Offshore wind turbines are about to become higher than the Eiffel Tower, allowing the industry to supply subsidy-free clean power to the grid on a massive scale for the first time.

Manufacturers led by Siemens AG are working to almost double the capacity of the current range of turbines, which already have wing spans that surpass those of the largest jumbo jets. The expectation those machines will be on the market by 2025 was at the heart of contracts won by German and Danish developers last week to supply electricity from offshore wind farms at market prices by 2025.

Just three years ago, offshore wind was a fringe technology more expensive than nuclear reactors and sometimes twice the cost of turbines planted on land. The fact that developers such as Energie Baden-Wuerttemberg AG and Dong Energy A/S are offering to plant giant turbines in stormy seas without government support show the economics of the energy business are shifting quicker than anyone thought possible -- and adding competitive pressure on the dominant power generation fuels coal and natural gas.

“Dong and EnBW are banking on turbines that are three to four times bigger than those today,” said Keegan Kruger, analyst at Bloomberg New Energy Finance. “They will be crucial to bringing down the cost of energy.”

About 50 miles (80 kilometers) off the coastline in the German North Sea, where the local fish and seagulls don’t complain about the view of turbines in their back yards, offshore wind technology is limited only to how big the turbines can grow. Dong has said it expects machines able to produce 13 to 15 megawatts each for its projects when they’re due to be completed in the middle of the next decade -- much bigger than the 8-megawatt machines on the market now.

Just one giant 15-megawatt turbine would produce power more cheaply than five 3-megawatt machines, or even two with an 8-megawatt capacity. That’s because bigger turbines can produce the same power from a fewer number of foundations and less complex grid connections. The wind farm’s layout can be made more efficient, and fewer machines means less maintenance.

“Right now, we are developing a bigger turbine,” said Bent Christensen, head of cost of energy at Siemens Wind Power A/S, in a phone interview. “But how big it will be we don’t know yet.”

David Fuller's view

I did not predict this 3 to 4 years ago but I am delighted that wind power is now becoming much more competitive and self-sufficient.  I still have concerns about maintenance costs relative to solar power but we will see.  One should not underestimate technological innovation in this era.