Celebrating Global Wind Day: Growth and Development in the Wind Power Sector
Global Wind Day is an event held each year on 15 June, aimed at informing people of the potential of wind energy and its importance to decarbonising the global economy. To celebrate Global Wind Day, we explore how wind power technology has developed through history, and how these developments have led to an industry in which patent protection is critical.
Ever since the Ancient Egyptians began to sail along the Nile over 7,000 years ago, humans have looked to exploit the power of the wind. Turbine configurations, in which the power of the wind is converted into circular motion, began to appear circa 200 BC, with simple windmills being used to power water pumps in China, and to grind grain in Persia and the Middle East.
The first wind turbine configured to generate electricity was designed by Professor James Blyth in Scotland, and patented in 1891 as GB19401. Blyth’s turbine is an early example of a vertical axis wind turbine (VAWT), in which the axis of rotation is perpendicular to the direction of the wind. Blyth’s turbine includes several bucket-like structures arranged around a central vertical shaft. In operation, the bucket structures “catch” the wind, and the resulting drag force causes the turbine to rotate around the central shaft. Blyth connected the central shaft to a simple dynamo to generate the electricity.
Of course, wind turbine technology has developed a long way since Blyth’s turbine. The vast majority of modern wind turbines are horizontal-axis wind turbines (HAWTs), in which the turbines rotate around central shafts that are parallel to the wind direction. Whilst the buckets included in Blyth’s turbine were designed to receive a drag force from the wind, modern turbines instead utilise aerofoil-shaped blades to induce a lift force, in much the same way as an aircraft wing. Generating a lift force in this way results in a much higher efficiency compared to turbines that rely on a drag force.
Despite being less common, vertical-axis wind turbines (VAWTs) continue to be developed by engineers and academics. Unlike Blyth’s turbine, modern VAWTs typically comprise aerofoil-shaped blades to generate a lift force, in much the same way as in HAWTs. One common vertical axis wind turbine is the Darrieus rotor, which was patented in 1926 as US13884426. This consists of curved aerofoil blades attached to upper and lower portions of a central vertical shaft. VAWTs typically exhibit a lower efficiency than their HAWT counterparts, but do provide a number of advantages. For example, the vertical axis of rotation means that the generator and gearbox can be situated at ground level, facilitating easy service and repair. Further, computer modelling has suggested that wind farms consisting of VAWTs could actually be more efficient than wind farms consisting of HAWTs, because VAWTs generate less turbulence in their wake.
Over the past few decades, engineers have strived to make the harnessing of wind power cheaper, more efficient, and more reliable, which has resulted in a huge amount of innovation in the sector. For example, a massive amount of research has gone into the optimisation of blade shape, with the aerofoil shapes of modern turbines typically being designed for higher speeds and to generate more lift than older blades. This means that modern turbines are much less bulky than those of the past, to the extent that the blades of today can be 90% lighter than blades of the 1980s (if the blades of the 1980s were scaled to modern lengths). Further, modern turbines may utilise techniques such as aeroelastic tailoring, which involves the implementation of anisotropy in the blade structure so that flapwise bending results in blade twisting. This technique, known as bend-twist coupling, means that the blade’s angle of attack can be automatically reduced in response to high wind speeds or gusts, limiting the flapwise load exerted on the blade. Modern blades may also include add-ons such as vortex generators and flow fences for reducing the amount of noise generated by the blade or reducing the size of a turbine’s wake.
More experimental configurations have rejected the concept of blades altogether. For example, the “Vortex Bladeless” system consists of an elastic rod connected to a vertical cylinder and exploits a phenomena known as vortex induced vibration (VIV). As air flows around the cylinder (a bluff body), a boundary layer is established at the cylinder’s surface. At some point, this boundary layer separates from the surface of the cylinder and forms a detached vortex. This detached vortex reduces the pressure at the surface of the cylinder, causing a force to be exerted on the cylinder in the direction of the vortex. Vortices are periodically shed at either side of the cylinder, and when the frequency of this shedding is the same as the natural frequency of the system, the system starts to resonate. In the vortex bladeless system, a magnetic confinement system controls the natural frequency of the system by varying the system’s apparent stiffness, ensuring that it matches the frequency of the vortex shedding, which is dependent on the wind speed. An alternator, typically without gears, shafts, or rotating parts, is connected to the base of the cylinder to convert the resulting oscillatory motion into electricity. This technology is still in its infancy, but with its potential to reduce the cost associated with wind-powered electricity generation, it will be interesting to observe its development.
In years gone by, the majority of wind turbines were constructed onshore, but it is now recognised that offshore wind farms are likely to be much more significant in the large-scale generation of electricity, because the area that can be exploited is much larger, and the wind typically blows more reliably and at higher speeds. Constructing wind turbines offshore brings with it a multitude of challenges to be overcome, from fixing turbines in position, to managing fatigue and corrosion. In response to the complexity and expense of fixing turbines to the seabed, especially in areas of deep water, engineers are now pioneering turbines that are configured to be supported by floating platforms. This has the potential to drastically reduce costs, and to open up new areas for potential exploitation.
The level of innovation across the wind sector continues to be strong, as shown by data presented in a report from the International Energy Agency (IEA). In the period between 2000 and 2019, patenting activity in wind power-related technologies generated over 17,000 IPFs (international patent families), which was second only to patenting activity in solar-related technologies within the low-carbon energy sector. There was a fall in patenting activity in wind-related technologies from the period 2010-2014 to the period 2015-2019, but this trend was exhibited across the whole energy supply sector, so it is not necessarily indicative of a long-term slow-down in wind power innovation.
Value of Patent Protection
Across the globe, wind power is now thought to account for between 5% and 6% of total electricity production, but this figure is as high as 21% in countries like the UK. With continued investment throughout the sector, these figures are expected to grow in the coming years, and it is thought that by 2027, the global market will be worth in excess of USD 125 billion. The size of this market means that patent protection for wind power-related technologies is, and will continue to be, immensely valuable.
This has been demonstrated by numerous high-profile disputes in recent years. For example, in December 2020, General Electric Co (GE) filed a legal complaint against the UK arm of Siemens Gamesa Renewable Energy (SGRE) for the infringement of the GE patent, EP1590567, at the High Court of Justice of England and Wales (HP-2020-000051).
The GE patent is directed towards a wind turbine generator that is capable of remaining connected to a power grid in periods where the grid voltage is temporarily reduced (low voltage ride through, LVRT). Large-scale electricity generators must be capable of this to conform with power grid interconnection standards. The invention defined in the GE patent achieves this by providing power from a backup source to components necessary for the generator to remain connected with the grid, such as a turbine controller and blade pitch control system, when a low voltage event is detected.
The legal action in the UK follows an extensive legal battle between GE and SGRE on the US equivalent (US6921985), in which some (but not all) of SGRE’s turbines were found to infringe. In this most recent UK action, GE are seeking an injunction to prevent the start of construction on at least two major UK projects (East Anglia Three and Hornsea Two), for which the total capital expenditure is estimated to be in the region of USD 7.9 billion.
This type of litigation is not new. In 2015, Enercon GmbH attempted to block the start of construction on the Westermost Rough and Gunfleet Sands projects, citing infringement of the Enercon patent, EP0847496 by turbines manufactured by SGRE. In this case, the High Court ruled in SGRE’s favour and found the Enercon patent to be invalid. However, the lengthy delays proved to be costly for project developers.
As the wind power sector continues to grow, the importance of patent protection is likely to become even more significant. To operate successfully, organisations should ensure that they have a thorough understanding of the patent environment in which they operate, and consider obtaining patent protection for any new technologies that could be commercially exploited by competitors.