Imagining gas transport

Jan. 4, 2016
Where has imagination gone in natural gas transportation? Where are the submarines? Where are the dirigibles?

Where has imagination gone in natural gas transportation? Where are the submarines? Where are the dirigibles?

Nowadays, pipelines get all the attention, some of it unconstructive. They're the cheapest way to move fluid hydrocarbons, after all. And, in places, they have compelling advantages of location.

No submarines here

The Fort Worth basin, for example. Last month, the US Geological Survey doubled its estimate of the Barnett shale's undiscovered, technically recoverable gas resource to 53 tcf. With all that potential gas supply conveniently situated in far-inland Texas, center of the pipeline and gas-market universe, there's scant need for ingenuity. Submarines? Forget it.

Unlike the Fort Worth basin, the Appalachian basin remains logistically underserved. Combined potential of the Marcellus and Utica shales exceeds the Barnett's. Initial assessments by the USGS of undiscovered, technically recoverable gas resources are 84 tcf for the Marcellus and 38 tcf for the Utica. Both plays are young.

But limitation of market access would be limiting development even if abysmal gas prices weren't already doing the job. It's that fact of gas life that attracts obstructionist attention. Pipeline opponents know transport insufficiency keeps gas in the ground.

The history of Alaskan natural gas affirms this relationship. Estimates of the states' gas reserves have been as high as 35 tcf. That's reserves, not resources: gas known to exist and to be economically and technically recoverable.

Now, though, the Energy Information Administration puts Alaskan gas reserves at only 6.7 tcf. The hydrocarbons haven't gone anywhere. They just have no way to move away from the North Slope and therefore can't be recovered. EIA slashed its reserves estimate in 1988. For submarine transport of natural gas, that was not a good day.

Yes, submarines once received serious attention as a way to move gas North Slope gas below Arctic ice. The final environmental impact statement for the ill-fated, 4,790-mile pipeline known as the Alaska Natural Gas Transportation System (ANGTS) in 1976 described two alternatives for underwater vessels.

In one, methane would have been liquefied at a deepwater port and loaded aboard 1,000-ft-long submarines with 170-ft beams for transport to Portland, Maine, where it would have been gasified and carried away in conventional pipelines. The scheme required 45 ships.

In the other alternative, gas would have been processed into methanol and carried in nuclear-powered subs. A less-intriguing marine option would have employed ice-breaking LNG carriers.

Other than the ANGTS system, proposals for land transport of North Slope gas were unexciting: dense-phase gas or methanol pipelines, railroads, and monorail. Ho-hum.

But then there was gas by air. Now that's something to think about.

One proposal was for carriage of LNG in pods under wings of 12-engine aircraft fueled by cargo boil-off. Each plane would have had a gross weight more than four times that of a Boeing 747-a limit, no doubt, to where these monsters might land.

Another creative proposal envisioned a flying machine called Helifloat combining attributes of the helicopter, buoyancy craft, and airplane. Central to the concept was what sponsors called "induction airfoil lift."

And then there was the dirigible-ah, the dirigible. A combination of LNG and unliquefied gas would be carried aloft in a streamlined, unmanned cargo ship with a length of 6,130 ft and maximum diameter of 1,345 ft, accompanied by a manned control blimp and drone scouts.

The 1976 document specifically targeted the New York-Philadelphia market for gas delivery by airship. The cost of Arctic gas delivery by this method was said to be comparable to that of pipeline gas from the Gulf Coast.

Zooming imagination

So let imagination zoom. Envision airships longer than a mile carrying Appalachian basin methane to New York, or, if not welcome there, to more-hospitable markets with space to land near pipeline connections. Imagine the political implications of so much destination flexibility.

Fanciful? Of course. But it's something for environmental obstructionists to fret about, which makes it worth a dream or two.