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Ahmad HemamiAhmad Hemami received his BS degree in Mechanical Engineering from the University of Tehran and his PhD in System Dynamics and Control from the Department of Aeronautical and Mechanical Engineering at the University of Salford, UK. Dr Hemami has several years of industrial, academic and research experience. Among his areas of expertise are robotics, control and automation, and wind energy. He has supervised several MS and PhD students, and has served as a consultant for industry. He has over 100 journal and conference publications. He is an adjunct professor at McGill University (Montreal, Canada).

Gear or No Gear, Not a Battle

Ahmad HemamiDirect-drive wind turbines using a permanent magnet synchronous generator have been developed after observing the problems with the gearbox. Nonetheless, nothing is 100% perfect. Obviously, during recent decades there have been efforts to advance the technology, in all directions. That includes improving the performance of the gearbox. One advantage in removing the gearbox from the loop is a reduction in the tower top weight, but this is not always possible. In a recent article by van de Kaa et al. (2020), the subject of the comparison of direct-drive turbines and geared turbines has been systematically studied to determine which technology will become the dominant one in the future. This implies that in the future the other technology needs to switch. The final conclusion of this study is that cost of energy and reliability are the two most important factors, and both technologies still have equal chance of success.
 
By Ahmad Hemami, McGill University, Montreal, Canada

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Battery Storage System for Deep-Water Wind Farms

Ahmad HemamiSome time ago, when thinking about the deep sea and transportation of electricity to the shore, it came to my mind that we could possibly use a (huge) battery system which could be charged in a wind farm and then deliver its charge to the onshore grid. Compared with transmission cables, the way that it is right now for all existing wind farms, this is not an ideal solution. Therefore, I set the idea to one side. But with the recent agreement between Canada and Germany, the idea was revived in my mind. If the wind farm is floating on the top of 500 metres or more of water and is far offshore, then the concept is worth being regarded as an alternative. After all, technically and financially, the numbers must be correct and suitable.
 
By Ahmad Hemami, McGill University, Montreal, Canada

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How Much Is the Cost of Wind Energy?

WT scale up limitFor a comprehensive course in wind energy that I teach, I spend a lot of time updating the numbers for the cost of various turbine components and their percentage of the total cost, as well as the cost of wind farms, for which turbine prices are only one part. As many may know, this is not a straightforward process, since the expenses are case sensitive, and there are no clear-cut figures for this.
 
By Ahmad Hemami, McGill University, Montreal, Canada

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Are Turbine Blades With Variable Twist Angle Practical?

Blade Adj twistAny new concept in an established manufacturing process or engineering operation will be costly to implement. In most cases it requires research and development, the cost of which must be absorbed by the company behind it. If the concept sounds ‘revolutionary’, at first it might seem either difficult or impossible to achieve. On the other hand, in many industrial applications – out of necessity – research and development is a continuous endeavour to make a product more efficient, have improved performance, cheaper and so on.
 
By Ahmad Hemami, McGill University, Montreal, Canada

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Time to Start Manufacturing Commercial Vertical Axis Wind Turbines

VAWT art 1A 2018 publication by Sandia National Laboratories (SNL) [1] indicates that an overall more economical choice of wind turbine for an offshore floating turbine is a vertical axis wind turbine (VAWT). SNL has performed a comprehensive and extensive simulation study using a variety of software for different aspects, from stresses in blades to the levelised cost of energy (LCOE). There are several aspects involved in the design and operation of a wind turbine and even more if it is on a free platform subject to wave forces. In this study, the point of emphasis is the lower LCOE, as a result of smaller platforms for a VAWT, mainly due to the lower centre of gravity compared with a horizontal axis wind turbine (HAWT). This study and others on VAWTs point to the direction of the technology for floating turbines. After all, if the cost of energy is the principal driver for selecting a technology, then a lower LCOE is the preferred choice.
 
By Ahmad Hemami, McGill University, Montreal, Canada

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How Many Wind Turbines Do We Need?

Table 1. Selected data for diverse regionsIt came to my mind to do some calculations of how many wind turbines we need to power the whole world with renewable energy. Of course, in the future when we run out of fossil fuels, or we are forced not to use fossil fuels any more to survive on Planet Earth, wind will not be the only alternative source of energy. Considering that hydro, wind, solar, wave, geothermal and other renewables may provide say 70–80% of the world’s energy needs in the future, it is reasonable to predict that wind energy will account for over 20%.
 
By Ahmad Hemami, McGill University, Montreal, Canada

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