Hydrogen from water and silicates

In chemistry news, from last July anyway, "green hydrogen". That's hydrogen made from water directly, and efficiently (low-energy).

Currently most of our hydrogen is made from methane, which isn't "green" because methane has carbon in it. Again, I don't care; but Our Betters make a show of caring, so the midwits care. Where I start to care is where I look at other planets which might not have the carbon but have the water ice. I'm thinking of Saturn's moons, here; and Callisto. Maybe some of those outer asteroids like Ceres. Although plenty of these have methane too.