Some of the geoengineering proposals include injection of aerosols into the upper atmosphere to reflect sunlight, "salting" the oceans with iron to encourage growth of zooplankta, use of large very thin sheets in space to reflect sunlight, growing and burying lots and lots and lots of trees ...
One would think geothermal of the hot rocks type would work in Hawaii where electricity is very expensive and hot rocks are at the surface. Indeed, there is a Federal geothermal research facility there and has been for decades. It has a small array of PV cells outside. I think it's more a demonstration thing than real, but whatever, they have major issues with hot rock geothermal in Hawaii. That is the state where this and wind and solar make the most sense because the alternative electricity source is burning imported petroleum. Winds are almost constant and reliable.
Wind and solar are growing in importance in the state. They still burn oil.
