ASK THE EXPERTS: Measuring Wind Energy Potential with an Anemometer

Intermediate

I would like to install a residential wind turbine at my lakeside property. Before I do, I want to measure the average wind speed to determine if there is sufficient wind energy. I want to use an exterior anemometer in an elevated location and measure the wind for several months. Can you recommend an anemometer that will best fit these requirements?

Ian Fairwell • Victoria, British Columbia, Canada

You are off to a wise start by making sure your site has sufficient wind. For a recent project, we purchased a wind measurement system from APRS World (aprsworld.com), and used their Solar Powered Wind Data Logger system (about $900). After the data was collected, we used Windographer, wind data analysis software from AWS Truepower, and Excel spreadsheet software to analyze the results.

Measuring wind speed at the top of a relatively tall tower that matches the proposed turbine height is recommended for accurate wind-resource measurement (see “Wind Matters” in HP158). But having a taller tower quickly increases the monitoring system’s cost. For example, APRS World sells a 97-foot tilting tower option from Bergey Windpower that lists for about $3,000. That puts your “wind interest” investment at $3,900, although you may be able to use the tower with your future turbine.

If you want to receive the data wirelessly, Etesian Technologies (etesian-tech.com) has a self-powered wireless anemometer and data logger. The anemometer alone retails for nearly $700 and they can provide a detailed quote for the entire system.

Renewable NRG (renewablenrgsystems.com) offers its 34m XHD NOW System, which includes a full suite of sensors and booms, plus cable and a data logger, and a 112-foot tilting tower. This cost of this system is about $8,000. The tower may be able to be used with a small-scale residential wind turbine after the data collection is complete—check with the turbine manufacturer to confirm turbine/tower compatibility.

Purchasing and installing a wind resource assessment system positioned near the proposed turbine height is expensive. Wind resource mapping has improved in accuracy and resolution, so the trend in residential wind has been away from direct wind measurement and toward a virtual assessment using wind maps, such as those offered by the U.S. Department of Energy (bit.ly/WindResourceMaps).

Some wind turbine suppliers perform free wind assessments for interested clients using wind-map data. Bergey Windpower (bergey.com) and their dealers have access to a digital wind resource map overlay for Google Maps, and can generate a report for your location. Primus Windpower (primuswindpower.com) will send you a wind assessment report given the details of your location. Others such as Pika Energy (pika-energy.com) provide self-assessment tools.

After a few months of measurement for our project, it was clear that our wind-map assessment agreed with the on-site measurements, confirming that the latest trend of relying more on digital wind map data is likely an acceptable pathway for residential wind.

Good luck in your endeavor. I hope your wind resource proves to be feasible for your residential wind turbine project.

Brent Summerville • Appalachian State University, Sustainable Technology Program

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