Constraints on Terrestrial Solar

A 2020 paper closely looked at constraints on solar power [1]. The authors considered the energy payback for solar and land use constraints to conclude that a global annual maximum of 1097 Exajoules ( 305,000 TWh ) was all that could be expected. This is equivalent to 34 TW of continuous power production. This is a surprising limit since the total primary energy consumption globally is about 160,000 TWh [2] or an average of 18 TW. This means that terrestrial solar only offers a factor of about 2 times more energy that could be collected than is currently used. Its not a lot of margin.

Using the substitution method [3], a factor of 2.5 could be applied to solar to make it comparable with fossil fuel power. This offers a factor of 5 time more usable energy. This is still not a lot of margin since the study did not include the energy payback for batteries and transmission lines.

Today, primary energy is about 18 TW, Population growth and increasing prosperity lead to an estimated need for between 95 and 123 TW of power [4] by 2100. Solar alone can not make that happen.

References
[1] Dupont, Elise & Koppelaar, Rembrandt & Jeanmart, Hervé. (2020). Global available solar energy under physical and energy return on investment constraints. Applied Energy. 257. 10.1016/j.apenergy.2019.113968.  - [LINK]
[2] Our World in Data - https://ourworldindata.org/grapher/global-primary-energy
[3] Our World in Data - https://ourworldindata.org/energy-substitution-method
[4] https://www.anthropocenemagazine.org/howmuchenergy/