Developing highly efficient small wind turbines
Small Wind Turbines (SWTs) could benefit locations which don’t have access to grid energy. But if they are to really take off in the energy market, costs for this renewable technology will have to be reduced, keeping electricity generation competitive and independent of subsidies. Towards this end, the European Commission has highlighted the role that Small and Medium Enterprises (SMEs), such as farms and small industry can play here. If located in areas where annual average wind velocity is higher than 5 m/s (metres per second), SWTs are frequently the best option. The EU-supported Eciwind project succeeded in developing technology for Small Wind Turbines (SWTs), reaching an attractive power coefficient (available power relative to wind speed) of Cp=0.5. Aerodynamic efficiency A unique feature of the Eciwind system’s aerodynamic design is that it enables electricity to be generated at very low winds, starting as low as 2 m/s. Crucial, given that lower wind speeds are common in many regions. Mechanical and aerodynamic efficiency is achieved by the pitch control system which varies the position of the blades, rotating on their axis, suitable for each engine rotation and a range of wind speeds. Angling the blades like this allows the generator to maximise power production from the start of their rotation, to their limit. The system protects the blades from overspeed during very strong winds, for example the angle of the blades is reduced when the power exceeds 10kW. The blades themselves take advantage of computational fluid dynamics which, alongside their specially designed aerodynamic profile, can cater for unexpected loads, for example during storms. This means that while the system generates considerable torque, air flows smoothly over the blades, creating half the noise levels of competitor systems. Even at 52 m/s, the maximum speed, the blades make no extra sound. Eciwind features an electronic control and monitoring system which continually displays various parameters of the wind turbine and can be accessed remotely for adjustments. To ensure safety, Eciwind incorporates protection systems which include: an active mechanical brake, a ‘flag position’ to stop the blades turning in the worst conditions and an electromagnetic brake. As project coordinator Mr Juan Antonio Vila says, “The unique thing about this technology is that we are using very similar procedures to big wind turbines, but adapted to be cheaper.” Part of a wider sustainable energy solution It was anticipated that the prototype would achieve 10kW at 11 m/s, but when installed it actually got 10kW at 9 m/s and 18kW at 11 m/s, an increase of 80 % on expectations. Eliminating some of the costly parts of current technologies, such as the gearbox, and optimising the cost/performance of the rest of the components has reduced maintenance costs and decreased the end user installation costs. “The barriers to uptake are not really about the technology nor the logistics, but rather lack of awareness about this technology’s existence,” says Mr Antonio Vila. “Rather than be a competitor to solar, as we incorporate solar inverters into Eciwind, wind energy can work perfectly in combination with solar. Indeed, 90 % of our installations are a combination of the two.” The joint venture between Enair Energy SL and Lancor is currently selling the 20kW SWT models and is hopeful, with the right investment, to be selling the 60kW versions within a couple of years.
Keywords
Eciwind, small wind turbine, energy, sustainability, environment, power coefficient, electricity, aerodynamic, blades, fluid dynamics, renewables
