Guest essay by Eric Worrall
Low carbon enthusiasts are promoting the idea of airships. But there is a sound reason why this form of travel was abandoned, other than the a few famous accidents.
How airships could provide the future of green transport
The UK is a leader in the airship revival, going head to head with France in an escalating global race
23 August 2020 • 8:00pm
Zeppelins and dirigible airships are with us again after eighty years out of favour – faster and hopefully much safer than in the inter-War era – promising ultra-low carbon air transport for the net-zero age.
It may not be long before we can start eating air-flown vegetables from Peru or blueberries from Kenya without feeling pangs of guilt. Fresh food may reach us in cargo Hindenburgs without the unconscionable CO2 footprint of jet freight.
If all goes well, we will be able to hop virtuously from Liverpool to Belfast in point-to-point travel, or Stockholm to Helsinki, almost in the time it takes for a regular flight from door to door. We can hope to lift off quietly from a field close to London in the early evening, retreat to a couchette after dinner and wake up in Barcelona, Rome or Val d’Isere.
As it happens, Britain is a throbbing centre of the airship revival, going head to head with France for global leadership. It could arguably capture part of the $120bn air freight market and displace a slice of the vastly greater truck haulage business in congested zones or regions with poor infrastructure.
Quite apart from famous accidents like the Hindenburg, Airships were abandoned because they are more vulnerable to weather than airplanes. That gigantic gas bag is a lot of surface area for updrafts or clear air turbulence to push on.
Proponents claim their new designs are capable of handling substantial bad weather, and they generate less wake turbulence than traditional aircraft. Wake turbulence is tornado like vortices generated by aircraft wings, which are sometimes blamed for damaging the roofs of people living near airports.
Hybrid Airships Could Change the Economics of Asia and Africa
The historic airship has a lot going for it. It can carry a large payload faster than a passenger liner. There is very little turbulence and it has an impressive range. They can hover or turn in place. Flying low, they don’t typically require pressurization.
And it has some serious drawbacks. It requires attentive ground crews to keep it near the ground when loading and unloading. It is vulnerable to wind gusts on the ground and in the air, where it must avoid bad weather at all costs. Hangar space has to be huge and, therefore, expensive. They are so huge, an old German airship hangar was converted into a large, covered waterpark. Using hydrogen in conjunction with flammable construction material is bad, bad, bad.
Because a lot of these bad things are surmountable, a company has decided to bring back the airship. It is a hybrid airship called Airlander. It is hybrid because it gets its lift from three sources; helium-filled bag, wing-shaped lifting body, and thrusters. Using these in combination allows the ship to land like a plane but with a much shorter runway. It can also hover and come straight down, doing a vertical landing or takeoff like a helicopter. It carries its own anchor mast and can withstand 80 kilometer winds without a hangar. Which is the point. It doesn’t need a hangar and requires only a two-person ground crew for the Airlander 10 with a 10 metric ton capacity and none for the Airlander 50 with a 50 ton capacity. Production models are expected to be in the air by 2020.
Note (to add to the confusion), the article above mentions turbulence, but means wake turbulence (generated by the movement of aircraft). I mentioned clear air turbulence, which is a dangerous weather condition.
There is another serious problem airships would have to address.
There are three gasses which have been used to loft commercial airships, hydrogen, helium and hot air.
Hot air requires a lot of heat to produce and maintain. While there are designs which involve solar heating (making the gas bag very dark, to absorb sunshine), nobody seems to be discussing this as an option, so let’s leave it for now.
Hydrogen is cheap, plentiful and extremely dangerous. It forms a flammable mixture with air at a wide range of concentrations, and can be ignited by the slightest spark. While there are debates about what caused the Hindenburg to burn so rapidly, there is no doubt the use of hydrogen as a lifting gas contributed to the fire.
Helium is inert, it cannot be set on fire. But the global supply of helium is extremely limited. For now helium is available for frivolous purposes like party balloons because there is also a limited set of uses for helium, but this would change very rapidly if commercial airships took to the sky. In addition, the world’s very limited supply of helium is very much tied to fossil fuel extraction – Qatar is a leading global supplier of Helium. If fossil fuel extraction is scaled back, no more helium.
There are other gasses which could conceivably be used, such as Argon. Argon can be extracted from the air, just under one percent of the atmosphere is Argon. But while Argon is lighter than air, Argon is a lot heavier than Hydrogen or Helium, so a much larger gas bag would be required to lift the same payload using Argon, if such an airship could be built at all.
So it seems inevitable that a commercial airship operation would have to eventually embrace flammable hydrogen as a lifting gas.
Lets just say I wouldn’t be keen to set foot on one.
via Watts Up With That?
August 25, 2020 at 08:44PM