How Big Can Wind Turbines Get?

this episode of real engineering is brought to you by skillshare home to thousands of classes that could teach you a new life skill over the past decade wind energy has seen astronomical growth rising from a worldwide total of 24.3 megawatts in 2001 to 650 000 megawatts in 2019 concerns in the 90s that wind energy could not be integrated into the grid reliably have all but vanished as we learned how to adapt our grids to handle the fluctuations in the wind with the right climate infrastructure and policy wind can form a substantial percentage of a country's energy generation we need to look no further than denmark to see the proof of this in 2019 denmark sourced 47 of its electricity generation from wind power that wasn't a single day that was the year-round average on one particularly windy day denmark actually produced 140 percent of its electricity needs with wind energy and thanks to robust interconnections with its neighboring countries denmark was able to sell the vast majority of that generation to norway germany and sweden denmark is ideally located to benefit from wind power but its closest rival in europe ireland is isolated in the middle of the atlantic with relatively primitive interconnection to the uk and only one pumped hydro station in the entire country yet ireland managed to generate 32.5 percent of its power from wind in 2019 grid operators are learning how to reliably integrate wind energy into the energy market place where energy is bought and sold almost like the stock market in countries like denmark it has evolved rapidly to adapt to wind energy becoming faster and more responsive using weather predictions to schedule and dispatch other power sources as needed i would be amazed to not mention the importance of natural gas in this equation a fast and responsive form of fossil fuel power that can quickly ramp up to supply power when winds die down natural gas is an unsung hero in this story and won't be going anywhere until we develop cheap and scalable energy storage solutions but it's undeniable the inertia is with wind power now and with offshore wind becoming cheaper and more attractive it will only grow stronger countries around the world are investing billions into wind energy technology and one fascinating trend has emerged over the past two decades wind turbines keep getting bigger the average wind turbine height and diameter has continually risen during that time in the early 1990s the average wind turbine was about 27 meters in diameter but year on year the average wind turbine has grown in diameter continually pushing the limit of what was possible continually increasing the power the turbine was capable of generating continually driving down the cost of electricity as the literal economies of scale kicked in you see the power a wind turbine can generate is dependent on its ability to convert kinetic energy from the wind into electricity so we can derive a very simple formula to calculate how much power a wind turbine can generate if it was 100 deficient by starting with the equation for kinetic energy we don't want energy we want power which is energy per unit time so we need to swap out this mass variable for a variable that defines how much mass passes through the circular area swept by a wind turbine per unit time for that we need the area of the circle the velocity of the air passing through that area and the density of the air if we swap these in we now have an equation that defines the power a 100 percent efficient wind turbine could extract from the wind with this equation we get a simple answer for why wind turbines keep getting bigger the area figure is determined by the radius squared by doubling the wind turbine blade radius which has been happening roughly every 10 years we are quadrupling the maximum power the wind turbine can generate and with that the cost of electricity for these turbines also plummets but how big can they get in 2019 a prototype version of the most powerful wind turbine was installed in rotterdam this massive 220 meter diameter wind turbine stands 260 meters tall measured up against the eiffel tower a city-dominating landmark it would stand at about 80 percent of its height but this isn't a static structure it's an incredibly powerful dynamic machine a single rotation of its blades is so powerful that it could keep the average uk home supplied with electricity for two days manufacturing these blades is no easy task requiring incredibly expensive specialized tooling lm wind power which was acquired by ge in 2019 manufactured the blades themselves and have had decades of experience in pushing the boundaries in what is possible it starts by manufacturing two massive molds that will form the shape of the blades this itself is a huge engineering challenge and requires a huge amount of capital investment molds require precise machining even small molds can be extremely expensive but these blades dwarf even the span of an a380 the mold needs to be capable of drawing a vacuum to squeeze all the layers of glass fiber together and push out air as the plastic resin is injected and needs to be able to apply heat to cure the resin too these are unique expensive pieces of tooling that drive up the capital costs of wind turbine blades general electric made a great decision in acquiring lm wind power the company has manufactured 228 000 wind turbine blades since 1978. in that time they've broken numerous records including the record for the delivery of the longest piece of cargo in history when they commissioned the biggest plane on earth the antonov an-255 to carry two 42 meter wind turbine blades from their manufacturing facility in china to their testing facility in denmark and that is often the limiting factor in how large wind turbines can be there is currently no technology that allows turbine blades to be separated into smaller modular sections that can be assembled on site the blade has to be transported as one solid piece and lifted into place by specialized cranes in the case of the halide x the 107 meter long blades had to be lifted 150 meters into the air by two monstrously large cranes there is a reason offshore wind farms have the largest wind turbines it's much easier to build a wind turbine factory directly next to a harbour as lm wind has done in normandy for the haliad x blades and load them directly onto massive ships capable of hauling them directly to the wind farm location trying to transport blades this size on winding roads and railways full of obstacles would be incredibly challenging and expensive if not just impossible in most cases transport and assembly costs which require specialized boats tooling and cranes to be purchased also decreases the cost advantage of building bigger this is all before getting to the design challenges as the blades get longer the forces on the structure grow too the longer the blade the faster the tip of the blade will be traveling being zero at the rotational center and increasing with the distance from the center of rotation longer blades will have higher tip velocities than shorter blades even if they have the same rotational speed this is a problem the faster the tip speed the louder the noise and this is actually the primary factor that limits the maximum allowable tip velocities to get around this larger turbines are designed to rotate slower but with a higher torque that higher torque requires a larger and heavier drive shaft capable of transmitting the torque to a larger and heavier gearbox capable of converting high torque low speed rotation into the lower torque higher speed rotation needed for the generator the increased complexity needed to deal with this higher torque results in a heavier and more expensive drivetrain which again reduces the cost advantage of the greater power generation but design problems don't stop there the next issue are the lateral forces the wind in parts on the wind turbine the tower and its foundations need to be strong enough to resist the force of the wind that is attempting to tip it over this force increases with the increased area of the blades and the blades also need to be stiff enough to resist the bending forces they experience the longer the blade the stiffer it needs to be to avoid the blade bending so far that it strikes the tower this is a major worry when stormy conditions are unavoidable some designers have proposed collapsible blades that rotate the nacelle so the blades have their backs to the wind and collapse like the branches of a palm tree in a hurricane this seems like over-engineering to me though and just introduces too much complexity and potential sites for failure we may be reaching the limit of what we can achieve with glass fiber reinforced plastics for blades as large as the halide x the heavier blade increases the centrifugal force attempting to yeast the entire structure apart the slower rotational speeds help mitigate this but it is imperative to minimize the weight of the blades to reduce the forces attempting to rip the blades off the hub if wind turbine blades keep growing manufacturers may have to consider making the switch to carbon fiber reinforced plastics but this for now is prohibitively expensive our goal after all is to reduce the cost of electricity these complex and interlinked design constraints have resulted in a slow but steady increase in wind turbine diameters as better and cheaper drive trains become available as aerodynamic optimizations reduce blade noise as materials and manufacturing techniques improve to reduce waste allowing for larger and larger wind turbines to be cost effectively designed manufactured transported and assembled ultimately reducing the levelized cost of electricity of wind power to the point that coal power stations are thankfully becoming an archaic relic of the past and during the writing of this episode this record-breaking hallyat x wind turbine was announced for use in the massive offshore wind farm off the coast of cape cod as offshore wind becomes cheaper and cheaper our ability to generate clean energy is going to skyrocket we are slowly learning how to make the most of the resources we have at our disposal here on earth and to do it sustainably which has been something i have been learning while growing the business surrounding this youtube channel we are managing to run three channels with just four full-time staff and to do that we all have to constantly learn and improve this year we made radical changes to our task management system and communication methods and we were helped along with the advice of my friend thomas frank who has a fantastic productivity class on skillshare called productivity masterclass create a custom system that works which will help you create a task management system that you will actually keep up we have also put a huge amount of effort into improving our 3d animations in blender and cinema 4d and you witness some of the fruits of these learnings in this video skillshare also has fantastic courses on multiple animation platforms 2d animation is actually an easy skill to learn i thought myself how to animate over a single long weekend for the first video on this channel you just need to take the time to learn lifelong learning is a mandatory for anyone trying to succeed in this world and no matter what you are trying to learn skillshare likely has a class to teach you with new years coming up there is no better time to set yourself a new skill to learn skillshare is an online learning community with thousands of inspiring classes for creative and curious people it's curated specifically for learning meaning there are no distracting ads and it's less than ten dollars a month with an annual subscription but the first 1000 people to sign up with the link in the description we'll get a free trial of skillshare premium so there is no monetary risk in trying it out and looking for a class that piques your interest before the trial ends if you are looking for something else to watch right now why not watch my previous video about our efforts to create renewable cargo ships or real sciences latest video detailing the strange blue blood of horseshoe crabs which has an incredibly important role in modern day medicine you

Channel: Real Engineering

Views: 870,456

Keywords: engineering, science, technology, education, history, real

Id: wr7QZ364jPY

Length: 13min 49sec (829 seconds)

Published: Sat Dec 12 2020

Reddit Comments

[u/Ericus1]

Neat.