If the power level and specific power of an SPS are known then an assessment of global energy requirements can lead to an estimate of the number of SPS's that need to be deployed and thus the mass of terrestrial or lunar material that needs to be place in geostationary orbit. An assessment of global energy requirements for the 21st century was done by combining the results of a carbon cycle model with an atmospheric carbon dioxide/temperature relationship and an energy/economics model. The carbon cycle model led to a conclusion that a 1% annual decrease in the use of fossil fuels is necessary to avoid a global greenhouse warming.

The number of thin-film SPS's needed may seem huge but, to put them in perspective, 230 GW also corresponds to roughly 230 new nuclear power plants coming online each year, or about one every day and a half.