Article

Materials data aid wind energy research

One way to advance wind energy is to try and destroy materials that potentially would make up a blade in a turbine. In a lab at Montana State University, three machines with two steel fists, roughly the size and shape of coffee cans, attempt to break materials. Held between these fists was a wafer of fiberglass and resin. Some of the machines pulled on a wafer, others pushed. “These machines keep grinding away around the clock,” said Montana State University’s John Mandell.

Pointing to one of the experiments, Mandell said, “this one has done more than 7 million cycles. But 10 million to 100 million is where the data are really valuable.”

Fiberglass, carbon fiber, resin: Combinations of these materials are the stuff of wind turbine blades. Modern blades reach lengths of up to 200 feet and weights of up to 50,000 pounds. They may spin half a billion times or more in their hoped-for 20-plus-year life spans.

Mandell and his team test the materials to ensure the blades live a long maintenance free life.

A professor of materials science in Montana State’s department of chemical and biological engineering, Mandell’s work is essentially about cheating time or compressing it. He plugs his lab data into various models and tries to predict how a particular composite material will hold up over years or decades from the tug of gravity and the stress of wind.

“A lot of effort has gone into these tests so that the data mean something,” Mandell said. “We’ve had to invent methods ourselves. It has been a great deal of work.” Current materials last much longer in the tests and are much stronger than the more... more [truncated due to possible copyright]  

Pointing to one of the experiments, Mandell said, “this one has done more than 7 million cycles. But 10 million to 100 million is where the data are really valuable.”

Fiberglass, carbon fiber, resin: Combinations of these materials are the stuff of wind turbine blades. Modern blades reach lengths of up to 200 feet and weights of up to 50,000 pounds. They may spin half a billion times or more in their hoped-for 20-plus-year life spans.

Mandell and his team test the materials to ensure the blades live a long maintenance free life.

A professor of materials science in Montana State’s department of chemical and biological engineering, Mandell’s work is essentially about cheating time or compressing it. He plugs his lab data into various models and tries to predict how a particular composite material will hold up over years or decades from the tug of gravity and the stress of wind.

“A lot of effort has gone into these tests so that the data mean something,” Mandell said. “We’ve had to invent methods ourselves. It has been a great deal of work.” Current materials last much longer in the tests and are much stronger than the more primitive materials from the early years of the study.

It is not fast work; it is simply faster work than observing a wind turbine blade in the field for 20 years. A fiberglass or carbon fiber sample can spend weeks or months, 24 hours a day, feeling the grip of the lab’s machines.

In 17 years, Mandell and Dan Samborsky, a research specialist, have accumulated 10,000 results on about 150 different composite materials. The research appears on Sandia Laboratory’s Web site as the “MSU/DOE Fatigue Database for Composite Materials.” It is one of the world’s largest open-access libraries on wind turbine materials and the largest in the U.S., according to Sandia. Researchers from around the world use the information.

“Within in the U.S., we are still doing the bulk of the testing that’s open literature,” Mandell said.

U.S. blade manufacturers and materials suppliers send Mandell materials for testing. He also creates his own composites with resin and cuttings from bolts of fiberglass and carbon fiber cloth. Over time, interest has shifted from fiberglass to carbon fiber. Though carbon fiber is stronger and lighter, it’s also more expensive.

Mandell works closely with fellow Montana State’s engineering professor Doug Cairns, who manufactures composite materials. Cairns looks to understand the intricacies of how to resin-infuse and cure layers of fiberglass and carbon fiber on a 150-foot-long blade.

The Department of Energy gave Mandell and Cairns, and their counterparts at Sandia, the first wind energy Outstanding Research and Partnership Development Award in 2003.

“In the 1980s and 1990s, wind was a boom or bust research technology, and putting up wind turbines depended strongly on subsidies,” Mandell said. “In 1987, wind cost 10 cents per kilowatt hour to produce. Now, it’s down to about 4 cents.”

That price makes wind competitive with new natural gas and coal-fired power plants, Mandell said.

“The United States has the best wind resources of any country in the world, and Montana has the fifth-best wind resources of any state,” he said. “The technology is efficient enough that huge areas from the Rocky Mountain front in Montana and Wyoming, across the Dakotas, are developable.”

In late 2005, Invenergy developed a 90-turbine wind farm on the transmission line near Judith Gap. The Judith Gap Wind Energy Center can produce enough electricity for about 36,000 homes, year after year. Though Mandell had no direct involvement in the project, he’s an enthusiastic supporter.

“I think they look great compared to smoke stacks. These big turbines rotate slowly. They remind me of sail boats,” Mandell said. “They are relatively quiet; they just turn in the wind and keep the lights on. I wouldn’t mind if they were put on the hills behind my house.”

For related information, go to www.isa.org/environment.


Source: http://www.isa.org/InTechTe...

AUG 17 2006
https://www.windaction.org/posts/4006-materials-data-aid-wind-energy-research
back to top