These are independent reviews of the products mentioned, but TIME receives a commission when purchases are made through affiliate links at no additional cost to the purchaser.

“I’m a pilot, and I love flying,” says Josef Kallo, co-founder of German company H2FLY. “But it’s always this headache that I’m burning too much fuel and destroying the planet I live on.” H2FLY set out to find a more sustainable alternative, converting a piloted, four-seat HY4 electric plane to run on liquid hydrogen. In September, the company announced a world-first for such a craft: It test flew the plane over Slovenia four times, including one flight that lasted more than three hours. Next up, H2FLY plans to convert a 40-seat passenger jet.

More Must-Reads from TIME

Contact us at

Hydration Made Fun
A Modern Flip Phone
A Saliva Pregnancy Test
More Than a Fast Car
A Breakthrough Bassinet