Solar-powered airships as climate-friendly air travel

Flying is the least climate-friendly form of transport, but demand for air transport is expected to continue to grow in the coming decades. Researchers are working on replacing jet fuel with sustainable fuels, hydrogen or battery-powered aircraft, but such technologies are not ready for large-scale use.

Reviving a century-old technology could be a faster approach to climate-friendly air travel, according to a new study. Powered by a shell of thin, flexible solar cells and highly efficient, lightweight batteries, airships have the potential to transport people and cargo across oceans at a much lower cost and climate impact than conventional aviation.

In the new study, the researchers envision a solar-powered airship more or less the same shape, size and design as the LZ129. This is the airship, better known as the Hindenburg, that crashed and caught fire in New Jersey at the end of a transatlantic voyage in 1937, making airship travel difficult for nearly a century. But a solar-powered airship would be much safer because there would be no flammable fuel on board, researchers say.

The airship envisioned in the new study would carry a 10-tonne battery and be covered in 7 tonnes of flexible solar cells – capable of providing enough energy for long-distance routes such as between London and New York. The battery will be charged before takeoff, which represents the only potential source of carbon emissions for the flight. The solar cells will provide power to propel the airship as well as recharge the battery to keep the craft in the air at night.

The researchers developed an algorithm to optimize battery size, charging time and battery usage during both day and night, and takeoff time to reduce flight time. They charted the fastest and most climate-friendly route for such airships to travel between London and New York and between Madrid and the Canary Islands—long- and medium-haul flights, respectively, that could hardly be replaced by other means of air conditioning— friendly voyages because they involve crossing water. They then calculate the climate impact and energy costs of these trips.

The climate impact of each kilometer traveled by a person in a solar airship would be about 5% of that of a conventional airplane flight, researchers report in International Journal of Sustainable Energy. The comparative climate impact of solar airship cargo transport would be even lower: about 1.4% of that of conventional medium-haul air cargo and 1% of that of conventional long-haul air cargo.

The energy costs of solar airship travel are similarly lower than conventional aviation.

The main disadvantage of solar airships is flight time – which increases by a factor of about three for medium-haul flights and six for long-haul flights compared to conventional aviation. The solar airship’s journey between New York and London will take two days and one night; the return flight from London to New York will take 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 that speed should be good for cargo transport and is faster than shipping cargo by sea, the researchers say. And for commuter trips, the slower speed can actually be an advantage. Airships are much more spacious than jet planes, with space for a passenger dining room and private sleeping quarters. With these comfortable accommodations, a multi-day flight can actually be an advantage, reducing jet lag for travelers at their destination, researchers say.

Source: Plum C et al. “Design and Route Optimization for an Airship with Onboard Solar Energy Harvesting.” International Journal of Sustainable Development Energy 2023

Image: Flying whales

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