Depends if the spheres require any steel reinforcement; the salt penetrates the concrete and absolutely wrecks rebar. Though I imagine spheres at depth (not to mention with a partial vacuum) can function like an arch and support themselves with compression, which concrete excels at.
We have seawater resistant concrete. We don’t need to plastic line it. It’s the turbine that’ll require the most maintenance.
Depends if the spheres require any steel reinforcement; the salt penetrates the concrete and absolutely wrecks rebar. Though I imagine spheres at depth (not to mention with a partial vacuum) can function like an arch and support themselves with compression, which concrete excels at.