In CNN's June 30, 2023 Giant kites could pull cargo ships across the ocean – and slash their carbon emissions
“What differentiates it from other wind solutions,” says Bernatets1, “is that the wing is not just pulled by the wind and countered by the ship.” Instead, it flies in figure-of-eight loops, which multiply the pulling effect of the airflow to give what he calls “crazy power.”
“Plus, we fetch the wind 300 meters above the sea surface, where it’s 50% more powerful,” adds Bernatets. The combination “explains why the power is tremendous for a system that is very compact, simple on the bow of the ship, and can be retrofitted on any ship, not just new ships,” he says.
1Airseas co-founder and CEO Vincent Bernatets
I'm hoping that my question about the aerodynamics and lift from a "giant kite" that "flies in figure-of-eight loops...300 meters above the sea surface" is sufficiently on-topic here.
When kites are used to generate electricity, you certainly need motion - perhaps it reels in and out or it lofts a rotating wind turbine or something else - you need substantial relative motion to generate substantial electrical power.
But a kite affixed to a ship and static relative to it can certainly provide mechanical power to the ship, at least when the wind speed is greater (and in the same general direction) as the ship's speed.
So... what's with the figure-eights?
Question: Why would a kite flying at 1000 feet in "figure-of-eight loops" serve to "multiply the pulling effect of the airflow" on the ship to which it is attached?