Customers control the Dandelion Air through a Nest thermostat.

Hannun's career, though, has been anything but slow. She studied civil engineering at Stanford University and then spent a year working on hydroelectric projects in the Philippines and water quality monitoring in Mexico. In early 2010, she took an entry-level position at Google and re-enrolled at Stanford for a master's degree in theoretical computer science. That led to a marketing role at X, which was originally called Google [X], inside the company. "At that time, X was very much in stealth mode," she explained, "so all of my friends made fun of me and said I had the easiest job in the world because I was doing marketing for a part of the company that did no marketing."

Her role quickly evolved into a "little bit of everything," or whatever the team needed help with. She worked on the launch of Google Glass and Project Loon, a network of high-altitude balloons that can provide internet access. Hannun extended the company's work by helping scientists access data, captured by the balloons, about a layer of the stratosphere that is typically hard to analyze. "It was a huge opportunity for atmospheric scientists to get this data so that they could improve climate models and just do research on it," she said.

"The scale of the saving was immense, and staggering."

Afterward, Hannun worked on a project called Foghorn, which investigated whether seawater could be turned into a replacement fuel for gas-guzzling cars and trucks. The project was eventually shut down, and Hannun was approached by Bob Wyman, a Googler based in New York, to look at geothermal heating instead. "I didn't really know what it was," Hannun admits. "So it triggered a lot of research. I had to get to know it and understand the barriers and the potential."

X, now a division under Google's parent company, Alphabet, looked at how much people were spending on heating and cooling in the US, as well as the potential savings if they switched to geothermal heating. "The scale of the saving was immense," Hannun said. "And staggering."

The large upfront fees were a problem, though. The team realized that the ground loop drilling was the biggest cost and, therefore, the greatest opportunity for technological innovation. These holes are typically dug out by large, intrusive drills designed for water wells over 1,000 feet deep. Most ground loops, though, only need to descend a few hundred feet. X prototyped a number of ambitious alternatives including a high-pressure water jet, a modified jackhammer that could worm its way underground and the use of liquid nitrogen to create frozen and easily chippable soil. Eventually, it found a solution that was smaller, faster and cheaper.

Becky Meier and Bob Connors were Dandelion's first customers.

X is meant for projects that require huge amounts of expensive research before they can be commercially successful. The technology was incomplete, but the team knew it could leave the safety of Alphabet and still thrive with its standardized product and improved heat pump. The drill was clearly important, but Hannun knew it could be developed alongside the rest of the business. She was also aware that the team would learn and iterate faster by completing systems in the real world.

"Geothermal is already a product that you can install. What we're doing is just improving it, making it better and less expensive," Hannun said. "But that is a process best done by iterating in the real world and getting things done. Seeing how it goes, improving, refining, testing. All of those things just require steady progress over time with some of these larger step changes, like with the drilling technology or the Dandelion Air."

In July 2017, Dandelion's so-called 'graduation' from X was official. "We just decided mutually with X to spin it out because it seemed like the type of business that could survive on its own," Hannun said. "One that would benefit from a more startup mentality."

"We just decided mutually with X to spin it out."

The drill is still a bit of a mystery. According to Hannun, the custom machinery has a vibrating head that causes the soil to act more like a liquid. It makes the ground easier to cut through and also accelerates the installation of supportive casing for the ground loops. "Our Dandelion drill is specifically designed for the residential geothermal use case," she explained. "It's much faster at putting in loops. It creates a lot less disturbance in the yard. And because it's faster, you don't have to pay for as much remediation for the yard and [garden] spoils removal."

Dandelion completed a "few dozen" systems last year. Of these, a few were installed with the company's own drill, Hannun said. The company is aiming for installations in the "low hundreds" this year and will use its bespoke machinery for "quite a few [homes] this fall," she said.