Concept: Natural Gas Delivery Via a NG-Powered Airship
14 May 2006
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| A sketch of a smaller airship. Credit: Jesse Blenn |
A small Bolivian company, Reparando SA, is exploring the delivery of natural gas (NG) delivery to remote areas by using an airship, rather than a pipeline. Reparando is a heavy equipment repair and road construction company that moved into selling and installing bifuel natural gas conversion systems for heavy-duty diesels (running the engines on 70% NG).
The company worked with Jesse Blenn, a US airship expert, on a preliminary design for a 150-meter airship capable of carrying about 35,000 Nm3 of natural gas . The basic design is extensible up to a length of around 300m, which would result in a ship capable of carrying about 300,000 m3.
At 35,000 m3, the volume is approximately equivalent to the compressed gas carried by three natural gas tank trucks. But in some areas of Bolivia where the roads are bad, it could take a truck up to one week to go 500 miles.
The ship as designed uses twelve internal inflatable gasbas: six for helium (the ship requires about 40% helium volume to lift the empty structure) and six for natural gas. The upper six bags hold the helium, the lower six the natural gas.
This, Blenn points out, is very similar to the design of the system used by the Zeppelin Graf Zepplin I (LZ 127) in which the lower bags carried fuel gas which weighed nearly the same as air, and deflated as the fuel was used. The LZ 127 racked up nearly 1 million kilometers in flight.
With the natural gas on board, the ship has additional lift to carry diesel fuel, although the goal is to convert the airship engines to run primarily on natural gas. The diesel serves as ballast and backup. When running on natural gas, the four engines would consume about 3% of the natural gas payload in a round trip of 1,000 kilometers at a speed of 100 km/h.
Discharge of the natural gas occurs through the mooring tower. The airship carries a normal operating pressure of about 35 mm water column, which will push the natural gas out within about 20 minutes through the twin NG valves.
The twin nose engines supply the pressure and the 35,000 cubic meters of replacement internal air volume). (Four other natural gas engines provide propulsion.)
The mooring tower will include a proprietary automatic valve connection (purged with CO2), and a seal and bearing system which conduct the gas down to a duct where an auxiliary fan maintains the flow to storage. The reverse process handles the filling, but the inflation pressure is supplied from the tower base, not the engines.
Blenn estimates that the airship could be built for around $US3 million (in South America). Airships, according to Blenn, have an operational life of about 10 years to first replacement of the outer fabric, and several decades for hard structures if refurbished.
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Looks like a neat idea...
Sure would be nice if we had such innovative thinkers in our automotive industry.
Posted by: Lucas | 14 May 2006 at 08:51 AM
Hmmm - I don't thnk it would want to be near this big an airship when it comes full laden for mooring in a breeze or as indicated, in a forest clearing in a remote area. While there would not neccessarily be a fire (NG is harder to ignite than H2), the risk seems rather high. IMHO they should consider using a larger number of compartments for the NG and fairly tough fabric for them, even at the expense of reduced payload.
Posted by: Rafael Seidl | 14 May 2006 at 09:01 AM
Looks like a good way to ship all that stranded nat gas without FT conversion costs. I've always liked blimps and vector thrust technology makes docking much more controlable.
Posted by: tom deplume | 14 May 2006 at 10:47 AM
Hmm, fuel air ship. Quite a good idea to transport natural gas. Some earlier air ships are using hydrogen, so natural gas shouldn't be too hard to handle then h2. Wonder if this thing can replace LNG tanker if built really big? How big is 35k m3 anyway?
Posted by: rexis | 14 May 2006 at 05:51 PM
The idea that terrorists could hijack an airship laden with enough natural gas to cause a rather remarkable explosion, 300,000 cubic meters worth, now THAT is spectacular. I like the idea of airships, a technology I believe we will see a great deal of in the future, but where they are allowed to fly, and where they are forbidden, is rather important. They aren't that fast, so the areas allowable would be reasonable, but limits on their operation must be considered long before they become operational.
Posted by: Ziv | 14 May 2006 at 05:56 PM
If the object is to allow access to stranded natural gas, it might be a better option for it to carry an LNG tank instead of diesel fuel. This would allow easy adjustment of buoyancy; vaporize some LNG to go up, burn some NG gas to go down.
Posted by: Engineer-Poet | 14 May 2006 at 08:42 PM
A blimp -- even one half-filled with NG -- would not make a particularly good terror weapon. Aside from being generally much slower than a typical jet airplane (this one is to run at around 60 MPH), it will also likely have even worse maneuverability. You can't just put one of these things into a dive and crash it into a likely target. You have to slowly vent off bouyancy gas to get it to go down.
Moreover, even if you were to crash it into something, or otherwise blow it up, the burning gas would dissipate from the envelope -- mostly upwards on account of the heat -- and flare off spectacularly but harmlessly. Unlike the jet fuel of the airplanes used in the 9/11 attacks, it won't persist in the immediate environment of the crash site.
The one thing you probably would want to do is not operate one of these things directly over a large city, because then someone could blow it up just for the sake of blowing it up, which would spread some burning wreckage across populated areas and, more seriously, inspire a civilian panic.
I would not want to be the pilot of one of these things, but I don't see a national security threat here.
Posted by: NBK-Boston | 14 May 2006 at 11:46 PM
NBK, I agree that the lack of speed is one safety aspect, but I am not sure about the gas flaring off harmlessly. Fuel Air Explosives are incredibly effective weapons, and though the NG is not an optimum fuel for FAE, i.e. it is not a liquid which can be easily aerosolized, but leave it to man to find a weapon in an innocuous transportation source.
I like the idea of using lighter than air craft, I was very impressed with the Walrus, and I think these vehicles are well worth building, but I think they should be used a significant distance away from population concentrations. I remember the movie Black Sunday, though it is not a completely appropriate comparison.
Posted by: Ziv | 15 May 2006 at 07:14 AM
I propose calling the first operational example Hindenburg 2...
Posted by: Scott | 15 May 2006 at 10:43 AM
not funny,
____Seriously, the Hindenburg's outer skin was coated with a mixture that was very similar to the fuel for the Space Shuttle's twin solid rocket boosters. Aluminum, Iron oxide and a binder. This is essentially rocket fuel. The Hindenburg's red, yellow, and orange flames were the reult of the inevitable combustion of the flammable skin. Hydrogen burns with an almost imperceptible blue flame. Many lab personnel using small hydrogen exposed flames/burners for various test and experiments have burned themselves because the flame is almost invisible in the visible spectrum. It is almost an accidental self-induced rite of passage for these lab staffs.
_
____The Shuttle's three main Orbiter engines burn liquid oxygen (LOX) with liquid Hydrogen (LH). You can see here in this link the Orbiter's engines firing at max and the flames fairly faint:
http://shemesh.larc.nasa.gov/images/shuttle-flame.gif
Posted by: allen zheng | 15 May 2006 at 11:20 AM
I would rather convert flare gas to methanol or use it onsite in a Stirling. LNG could become a very lethal terrorist weapon. If we used more solar thermal, there would be no need for LNG at all.
Posted by: Paul | 15 May 2006 at 02:43 PM
Interesting how the terror fear creeps into so many energy discussions. Precautions need to be made but making a bomb out of a blimp is really a stretch. There are so many hazardous substances regularly transported in our country which terrorists could use against us but haven't makes my point. Terrorists are focused on areas where they can get either media attention or on specific government locations. A blimp filled with nat gas is outside their mindset.
Posted by: tom deplume | 16 May 2006 at 10:12 AM
A hijacked blimp filled with natural gas could be taken out by one guy in a traffic helicopter willing to sacrifice himself. An LNG tank hitting the outside of a skyscraper that slowly would split, spill, fall and begin evaporating immediately; it would rise and dissipate quickly whether it ignited or not. Compared to a jetliner, it's not a threat.
Posted by: Engineer-Poet | 16 May 2006 at 02:46 PM
I don't think that taking into consideration the fact that there are terrorists looking for ways to kill us is 'fear', it is common sense. NG airships are not an optimal bomb, but the larger the vehicles capacity, and this would be huge, the less efficient the explosion needs to be while still making an incredible mess. The idea that because making FAE out of NG would be novel doesn't mean it is something we should ignore. Build the airship, use it productively, and keep in mind that it is a possible threat. EP, I think your comment was tongue in cheek, but you may be missing the point about how terrorists would use LNG carriers, the problem there is the larger tankers. The threat, according to Coast Guard, is real.
http://www.iwar.org.uk/pipermail/infocon/2005-May/002573.html
I think LNG tankers are more of a threat than a NG airship, but the problem is still there, the only difference is one of degree. And kamikaze traffic helicopters are probably not a sign of a well thought out plan for optimizing the security of the US.
Posted by: ziv | 16 May 2006 at 04:16 PM
True that an NG blimp will be huge, dangerous or not it will still create fear among normal people.
Really need a kamikaze traffic chopper to take it out? I was like imagin just one shot it will puncher the whole thing up. :p
Posted by: rexis | 18 May 2006 at 12:56 AM
The fist 300,000 cubic metre airship should be named "Addison Bain" (Google that name). Airships are an unlikely terrorist target. The fuel load (or hydrogen, if helium was unavailable) would disperse upwards (the target is likely to be below the aircraft) and any debris falling to earth would be lightweight components unlikely to penetrate most roofing materials.
In the first world war airships survived multiple machine gun attacks and still made it home, even with six inch holes in the outer fabric.
Painting the outer skin with nitro-cellulous is a definite no-no.
The "Black Sunday" scenario is probably a better terrorist plan than trying to ram a solid building with a flying bouncy castle. Wouldn't be easier and more effective to hijack a road tanker ?
Posted by: Owen | 15 November 2006 at 08:37 PM