Based on more than 11,500 hours of computer simulation, the research found that Vertical Axis Wind Turbines (VAWTs) boost each other’s performance when clustered together, with grouped pairs seeing a 15 per cent jump in output. This is in contrast to the more traditional Horizontal Axis Wind Turbines (HAWTs), which produce turbulence that affects the performance of other HAWTs downwind in a group.
"Modern wind farms are one of the most efficient ways to generate green energy, however, they have one major flaw: as the wind approaches the front row of turbines, turbulence will be generated downstream,” said lead author of the study, Joachim Toftegaard Hansen, and engineering graduate at Oxford Brookes.
"In other words, the front row will convert about half the kinetic energy of the wind into electricity, whereas for the back row, that number is down to 25-30 per cent. Each turbine costs more than £2 million/MW. As an engineer, it naturally occurred to me that there must be a more cost-effective way."
According to the researchers, VAWTs not only avoid the reduction in power due to turbulence, they actually enhance collective performance when grouped together correctly. Grids of VAWTs could also be more tightly packed, gaining even more efficiency over the farms of horizontal wind turbines we currently rely on.
"This study evidences that the future of wind farms should be vertical,” said research lead Professor Iakovos Tzanakis, from Oxford Brookes’ School of Engineering, Computing and Mathematics (ECM).
“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 wind power due to play an ever more important role in the global transition to green energy, harvesting that power as efficiently as possible becomes increasingly vital. The study, published in the journal Renewable Energy, is claimed to be the first to comprehensively analyse multiple aspects of wind turbine performance, including array angle, direction of rotation, turbine spacing, and number of rotors. It is also claimed to be the first research to investigate whether performance improvements hold true for three VAWT turbines set in a series.
"The importance of using computational methods in understanding flow physics can't be underestimated,” said co-author Dr M Mahak, a Senior Lecturer at ECM.
“These types of design and enhancement studies are a fraction of the cost compared to the huge experimental test facilities. This is particularly important at the initial design phase and is extremely useful for the industries trying to achieve maximum design efficiency and power output."
