The Differential Wind Turbine was invented by Corten in 1999 at the Energy Centre of the Netherlands. Initially designed with a fixed foundation, Corten improved the set-up in 2007 by mounting two turbines symmetrically on a ship. The setup was realized with financial support of Suzlon Energy and offers several advantages: 

 

• Equal inflow for both turbines
• Wind speed control via the ship's diesel engines
• Adjustable wind shear by modifying turbine altitude
• Interchangeable rotors to eliminate systematic errors

 

The concept was never patented, allowing free use to facilitate further development of wind energy.

 

A major challenge in wind energy is the ±5% uncertainty in rotor efficiency measurements due to variable inflow conditions. Many proposed rotor improvements have less than a 5% impact, making validation difficult. The Differential Wind Turbine overcomes this by comparing a standard rotor with a modified one. Because both experience identical inflow conditions, uncertainties cancel out, allowing efficiency improvements to be measured with an accuracy better than 0.5%.

 

The setup validated the first slender blade design (blue) versus the best conventional design used by Suzlon. The slender rotor produced 6% more energy at the same loads.