A plane with a top speed like a homing pigeon is set to embark on a landmark round-the-world flight powered only by the sun's energy, organizers said on Tuesday.

Solar Impulse 2, the first solar-powered plane to be able to fly for several days and nights, will travel roughly 35,000 kilometers - including a five-day stretch above the Pacific Ocean - without using a drop of liquid fuel. It is scheduled to land 12 times along the way.

"We want to demonstrate that clean technology and renewable energy can achieve the impossible," said Solar Impulse chairman Bertrand Piccard, the scion of a dynasty of Swiss scientist-adventurers. "Renewable energy can become an integral part of our lives, and together we can help save our planet's natural resources."