Newswise — Flying is the most damaging mode of transportation for our climate. At least, up until now. But work is already underway to investigate technical alternatives to conventional aircraft. For example, airships with highly efficient solar cells and extremely light batteries on board. Prof. Dr. Christoph Pflaum from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), together with Prof. Dr. Agnes Jocher from the Technical University of Munich (TUM) and the FAU student Tim Riffelmacher, has investigated which route a solar airship would have to take in order to fly from London to New York as quickly and as climate-friendly as possible.

The findings were published in the International Journal of Sustainable Energy.

Flight is the most harmful mode for our environment. Yet, research is underway to explore alternative technical options for traditional airplanes. For instance, solar airships equipped with super efficient solar cells and ultra-lightweight batteries. Prof. Dr. Christoph Pflaum, from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), along with Prof. Dr. Agnes Jocher from the Technical University of Munich (TUM) and FAU student Tim Riffelmacher, have analyzed the most time-efficient and eco-friendly route a solar airship would need to take to travel from London to New York.

Prof. Dr. Christoph Pflaum, an expert in numerical simulation using high-performance computers, believes that solar-powered airships offer a quick and cost-effective solution for making aviation more environmentally friendly. "By relying on solar airships, we can significantly reduce the impact of aviation on the climate," he said. Along with FAU student Tim Riffelmacher and Professor Jocher from TUM, Prof. Pflaum has published a paper titled "Design and route optimization for an airship with onboard solar energy harvesting".

Climate-friendly and cost-effective air travel

According to Professor Pflaum, their calculations indicate that solar airships have the potential to significantly decrease both transportation expenses and CO2 emissions associated with air travel. The researcher has developed a deep enthusiasm for solar-powered air travel throughout his investigations and enthusiastically enumerates its various advantages. "Solar airships are undeniably environmentally friendly since they are outfitted with exceptionally light and immensely efficient thin-film solar cells that recharge continuously throughout the flight. Consequently, no combustion-related discharges are produced during the airship's operation," he explains.

The airship's battery only requires power from the grid to recharge before takeoff, and even this process has minimal CO2 emissions. "At most, only five percent of the amount of carbon dioxide produced by traditional air transport is emitted," Prof. Pflaum explains, pointing to the statistics. When compared to long-haul cargo flights, solar airships generate less than one percent of CO2 emissions. For medium-haul flights, the figure is approximately 1.4 percent, while for passenger transport, it is roughly five percent.

"Currently, the solar airship we are discussing does not exist, but there is a company in California that is making significant investments in developing a fully rigid airship, which will be the first of its kind in 90 years. This airship will provide ample space and excellent protection against wind and weather," Professor Pflaum states with enthusiasm.

The technology for solar airships can be implemented rapidly, but it has been overlooked for decades. "Undoubtedly, the tragedy of the airship LZ 129, famously known as the 'Hindenburg,' has contributed to the lack of progress," the professor acknowledges. "At 245 meters long and 41.2 meters in diameter, LZ 129 was one of the most extensive aircraft ever constructed, and it was a genuine sensation during its inaugural voyage in March 1936. However, just a year later, it caught fire upon landing in the United States and was entirely destroyed." This event led to the end of airships for a long time, but now they are being reconsidered with solar cells on board, and significant efforts are underway to develop a "real game-changer."

With these new models, no one needs to be afraid of a fire, as the airships are neither filled with combustible hydrogen nor with any other fuel.

The researchers are convinced that the cost factor also favors the use of solar airships since the energy consumption expenses of solar-powered airships are significantly lower than those of conventional aircraft, according to their present calculations.

Two to three days for a flight across the Atlantic

"Do solar airships present a genuine technical alternative to traditional aircraft?" we asked. "It seems promising," Professors Pflaum and Jocher concur. "However, we must adjust our expectations regarding flight time since an airship travels much slower than an airplane."

Several FAU students conducted simulations and calculations in their Bachelor's and Master's theses to determine how fast an airship equipped with solar cells could fly and which route it would need to take to optimize wind and weather conditions and sun positioning. Most recently, Tim Riffelmacher addressed "Charging optimization of the battery in a solar airship with simulated annealing" in his Bachelor's thesis.

Tim Riffelmacher is also very passionate about solar airships and examined battery usage during day and night in his simulations. "The battery is charged before the flight and must then last for long distances," explains the young researcher. "This is easier said than done since there is no sun at night and the solar cells do not generate electricity." However, optimizing the charging process can make many things possible.

Based on their work, Riffelmacher and the other students demonstrated that national, continental, and even intercontinental flights with acceptable flight duration are feasible. "According to our calculations, a flight across the Atlantic from New York to London takes about two days and one night," summarizes Prof. Dr. Christoph Pflaum. "In the opposite direction from London to New York, we calculated a flight time of three days and two nights."

Professor Pflaum believes that the slower pace of travel in airships could also be an advantage for passengers who are looking for a more relaxed and comfortable way of traveling. With ample space for amenities like dining rooms, lounges, and stylish double rooms for passengers, airships could provide a unique and luxurious travel experience that is not available on conventional aircraft.

Journal Link: International Journal of Sustainable Energy