Description
The most common SWT market offer: 3-blades horizontal rotor usually works best at wind speed of 8-10m/s, while typical wind speed in Poland is 3-6m/s. Lack of optimized layout results from one reason: aerodynamics of SWT requires specialized design tools and high level of expertise and thus optimization is too expensive for SWT makers. The objective of the project is to develop SWT layout better suited for low wind speed. The new design will help to popularize usage of renewable energy sources among individual users thanks to improved SWT Return On Investment. This will be possible by presentation of technical project of efficient small wind turbine with inclusion of conversion system schematics, being proof that SWT running inland can be an efficient source of energy. New design will be beneficial for each party of SWT market i.e. makers, sellers and end users. Researchers UiA will feed in expertise in wind turbine exploitation and in-deep knowledge of conversion and steering systems. The project will enhance research cooperation between Polish and Norwegian partners. What’s more, two students were choose to obtain PhD title from both Polish and Norway Universities.
Summary of project results
Small Wind Turbines (up to 100kW nominal power) are often treated as separate branch of energy sector. The main purpose of these devices is to act as an supporting energy source installed on farms or small factories. Unfortunately, in the real world, the Small Wind Turbines (SWT) are not that popular. Various reports on the state of small wind energy sector indicate the main obstacles to the rapid popularization of this form of energy conversion. The project STOW focused on economic and technical issues. Economic problem can be defined as poor ROI, while the most important technical obstacle is the low wind energy available in Poland and Norway inland. The specific goal of STOW project was to develop SWT optimized to the wind conditions, but economy should be the driving factor behind the new SWT design. This comes from the fact, that physical constraints, like Betz limit or low wind speed, makes very sophisticated solutions unjustified. In other words, a wind turbine that will work at low wind speed should be simple to minimize its unit price. On the other hand, though, the turbine should be effective enough to allow energy production even at the very low wind velocities. Research conducted in the project were aimed to find the balance between energy effective design and low price of the final product.The proposed SWT design is the best compromise between mentioned factors. Layout of choice is three blades, horizontal axis SWT, shroud augmented. Blades airfoil and shroud geometry were carefully developed with the best efficiency in mind, while design of shroud, support structure, choice of materials and energy conversion circuits were developed taking into account low costs of production and maintenance. It is worth to mention, that optimization of turbine aerodynamics was done based on the wind tunnel tests, as well as reliable weather data taken from the numerical weather forecasting model. During the course of the project it was decided, that scaled prototype of SWT will be built. It should be stressed out, that this decision went beyond original project scope of work and thus it was declaration to give additional value within already defined time frame and budget. On the other hand, the SWT prototype will give unique opportunity to acquire reliable and undisputable data allowing to calculate SWT efficiency. The prototype, scale 1:2, was assembled and tested in the wind tunnel. It will be mounted on the roof of a buildings in the first quarter of 2017.
Summary of bilateral results
The final design of the STOW turbine is the result of the bilateral work between. Every single partner was responsible for different aspects of the technical project. Lodz University of Technology was responsible for aerodynamics of the turbine, Military University of Technology was responsible for mechanical design and University of Agder developed control/energy conversion systems. Such division of work assured, that all the aspects that are important for the turbine design were developed on the top possible level of knowledge and quality. It is obvious, that consistent technical project conducted in described above environment require very good communication and information exchange. Number of mutual visits and ongoing every-day communication led to successful outcome of the project. Of course, mutual visits gave also an opportunity to have more broad view on partner countries. It was occasion to learn more about society, education system, or simply – to sightseeing. One of the important outcome of the project is attendance of polish student in the PhD course in University of Agder. Due to some logistics problems he was not able to finish all the courses within the project time frame, nonetheless he should be able to finish PhD course within a year.