Wind and solar power will replace coal at a Colorado furnace.

Sparks flew a hundred feet in the air. Bare metal shrieked as powerful jolts of electricity passed through a furnace that melts scrap — like old cars and tossed-out refrigerators — into puddles, turning them into shiny recycled steel.

As I watched recently, the great arc furnace at one of the nation’s most storied steel mills was sucking in more electrical power than any other machine in Colorado, produced in part at a plant a few miles away that burns Wyoming coal by the ton.

But the electrical supply for the mill is changing.

A huge solar farm, one of the largest in the country, is to be built here on the grounds of the Evraz Rocky Mountain Steel mill. In addition to producing power for the giant mill, the farm, Bighorn Solar, will supply homes and businesses across Colorado. So far as I can tell, Evraz Rocky Mountain will be the first steel mill in the world that can claim to be powered largely by solar energy.