US: Cutting Concrete Use at Wind Farms by 75 Percent

An Oregon startup is developing a new foundation system for wind turbine towers that cuts the amount of concrete used by 75 percent – reducing CO2 emissions, shortening wind farm construction times and lowering the overall cost of wind energy.

RUTE Foundation Systems and a research team at Portland State University are receiving early-stage investment support from Oregon BEST to commercialize the new technology, which could speed wind farm development and keep millions of pounds of carbon dioxide out of the atmosphere.

Current wind turbine tower installation involves pouring a very large concrete footing at the base of each 300-ft. tower. The footings are nine feet thick, 60 feet in diameter and require 30 to 40 truckloads of concrete – approximately 300 cubic yards. Each footing weighs about two million pounds and is not removed from the soil when a turbine tower is decommissioned.

"We've developed a manufactured assembly of anchored grade beams that saves a lot of concrete, transportation costs, construction time and carbon dioxide," said Doug Krause, founder of RUTE Foundation Systems. "Using this footing saves wind farm developers time and money, is more environmentally friendly and reduces the cost of bringing renewable energy to the world."

Construction of a single wind farm with up to 50 turbine towers takes many months to complete in ideal conditions. Weather and curing of the concrete used in the footings can impact wind turbine delivery schedules, dragging out overall construction time and increasing costs.

"Our foundation system is delivered fully hardened, so there is very little risk as to if it will be installed, cured and ready when the turbine is delivered to the site," said Krause, who uses the analogy of a massive Douglas fir tree held in place by a root system that weighs much less than the total weight of the tree.

Because the components in the RUTE system are made in a beam manufacturing plant, the finished product is three times stronger than cast-in-place concrete. And using less concrete requires less cement, a material that is extremely energy-intensive to make and generates CO2 during production. The RUTE system can save as much as six million pounds of CO2 emissions for a single wind farm, Krause said.

The company is working with Franz Rad, a Portland State University professor of civil and environmental engineering, to design instrumentation and procedures to monitor beam flexure in a range of soil and weather conditions. The work at PSU involves structural analysis, stress analysis and design of the beams and the supporting hub. It will provide critical validation of the material properties and structural design before initial field studies begin.

“It is interesting and challenging for me and my grad students to look at replacing massive concrete footings with a new foundation system that has post-tensioned beams connected to a hub,” said Rad. “Computer models show us the strength and stiffness of the foundation, and in the process grad students learn about practical design, structural innovations and developing specifications for a field monitoring program."

RUTE Foundations is also working with a technical team that includes Nishkian Dean Structural Engineers in Portland Ore., and Marvel Bridge Engineers in Denver, Colo.

Oregon BEST is supporting the project with $66,000 in early-stage investment funding. Ken Vaughn, Director of Commercialization Programs at Oregon BEST, said the project is an example of how a relatively mature clean technology can be improved through innovation, resulting in multiple benefits.

"This really shows how innovating an existing technology can further reduce the cost of renewable energy, while also cutting greenhouse gas emissions," Vaughn said.