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How a four-legged mowing system keeps solar farms producing energy

Despite the advantages they offer in terms of leveraging renewable resources, solar farms also bring with them special challenges. Among these is controlling vegetation growth around the panels--essential for ensuring a consistent, stable power source, but a laborious and time-consuming task. While some facilities use traditional or automated lawn mowers, others are taking a four-legged approach.

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  • Judy Woodruff:

    With solar power farms popping up around the country comes the task of controlling vegetation growth under and around the panels.

    From the Cronkite School of Journalism, Amanda Mason brings us one unique mowing system.

  • Amanda Mason:

    The Red Horse solar and wind project provides Tucson Electric Power with up to 71 megawatts of clean power a year.

  • Joseph Barrios:

    Solar power is great in many ways. It's good for the environment. The cost of installing and delivering solar power is coming down all the time.

  • Amanda Mason:

    Joseph Barrios is the spokesperson for Tucson Electric Power.

  • Joseph Barrios:

    And one the things that we look for are ways to make solar energy more reliable.

  • Amanda Mason:

    And that reliability depends a lot on keeping grass from growing too high.

    Enter 200 sheep whose appetites help keep 250,000 solar panels on 1,300 acres operating.

  • Rusty Cocke:

    Easy, Katie. Easy. Take them slow. Take them slow.

  • Amanda Mason:

    Rusty Coke is a sixth-generation Arizonan rancher who has leased his sheep out to the solar field for close to two years.

  • Rusty Cocke:

    Well, sheep, because there — they don't eat — they don't eat wires, like goats, they're small enough — like, when the panels, when they oscillate, and they're real low on the ground, you can't really run cattle out here to keep them down.

  • Amanda Mason:

    If the sheep weren't here, the grass would be growing to about this height, which would create a problem for the solar panels, because the solar panels are moving in order to capture the sun.

    And if the grass is too tall, then they only collect about half of the energy needed.

    The solar field provides power to 211 homes per year. So, every solar panel matters. And that means every sheep needs to do its job, which isn't without its challenges, including protecting them from predators, such as eagles and coyotes.

    Enter Luciano and his canine friends. At least three dogs are responsible for this herd of herbivores.

  • Rusty Cocke:

    The dogs are what make the whole deal possible. If it wasn't for the dogs, the predators would pick them apart.

  • Amanda Mason:

    Extra protection is provided by humans.

  • Rusty Cocke:

    So, after a while, I just got so distressed about losing sheep, that I brought them home and let them have the babies at my house. And then I brought them back after they were a couple years old.

    And when I brought them home, my daughter went crazy and started naming all of them.

    (LAUGHTER)

  • Rusty Cocke:

    She's 8 years old, and she loves them.

  • Amanda Mason:

    It's not cheap to maintain a live mowing system. But Tucson Electric Power says the extra effort makes it possible to bring clean power to their customers.

    For the "PBS NewsHour," I'm Amanda Mason with Cronkite News in Willcox, Arizona.

  • Judy Woodruff:

    One of those stories you have to love.

    Online, as Hurricane Lane barrels down on Hawaii, we explore how this storm is reminiscent of Hurricane Harvey, which made landfall in Texas a year ago Saturday.

    That's on our Web site, PBS.org/NewsHour.

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