Big things usually have small beginnings. That’s certainly the case with wind power in the United States. At the turn of the century wind farms contributed a negligible amount of electricity to the grid. But that changed as the technology and economics improved. Wind power’s share of American electricity generation jumped to 1.5 percent by 2008 and 6.3 percent by 2017. It’s poised to send more electrons to the grid than hydropower before the end of the decade.