No, all natural gas with number 2 oil (diesel) as a backup. The co part comes from the fact the Brayton and Rankine cycles are working together. The former being how a gas turbine works and the latter being how a steam system works. I can go into more depth but it's boring. I like renewables, just not as a blanket one size fits all solution. People tend to form an oppinion about this kind of thing based on vibes not reality, experience or math. I've worked at hydro plants before and like I said am mostly qualified legally to work in nuclear.