Wind Towers Finding Concrete Ways to Grow Taller
June 1, 2016
Nuclear struggling. Wind is the cheapest source of electricity in the US, and getting cheaper. Subsidies or no.
Wind power engineering is governed by a simple fact: The higher you go, the stronger and steadier the wind gets and the more power you can generate. So the evolution of wind power over the years has largely been a process of building bigger and bigger blades and perching them atop higher and higher towers.
The turbine being assembled in this video, by MidAmerican Energy, will be the tallest land-based wind turbine ever built in the US, with a hub height (ground to center of blades) of 115.5 meters (379 feet) and a capacity of 2,415 kW. It’s not quite up to the level of the best turbines in Europe, but it’s mainly meant as experiment.
In 2014, the average cost of Power Purchase Agreements for new wind power in the US was around 2.35 cents per kwh, the lowest it has ever been. In the windiest parts of the great plains, prices are as low as 2 cents per kwh.
The above graph from the NREL 2014 Wind Technologies Market Report uses subsidized numbers. Even after removing the effects of the major federal subsidy, the Wind Production Tax Credit, new wind power in the US costs an average of 4 cents per kwh or less.
NREL’s projection of the capacity factors of future wind turbines is, of course, just a projection. NREL has an excellent track record, yet we won’t truly know the achievable capacity factors for 140 meter wind turbines until we have a number built in the US.
Actually building them is quite a challenge, however. Wind turbine components are built in factories and then transported to the site. But as wind turbines have grown larger, transportation has hit the limits of what can be moved by road.
Consider the following images from DOE’s Wind Visions report, showing the challenges of moving a segment of a wind turbine tower (first image) and of moving a single blade of a wind turbine (second image).
These images depict the challenges of transporting current wind turbine components. To move pieces of 140-meter turbines (more than 500 feet tall), new steps are needed.
The new frontier is to assemble more of the wind turbine at the site, using parts that fit in ordinary semi-trailer or flat-bed truck cargos. That’s the approach used by GE’s Space Frame wind towers, which use a scaffolding-like approach to wind turbine construction. And it’s also the approach used by a number of companies working on wind turbine blades that can be shipped in pieces and assembled into full-length blades on site.
None of this is impossible. Germany’s wind industry already averages 120 meters for new wind turbines, with some as tall as 140 meters. But deploying these in the US will require innovation.