When the NASDAQ opens on Wednesday morning, the exchange will include a new ticker symbol: FRVO. The company, Fervo Energy, is in the geothermal electricity business and aims to raise $1.8 billion . An initial public offering of that magnitude would be one of the biggest Wall Street debuts for renewable energy in U.S. history and a promising sign for clean tech’s future. “This is a very, very big deal,” said Gernot Wagner, a climate economist at Columbia Business School. “Money speaks.” At the simplest level, geothermal generation is the process of harnessing the heat within the earth to produce steam, which then spins turbines to generate much-needed electricity. But locating suitable geology and getting deep enough to make power on a utility-scale isn’t easy.…