Actually, what we are looking for is the rating point (yes, it is at an unusually high speed), since the article gives the power output for, but as far as I can tell, not the associated wind speed. It does say, however:
Without the wind speed for the rating point (unless someone can find it...?), it is hard to know for sure, but here is a turbine rated for 5 kW at 22 mph wind speed, with a diameter of 20 ft....each Wind Tree can produce an average of 3.1 kW of power, 280 days of the year, enough to power 15 streetlights.
Although traditional wind turbines can generate 5-6 kW, their large size means they require strong winds to get moving, meaning they generate power for fewer days a year. Also, their huge size - towering up to 120 feet (36 meters) tall with the blade rotary diameter of up to 43 feet - means many find them an unattractive option. In comparison the Wind Trees are a rather petite 36 feet (11 meters) high and 26 feet (8 meters) wide.
The turbine I linked costs $10,000. So you can buy three of them for the cost of one Wind Tree. We can't know for sure how they compare without the rating point for the Wind Tree, but for less than a third the price for the Wind Tree's 5-6 kW you can get one conventional turbine to generate 5 kW while sweeping-out less area. Or buy three for the same price as a Wind Tree.Each Tree costs $36,500 (€29,500)