B. Lansdorp and W.J. Ockels (The Netherlands)
Kites, Energy, High altitude, Ground station.
This paper presents the design of a 4 kW Laddermill
groundstation. The Laddermill is a novel concept to
harvest electricity from high altitude winds. The concept’s
operating principle is to drive a generator with kites.
Several kites are high in the air at an altitude of more than
1 km. All kites are connected to a single cable that
connects to a drum in the groundstation. The lower part of
the cable is connected to the kites and is wound around a
drum. The kites pull the rope from the drum, which in
turn drives a generator. When all of the cable is pulled off
the drum, the kites fly down in a configuration that
generates significantly less lift than during the ascent.
This way the lower part of the tether is retrieved onto the
drum and the process is repeated. The concept allows very
large single unit power. At Delft University of
Technology, a 2 kW test model of the Laddermill was
constructed and tested successfully. From this 2 kW
Laddermill several valuable lessons were learned. Taking
the lessons learnt into account, a 4 kW groundstation was