When it comes to reducing carbon emissions by 2030, Duke Energy knows that more coal plants must be shut down and solar farms must be built.

That’s when the future gets murkier, and top company officials say they’re looking into the possibility of hydrogen, a long-studied fuel that hasn’t been widely used.

Hydrogen’s potential for utility companies is clear: It produces only water or vapor when burned, with no emissions of any kind of greenhouse gas. Dominion Energy is conducting a pilot project in North Carolina, and other companies are investigating how much hydrogen they can blend with natural gas in order to sell what they call a cleaner product via the existing pipelines and distribution network. Hydrogen, on the other hand, continues to be met with skepticism.

Carbon dioxide emissions are generated during the process of separating hydrogen from other substances, particularly natural gas. Many also wonder if utilities can use hydrogen as an excuse to keep investing in gas infrastructure rather than renewable sources.