Nuclear energy is having a moment.

Europe recently moved to issue green bonds for the power source, and Germany signaled that it may scrap plans to shut nuclear facilities given the country¡¯s energy crunch. Silicon Valley is also embracing nuclear fusion, an unproven technology that promises abundant, cheap and clean energy in the not-too-distant future.

The new U.S. Senate climate pact includes federal funding and incentives for fusion, building on last year¡¯s surge of financing. Now, companies are getting in on the sector, plowing even more money into ventures that are taking the most difficult paths to make fusion¡¯s promise a reality.