pound/cubic foot hydrogen) enough to fill a 14,000 cubic foot balloon. (Greenwood 223). Later, the Germans used railway wagons that weighed 30 tons and carried almost 100,000 cubic feet hydrogen. (233) The American military neglected the balloon after the Civil War, but in 1891-3, the Signal Corps decided to add a tethered balloon and fill it with hydrogen from pressurized (120 atmosphere) cylinders. (Crouch 519ff).
Airships have much greater mobility than military balloons, so we aren't limited to 'front line' options, but the rail network is much less developed in the 1632 universe.
The total cost of compressing and shipping hydrogen to a remote airship facility can be high. For 12.5 cubic meters hydrogen, compressed and shipped 300 miles, and empties returned, Schmidt estimated (1900) 29.5 cents to produce the gas, 2.5 to compress it, 16.25 as interest on the purchase cost of the tanks, 2 for labor, and 62.5 for the two-way freight, for a total of $1.13-9 cents/m3. (Englehardt 129).
In 1915, Fourniols compared the cost of producing hydrogen at a cheap-to-operate hydrogen plant and shipping it in compressed form, to generating it on site using the hydrolith process. The former produced hydrogen at a cost of only 0.4 francs/cubic meter. But compression and transport of 50,000 cubic meters for an unstated distance increased the cost from 20,000 francs to 960,000. In contrast, the same amount of hydrogen could be produced by the field process for 324,000 francs, of which only 40,000 was transport-related (carriages for the apparatus and reagents). (Ellis 534).
At some point, high pressure hydrogen pipelines, like the early-twentieth century one from Griesheim to Frankfurt, might reduce transport costs. (Ellis 440).
There are two complications with storing hydrogen; its great capacity for diffusion through other materials, and its ability to embrittle metals, include steel (Kirk-Othmer 13:851). That may limit the useful life of storage cylinders.
The contents of a gas cell will become corrupted as hydrogen escapes and, more slowly, air enters. The hydrogen in this 'spent gas' may be recovered for re-use by an adaptation (Greenwood 233) of the Linde-Frank- Caro liquefaction method used to separate hydrogen from carbon monoxide in the water gas processes.
To avoid explosions and fire, and maximize lifting power, it's important to know how pure the produced hydrogen is, and what other gases it's contaminated with. Hydrogen may be measured by combustion with excess oxygen, or by measurement of the thermal conductivity of the gas. Carbon monoxide will blacken paper moistened with palladium chloride, or it can be quantified by measuring the carbon dioxide formed by its reaction with hot iodine pentoxide. Carbon dioxide, in turn, is detected by its reaction with lime water or barium hydroxide. (272). Oxygen is revealed by blueing if the gas is bubbled through a colorless cuprous salt solution.
We can measure arsenic with the 'mirror test' beloved of early detective stories, and hydrogen sulfide by its reaction with a lead acetate paper. (Greenwood 235ff, 254, 272; Taylor 193ff).
I leave it up to the reader to determine the extent to which these detection methods would be known in Grantville Literature, and how soon the necessary reagents and apparatus could be produced.
In the 1630s, I believe that electrolysis, whether of water or alkali, should be the dominant method of hydrogen production in Grantville itself. There's ready access to electricity, which, for the reasons I set forth in Cooper, 'Aluminum: Will O' the Wisp?' (
And we don't have to worry about compressing the gas if the airship station is in Grantville. If we electrolyze water, we have the further advantage that we are producing oxygen (which itself is valuable) and the hydrogen is going to be of extremely high purity (at least if we use distilled water).
Otherwise, the practicality of electrolytic hydrogen will depend on whether electricity is available. That in turn first requires either the proximity of a river with a suitable gradient and flow rate (for hydroelectric power), or of fuel (coal, oil, wood, etc.) to burn. And secondly, you need the turbine for converting the kinetic energy of falling water, or the boiler and steam engine (piston or turbine) for converting the chemical energy of the fuel. I considered this, in a rail electrification context, in Cooper, Locomotion: The Next Generation (
Unfortunately for Copenhagen, which in canon is a leader in airship development, Denmark is not well suited for electric power generation of any sort. As we know, Marlon Pridmore chose to rely on the steam-iron process. However, generating steam requires heat, and plainly the Danes are burning some kind of fuel to do it. With no waste, you need nine grams of water to make one gram of hydrogen (0.42 cubic feet), and to make several hundred thousand cubic feet of hydrogen is going to require a heck of a lot of fuel. My guess is that the Danes will establish a big steam-iron plant that is on the Copenhagen-Venice route and near to a coal field or at least has ready river or rail access to a coal field. Hannover is a possibility, but coal would probably be cheaper near Cologne, and they could add service to Amsterdam and Hamburg. The airship would make a 'pit stop' when its gas cells were getting dicey.
I think that there will also be some experimentation, by would-be airship powers, with the steam-carbon and steam-hydrocarbon processes. The former uses coal, which is abundant in western Europe, and the latter can make do with petroleum fractions that aren't useful as vehicle fuels. And of course, if you have carbon or hydrocarbon for use as a reactant, you can presumably use some of it as fuel for steam-making.
We know that there is going to be rapid scale-up of both iron and sulfuric acid production, which will provide some initial impetus to explore the potentialities of the wet method. If the Civil War buffs in Grantville have particulars of Lowe's hydrogen generator, that will also give it a boost. However, acid-iron has too many disadvantages to be attractive in the long-term.
The search for oil will inevitably result in the discovery of natural gas reservoirs, like that in the Grantville area. The pyrolysis of coal, to produce organic chemicals such as benzene, will produce coal gas as a byproduct. The accelerated development of chemical knowledge will lead to the relatively early discovery of catalysts suitable for reforming methane (and other volatile hydrocarbons) from natural gas or coal gas. This will facilitate stationary hydrogen production.
Of the classic field methods, I think silicol will be the first one to become practical in the 1632 universe. A crude silicon can be made easily enough, and there is going to be demand for ferrosilicon by the steel industry and that will help bring costs down.
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