CAIRO—On a hot, hazy Thursday in early September, life in the Egyptian capital ground to a jarring halt.

Two of the three metro lines came to a standstill, several popular cable networks were knocked off the air, and the nightly Sound and Light show for tourists at the Giza Pyramids went dark. Most residents were left to stew for hours with intermittent air-conditioning.

For several years now, Egypt has struggled with power outages that have bogged down its ailing economy and disrupted daily life, even driving schoolchildren in some poorer districts outside to study by streetlight.

The Arab world's most populous state simply doesn't produce enough energy to meet demand, and it lacks the cash to import fuel. Political upheaval has left previous