Flying is the most climate-unfriendly mode of transportation, yet demand for air travel is projected to continue to increase in the coming decades. Researchers are working on replacing jet fuel with sustainable fuels, hydrogen, or battery-powered airplanes, but such technologies aren’t ready for wide-scale use.
Relaunching a century-old technology could be a faster approach to climate-friendly air travel, according to a new study. Airships powered by a skin of thin, flexible solar cells and highly efficient, lightweight batteries have the potential to move people and freight across oceans at much lower cost and climate impact than conventional aviation.
In the new study, researchers envision a solar-powered airship more or less the same shape, size and design as LZ129. This is the airship better known as the Hindenburg, which crashed and caught fire in New Jersey at the end of a transatlantic voyage in 1937, putting a damper on airship travel for nearly a century. But a solar-powered airship would be much safer as it would have no combustible fuel on board, the researchers say.
The airship envisioned in the new study would carry a 10-ton battery and be covered with 7 tons of flexible solar cells – capable of providing enough energy for long-haul routes such as between London and New York. The battery would be charged before takeoff, representing the only potential source of carbon emissions for the flight. The solar cells would provide the power to propel the airship, as well as recharge the battery to keep the ship aloft at night.
The researchers developed an algorithm to optimize battery size, the timing of battery charging and use during both day and night, and time of departure to reduce flight times. They mapped out the quickest and most climate-friendly route for such airships to travel between London and New York and between Madrid and the Canary Islands – long-haul and medium-haul flights, respectively, that are difficult to replace with other means of climate-friendly travel because they involve water crossings. Then they calculated the climate impact and energy cost of these journeys.
The climate impact of each kilometer a person travels by solar airship would be about 5% of that involved in a conventional airplane flight, the researchers report in the International Journal of Sustainable Energy. The comparative climate impact of freight transport by solar airship would be even lower: about 1.4% that of conventional air freight for medium-haul distances and 1% that of conventional air freight for long-haul distances.
The energy consumption costs of solar airship travel are similarly lower than that of conventional aviation.
The main downside of solar airships is flight time – which increases by a factor of about three for mid-haul flights and six for long-haul flights compared to conventional aviation. The solar airship journey between New York and London would take two days and one night; the return flight from London to New York would last three days and two nights (due to less favorable winds). The journey between Madrid and the Canary Islands would take between 7 and 20 hours, depending on the altitude of the flight and the season of the year.
But this speed should be fine for freight transport and is faster than sending freight by sea, the researchers argue. And for passenger travel, the slower speed could actually be an advantage. Airships are much more spacious than jet planes, with room for a passenger dining room and private sleeping quarters. With those comfortable accommodations, the multi-day flight could actually be an advantage, reducing jet lag for passengers at their destination, the researchers argue.
Source: Pflaum C. et al. “Design and route optimisation for an airship with onboard solar energy harvesting.” International Journal of Sustainable Energy 2023.
Image: Flying Whales