Planes Are Ruining the Planet. New, Mighty Airships Won’t.

Some scientists are serious about resurrecting zeppelins for low-carbon travel

Rendered image of a hybrid airship. Credit: Lockheed Martin.

This August, Greta Thunberg sailed across the Atlantic in a zero-emission sailboat to protest the high carbon footprint of plane travel. But there’s good reason to think she may someday travel to climate protests via airship — the same giant aircraft, buoyed by gas-filled balloons, that were popular in the early 20th century. Faster than cargo ships and able to alight inland as well as on a beach, many airships, also known as dirigibles, have fewer emissions than boats, and all are much more carbon efficient than planes.

While interest in early dirigibles waned after they proved too slow and, occasionally, too dangerous, climate change is making plane travel increasingly contentious. Now some scientists are considering airships as a serious transportation solution.

Unlike planes, airships don’t need to burn much fuel to take off and propel themselves. Because they move more slowly than planes, they’re being eyed as a much more carbon-efficient way to move air cargo, which is set to triple in the coming decades, according to the International Air Cargo Association. “An airship produces 80% to 90% fewer emissions than conventional aircraft,” said Jean Baptiste Meusnier, spokesperson for the International Air Transport Association.

A paper in the journal Energy Conservation and Management published in September posits that just one airship could move 21,000 tons of stuff using almost no energy at all if we used airships to harness the free winds of the jet stream, the narrow band of fast-moving air above the troposphere, where planes fly. These winds, which average 100 miles per hour and can be as speedy as 250 mph, could propel an airship from Denver to China in about seven days or from Los Angeles to Tokyo in four, says Julian David Hunt, of Austria’s International Institute of Applied Systems Analysis and the paper’s first author.

The airships Hunt proposes would fly in the stratosphere, where there are additional advantages besides free wind. “You can plan a long time in advance, because the weather forecasting is much better — there are fewer disturbances, and it’s easier to predict wind patterns in the stratosphere,” he says. He envisions a round-the-world drop-off and pickup route for airships to deliver cargo for little to no energetic cost, and he’s not alone.

“You don’t really need to fly above the weather.”

Bob Boyd, a program manager at Lockheed Martin’s Skunk Works, explains that the physics of airships makes them inherently energy efficient. “Buoyant lift is a much more efficient method to move through the sky than direct lift,” he says. Planes and helicopters rely on direct lift, which is powered by burning fossil fuels, while buoyant lift relies on the natural properties of gases like hydrogen and helium, which are lighter than air and don’t need to be burned.

However, Hunt’s high-altitude vision for soaring through the jet stream requires ultraflexible materials for the ship envelope that do not yet exist. The air pressure is lower above the stratosphere, creating pressurization issues for airship design. “Materials that are structurally sound has been one of the challenges,” says Jason Rhodes, a senior research scientist at NASA’s Jet Propulsion Lab. That’s one reason most companies gearing up to build commercial airships are looking to fly below the stratosphere, at an altitude of 5,000 to 6,000 feet, which will eliminate pressurization issues and reduce time spent on vertical travel.

These lower-flying vehicles, known as hybrids, are likely what we’ll see in the nearer future. Aerospace company Lockheed Martin’s hybrid prototype sports three cartoonish bubbles up front to help with navigation and engines to assist with maneuverability. The company’s hybrid design uses 20% aerodynamic lift — a lightly fuel-powered boost for a bit of a “plane-like effect” — and helium for the remaining 80% buoyant lift, Boyd says. The end result uses significantly less fuel than a plane and can access many areas other vehicles can’t.