A team of multinational researchers has descended to Aalto Ice Tank in Finland to study the interaction between large turbines and frosty conditions in detail. The findings from their experiments could one day enable us to put offshore wind farms in the coldest of regions on the planet.
Even as countries have moved forward with plans of adopting renewable sources of energy, the installation of wind farms is limited to warmer areas. This is primarily because we simply do not know how the large turbines perform in frosty conditions.
"We don’t actually know what kinds of force and pressure ice creates on off-shore wind turbines," said Arttu Polojärvi, assistant professor of ice mechanics at Aalto University. "This is the first time anyone has carried out fully controlled model-scale laboratory experiments to find out."
Polojarvi has teamed up with researchers from the Delft University of Technology, and Siemens Gamesa Renewable Energy to test these unknowns in the world’s largest indoor ice basin.
When turbine meets ice
Measuring 131 feet by 131 feet (40m by 40m), the Aalto Ice Tank is one of the few places on Earth where researchers can create large sheets of ice and precisely test how it interacts with man-made materials.
Even the massive size of the ice basin does not allow for life-size testing of a wind turbine. So, the researchers made a 30:1 scaled model and used numerical modeling to simulate wind and other conditions that the turbine faces in the sea.
According to the research team’s estimates, the turbine model they are testing could be experiencing loads of eight meganewtons - about one-tenth the force Starship’s Heavy Booster will exert as it tries to leave the planet or the thrust of 16 aircraft engines put together.
The experiments are also being carried out at temperatures of 12° Fahrenheit (up to 11° below zero) to realistically test its interaction with ice as it breaks. "The preliminary results show something that we haven’t seen before in other structures, like lighthouses, channel markers, or oil and gas platforms. A wind turbine is very tall and slender and can move a lot; what we’ve seen in our experiments seems to be a totally new type of ice-induced vibration," said Hayo Hendrikse, assistant professor in ice-structure interaction at TU Delft.
Based on the data collected, the researchers are now trying to test various scenarios that wind turbines placed in chilly waters of the Baltic Sea in Europe or Grear Lakes in the U.S. might face over its 50 year lifetime.