U.S. utilities are increasingly exploring the use of what is called green hydrogen made from wind and solar energy to reduce emissions from power plants and pipelines.

The early investments by companies including NextEra Energy Inc. and Dominion Energy Inc. are expected to help commercialize a costly technology that has been slow to develop despite its ability to provide a steady source of carbon-free power. Utilities and policy makers are beginning to view the technology as necessary to support ambitious renewable-energy…