Record-breaking windturbines – Part II

Here is the second part of last year’s article on record-breaking wind turbines, which reviewed record-setting models such as GE1.5, E-126 or Haliade-X. In this new issue we will review wind turbines that, for one reason or another, deserve to be included in the wind hall of fame.

 

The largest hydraulic power train: SEA ANGEL 7 MW – MITSUBISHI

 

This is the offshore model that Mitsubishi developed before forming the now defunct JV with Vestas. In fact, it was developed for a few years in parallel with the V164. It is a 7MW turbine with a 167m diameter. Two prototypes were installed: one in 2014 at the Hunterston (Scotland) test site and the second at the Fukushima forward floating offshore site in 2015. The Scotland prototype was demolished in 2019 as can be seen in this impressive video.

 

As if all the demolition of one prototype and having the other in a floating offshore installation wasn’t enough to earn it a place in this article, this model included a first-rate technological oddity: a hydraulic powertrain developed by Artemis. The theoretical advantages of this so-called DDT (Digital Displacement Transmission) system were lighter weight and greater reliability, but the truth is that commercially it has not made any progress.

 

Mitsubishi abandoned this development and focused all its efforts on the Vestas V164, so we will never know the real possibilities of this concept, but there is no doubt that it was a first class technological development.

 

The largest multi-rotor turbine: VESTAS MULTIROTOR

 

 

Vestas surprised in 2016 with the installation of a very special prototype: a multi-rotor turbine. Specifically, the project integrated 4 older V29-225kW in a tree-like structure with new converters and control system. The objective was to investigate whether this type of distributed configuration provided advantages from the point of view of energy production and load reduction.

 

 

The prototype was installed at the validation centre in Riso (DK) and was dismantled in December 2018. There are several technical publications on the results of the validation period where it is concluded that there is an increase in production of around 1.5% thanks to the lower turbulence of the array. In the excellent blog windfarmbop there are a couple of articles that go into more detail on this demonstrator.

Regardless of the scientific results of the project, the turbine is one of the most curious the industry has ever seen.

 

The largest two-bladed turbine: MINGYANG SCD 6.0

 

 

This turbine holds the record for being the largest two-bladed turbine ever installed, but it also has a working offshore prototype. It is a technology called SCD (Super-Compact Drive) developed by the company Aerodyn in 2007 and has a multitude of striking features:

– Two-bladed

– Downwind

– Integrated powertrain with a self-supporting electrically excited synchronous generator (no permanent magnets) integrated with a 2-stage gearbox.

 

 

If anyone wonders why two-bladed and downwind, here are the advantages presented by Aerodyn:

 

 

This Aerodyn design was licensed in 2014 to a Chinese company called Mingyang, who installed the prototypes. Specifically, the offshore prototype is a 6 MW, 140m rotor model that is installed in Rudong, China. As can be seen in the photo, the foundation structure is quite unusual as it looks like a 6-legged evolution of the classic tripod.

 

Aerodyn evolved the offshore SCD concept towards floating developments, but it seems that Mingyang has followed another path as it recently announced its first floating project with a standard 5.5MW three-bladed turbine. We will see if the SCD concept for offshore succeeds with any manufacturer, but I suspect it will be difficult to see such special turbines competing on cost with traditional turbines.

 

The biggest airborne turbine: MAKANI M600

Perhaps the most technologically impressive turbine ever is this 600kW Makani offshore prototype.

 

 

As explained on their highly recommended website, the system consists of an aircraft attached to the base by a cable whose propellers serve to “take off” from the base and once it is at 300m altitude, it begins a kite-like flight where the propellers become electrical generators that transmit the power generated to the base via the attachment cable.

 

 

The company was created in 2006 and generated a lot of expectations and media noise when in 2013 it was bought by Google with the aim of turning its designs into commercial products. Suddenly the crazy idea of generating electricity with airborne turbines seemed more real with a giant like Google behind it. Moreover, the 600kW prototypes that were tested made it look like things were moving forward but in 2020, Google decided to drop the project and although it was rumoured that Shell was going to be the new backer of the idea with the offshore approach, it seems that in the end the project has been definitively cancelled, although all the intellectual property and the work done is freely available, which is rare to see but will help future developments.

 

The excessive complexity of the concept seems to have been the cause of the failure. The truth is that combining the complexities of designing an aircraft, multifunction generators, cable loads, aerodynamics of the whole thing, autonomous control, etc. sounds like a good engineer’s dream but a product manager’s nightmare. In fact, the offshore prototype seen in the video above crashed when the control failed and was unable to return to its base during one of its flights.

 

Makani’s failure was a bit of a blow to expectations for this type of turbine, but it has not discouraged other companies such as SkySails Power who continue to develop simpler airborne windturbine concepts that we may one day see in large-scale commercial projects.

 

Largest turbine in development: MySE 16-0-242

 

 

As we explained in detail in the post dedicated to the new offshore turbines, the fight for the most powerful offshore turbines is hotting up. When Vestas announced last February a 15MW turbine with a 236m rotor, the prototype of which is planned for 2022, nobody thought that the record for the most powerful turbine would be so short-lived because last August, Mingyang surprised everyone by announcing an even bigger giant: 16MW and a 242m rotor.

 

Its dimensions are hard to believe: 118m blade (equivalent to putting 7 trailers in line), a swept area of 46,000 m2 (equivalent to 6 football fields) and an average annual production of 80GWh (enough to supply 20,000 average homes).

 

But if its dimensions are hard to imagine, its development plan is also impressive: prototype production in 2022, type certification in 2023 and series production in 2024. It is clear that MingYang’s bet is serious and could be a threat to the hegemony of the Big 3.

 

This is the end of the second part of the series on iconic turbines and although it’s hard to believe, there are still some of them left waiting on the bench to come out, but that will be in the third chapter if it comes. In the meantime we will enjoy these marvels of wind technology.