IDAHO CITY, Idaho — Cloud seeding has been around for decades. It started out as a way to make rain for growing crops. But these days in the Mountain West, it’s used as a way to make more snow.
Cloud seeding is often misunderstood. “It’s not something that we use to eliminate a drought,” says Derek Blestrud, a meteorologist with Idaho Power.
It’s the process of increasing the amount of rain or snow fall during a storm. Cloud seeding is a water-management tool, says Blestrud.
There are various methods of cloud seeding. Most of them involve a material called silver iodide.
You can drop silver iodide out of an airplane or fire it into the air by cannon. Or you can burn silver iodide using a propane torch mounted to a tower — that’s the method being used by Idaho Power.
Whatever cloud seeding method is used, silver iodide attracts water droplets in the air. Because silver iodide super-cools those water droplets become rain or snow that falls to the ground.
Idaho Power pays for and operates two cloud seeding programs in Idaho. The programs include 36 cloud seeding towers.
Brandal Glenn is a field engineer for Idaho Power. He builds and maintains the cloud seeding generators that are located along remote mountain ridges.
Glenn says each tower is 26-feet tall. The tower’s lattice structures hold several circular tubes full of combustible materials mixed with a metallic solution. At the top of the tower is a mast with a nozzle that burns a propane mixture, sending a plume of heated material into the sky.
A small solar panel provides the tower enough power to run a satellite modem. This modem allows the three meteorologists who run the operations to turn it on and off from the Idaho Power building in downtown Boise.
Idaho Power is seeding clouds as part of its strategy to make sure there’s enough runoff from melting snow in the summertime. That translates into water in rivers — and more water means more power generated by those rivers’ hydroelectric dams.
Blestrud says Idaho Power’s cloud seeding has added as much as 15 percent to the annual snowpack — roughly 2 more inches of snow for every foot of snowfall. The deeper the snow is, the longer the snow sticks around and the longer it stays cool in the spring and early summer.
For Idaho Power, it means more water to turn the turbines at its many dams. Blestrud says the amount of power that can be generated from this is roughly 100,000 megawatts, which is enough to power about 700,900 homes for a year.
Though cloud seeding isn’t new — some early projects here in the Northwest happened as early as the 1940s — there are still questions about its effectiveness as well concerns about impacts on the environment.
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