Innovators gear up work on ‘green’ hydrogen plane with plans for nonstop 9-day trip around Earth

LES SABLES D’OLONNE, France (AP) — When aviation pioneer Bertrand Piccard a decade ago spearheaded a much-hyped flight around the world in a plane powered by sunlight, it raised awareness about climate change but held little promise of revolutionizing air travel.

Now, the 66-year-old Swiss adventurer behind Solar Impulse is aiming higher, in hopes of heading toward greener commercial flight, this time using super-cooled liquid hydrogen.

From a workshop on France’s Atlantic coast, Piccard and his partners are ramping up Climate Impulse, a project started last February to fly a two-seater plane around the globe nonstop over nine days fueled by what’s known as green hydrogen. That’s hydrogen split out of water molecules using renewable electricity through a process called electrolysis.

The Climate Impulse team, whose backers include Airbus and a science incubator called Syensqo (pronounced “science-co”) born from Belgian pharmaceuticals company Solvay, presented its first-year progress to reporters Thursday in Les Sables d’Olonne, an oceanside town better known as host to the Vendee Globe round-the-world sailing race.

When will Climate Impulse get off the ground?

First test flights are planned next year, but the grueling round-the-world trip is set for 2028. Made with lightweight composites, the plane is dependent on several untested innovations and is far from a sure bet.

Piccard says a major airplane manufacturer wouldn’t take on the risk of producing a prototype such as Climate Impulse in case it fails.

”It’s my job to be a pioneer,” he said in an interview. “We have to show it’s possible, then it’s a big incentive for the others to continue.”

Even if the project is successful, experts say green hydrogen-powered flight on a commercial scale would be decades away at best. The project has lured tens of millions of euros (dollars) of investment, and the team of dozens of staffers is growing.

The solar-powered plane a decade ago was a technological feat, but wasn’t scalable, said Raphael Dinelli, the Climate Impulse engineer and co-pilot.

To accommodate 100 passengers, a souped-up Solar Impulse version would need solar-paneled wings with a span up to 300 meters, he said. Limited in range, the plane flown in 2015 also made 14 stops during its globe-circling trip.

The goal for Climate Impulse is to take off unassisted, fly some 40,000 kilometers (about 25,000 miles) around Earth along the Equator at a gentle speed of about 200 kilometers per hour (125 mph), and return to its starting point with no mid-air refueling — and with no stops at all.

How is Climate Impulse supposed to fly?

The controlled release of liquid hydrogen from ultra-insulated tanks under the airplane’s wings causes it to heat into a gas, a bit like how pressurized water vapor powered 19th-century steam engines. But instead of a mechanical operation in a steam engine, energy from the hydrogen evaporation seeps into the membrane of a fuel cell that powers the plane.

Because it’s hydrogen, the only emissions will be water vapor. Still, outside experts caution that the environmental impact of such water-vapor “contrails” remains unknown in a real-world or large-scale scenario.

Many minds have been looking at alternatives to carbon-based fuels to clean up air travel, which the International Energy Agency says is responsible for about 2% of global emissions of heat-trapping carbon dioxide.

Hydrogen has been used in flights for decades but as a gas, not a liquid. Use of liquid hydrogen will take time to scale up. Fossil fuels, which are cheaper and more efficient, still produce most hydrogen today.

Many governments want to produce more green hydrogen, but for now, the world can’t make enough clean electricity for power needs on land, let alone to generate enough for wide-scale use by planes in the air.

What’s progress like so far, and what’s next?

In the last year, the team has built the cockpit shell, started building the wing spar, and finalized interior components. They include swivel seats, a bunk and a stationary bicycle-like workout system to promote blood circulation for the two co-pilots who will be cramped in a small plane in low-oxygen conditions over nine days.

The hardest parts await.

Tests are planned this year on the fuel cells and propulsion systems, to see if the electric motor, propeller and batteries could work for an initial fully-electric flight phase.

The trickiest part is to regulate the flow of liquid hydrogen to ensure efficient consumption over the longest range possible, Dinelli said.

Another challenge: the liquid hydrogen must be maintained at minus 253 degrees Celsius (minus 423 Fahrenheit), or nearly absolute zero. Construction of a leak-proof tank is essential. Liquid hydrogen is highly flammable, so any seepage could have devastating results.

What are the prospects for green hydrogen in flight?

Liquid hydrogen, until now, has perhaps most prominently been known as a propellant to blast rockets into space.

Airbus calls hydrogen an important “pathway” in its aim to get low-carbon commercial planes to the market by 2035, and cites estimates that hydrogen could cut carbon dioxide emissions from aviation by half.

Powering planes by electricity is far behind the adoption of electric vehicles on the ground, says one outside expert.

“We have not had a ‘Tesla moment’ in aviation yet,” said Nikhil Sachdeva, a principal at consulting firm Roland Berger who has no connection to the project. “Hydrogen has the potential to be that for aviation, which is why it’s worth doing this right.”

The weight of batteries, important for electric vehicles on the ground, is even more important in aviation.

Plus, using super-cold liquid hydrogen is “extraordinarily difficult, and we can barely do it for a few minutes right now. And here we’re talking about doing it safely for hours,” Sachdeva said.

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Keaten reported from Lausanne, Switzerland.

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