When giving speeches and talking to audiences, I’ve often been struck by how few Americans, even those who are highly educated, have any idea where the energy they use in their home or business comes from. I’ve asked college students where the electric power is generated, and they shrug and then point to the electric socket in the wall. The electric currents just come magically through that plug.

For millennials, supporting green energy is cool and even virtuous. It’s a popular and costless way to save the planet — until the power doesn’t flow through the grid. Then the laptops, hairdryers, Netflix shows, computer games and iPhones run out of juice.

That may happen one of these days — and in the not-too-distant future (just ask Californians about blackouts), when the sun isn’t shining and the wind isn’t blowing.

Stephen Moore is a senior fellow at the Heritage Foundation and an economic consultant with FreedomWorks. He is the co-author of “Trumponomics: Inside the America First Plan to Revive the American Economy.”