Missouri wind speeds for energy production lower than predicted

COLUMBIA, Mo. –Average wind speeds in Missouri are lower than reported on a
state-produced wind map, said a University of Missouri atmospheric scientist.
This finding may affect utilities and private investors planning to build wind
turbines to provide clean, renewable energy.

Lower-than-predicted wind speeds also may make it harder to meet goals set
in 2008 by Missouri Proposition C, which requires investor-owned electric
utilities to obtain a gradually increasing percentage of their energy from
renewable sources.

In a two-year study, MU atmospheric scientist Neil Fox gathered data from
10 wind towers across the state. At 100 meters (230 feet) above ground level,
the height at which wind turbines operate, wind speeds averaged between 0.1 and
1 meter per second slower than estimated on a wind map produced by the Missouri
Department of Natural Resources (DNR).

“While this is not good news, on the positive side, it is better to know
the genuine wind speed rather than overestimate things,” Fox said. “To reach the
targets of Prop C, we will need to use a range of renewable sources, and the
amounts of each type of energy have to be based on accurate data.”

The DNR wind map used measurements of ground-level wind speeds and other
data to estimate wind speeds at turbine height, he said. “Characterizing how
wind changes as we go up above the surface is actually very difficult. The
standard equations that get used don’t always work very well.”

The strongest winds are in the northwest corner of the state. Fox said
these sites appear to be the ones where the errors are smaller.

“In northwest Missouri, where most wind farm development to date has taken
place, we’d expect to see slightly less power generated than we might have
thought before,” he said. “Developers are not going to get quite the same return
on their investment as they thought.”

The disparity is worse in other parts of the state, though Fox said that
wind power in those areas still has potential for niche applications. “There may
be a role for smaller turbines, for personal or community-based power generation
rather than these large wind farms that a utility company would build.”

He noted that two years might be too short a time to establish a definitive
climatology. The DNR wind map drew on data sampled over a 15-year period. Both
data sets contain uncertainties calling for more investigation, he said.

“We may find that these last two years we’ve been measuring were the worst
two years in history,” Fox said. “Or we may find they were the best two
years.”