An innovative turbine that could halve the cost of offshore wind - and double the amount of harvested energy - is set to begin testing in Norway. The 19m (62ft) contra-rotating vertical-axis turbine is a prototype of a design that could scale to unprecedented size and power.
As we know, most wind turbines look like a propeller on a tall vertical shaft. That's fine close to the coast where they can be built into shallow ground.
However, once you take the concept out into the deep ocean, where the vast majority of the world's best wind power resources are, and scale it up, it's a design that makes less and less sense. All the heavy bits are right up the top, so it's difficult and expensive to build and maintain a floating version that doesn't want to tip over in the wind.
That's what makes World Wide Wind's contra-rotating design such a fascinating alternative. They have flipped the weight issue around. All the heavy generator components are located at the base, under water - below the turbine's floating pontoon, and requiring only a set of mooring anchors. That creates enough weight at the bottom to keep the whole thing from toppling over into the sea. Clever stuff.
Meanwhile, the lower turbine is set to rotate in one direction, and the upper one, mounted on a pole that runs up the middle of the lower one, is set to rotate in the other direction. More clever stuff.
Thus, whichever way the wind's blowing, the floating structure passively tilts to an optimal angle, and the two turbines begin turning in opposite directions, effectively doubling the speed at which system harvests the wind's clean energy.
"You can think of that as a way to double your power generation, or as a way to reduce your generator cost by half," says the company. "So it's lower cost, it's much more scalable, and any maintenance happens at the bottom and not hundreds of feet up in the air."
Wind will generate approximately 8 percent of global clean energy this year and is expanding fast due to enormous investments around the world. If this new prototype proves successful, the good news is that new installations could prove twice as productive in the future.