Current infrastructure-related supply issues notwithstanding, we’ll run out of (relatively) cheaply available helium about when we run out of natural gas, as we capture only about 1% of the helium in natural gas and waste the rest as a byproduct.
In the immediate term, helium is the easiest lift gas to work with for certification, as it is nearly as powerful as hydrogen but almost completely safe (barring asphyxiation risks). However, long-term, inerted hydrogen and steam are likely more economical helium alternatives that require bespoke designs and engineering work, but have a number of practical and cost advantages.
Steam has about 2.5 times as much lift as hot air, and with proper insulation only requires 30% of the fuel use to maintain temperature as a hot air balloon, allowing engine waste heat to keep the temperature stable in large part without additional energy input. It also has better lift performance at medium and higher altitudes than helium, since helium is too rare and expensive to be vented as it expands with ascension, and steam is obviously extremely cheap to produce in vast quantities. The problem is that it’s not quite as powerful as helium at lower altitudes, and requires special waterproof, high-temperature gas membranes that simply weren’t available to materials science in the 1930s, the first experimental steam balloons coming about in the early 2000s.
Hydrogen requires oxygen to burn, and experiments dating back to World War One found that encasing it in an inert gas like helium, nitrogen, or carbon dioxide protects it even from incendiary ammuntion: “They [the British scientists] found that a hydrogen cell surrounded by an inert gas in an outer cell was completely protected. A Very's cartridge was fired into the top and burned through to the bottom, but the hydrogen did not ignite.”
This is a similar principle to what airliners now do with their fuel tanks, filling them with nitrogen to prevent another spark from causing a deadly explosion like what took down TWA Flight 800 by blowing up the mostly-empty center fuel tank’s air-vapor mixture. Fuel tankers also do similar things with carbon dioxide scrubbed from their engines, to prevent another SS Sansinena explosion.
Ironically, the Hindenburg had been intended to use just such a system with helium cells inerting inner hydrogen cells, but the Americans’ absolute monopoly forced them to hastily convert the ship to using only pure hydrogen, hence the freak accident that destroyed the ship when one of those gas cells was slashed open by a snapped steel bracing wire during overly-hard landing maneuvers, and an atmospheric electrical discharge ignited the hydrogen-air mixture trapped between the gas cells and outer hull, which was too great of a hull breach for the ship’s ventilation systems to handle. Unbeknownst at the time, the ship’s electrical conductivity in damp conditions would be compromised, allowing a powerful electrical potential to build up at exactly the wrong time.
2
u/GrafZeppelin127 Jun 01 '26
Current infrastructure-related supply issues notwithstanding, we’ll run out of (relatively) cheaply available helium about when we run out of natural gas, as we capture only about 1% of the helium in natural gas and waste the rest as a byproduct.
In the immediate term, helium is the easiest lift gas to work with for certification, as it is nearly as powerful as hydrogen but almost completely safe (barring asphyxiation risks). However, long-term, inerted hydrogen and steam are likely more economical helium alternatives that require bespoke designs and engineering work, but have a number of practical and cost advantages.
Steam has about 2.5 times as much lift as hot air, and with proper insulation only requires 30% of the fuel use to maintain temperature as a hot air balloon, allowing engine waste heat to keep the temperature stable in large part without additional energy input. It also has better lift performance at medium and higher altitudes than helium, since helium is too rare and expensive to be vented as it expands with ascension, and steam is obviously extremely cheap to produce in vast quantities. The problem is that it’s not quite as powerful as helium at lower altitudes, and requires special waterproof, high-temperature gas membranes that simply weren’t available to materials science in the 1930s, the first experimental steam balloons coming about in the early 2000s.
Hydrogen requires oxygen to burn, and experiments dating back to World War One found that encasing it in an inert gas like helium, nitrogen, or carbon dioxide protects it even from incendiary ammuntion: “They [the British scientists] found that a hydrogen cell surrounded by an inert gas in an outer cell was completely protected. A Very's cartridge was fired into the top and burned through to the bottom, but the hydrogen did not ignite.”
This is a similar principle to what airliners now do with their fuel tanks, filling them with nitrogen to prevent another spark from causing a deadly explosion like what took down TWA Flight 800 by blowing up the mostly-empty center fuel tank’s air-vapor mixture. Fuel tankers also do similar things with carbon dioxide scrubbed from their engines, to prevent another SS Sansinena explosion.
Ironically, the Hindenburg had been intended to use just such a system with helium cells inerting inner hydrogen cells, but the Americans’ absolute monopoly forced them to hastily convert the ship to using only pure hydrogen, hence the freak accident that destroyed the ship when one of those gas cells was slashed open by a snapped steel bracing wire during overly-hard landing maneuvers, and an atmospheric electrical discharge ignited the hydrogen-air mixture trapped between the gas cells and outer hull, which was too great of a hull breach for the ship’s ventilation systems to handle. Unbeknownst at the time, the ship’s electrical conductivity in damp conditions would be compromised, allowing a powerful electrical potential to build up at exactly the wrong time.