For a 150-metre-high wind turbine standing in churning ocean waves, the forces acting on it are enormous. To stay upright, the structure is anchored to concrete and steel foundations drilled hundreds of metres into the sea bed. The process of securing it can take weeks, and costs up to $100,000 a day.
Now there’s a plan to anchor turbines in place using what is effectively a giant suction cup. Anybody who has tried, and failed, to attach their smartphone to a car windscreen using a suction mount might be forgiven their doubts.
The man behind the plan is Lorry Wagner. He built his career in nuclear energy but sees a big future in renewables. His Icebreaker project to site six wind turbines in the waters of Lake Erie in Ohio, has won $40 million in support from the US Department of Energy.
The innovation is being driven by a surging demand for renewable energy. Meeting that demand while keeping the cost of generation low enough to make the energy economically viable has always been the challenge. Suction-mounted turbines will cut costs dramatically. So how do they work?
Creating an underwater vacuum
The suction mount, or Mono Bucket, is a 400-ton metal drum about 20 metres in diameter. It is lowered into the water by a ship or barge.
After the bucket hits the bottom, the water is pumped out of the interior and a vacuum is created, drawing the bucket up to eight metres into the sediment. The forces at work are the same ones that pull off your wellington boots when you walk through deep mud.
“It isn’t the stickiness of the mud that pulls the boot off, it’s the suction that is created underneath that is the main force,” Wagner says. “Same thing with the Mono Bucket.”
It is the combination of the drum’s weight and the vacuum it creates that makes it secure enough to support a huge wind turbine. If the Lake Erie pilot project is a success, the cost of renewable energy may fall as cheaper turbines pump out more power.