We don't have that much excess power generation. We even have to occasionally limit power delivery to heavy users
Increasing power generation that much requires tough choices: we'd have to ruin the environment some way. We just don't have that many locations left for hydro or geothermal. Most locations that remain are popular tourist sites—destroying them would be bad for the economy—important ecosystems, or would require improvements to the grid that nobody seems to be willing to pay for