The hike in fuel oil prices and stricter emission regulations from the International Maritime Organisation has encouraged ship owners to try new ways of powering their vessels. One method is to attach a towing kite to the ship to harness windpower and reduce the consumption of fuel oil. This can save between 10% and 35% on annual fuel bills, depending on how much it is used and the wind conditions. This is currently being tested on a Bremen-based ship. Another method is to use Flettner rotors on the ship’s deck to channel surrounding wind. This produces a lifting force, which is turned into a controlled forward-propelling force.