What’s made of iron, salt and water, and can be bigger than a truck? Iron batteries! These lithium-ion battery alternatives are made from simple, common materials and store massive amounts of electricity for more than twice as long as traditional batteries — perfect for a future in which electric grids rely more heavily on solar and wind power. Iron batteries are also cheaper and safer than traditional lithium-ion batteries, which have been known to burst into flames and deteriorate over time.

• One iron battery the size of a shipping container can power 34 U.S. homes for 12 hours. 

• Renewable energy was the only energy sector to experience growth in 2021.