Solar Impulse made headlines last year when a solar-powered single-seater plane travelled from California to New York. The plane, which was equipped with 12,000 solar cells and four electrically-powered propellers, was the first aircraft running on renewable energy that was able to fly non-stop for 24 hours. It carried batteries that were charged during the day, so the plane would be able to fly at night .
Renewable energy company Masdar recently announced that their next generation solar-powered airplane would attempt to circumnavigate the Earth next March, starting its journey in Abu Dhabi.
Masdar's newest plane, Solar Impulse 2 , has 17,000 solar cells installed on its wings, which have a span of 236 feet (72 meters)—longer than that of a Boeing 747. Moreover, the aircraft only weighs 5,070 pounds (2,300 kilograms), less than a Toyota Tundra pickup truck, as company officials point out. The plane can fly at a speed between 36 and 140 kilometers per hour, with a maximum power of 70 horsepower. The round-the-world trip will take approximately four to five months, with the longest legs over the oceans lasting up to 120 hours at a time.
Solar Aircraft Technology
Solar Impulse is not the first solar-powered airplane. Solar aircraft technology has actually been tested since the 1970s , but has gained immense traction only in recent years. This is largely because the demand for renewable energy sources has increased and solar technology has become more efficient and affordable. While Solar Impulse is piloted, other solar airplanes are UAVs (unmanned aerial vehicles), such as NASA's Helios Prototype or QinetiQ's Zephyr. However, these planes were mainly developed for communications and surveillance purposes.
In general, solar aircrafts are flat and thin, so they can be lifted up by the wind without being jerked around. The Solar Impulse model features a customized fiber honeycomb sandwich structure, which keeps the aircraft light yet robust. Encapsulated solar cells are located on the upper wing surface, while nacelles containing lithium polymer batteries are positioned under the wing. Four brushless, sensorless motors are also mounted below the wings. Solar Impulse 2 has been slightly modified: it has a larger, non-pressurized cockpit and advanced avionics, such as autopilot. Moreover, it features supplemental oxygen and other environmental support systems that permit the pilot to cruise at an altitude of 39,000 feet (12,000 meters).
Helping Solar Take Off
Both Solar Impulse airplanes were manufactured in Switzerland and are piloted by Swiss psychiatrist and aeronaut Bertrand Piccard and Swiss businessman Andr é Borschberg. The project team will travel to Abu Dhabi in January and spend two months training and testing with Masdar before taking off.
“We have chosen this location as being the best and most suitable departure and return point for the round-the-world tour, due to its climate, infrastructure and commitment to clean technologies," Borschberg said in a statement . Masdar, which is a unit of the Abu Dhabi government's investment vehicle Mubadala, has invested billions of dollars in clean energy . Masdar is in the process of building the new headquarters for the International Renewable Agency in Masdar City, Abu Dhabi. This dual headquarters will be a sustainable 32,000-square-foot structure, housing both Masdar and the international agency.
Those involved in the Solar Impulse program hope that the ambitious project will convince skeptics that solar energy is a worthwhile alternative to fossil fuels. “We wanted to demonstrate the viability of this revolutionary clean technology,” stated Masdar's chief executive, Ahmad Belhoul. If all goes as planned, the first solar-powered round-the-world plane trip should be completed toward the end of summer 2015. If the Solar Impulse journey is successful, it might help solar technology do more than take off—it could help it soar.