The unpredictability and the variability of wind speed and direction is one of the biggest challenges that scientists face in turbine construction. Turbines generally work best and produce maximum amounts of electrical energy in the presence of steady and strong wind flow. But they can be damaged easily with sudden wind bursts, wind shear and turbulent winds. Because of this, the search for suitable turbine models that can answer all these are one of the most pressing issues in the turbine industry.
One of the newest turbine models that show great energy harvesting potential is now being developed by the Syracuse University’s L.C. Smith College of Engineering and Computer Science. Their model is an intelligence-based machine that can shift blade angles to different positions, depending on the current wind speed and direction for better airflow control. The shifting of the blades to different angles can maximize the harvesting of mechanical energy and increase over-all efficiency of the system.
This is just one of the many new ideas that scientists are coming up with to improve the wind harvesting potential of wind turbines. In 2007, a new wind turbine blade design was created by people at Sandia National Laboratories. The new blade design aimed to reduce the COE or cost of energy in wind turbines situated at areas with variable or low wind speeds. The invention made wind turbine construction possible even at areas with low wind speeds.
The blade was 27.1 meters long, almost three meters longer than the original design. The length is especially made to improve energy capture, even at low wind speeds. Aside from that, the new blade design was curved towards the trailing tip, allowing it to withstand turbulent and sudden wind gushes and reduce the tension load on the entire length of the blade. This project was actually done hand in hand with the Low Wind Speed Technology Project by Knight and Carver which aims to construct wind turbines and harness wind energy from sites with low but constant wind speeds.
A scientist working in the University of Minnesota also came up with a new turbine blade design that can reduce drag. The resistance brought about by winds beating on the turbine blades are one of the major causes of repairs and replacements. The new design involved the placement of groves along the turbine blades, allowing air to flow more freely along the structure and thus, reducing drag. The grooves are triangular in shape and are only 40 to 225 microns deep, barely visible to the human eye. The design was patterned after the very same grooves placed in Airbus airlines which reduced body drag by 6%. But because airplane wings are a completely different structure compared to wind turbines, drag reduction may just be at a lower 3%, but still a significant figure for wind turbine efficiency.
Another issue in large scale wind turbine construction is the spacing of two or more wind turbines. The issue is on how to arrange wind turbines that will make the most out of the present wind speeds. Scientists have calculated optimal spacing distances for large scale wind farms to optimize energy harvests. According to Charles Meneveau, head researcher at the John Hopkins University, wind turbine spacing should actually be much farther apart than what they are made today. Rotating turbine blades can create eddies, disrupting wind flow to other wind turbines found downstream. Thus, they should be spaced further apart in such a way that wind disruptions will not affect the efficiency of other wind turbines found nearer the area. Although wind flow is very difficult, if not impossible to simulate in real time, computer generated models and small-scale simulations have brought scientists several steps closer to the real scenario. This discovery can contribute a lot to establishing large scale wind farms, giving them better numbers on how to balance cost and efficiency in wind farm construction.
A team from the University of Alcala and the Complutense University in Madrid has also created models for predicting wind speed and direction in wind farms up to two days in advance. Such data is valuable in positioning wind turbines according to variability in wind speed and direction. Another key to more efficient turbines is correct site selection itself. Recent studies have revealed that the reduction of wind turbulence flowing to wind mill farms can significantly increase the efficiency of wind farms. Now, selecting sites that create this kind of condition is possible and even easier with available meteorological data.
Up until today, scientists, companies and governments are still investing in researches and projects that aim to improve efficiency and optimize harvesting capacity of wind turbines all around the globe.