“Citius, altius, fortius,” is the Olympic motto. It translates into “faster, higher, stronger,” – the mission pursued by the wind energy sector for years. Hub heights of 150 metres or more have long ceased to be a rare sight – especially at sea. Adding the wingspan results in a total height clearly in excess of 200 metres. These wind giants thus easily eclipse the Cologne Cathedral, which extends a “mere” 157 meters into the sky.
In terms of onshore wind farms, a project located in Sweden will soon set new standards. Situated in the vicinity of Karlstad on the northern shores of Vänern, Europe’s largest inland lake, the Knöstad wind farm is set to get its turbines spinning in the second half of next year. Danish project developer Eurowind has just placed an order for eight rotors with turbine manufacturer Siemens Gamesa – and they definitely pack a punch: With a rotor diameter of 170 metres, the model on order sets a new size record for wind turbines on terra firma. Just one of these high-output rotors can generate enough electricity for approximately 5,000 households per year.
The German/Spanish equipment manufacturer presented the new SG 5.X model series last year. The series consists of two turbine variants with different outputs: the SG 5.8-155 and the SG 5.8-170. As customary in the sector, the last number indicates the rotor diameter. The SG 5.8-170 extends the rotor sweep of its predecessor, the SG 4.5-145, by more than a third. This results in a commensurate increase in annual energy yield.
Sweden seems to provide good turf for the new series, as the very first order for the SG 5.8-155 also originated from that country. Placed at the end of 2019, it will be filled to set up 35 wind turbines as part of the Skaftåsen project in Middle Sweden in 2021. One of the world’s largest per-capita power consumers, the country has its sights on doubling its wind capacity from 7.4 to 14.9 gigawatts by 2023. Moreover, the government in Stockholm has set the goal of 100 percent electricity generation from renewables by 2040.
As in many other areas in Sweden, the windy forest region on Lake Väner has strict standards for projects involving onshore giants such as the SG 5.8-170. To comply with local height regulations, the hub heights of the Knöstad wind farm will max out at a “mere” 115 metres – clearly falling short of those of many of the onshore super-turbines. This means that the rotor tips will pass just above the tree tops of their forest location. However, the engineers in charge are convinced that the project can be implemented without a hitch.
Going back to the Olympic motto quoted in opening, it goes without saying that development isn’t standing still. Prototypes of future offshore wind farms with rotor diameters measuring 190 to as many as 220 metres have already been showcased.
Photo credit: © Siemens Gamesa