Delaney Hall

That's why the supply of electricity must always meet the demand.

Not too much, not too little.

But here's what makes this whole system even more complicated.

The grid isn't just one power plant serving one city.

It's a massive group project, an interconnected system that stretches across huge distances with many power plants and many utilities, all trying to balance supply and demand in real time.

In the U.S., there are actually three grids, the Eastern Grid, the Texas Grid, and this is the grid that matters most for Phoenix, the Western Grid.

The Western Grid is huge.

It stretches from Western Canada down to Mexico and from the Pacific coast to the Rocky Mountains and beyond.

The Western Grid includes coal plants and solar farms and hydroelectric dams, and it ties together dozens and dozens of utilities across multiple states.

Some are for profit, some are municipal, and some are co-ops.

The thing to understand is that the grid is not just physical infrastructure.

It's an immense web of social, political, and economic relationships.

The fact that it works at all is just completely phenomenal.

Within the Western Grid is Phoenix, Arizona.

And a central piece of Phoenix's relationship with the larger grid is a utility called the Salt River Project, or SRP.

When you flip on your air conditioner in Phoenix, that electricity might come from a hydroelectric dam in Oregon, or a solar farm in the Arizona desert, or a natural gas plant somewhere in between.

SRP's job is to coordinate all of that, taking power from neighboring utilities when Phoenix needs it, and managing the moment-to-moment balance between what the city demands and what the grid can supply.

This is Angie Bond Simpson.

She works for SRP, and her job, in essence, is to make sure that Phoenix never runs out of electricity, especially in the summer.

As we've learned, the grid has to stay in balance.