30 % efficient power plant? That is low, like… below the level of a stationary diesel engine (generator). A cogenerating power plant is at 60 % and can be as high as 80 % when the thermal energy can be used near the power plant.

In other words: you are correct when you compare to such an outdated power plant, but since you already have to build new, you need to compare to a new, efficient plant without hydrogen generation.

Even in the context of nuclear power, 30 % is very low and a new reactor would be at nearly 50 % just for electricity. But with nuclear the hydrogen generation would make sense, but absolutely not for use in fuel cells. Hydrogen is needed everywhere where they currently need to use methane.