What is meant by this statement: hydrogen is only as environmentally clean as the energy used to make it.?

Agree with Metaphor; the point presumably being made is that Hydrogen could be considered clean since it`s relatively inert and non-polluting, but in order to EXIST as hydrogen -not it`s natural state- processes have to be carried out to extract or disengage it from whence it has come, and therefore the energy used / pollution caused etc., by these processes are part -even if unjustly, the hydrogen was probably quite content on its` own!- of the `footprint` of the Hydrogen itself. Sorry.