The truth is that renewables (well, aside from biomass; that's usually what those arguments boil down to, so don't use biomass as your renewable source) scale just fine. The Earth is constantly struck by 100,000 terawatts of sunlight, and global primary energy demand is less than 20 terawatts.
In the very long term, humanity might face a problem with exposure of crustal rocks by mining operations. This causes reducing materials in the rocks to react with atmospheric oxygen, gradually depleting that oxygen. The long term solution to that will be to bury some reduced materials to compensate (the production of those materials released oxygen when oxides or CO2 were reduced). So, some level of sustained burial of waste material is not only acceptable, it's likely to be necessary.