That's more or less the pitch of the oil industry. And they seem to be very successful in getting billions in subsidy to do it. That's on top of the subsidies they are getting to exploit fossil fuels. The problem is that this is just green washing their "lets put more co2" in the atmosphere strategy for an other few decades. Because that's exactly what this is. It legitimizes that strategy and they are lobbying hard for this.

Nevertheless, transitioning grey hydrogen to blue hydrogen is probably a good thing. There's a lot of demand for hydrogen already in various industrial applications that are currently mostly using grey hydrogen. And transitioning more of our industry to hydrogen is key to de-carbonizing it. So, whether we like it or not, the hydrogen market is going to grow a lot in the next decades and it is probably going to be mostly blue+grey hydrogen for the foreseeable future produced by oil and gas companies and only little bits of green hydrogen.

The problem with green hydrogen is that it is magnitudes more expensive than blue hydrogen, which in turn is more expensive than the grey variety. Green hydrogen requires renewable energy and green hydrogen is just not a particularly efficient application of that energy as you need rather a lot of it.

A kilo of hydrogen is the equivalent of about 33 kwh. The market price of hydrogen varies wildly depending on how it is produced, transported and stored. The green variety is about 7$ per kilo. Or about 21 cents per kwh. Grey hydrogen (the dirty stuff) is about a dollar in the best cases. That's still about 3 cents per kwh. Grid prices for renewables vary widely but in the areas most likely to get involved with green hydrogen (i.e. middle east) they are between 1 and 2 cents per kwh for some recent renewable setups. So that's a factor of 3-21x depending on how you look at it. Blue hydrogen is somewhere in the bottom of that range.