Ipswich Wind’s process was comparatively
quick with only eight years between the start
of the site survey and the start of production.
These turbines nearly always have a hub elevation of at least 80 m, and thus require FAA
approval even in cases that don’t otherwise
require Federal agency sign-offs.
There are, however, small-scale vertical-shaft machines that invite one to look at
wind generation from a different perspective.
Horizontal-shaft generators are usually built
to utility-power scale, providing capacities
between a large fraction of 1 MW to 8 MW.
They connect to a generic base load through
distribution cables, mitigating the power demand serviced by traditionally fueled generators.
By contrast, manufacturers of small vertical-shaft generators usually
size their products between single digit and several tens of k W — between one and three orders of magnitude smaller than the utility-class
turbines. Vertical-shaft generating systems do not require steering
mechanisms — they are always facing into the wind — nor do they
require blade-pitch adjustment, which greatly simplifies their mechanical design.
Customers often size and site these small generators for a specific load
or installation. An early example is the 50 k W vertical-shaft generator
from Eastern Wind Power. The 50 k W Sky Farm turbine uses a Siemens
inverter to automatically sync with and connect to the local power grid.
The turbine blades are only 20 feet high and the machine occupies a
footprint of only 16 feet on edge. Multiple
vertical-shaft wind turbines can share a site
with only 16 foot spacings — useful for roof-
top installations or ground-level applications
with space restrictions.
Originally designed for permanent installations, this design has been adapted for
portable applications including disaster relief,
rural electrification micro-grids, rural communication ground stations, and military field
Smaller still, a hybrid wind/solar generator
from Wing Power Energy supplies off-grid
loads such as 4G LTE communication base
stations. The system also maintains the charge
for a seven-day backup battery, which supplies power on still evenings
and in case of multiple days of overcast skies. The Wing Power Energy
design can provide power in areas where utility service is unavailable.
Communication companies, such as Verizon, can use these systems to
fill in their coverage maps, particularly in rural areas.
Retailer Walgreens is using a pair of Wing Power Energy turbines
with 850 solar panels and a geothermal system to power what the company asserts is the nation’s first net-zero-energy retail store, located in
Evanston, IL. A goal of Wing Power Energy’s blade design is to produce
useful power at low wind speeds. The company claims a cut in speed
of only 5 mph making the system attractive in locations otherwise not
well suited to wind energy capture.