Google parent company Alphabet is in discussions to spin out a molten-salt energy storage project in a transaction with Breakthrough Energy Ventures, a $1 billion fund devoted to energy research, MIT Technology Review reported.

It is unclear if a deal has been finalized or how much money may be involved.

Nobel Prize winner Robert Laughlin is leading the energy storage effort, code-named Project Malta. The plan is to store thermal energy, converted from solar and wind electricity, in giant tanks of molten salt. The technique could prove cheaper and more efficient for longer-term storage of renewable energy.

Now a physics professor at Stanford, Laughlin revealed in a talk that a deal was in the works. In the abstract of the talk, McLaughlin mentions “secret project at X code named ‘Project Malta,'” and says that “spinoff activity associated with Bill Gates’s Breakthrough Energy Ventures is presently underway,” MIT Technology Review reported. The abstract also references a patent, issued to Google and X Development in April, for molten-salt technology.

X is a division of Alphabet devoted to long-term research projects and was formerly known as Google X.

Energy storage can overcome the biggest limitation of modern renewable power, which is why it is one of the primary areas of focus for Breakthrough Energy Ventures. The $1 billion investment fund boasts an all-star roster of investors along with Gates, including Jeff Bezos, Jack Ma and Richard Branson.

Read more about Project Malta and Breakthrough Energy Ventures in MIT Technology Review.