Elon Musk, the CEO of Tesla and SpaceX who briefly passed Amazon CEO Jeff Bezos as the world’s richest person before a slide in Tesla’s stock price dropped him back a spot, recently asked his Twitter followers for advice on how to best give away his money.

“Am donating $100M towards a prize for best carbon capture technology,” Musk tweeted, adding that he would provide “details next week.”

Am donating $100M towards a prize for best carbon capture technology

— Elon Musk (@elonmusk) January 21, 2021