The majority of the world’s energy, other than hydro and nuclear, is produced by fossil fuels like coal that emit an overwhelming amount of carbon dioxide. But there’s some good news here, too. New green technologies are allowing the world to produce more carbon-free energy from solar and wind power. Maybe you live near a wind farm or have seen solar panels near your school.

But to stop climate change and make energy affordable for everyone, we’re also going to need some new inventions.

Why? Solar and wind power are reliable energy sources so long as the sun is shining and the wind is blowing. But people still need dependable energy on cloudy days, at nighttime, and when the air is still. That means power companies often back up these renewable sources with fossil fuels like coal or natural gas, which emit greenhouse gases.

It would help, of course, if we had a great system for storing solar and wind power. But right now, the best storage option is recharg