Wind Project Performance 1994 Summary WPRS performance results
also have been categorized by horizontal or vertical axis
machines. When comparing performance of horizontal and vertical
turbines, it should be recognized that vertical axis turbines
used in California at the present time represent relatively old
technology. No new capacity has been added since 1986. The
California wind industry continues to be dominated by horizontal
axis machines accounting for 94 percent of all capacity and 100
percent of new capacity. Comparison of performance indicates a
23 percent capacity factor for horizontal axis turbines compared
to a 9 percent capacity factor for vertical axis turbines
(Figure 12 -- Capacity Factors by Turbine Axis). Performance by
kWh per square meter was 810 for horizontal axis turbines
compared to 513 for vertical axis turbines (Figure 13 -- kWh Per
Square Meter production by Turbine Axis). WPRS data does not
explain why the variation in kWh per square meter performance
between horizontal and vertic