What are the advantages?
Both wind speed and consistency increase with altitude as the effects of the earth's surface decrease. Shown below is the vertical wind speed distribution for the entire year of 2006 at a measurement station in Payerne, Switzerland. Even though the average on the ground is quite low (~2m/s), at just 500m the average increases to about 6m/s and at 1000m is almost 8m/s, a magnitude which would be regarded as excellent for a conventional wind turbine. Since the power contained in the wind increases with the cube of the wind speed, this results in a very large increase in power available. The implications of these phenomena are three fold:
- Less Materials - as the power density of the wind is higher at altitude, smaller aerodynamic devices are required to capture the same energy. Also, as these high altitude winds can be accessed without the need for an enormous tower, the material requirements for the entire system are drastically reduced.
- More Energy Produced - as the consistency of the wind and the relative proportion of investment made in the aerodynamic structure is small, the optimum capacity factor of the system will be higher. This means that for an installed nameplate power capacity, the total energy produced by the system will be much higher compared to a wind turbine.
- Cheaper - economically, the implications of these two points are that the cost per MW and the cost per MWh of a kite power plant will be significantly lower than a wind turbine, and potentially lower than a thermal power plant. Initial estimates from Polytechnic Torino [7] and Joby Energy indicate a levelized energy cost below 50 USD/MWh. In comparison, modern wind farms come out at around 100 USD/MWh.
Vertical wind speed distribution for the entire year of 2006 at a measurement station in Payerne, Switzerland.