From Worldskyrace.com: “Buoyant Flight is an inherently efficient form of transportation. This is the main reason why skyships were so promising in the1920s when airplanes still seemed a speculative venture. While today they are forgotten by many, skyships were actually very successful. By 1937, commercial passenger skyships of the Deutsche Zeppelin Reederei (DZR) had flown over half a million passenger-hours and a total of 52 million passenger-km safely on regional, transoceanic, transcontinental and artic voyages.
All of this was accomplished using then state-of-the-art technology that by todayâ€™s standards would be considered quite primitive. The lifting gas used, flammable hydrogen, was contained within large cells made from the membranes of cow intestines. The hull was covered in a doped cotton canvas, and control systems were operated manually by a large crew. Nevertheless, due to their efficiency, skyships still did perform astounding feats and set records for aerial transportation.” Airships Environmental Impact – Reducing CO2