Greenwashing Hits Microwind Turbines, Perform 1/3 of Performance Expectations has a post on Massachusetts microwind turbine project.

Study: Microwind turbines a tough sell in Mass.

by Martin LaMonica

BOSTON--Despite the growing enthusiasm for home wind turbines, an analysis of microwind turbines in Massachusetts found that they fell short of performance expectations.

The Massachusetts Renewable Energy Trust commissioned a study last year to review electricity output from 21 small wind turbines in the state and the results were surprising: the data showed that the estimated production was about three times higher than the turbines' actual production.

Oops, the estimated production was three times higher?  And as the article states few ever go back and measure the performance in the field.

The analysis is not the final word on small wind generators, but is significant because few states have done similar reviews, say the study's authors.

The Swift wind turbine from Cascade Engineering, one of many new small wind turbines now available or being developed.

(Credit: Cascade Engineering)

The Massachusetts Renewable Energy Trust was "taken aback" at the discrepancy in expected versus actual performance and made changes to its "small wind" rebate program earlier this month to address the issue, said James Christo, a program director from the quasi-public state agency. Christo spoke on a panel on small wind--defined as less than 10-kilowatt capacity machines--at the Northeast Sustainable Energy Building Energy Conference here last week.

What are some of the issues.

Data problem
The Massachusetts state analysis tried to pinpoint the reason for the underperforming turbines and found that installers often worked without sufficiently good information.

Area wind maps for the region tended to overestimate on average by 10 percent how good the wind was for certain locations, according to Shawn Shaw, an analyst at the Cadmus Group who worked on the study.

Another problem is the rated capacity--how much electricity a turbine can produce--that manufacturers publish aren't always reliable for extrapolating expected performance, Shaw found. Industry associations are trying to come up with standard ways of reporting capacity which will help, he added.

"You want to be internally honest about your (wind resource) assessments," Shaw said. "The economics are going to probably be the best driver in Massachusetts."

A state like Massachusetts has a good wind resource near the coast, but its hilly and woody terrain means that finding a good site requires some investigation.

Installers and customers should be aware, for example, that nearby obstructions can have a significant impact. A 100-foot wind tower placed next to a 50-foot tree is effectively the same as a putting turbine on top of a 50-foot tower, which means it will get a lot less wind, Shaw said.

The results from the Massachusetts study echoes a similar survey done in the U.K. over the past two years, called the Warwick Trials.

That study focused specifically on urban microwind turbines, some of which were roof-mounted. Overall, it found that the performance of these systems fell below expectations as well and that a number suffered technical glitches.

"The truth of the matter is that (urban wind) hasn't been studied very much, at least in the U.S.," said Shaw. "There's a tremendous amount of uncertainty."

And, now they are going to do what should have been done in the beginning.  Set up a performance lab to evaluate devices.

To test urban wind turbines, Christo said the Massachusetts Renewable Energy Trust is sponsoring a "science experiment" to put up five turbines from different manufacturers at the Museum of Science, a project expected to go up this spring.