Propeller wind turbines, now common throughout the world, may be replaced with more compact and efficient vertical turbines in the future.
According to research conducted by Oxford Brookes University, vertical turbines are far more efficient than traditional turbines in large wind farms, and when used in pairs, the vertical turbines can increase performance by up to 15%.
An Oxford Brooks University team led by Professor Iakovos Tzanakis used 11,500 hours of computer simulation to illustrate that wind farms run more efficiently if turbine blades are replaced with vertical axis generators (VAWTs), rather than propeller blades.
Vertical turbines vs Traditional windmills Turbines
In this study, large VAWTs will reportedly outcompete current HAWT wind turbines for the first time at a realistic scale.
VAWTs spin with an axis vertical to the ground, and their behavior differs from that of conventional propellers (HAWTs). In the research, VAWTs performed better when arranged in grid forms, which is why locating wind farms to maximize outputs is key to wind farm design.
Professor Tzanakis comments “This study evidences that the future of wind farms should be vertical. Vertical axis wind farm turbines can be designed to be much closer together, increasing their efficiency and ultimately lowering the prices of electricity. In the long run, VAWTs can help accelerate the green transition of our energy systems, so that more clean and sustainable energy comes from renewable sources.”
With the UK’s wind energy capacity expected to almost double by 2030, these results can be used to design more efficient wind farms, visualize large-scale wind energy harvesting methods, and ultimately improve the renewable energy technology to more quickly replace fossil fuels as energy sources.
According to the Global Wind Report 2021, the world needs to install three times as much wind power over the next decade in order to reach net zero targets and avoid the worst impacts of climate change.
Joachim Toftegaard Hansen, lead author of the report and graduate of the Bachelor of Engineering program, says modern wind farms have one major flaw: as the wind approaches the front row of turbines, turbulence is generated downstream, which can damage the subsequent rows.
In other words, the front row will convert about half the kinetic energy into electricity, while the back row will only do so at 25-30%. Each turbine costs more than £2 million/MW, so I figured there must be a more cost-effective way.
This is the first study to comprehensively evaluate many aspects of wind turbine performance, including the array angle, rotation direction, turbine spacing, and number of rotors. This is also the first study to determine whether the same performance improvements occur when three VAWT turbines are linked together.
In the article, co-author and senior lecturer Dr Mahak says: “Computational methods are critical in understanding flow physics. Such studies are less costly than the large experimental test facilities. This is a critical element during the early design stage.
Joachim Toftegaard Hansen, Mahak Mahak, Iakovos Tzanakis. Numerical modelling and optimization of vertical axis wind turbine pairs: A scale up approach. Renewable Energy, 2021; 171: 1371 DOI: 10.1016/j.renene.2021.03.001