Bill Gross is best known for founding the technology incubator Idealab in 1996, after starting a handful of companies in software, education tech and online services spaces.

In the quarter-century since, Idealab has has started more than 150 companies and had more than 45 successful exits. Today, Gross devotes virtually all of his time to being the CEO of clean energy company Heliogen, which he launched out of Idealab in 2013, scoring Bill Gates as an early investor.

But Gross has always been a climate tech entrepreneur. He’s just had to wait for the world to catch up with him a bit.

He actually started a solar device company when he was in high school, long before he got into software, and the money he made helped him pay for college.

Gross grew up in the San Fernando Valley in Los Angeles. When he was 15, in 1973, gas was rationed after OPEC imposed an oil embargo against the United States in order to punish the U.S. for providing support to Israel in the Arab-Israel war.

“You only could buy five dollars of gasoline per day. And I remember that my mother couldn’t buy enough gasoline to drive me to school,” Gross told CNBC in a video interview earlier in the fall.

So Gross had to ride his bike to high school. “As I’m riding both ways on the bicycle, I’m sitting here thinking, ‘It’s crazy that there’s somewhere else in the world that could decide to cut off your fuel supply, the thing that people need for their livelihood.’ I didn’t understand anything about climate change, or energy or anything. I just thought, ‘Someone else could do that?! That’s crazy.'”

This thought is still relevant now almost 50 years later, as Russia has cut off supplies of gas it is sending to Europe in response to the Ukraine war.

Gross went to the library after school to read about alternative renewable forms of energy such as solar energy and wind energy in the likes of Popular Science or Scientific American magazines. He got excited about the idea of renewable energy, had just taken trigonometry in school and used his newfound knowledge of both to make a couple of devices based on the idea of catching the sunlight and concentrating it.

One device he made was a parabola-shaped solar concentrator that could be used to create a solar oven or solar cooker. The other was a Stirling engine, which converts heat energy into kinetic or mechanical energy.

“Because I was reading Popular Science magazine, I saw people used to take out little ads in the back,” Gross told CNBC. “And I had $400 of bar mitzvah money leftover, so I took out a small add in the back of Popular Science advertising ‘Kits and plans to make your own solar concentrator,’ and I started selling them!”

He would go on to sell 10,000 of these plans and kits starting at $4 apiece. Personal computers didn’t yet exist, so he typed the material on a typewriter and made the drawings himself by hand.

He put what he made towards his college tuition. People from all over the country bought the kits and would send Gross a check or cash. It was his first foray into entrepreneurship, which was exciting, he said, and the experience served to change the trajectory of his life in other ways, too.

“I was really passionate about it back then. It really affected my life,” Gross told CNBC. “I wrote about that little business I started — it was called Solar Devices — on my application to college and it got me into CalTech. So it probably had a huge impact on my direction.”

In 2010, Gross heard Bill Gates speak at a TED conference about needing to make energy and energy storage cheaper. After that talk, Gross approached Gates and shared his idea of using computational power to improve the efficiency of solar power. Gates ended up investing in Gross’s idea, seeing the potential to replace many industrial processes that require high heat and burn fossil fuels to get there.

In 2013, Gross launched Heliogen, which uses artificial intelligence to position a collection of mirrors located in a circle around a central tower to reflect the sunlight back with maximum impact.

One critical component of Heliogen’s approach is built-in energy storage. One limiting factor for solar energy is its intermittency, which means it only delivers power when the sun is shining. But Heliogen stores energy as heat in a thermos of rocks — something traditional solar panels cannot do without batteries, as they turn the sun’s rays immediately into electricity.

“We’re gathering the energy when the sun is out. But we’re delivering the energy continuously because the energy is coming out of the rock bed,” Gross told CNBC. “And basically we are recharging the rock bed, like you would recharge your battery. The difference is a battery expensive, and rock bed is cheap.”

In 2019, Heliogen announced it had successfully concentrated solar energy to temperatures over 1,832 degrees Fahrenheit.

“Heliogen is the culmination of my life’s work,” Gross told CNBC, because it uses both software and renewable energy expertise.

The company had its first prototype in 2015, “but then, still, nobody cared. Couldn’t get any customers,” Gross said. He did get a couple of customers, but, it was still “struggling, struggling, struggling.” By 2019, Heliogen had the first large-scale system built and this time, “the world went crazy,” Gross said. “We got so much press and publicity, and customers started calling us all over who wanted to replace fossil fuels with concentrated sunlight, and then Covid hit,” Gross said.

After a bit of a Covid slowdown, interest started picking up again as the urgency around decarbonizing mounted and as energy price volatility made companies rethink their energy supply strategies, Gross said. The company went public via SPAC in a deal that landed $188 million of gross cash proceeds to Heliogen and on Dec. 31, 2021, Heliogen started trading.

The company is not yet profitable, losing $108 million in the first nine months of the year, but that’s expected as the company scales, according to Gross.

“We projected we would run at a loss for the few years of operation as we drive down the cost with volume production and the renewable energy production learning curve,” Gross told CNBC.

Heliogen’s first commercial grade project is in the final stages of permitting and aims to break ground next year in Mojave, California. The concentrated solar field is funded with $50 million from Woodside Energy, a wholly owned subsidiary of the Australian energy producer Woodside Petroleum, and $39 million from the U.S. Department of Energy.

While Gross has been ahead of the curve for most of his climate career, he’s confident the industry is catching up with him now. As the urgency surrounding climate change has become more widely understood, corporate executives face pressure from stakeholders to clean up their corporate emissions.

“But then the final straw was price of fossil fuels went up like crazy. The price of fossil fuels after Russia invaded Ukraine is a game changer,” Gross told CNBC. “Now, it’s not just for CO2 emissions, now you can save money. Now, this is the ultimate thing, which is make the energy transition be about reducing your cost, not about increasing your cost.”

There’s no time to waste.

“When I was a teenager, there was 320 parts per million of CO2 in the atmosphere,” said Gross, who is now 64 years old. “And today, there are 420.”