Anyone who walks past Sebastian Harms’ garden in the Lower Saxony community of Thüdinghausen looks twice. A strange tree has been standing there since the turn of the year: its trunk is made of steel, its branched branches do not bear green leaves, but rather 36 small green plastic turbines that rotate in the wind. It is the first so-called wind tree in Lower Saxony – and for its owner a step towards energy independence.

What is behind the wind tree?

The wind tree originally comes from the French company NewWind, which went bankrupt in 2016. The successor company New World Wind (founded in 2017) continues to produce and market the technology. Managing director Luc Eric Krief and his team traveled to Lower Saxony specifically to set up the system. “We have already installed over 200 wind trees around the world,” says Krief the “Hessische/Niedersächsische Allgemeine”.” (HNA).

The principle: On a steel trunk with steel branches there are so-called aeroleafs – patented microturbines with a vertical axis of rotation in the shape of a leaf. The aeroleafs rotate independently of each other: if one unit fails, the others continue to supply power. Cables and technology are hidden in the trunk and branches. There are different models. According to the manufacturer, in the hybrid version it is even possible to generate electricity from wind power and solar modules at the same time.

Electricity through wind

According to the manufacturer, the turbines start rotating at a wind speed of around 2.5 meters per second – a value at which conventional wind turbines still stand still. The system is intended to provide energy almost all year round. According to the manufacturer, the electricity generation itself should be almost silent.

Harms already has two photovoltaic systems with an output of up to 10,000 watts each. “The wind tree will help my home become more self-sufficient from the energy supply,” Harms tells “HNA”.

The highlight: If the solar cells of the photovoltaic system do not provide electricity at night or in the cloudy winter, the wind tree should continue to make its rounds. Each of the 36 Aeroleafs delivers up to 300 watts – in total the system theoretically has an installed output of 10,800 watts.

Harms wants to analyze the actual power input from his wind tree in detail in the next few weeks. By 2029, he plans to cover 100 percent of the energy needs for his home, office and electric car himself.

It is still unclear whether the investment will pay off. Many experts express concerns about commercially available small wind turbines: the economic viability depends heavily on the specific wind potential at the location. In a poor location, the electricity production costs could be over one euro per kilowatt hour – far above the market price. The amortization over 20 years is then hardly achievable. With a favorable location and a high proportion of self-consumption, the bill would look better.

Wind trees in Germany

Germany is not a blank spot on the world map for small wind turbines – but the tree-shaped devices are still few and far between in this country and are primarily used by companies. The very first wind tree on German soil was installed in the Ruhrpark shopping center in Bochum in November 2015 and has since been supplying the parking lot lighting system with renewable electricity. The installation followed in 2016 at the German headquarters of Endress+Hauser Liquid Analysis in Gerlingen near Stuttgart. The wind tree there still stands today and, among other things, powers an electric charging station.

Sebastian Harms’ system in Thüdinghausen is now the first private wind tree in Lower Saxony. So far, it has primarily been companies and municipalities that have relied on the technology in Germany.