Ahmad 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).A wake-up call from scientists has given rise to agreements between responsible governments to make the effort to prevent a possible catastrophe by setting up plans and standards for emission control and decarbonisation in the form of net-zero target mandates and sustainable energy programmes. Considering the rather short window of time, a crucial question is ‘Is it possible?’
Going back 50 to 55 years, when more attention was focused on wind energy, both vertical axis and horizontal axis turbines were made and their practical potential for large-scale commercial energy production evaluated. The winner came out to be the horizontal axis propeller type wind turbine. At the time, parallel with extensive research on the propeller turbine, many Darrieus turbines were built at both research and commercial scale. The largest was 96 metres in height and 64 metres in diameter and it was in operation for 5 years before it stopped working due to damage in the gearbox, which was too expensive to repair. A great number of smaller units were also commercially built and operated (especially in California) in the 1980s.Direct-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.Some 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.
For 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.
Any 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.