Dirigible ideas range from the practical ? above, a Zeppelin NT carries sightseers over Germany ? to a plan for a floating hotel . New materials, including nonflammable gases, make the airships safer than those in an earlier era.

By JOHN TAGLIABUE

PARIS - Imagine gliding in a floating hotel over the Serengeti, gazing down at herds of zebra or elephants; or floating over Paris as the sun sets and lights blink on across the city as you pass the Eiffel Tower.
Such flights may one day be possible, if the dream of Jean-Marie Massaud, a French architect, comes true.
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 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, New Jersey, killing 36 crew members and passengers, abruptly ending an earlier age of airships. But because of new materials, including nonflammable gases, 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 worked out the technical details, nor has he found financiers or corporate backers for his project - to create a 210-meter 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 competition. Mr. Massaud says that Emirates and Air France have expressed interest in Manned Cloud. But with top speeds of around 160 kilometers 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 Jerome 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.”
A dirigible, or rigid airship, has a metal frame, these days usually part aluminum, part carbon fiber, covered with a synthetic canvas. A blimp, in contrast, is a big, inflatable balloonlike sack filled with a lifting gas. Blimps are far less maneuverable than dirigibles and can lift less.
Today’s airships fly with helium, an inert gas, as did the Hindenburg until the United States imposed an embargo on what was then a fairly valuable commodity. Hence, the Hindenburg had to start using inflammable hydrogen on its flights.
By the time of the explosion, zeppelins had carried about 405,000 passengers across the Atlantic.
French political leaders are among those who believe the ships can do more than ferry tourists. For two years, Jean- Marc Brule, a Green Party leader and mayor of Cesson, near Paris, has pushed through budget amendments to finance dirigible research.
“With global warming and the oil crisis,” he said, “it’s good sense to realize this dream.”