Services - Windspeed Package

Suited for mid-sized wind turbine projects with hub heights not to exceed 200'. On-site measurement of your wind resource with long-term airport correlation.

WindSpeed Package Offer Sheet [pdf]

Met Tower Option

  • Good for sites near buildings or trees
  • 40m (130' tall)
  • 4 anemometers, 1 vane, 1 temp sensor
  • On-site minimum 3 months

COST-$11,800*

*requires verification on availability at your location

SODAR Option

  • Good in open site (no echoes)
  • Can measure from 10m to 60m+
  • On-site minimum 1 month

COST- $10,600*
 
*requires verification on availability at your location

What is included in the WindSpeed Package:

The WindSpeed package includes:

Task

  • Site evaluation and assistance with the site selection

  • Preliminary Long-Term Wind Speed Estimate

  • Wind Measurement Campaign - See Options 1 or 2

  • Raw data collection and cleaning

  • Obtaining Long-Term Reference data (ASOS/Airport or other) and converting it to useable format

  • Performing multiple correlations and using the best match for producing long-term data set

  • Creating a Report for the Long-Term Wind Speed estimate with Net Energy Output for 3 turbines

  • Administrative and Other Cost

Option 1 - SODAR

  • SODAR - Installation and Removal

  • Installation/Removal - Travel, Two times

*wind speed accuracy based on 1 month measurement = 6-10%

Option 2 - Met Tower

  • 40m tower - Install

  • 40m tower - Take-Down

  • Travel based on 250 miles one way at $1.25/mile two times

*wind speed accuracy based on 3 month measurement = 5-8%

*Consultant may keep measurement device longer at site to obtain needed data for this level of accuracy

WindSpeed Benefits

  • Reduce energy production estimates to +/- 10% from +/- 50%.

  • Obtain grants - many grant agencies need on-site wind data before awarding.

  • Satisfy lender requirements - lenders want certainty that in worst year the savings/revenue will exceed the loan amount.

  • Verify location is best choice for wind production on the site before spending large $$$ on installation.

The below table (AWS Truewind, Feb. 2006, North American Windpower) shows how wind prediction error decreases quickly with number of months of measured data. The error starts at 17% (or greater) with no monitoring, and decreases to approximately 2% within 12 months. Even just 3 months of data can decrease error by half and that means a much more accurate prediction of energy.

Table 1. Data Sensitivity Related to Study Length
Monitoring Period (months) Standard Error
1 6.4 - 11.8
3 4.9 - 10.3
6 3.5 - 7.8
12 1.2 - 2.8
24 0.6 - 1.5

Example of Uncertainty reduction for N100 turbine

Project site average wind speed is 5.5 m/s (12.3 mph) at 37m (121') height above ground. Northern Power Systems 100kW wind turbine with 21m rotor on 37m tall tower. Assumed 15% losses to convert from gross energy estimate to a net energy amount expected for one year. Annual production estimate at 5.5 m/s is 142,000 kwhrs.

Table 2. Sample 5.5 m/s wind site reduction in uncertainty with measurement intervals
Number of months of data Avg.% variability wind speed annual wind speed-lower limit (m/s) Annual Energy Estimate - lower (kwhrs) Percentage increase in energy and revenue certainty
0 17 4.57 87,000 None
1 9 5.01 112,000 28.7%
3 7.5 5.09 116,000 33.3%
6 5.6 5.19 122,000 40.2%
12 2 5.39 133,000 52.9%