Less than a year after groundbreaking at
Entercom Denver’s KEZW(AM) transmitter site, ribbon-cutting ceremonies were
held in October to mark the startup of a 100 kW solar array that powers the
station’s transmitter and related equipment.
believes KEZW is the largest U.S. radio station with facilities powered by the
company believes this makes KEZW the largest radio station in the United States
to be powered by the sun. It says its monthly energy costs have dropped by 80
sets KEZW apart from other such installations is the scale of its operation.
“A lot of stations say they’re powered by wind or solar,”
said Jeff Garrett, director of engineering for Entercom Denver. “But that
usually means a part of the energy comes from renewables, or it is a
solar array is able to power the transmitter site 100 percent on most days when
there is sufficient sunlight.”
in late October, the array was able to power the site fully. KEZW operates on
1430 kHz with 10 kW day and 5 kW night using a Nautel MD-10 transmitter driving
a five-tower array.
A number of pieces need to fall into place in
a project of this scale. Most important, according to Garrett, is a commitment
from top management to get the job done.
“A lot of companies speak the words about going green,
but Entercom’s management has consistently backed energy saving programs that
work.” The company said the project is part of an environmental initiative
called 1Thing, as in “do one thing to improve the environment each day.”
Entercom CEO David Field and Director of
Sustainability Jamie Field discuss the array project with Denver DOE Jeff
KEZW also was fortunate in having the necessary real
estate. There was plenty of land at the transmitter for the
Also important are federal and state tax incentives for
renewables. “Everyone is in favor of renewable energy, but they’re also looking
at the bottom line. Anything that drives down the upfront costs will make the
project more attractive.”
Beck, vice president, technical operations and news, talk and sports programming
for Entercom, said, “We were able to participate in a now-expired federal
program which allowed certain facilities to qualify for a federal cash
incentive instead of a tax credit. The state of Colorado also has a repurchase
program through the local utility, which helped make this project work for us.”
He speculated that this financial landscape might change in the future because
a lot of the incentive programs at the local and federal levels came under
scrutiny during the so-called fiscal cliff discussions.
station also needed to consult state laws. “The largest system we were allowed
to build was 130 percent of our rated load,” said Garrett. Such legislation
prevents organizations from becoming independent power companies.
solar project isn’t the first energy conservation initiative at KEZW. Five years ago, the lamps in the five AM
towers were replaced with LEDs.
“I had to rewind the toroids so we could get enough power
to drive the remote control sensors,” said Garrett. He adds that before the LED
upgrade, the station used about 7 kW of power per year just to light the
Garrett had built a wind- and solar-powered facility at
KFMU(FM) in Steamboat Springs, and while he was enthusiastic about this solar project,
he had several concerns.
“I wasn’t sure about storing the energy, and how
batteries would work at the scale we were planning. Also, the interactions
between AM array and solar gear were a concern.” How would a strong RF field
affect the inverters? How would the solar-panel array influence the AM pattern?
An unidentified technician from REC Solar installs inverters
on the wall of the transmitter building.
Garrett and staff engineer Derek Jackson conducted some
experiments and did the preliminary work. Inverters were delivered to the
transmitter site and tested. They delivered a clean sine wave output, and didn’t
seem to be sensitive to RF. Before construction, the engineers did a partial
proof so there were baseline measurements of the AM pattern. They consulted the
site’s blueprints and marked out ground radials and other buried cables so
there would be no accidents while holes were being dug for pilings.
plans progressed, they decided to forego battery power and simply feed the
inverters directly into the grid. This meant the station would be on the grid
during nighttime hours; but it also simplified the installation, allowing the
power grid, emergency generator and solar array to work together harmoniously.
utility company installed metering equipment at the site to track how much
power KEZW was contributing to the grid. The solar array generates 100 kW of
power, and 85 kW are available from the inverters.
Solar of San Luis Obispo, Calif., was hired as the general contractor, and
Hatfield & Dawson Consulting Engineers of Seattle were signed on to develop
a plan to preserve the integrity of the AM pattern as the solar array was
we had to cadweld grounding pigtails to everything and tie it all onto a copper
strap that connected to the AM ground system,” said Garrett. Some minor
retuning of the AM array was necessary as construction trailers were on site.
After work was completed, the site was retuned, and the settings matched the
concern was the effect on the solar system of load switching from the 10 kW day
to 5 kW night patterns, but that turned out not to be a problem.
and Jackson’s testing, planning and hard work paid off.
“The solar system has worked perfectly from day one. The
efficiency of the new inverters and solar cells is impressive. Many days we are
generating more power than we are using.”
The sun bathes solar
panels being installed between snowstorms in early 2012.
The real payoff however is in the bottom line. “Last year
our electric bills for the transmitter site were $1,200–$1,300 [monthly]. This
year, for July and August, it dropped to $270.” And that’s in addition to
earlier power-bill savings from installing LED beacons.
Tom Vernon is a longtime contributor
to Radio World. He wrote about graphics for radio in August 2012.
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