Cooling requirements? I noticed that discussed in the report. But I think it's a non-issue. Even at the levels you assume, the heat load isn't large enough that it would need to constrain plant location. Dry cooling could handle it well enough.

More fundamentally, though, if the plant uses steam electrolysis, there's essentially no heat load at all. Electrolysis is an endothermic reaction; cell efficiency will be 100%, because ohmic and polarization losses in the cell are less than the thermal energy that the reaction will soak up. Even with recuperators on the hydrogen and oxygen exhaust streams to heat the incoming steam and help boil the water, you'll end up having to add resistance heaters to maintain temperatures in the electrolysis cells!