A lot of noise in the small-wind industry comes from each developer testing and claiming different characteristics for their turbines. That makes comparing one with another a difficult task for consumers. OEMs for utility-scale turbines turn to companies like Germanischer Lloyd for a third party seal-of-approval. Small wind had nothing like GL until recently, when AWEA issued its certification guidelines for the market segment. WindTamer VP Bill Schmitz represents one of the first small-wind companies to pursue certification for its 1 and 5-kW ducted turbines.
But if the turbine works, why bother with testing? “Certification gives credibility to our machine, especially as we sell to more sophisticated customers,” explains Schmitz. Certification also offers more opportunities. For example, he says the New York State Energy R&D Agency provides funding for certified companies in the form of a rebate to purchasers. One rebate pool for $3.2 million gives home owners $1,000 to $8,000 off the cost of installation.
Certification emphasizes testing to ensure the turbines won’t fall down or throw a blade, anything that would give the small-wind industry a black eye. Intertek will test for the criteria specified in the standard. “The value of certification is that it sets a bar for manufacturers,” says Intertek’s Troy Hewitt, who leads test teams. “It provides a minimum performance standard in terms of safety, power output, and durability. So having the certification assures regulators and consumers that the turbine meets certain standards. Without that, it is an open question as to whether or not a turbine will last an advertised lifetime, and whether it will deliver what the manufacturer claims.”
Two important tests gage safety and blade strength. A static blade test makes sure it does not break under a prescribed load. Load verifications are made where the blades attach to the hub, where the hub attaches to the nacelle, where the nacelle attaches to the tower, and other points of stress. The AWEA standard excludes the tower.
Other tests measure acoustics, a great concern for small turbines because they tend to be close to residential areas. Testing also provides an annual energy production figure. The standard calls for a minimum of six months duration testing with a particular amount of time at several wind speeds. At the end, the investigation looks for abnormal wear or degradation, and makes a calculation as to whether or not the turbine will last an expected life. Schmitz says his company designs turbines to last 20 years.
“In a design review, Hewitt’s team looked at our drawings and made useful recommendations,” Schmitz says. “We got interim reports, so we think certification is a valuable learning tool.”
As certification becomes more important, Hewitt recommends early involvement with turbine developers. “The sooner we are involved in the design phase helping them understand certification requirements, the more likely it is they won’t have to launch a redesign effort because they are close to production,” he says. What’s more, Canada may adopt the standard as a guideline.
Filed Under: O&M, Safety