which regulate reimbursement in the case of nationalisation.

Which is to be equitable between the interest of the owners and society. That is, in a nutshell, below market value.

that could just as easily be interpreted as the energy they produce being in the service of energy production for the entire country

Yeah no that's not how externalities work. They're creating damage with that coal, even to break even it has to be curbed in some way, much less for them to do good. If you want to mount that defence don't create externalities.

As for your landlord comment, which honestly is an entirely different matter in and of itself, that basically won’t fall under ‘land, natural resources or means of production’,

For those big landlords those apartments are means of production of rent. Wouldn't work for smaller investors or even private abodes but we're talking about companies with 2000+ (IIRC) apartments, here.