"How does solar energy work when there's no sun?" has been a question for pretty much about as long as solar energy has been a thing.

Of course people wouldn't want solar panels on their houses if installing them meant that, come sunset, the movie they were watching suddenly shut off, forcing them to read by candlelight like colonial settlers. Making solar power a viable option, even when the sun sets or disappears behind some clouds, was one of the first things scientists and engineers had to figure out.

Photo by Andreas Rentz/Getty Images.

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How Costa Rica went without fossil fuels for 76 days and what we can learn from it.

While we were all playing Pokémon Go, Costa Rica helped save the planet.

If Costa Rica were a kid going back to school, it would have a pretty awesome story to tell when asked what it did over its summer vacation.

Image via iStock.

"Oh nothing. I just ran entirely on renewable energy for 76 days. BOOYAH!" Costa Rica would say proudly.

OK, so this is the Costa Rican women's volleyball team celebrating their own victory at the Rio Olympics, but they'd probably be pretty pumped about renewable energy too. Photo by Yasuyoshi Chiba/Getty Images.

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The Chernobyl meltdown on April 26, 1986, remains the most ruinous nuclear catastrophe in world history.

More than 30 people died in the immediate aftermath, and cleanup costs ran into the billions of dollars.

After the meltdown, the city and surrounding areas were evacuated, leaving 1,600 square miles of radioactive real estate rotting away in what was then the Soviet Union, now Ukraine.

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For 7 hours last week, Germany paid its citizens to use electricity. For reals.

The question facing the shift to clean energy is 'when' not 'if.'

For a few hours on May 8, Germany was generating so much renewable electricity that people were actually getting paid to use energy.

Seriously. Here's a chart:

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