Modern gas turbines can be converted to hydrogen or hydrogen/gas blends. The idea is to use gas now then convert to hydrogen when commercial, renewable hydrogen is available. One idea is to use renewables to do hydrolysis and effectively use hydrogen as a battery.
The US energy segment has decreased CO2 emissions in the last decade and switching from coal to gas is a big part of the reason.
Hydrogen isn't an energy source it's an energy storage mechanism. You create hydrogen from other sources. Most commercially available hydrogen comes from natural gas already. So you're wasting a ton of energy by converting the natural gas to hydrogen and then burning it again. Hydrogen is just another form of battery.
If you convert natural gas to hydrogen, you can sequester the CO2 produced. The hydrogen production facility can operate 24/7, with the hydrogen stored and only being used when necessary. In this way, natural gas could continue to back up renewables (or back up renewables + short term storage) without CO2 emission, at a capital cost per kW far below nuclear plants.
(The same argument applies to "green hydrogen"; which would be chosen would depend on economics.)
Pet peeve: hydrolysis a chemical reaction where water is used to break apart two other things (like, say, amino acids). The use of electricity to break water into hydrogen and oxygen is electrolysis.
The US energy segment has decreased CO2 emissions in the last decade and switching from coal to gas is a big part of the reason.