As the cost of fuel soars and the pressure mounts to reduce carbon dioxide emissions, several schemes for a new generation of airship are being considered by governments and private companies. “It’s a romantic project,” said Mr. Massaud, 45, sitting amid furniture designs in his Paris studio, “but then look at Jules Verne.”

It has been more than 70 years since the giant Hindenburg zeppelin exploded in a spectacular fireball over Lakehurst, N.J., killing 36 crew members and passengers, abruptly ending an earlier age of airships. But because of new materials and sophisticated means of propulsion, a diverse cast of entrepreneurs is taking another look at the behemoths of the air.

Mr. Massaud, a designer of hotels in California and a stadium in Mexico, has not ironed out the technical details, nor has he found financiers or corporate backers for his project — to create a 690-foot zeppelin shaped like a whale, with a luxury hotel attached, that he has named Manned Cloud.

But not all projects are as fanciful as Mr. Massaud’s. For example, a French technology start-up, Aerospace Adour Technologies, is working with the French post office to study the feasibility of transporting parcels by dirigible. Also in France, Theolia, a company specializing in renewable energy, is financing a dirigible, and plans a test flight across the Atlantic.

In Germany, Deutsche Zeppelin-Reederei, the successor to the operator of the Hindenburg, has had success with a new generation of airship it uses to transport sightseers and scientific payloads.

The trend is not entirely new. Zeppelin-Reederei carried 12,000 passengers on sightseeing tours over southern Germany last year. Aerophile, a French company that revived tethered balloons, which compete with dirigibles as carriers of passengers, advertising and scientific instruments, was founded by two young French engineers in 1993.

The aircraft industry is not exactly bracing for a dogfight. Mr. Massaud says that Emirates and Air France have expressed interest in Manned Cloud. But with top speeds of around 100 miles an hour and a maximum capacity of several dozen passengers, dirigibles are expected by most aviation experts to remain niche vessels for ferrying tourists, advertising and occasional scientific payloads.

“A dirigible is something magical,” said Jérôme Giacomoni, who was 25 when he founded Aerophile with a friend. “But most of the ideas are crazy.”

Dirigibles, he said, “are very sensitive to storms. Their size requires large landing spaces; economically they’re not feasible.”

Not yet, say dreamers like Mr. Massaud. But gasoline prices are pushing airlines to reduce the number of flights and retire older, less fuel-efficient aircraft. Aircraft manufacturers like Boeing and Airbus have responded by promising planes that use less fuel and produce less carbon dioxide.

Such concerns pushed Mr. Massaud to start thinking about dirigibles. Five years ago he worked on a design for a resort community in Palm Desert, Calif., but the result was so radical, involving tents rather than fixed buildings, that its developers balked. “They said to me, ‘You French, you’re all Communists!’ ” he said.

So Mr. Massaud conceived of Manned Cloud, a helium-filled dirigible shaped like a whale, with a cruising speed of 80 miles an hour and a cabin to accommodate 50 overnight guests and a crew of 25. “The large whales made a choice in evolution to live in harmony with their environment,” he said. “They are symbols of life in harmony with nature.”

Mr. Massaud submitted his design to the French aerospace agency, whose experts suggested he reduce the number of passengers to 15 and made other recommendations, but withheld judgment on his design’s feasibility.

“There are niches where dirigibles might still serve,” said Philippe Guicheteau, special adviser for military aeronautical systems at the agency, which goes by the French acronym Onera.

In the United States, research into dirigibles continues, but mainly for military purposes. In 2005, the Defense Advanced Research Projects Agency, or Darpa, briefly explored using airships to transport freight over long distances. Two other projects involving high-altitude airships, mainly for communications, continue. [Read More]