You know the vertical axis wind turbines? I mean not the traditional blade based turbines but those with vertical axis which don't make sound or cause vibration.
A company called Windside makes them in Finland.
PhD Bertil Brännbacka from the University of Vaasa wrote his dissertation about these Windside wind turbines. He had his public defence in August 2015.
In his thesis called "Technical improvements of Windside wind turbine systems" Brännbacka aimed to find methods of improving the charging of batteries at low and high
wind speeds by developing auxiliary devices using original components.
He tested Windside wind turbines in real wind conditions and he developed two new techniques: an automatic reversible star-delta switch and a hollow shaft.
According to Brännbacka's thesis the new automatic reversible star-delta increased the annual energy yield of the small turbines by nine percent.
More information in the press release of the dissertation. You can download the pdf file of Brännbacka's dissertation here.