Small wind turbines are becoming increasingly important in the field of renewable energies. With their ability to generate clean electricity from wind, they help reduce dependence on fossil fuels and support the transition to a sustainable energy supply. Unlike photovoltaics, however, the still young market for small wind turbines is complex and characterized by a multitude of different construction types, power classes, designs, and technical concepts. A thorough understanding of their properties, technologies, and significance in the context of renewable energies is crucial for the development of a sustainable energy supply.
Horizontal and vertical small wind turbines
The components of a small wind turbine
A small wind turbine consists of several key components that are crucial to its operation:
rotor blades
The rotor blades are a fundamental and defining component of a small wind turbine. They capture some of the kinetic energy of the incoming wind and convert it into mechanical energy. Together with the rotor hub, the rotor blades form the rotor. The aerodynamic profile, size, and pitch of the rotor blades significantly determine the performance of the small wind turbine.
hub
The rotor blades are suspended from a central connecting element, the rotor hub. This transmits the rotational movement of the rotor blades to the rotor shaft.
rotor shaft
The rotor shaft transfers the rotational energy of the rotor blades directly or indirectly via an intermediate gearbox to the generator. It is the most heavily loaded component in the wind turbine's powertrain.
generator
In the generator, the kinetic energy of the wind is converted into electrical energy. It consists of a rotor and a stator. The movement of the rotor in the stator creates electromagnetic interactions that generate electrical energy in the stator.
Gearbox or direct drive
There are two different types of wind turbines: gearless (direct drive) and those with a gearbox. In gearless systems, the rotor's rotational motion is transmitted directly to the generator's rotor, while in the latter system, the rotor's motion is transmitted from the rotor shaft to the generator via a gearbox. Generally, gearless systems are heavier and more expensive for the same power output. Wind turbines with gearboxes, on the other hand, are more complex and require additional attention during service and maintenance. Both designs are available on the market today and are constantly being developed further.
steering
The control electronics performs key tasks related to operational and plant management, safety monitoring, data acquisition, and communication. It monitors power quality and protects the plant from damage. The control system consists of electrical switching elements, sensors, fuses, contactors, and connectors, as well as intelligent system software.
Wind tracking
Small wind turbines with a horizontal axis must always be aligned with the wind direction to optimally utilize wind energy. Passive systems in the form of wind vanes mounted behind the turbine are predominantly used here. Modern small wind turbines have active yaw systems. The wind direction is determined by wind sensors and transmitted via the control system to the yaw drive. This automatically steers the turbine and optimally aligns it with the wind.
Tower and foundation
The tower and foundation form the supporting structure of the wind turbine. The tower provides the necessary height to better direct the wind flow to the rotor blades. For small wind turbines, the towers are typically designed as freestanding or guyed tubular or lattice towers. The foundation ensures the stability of the small wind turbine. These are usually reinforced concrete foundations embedded in the ground, ensuring a firm and secure anchorage.
Technologies for 2 kW small wind turbines
Typical designs and configurations of 2 kW small wind turbines vary depending on the manufacturer and model. There are vertical and horizontal turbine types, as well as various rotor blade configurations and tower designs. 2 kW small wind turbines typically use materials such as aluminum alloys for the tower and fiber-reinforced plastics for the rotor blades. These materials offer a good balance between strength, weight, and cost. The power curves and efficiency of 2 kW small wind turbines depend on various factors such as wind speed, rotor size, and the aerodynamic properties of the rotor blades. Maintenance and operation of 2 kW small wind turbines require regular inspections and maintenance to ensure the performance and reliability of the turbines. This includes checking the rotor blades, lubricating the moving parts, and monitoring the electrical components.
Technologies for 5 kW small wind turbines
Compared to the 2 kW variants, 5 kW small wind turbines offer higher power and higher efficiency. They are generally larger and more robustly constructed to withstand higher loads and generate more energy. Innovations in 5 kW small wind turbines focus on efficiency improvements and improved materials. For example, advanced rotor blade profiles and aerodynamic designs are used to increase efficiency and optimally utilize wind flow. Modern turbines feature intelligent control systems that optimize energy flow and ensure grid stability. Economic aspects such as acquisition costs, operating costs, and feed-in tariffs influence the economic viability of 5 kW small wind turbines. The long-term financial benefits depend on local wind conditions, electricity prices, and government subsidy programs.
Price and profitability of small wind turbines
The cost planning for a small wind turbine varies depending on size, output, and location. The acquisition costs for small wind turbines range between €3,000 and €10,000 per kW of installed capacity. The economic viability of small wind turbines depends on various factors, such as the wind conditions at the site, feed-in tariffs, existing energy costs, and operating costs. A careful site analysis and profitability calculation are therefore crucial for assessing profitability.
Small wind turbines as an important lever in the energy transition
Small wind turbines offer a wide range of opportunities for a sustainable energy supply and contribute to reducing greenhouse gas emissions. Continuous development and innovation in this field are crucial for their efficiency and cost-effectiveness. Future challenges lie in further increasing performance, integrating intelligent control systems, and reducing costs. The use of small wind turbines can help advance the energy transition and shape a clean and sustainable energy future.
