Calculating Output... Accurately!

Wind proponents like to describe a project's capacity as 'enough to power XXX homes'. Even though this ignores the fact that residential use accounts for only one third of the total electricity consumed, it is a handy shorthand so long as it's calculated correctly and accurately this is not a problem. Most people find it easier to visualize the amount of electricity consumed by 2,000 homes than 22,080 MWh.

Unfortunately wind project developers always misrepresent this figure and hope that nobody checks the underlying assumptions. They inflate the number of households to be served in order to make their projects appear to be more significant. For example, when First Wind wanted LURC to extend the boundary of the wind permitting expedited zone to include Kossuth, they had to convince the LURC Commissioners that the Kossuth addition would make a significant contribution to Maine's wind energy goals. In this context, First Wind Attorney Neil Kiely presented the following oral and written testimony (Champlain Wind LLC, 9/22/10 Presentation to LURC, page 2):

"... a 57 MW facility would generate enough energy to serve the electricity needs of approximately 23,500 residential households."

This is a very misleading statement for several reasons:

1) The Number of Turbines. The Kossuth extension being considered does not represent a 57 MW facility. Mr. Keily included all the turbines planned for the Carroll Plt. in this calculation. He apparently multiplied 25 turbines times 2.3MW each to reach this total. In reality, the Kossuth portion of the project would entail 7 turbines of 2.3MW each for a total nameplate capacity of only 16.1 MW.

2) Nameplate vs Actual Output. The rated capacity of the Siemens turbine is 2.3MW. But that is not their expected output. It is the absolute maximum electricity that turbine can generate in a perfect world, with perfect winds. This is called the 'Nameplate Capacity'. It assumes that the turbine will turn at optimal speed 24 hours a day, 365 days a year with no downtime for repairs or maintenance. Obviously this completely absurd.

The wind industry as a whole, and First Wind in particular, try to keep the actual output figures for operating turbine facilities a secret. They say that if they were to divulge these trade secrets their competitors would know their costs. The real reason is that the actual output is such a small fraction of nameplate output that if these figures were known the generous subsidies and preferential treatment they capitalize on would end. While First Wind tells us the 'industry average' figure is 30% - 40% of rated nameplate capacity. Not likely. The one project for which we have access to real-time figures is at the University of Maine at Presque Isle. Over the past year and a half it's produced electricity at 11.7% of its nameplate capacity. Click here for details.

3) Household Consumption. The final figure in this calculation is the amount of electricity consumed annually by the average household. In his testimony, Mr. Kiely used a figure of 6.38MWh. He is making the assumption that the electricity from the Kossuth project will be used by Maine households. That's a convenient, if disingenuous, way to calculate the number of households the project will serve. There is no indication that the power generated in Kossuth will be used in Maine. In fact, because Maine is a net exporter of electricity it would be more honest to assume it will be used elsewhere. According to the US Department of Energy, in 2008 the average US household used 11.04MWh annually.

Here's a calculator that comes in handy when checking the honesty of a developer's output figures: