm in the same situation with a vehicle here in Idaho, but in Utah they have stations every 100 miles along the I-15. I think it's here to stay for vehicles, ten years sounds about right for planes.

Here's some info on CNG. I just got back from a trip to Washington to haul back a fuselage with some good landing gear. I bought an old chev pickup with CNG (turned 300K on the trip). I had it figured out and I was supposed to make the trip for $125 up and $180 back. Didn't work out that way. In Utah it is no problem finding fuel for $1.25/gal but it is pretty scarce everywhere else. Some states don't have any public stations.

I topped off in Brigham City but when I got to Nampa I couldn't fill up. There were only two public stations on the way, one in Boise and one in Nampa. There are more stations but most are private for garbage trucks and municipal vehicles. I have the old 3000 PSI system and the station in Nampa only filled 3600 PSI systems so I had to finish the trip up on gasoline. You can use the 3000 pump to fill a 3600 system but you can't use a 3600 pump to fill the 3000 systems. They use a different fitting. I need to just make an adapter with a regulator so I can use the new pumps.

Seattle had stations and the fuel there was 2.05/gal. A guy in Seattle told me if I could use the 3600 pump, I could get 2 more gallons in. Don't think I'd try that but a couple people have told me the tanks are the same. Not sure if they are really gallons either but that is how the pumps read. I think it's a gallon equivalent.

I love using it but it gives you worse mileage and less performance. It was hard pulling a trailer unless it was flat. I'm sure newer trucks do a lot better on it and you can even get Diesel/CNG systems now. To fill it, it doesn't take long. Maybe 5 minutes. It just slows way down right there at the end. I have two big tanks under a tool box and the most I have ever got in was 14.5 gallons. Even big looking tanks don't hold much because the walls are probably 4 " thick and really heavy. It's an aluminum tank wrapped in fiberglass and they are pretty indestructible.

Watch some videos on You Tube of them crashing CNG cars, ( http://www.youtube.com/watch?NR=1&v=Z51NxNEBE4g ) they can take a Lot of abuse. Don't think you could use them in a plane because the tanks are so heavy but anything is possible. I doubt the systems for your house take all night to fill your car. It is basically a compressor but it has to pump 3000 or 3600 lbs. Probably takes longer than the commercial stations.

Some things I have learned with CNG:
1. Make sure you have a dual fuel system if you want to use the vehicle to travel in.
2. Get one that is the newer 3600 PSI system.
3. Check your tanks if your buying used because they are really expensive and they are only legal for 15 years on the older ones and 25 on the newer ones.
4. Don't run it all the way out by using it while decelerating or you will need to find an older pump to fill it with. Newer "Smart Pumps" will think there is a leak if there isn't enough pressure in your system and shut off.
5. More than half of the stations are private so call ahead if your planning on using them.

If you used a car to commute and could fill at home that would be great. This old truck costs about the same to drive as my Diesel Jetta. I love it!

Good info. I'm finished with phase 1, I got my hanger converted to natural gas. I'm now shopping refill stations. The plan is to leave my vehicle attached to the line overnight to refill.

20 years from now the fuel of choice will still be able to be carried in a bucket. I remember when propane was the rage. I had a pickup that ran on propane and the tank took 20% of the pickup bed.

Electric cars are a joke. About 50% of electricity comes from coal. Where I live they are going to tear down the dams on the Klamoth River. So much for that cheap power.

Tim

I agree that in the near term, liquid fuel will be our choice for transportation. In cars/trucks within the next 10 we will transition to natural gas or electric here in the US. NG is cheap and burns clean, except for carbon emissions.

I hope to see hydrogen replace natural gas in the next 20 years.

A company I know of is developing a process to separate any kind of natural material/waste (wood, grass, human waste) into its elemental form: Carbon, Hydrogen, Nitrogen primarily. The carbon can be used as a building material...airplanes, cars, etc. The Nitrogen can be used as a fertilizer. The hydrogen is burned as fuel. Hydrogen can be burned in most internal combustion engines with a fuel system retrofit that they are also developing. Hydrogen can be used to run a furnace, boiler or kitchen stove. When you burn H2 you get water and heat....no other emissions. They have a storage tank technology that was just patented. Doubles, if I remember correctly, the amount of gaseous fuel you could store at a particular temp and pressure. Waste recycled into clean energy, it's the holy grail that can be used within our existing infrastructure (gas pipelines, engines, furnaces). I hope they make it work in airplanes as well, but I don't know how heavy these tanks are?

There's really no reason that we couldn't run CNG or better yet water as a fuel now, except the people who control the fuel supplies, run the world. Denny Klein and Stan Meyers developed technology to separate the Hydrogen from water and use it as a fuel. The only emissions are water. Meyers spent years getting worldwide pattens just to be murdered because of his invention. Funny, same thing happened to Rudolf Diesel.

http://www.youtube.com/watch?v=vKM4pb9Oxrg

http://www.youtube.com/watch?v=PSS1ZMdt ... re=related

http://waterpoweredcar.com/stanmeyer.html

http://www.youtube.com/watch?v=p_cFi_kK ... re=related

http://www.dieselveg.com/rudolf_diesel.htm

emwhiteman wrote:I hope to see hydrogen replace natural gas in the next 20 years.

Hydrogen is a really inefficient source of energy at the moment. Calorie for calorie, it is far more efficient to use the feed stocks directly (NG, coal, petroleum, biomass). The benefit of hydrogen is as a niche energy carrier, not as an energy source. it has its uses, but probably not as a replacement for the original feed stocks.

emwhiteman wrote:When you burn H2 you get water and heat....no other emissions.

Actually, NOx emissions can be considerably higher when using hydrogen as a fuel if it is burned relatively efficiently. Nonetheless, these can be mitigated in the same way that petroleum engines do it- by burning less efficiently, and without the CO and particulate issues that petroleum engines suffer.

Hydrogen will be a player in certain niches, but the costs right now favor other directions for aerofuel development in the near future.