Kathy Hannun

Geothermal should be a super-promising home heating and cooling technology, but installation makes a mess of your yard and has traditionally required a big cash outlay. In 2017, Kathy Hannun spun her company, Dandelion Energy, out of X, Alphabet’s innovation lab, to fix both of those problems. With degrees in civil engineering and computer science, Hannun has led the startup's development of re-engineered geothermal systems that are far faster and less damaging to install than conventional versions. Dandelion also offers loans to customers, letting them sign a 20-year contract starting at $135 per month for a typical system rather than paying $20,000 up front. In April, the company began a partnership with energy giant Con Edison, which gives customers $5,000 to switch to Dandelion (and help relieve some capacity problems on gas lines). Now with 59 employees, Hannun's startup has raised $23.5 million to date. --Kimberly Weisul