Long-Term Laddermill Modeling for Site Selection

Non-powered flight vehicles such as kites can provide a means of transmitting wind energy from higher altitudes to the ground via tethers. At Delft University of Technology, construction and testing of such a high altitude wind machine is ongoing. The concept is called the Laddermill. It generates energy by pulling a line under high tension from a drum with a kite and retrieving it under low tension. The change in tension is achieved by changing the angle of attack and flight pattern of the kite. This paper presents a modeling and optimization approach that can be used to help design Laddermill systems for particular sites around the world. Some crude assumptions are used to derive the average power that can be produced by a Laddermill system, taking into the most important system parameters. Historical wind data is used to size the kite and cable diameter needed to produce a 1 MW machine for the least cost.