Mr. Gates’s remarks came during a telephone interview in which he described details of the investment fund. The backers include Mr. Gates and 19 other investors, including Jack Ma, founder of the Chinese e-commerce giant Alibaba, and the venture capitalists John Doerr and Vinod Khosla. The fund will have a life span of 15 to 20 years.

The fund will consider investing in electricity generation and storage, transportation, agriculture and energy-system efficiency. Seed money for start-ups and projects ready for commercialization, among other efforts, will be considered, fund officials said.

Mr. Gates’s plans to establish a fund were first announced at the United Nations climate talks in Paris in November 2015. At the same meeting, the United States and about 20 other nations pledged to double their spending on clean-energy research and development under a plan called Mission Innovation.

Mr. Gates said that in the year since Paris, a number of countries had followed through on the plan. “I do hope the U.S. and other countries continue along the Mission Innovation path,” he said.



Mr. Gates backs a string of clean-energy projects, including the nuclear reactor start-up TerraPower, and Aquion Energy, a company developing batteries made from nontoxic materials like saltwater. Mr. Gates also provided seed money for Carbon Engineering, a start-up led by the Harvard University physicist David Keith that is testing a process to capture carbon dioxide from the atmosphere.

But those projects have yet to yield real-world results. Eight years after it was founded, TerraPower has not built a working prototype. Last year, it said that it was shifting some of its focus away from what had appeared to be a promising “traveling-wave reactor” design that burns fuel made from depleted uranium. The start-up is now exploring a different nuclear concept based on molten chloride reactor technology, which uses a molten salt mixture, instead of water, as the primary reactor coolant.