Most important steps to build out a completely renewable energy system
On January 21, 2021 a new paper (Williams et al. 2021) was published that claims that an energy system can provide 100% carbon free energy to power the entire economy of the USA economically. This paper describes how to build an energy system that provides all energy to the economy and releases no carbon into the atmosphere by 2050. This conclusion is similar to Jacobson et al. 2018 (Jacobson et al 2015 at SkS) and Connelly et al. 2016 previously described here at SkS. Williams et al modeled eight different scenarios representing slightly different pathways to reach net zero and net negative CO2 emissions by 2050. The cheapest option uses some fossil fuels with carbon capture and storage (CCS) and has a small amount of nuclear power. A completely renewable energy system with no fossil fuels or nuclear is slightly more expensive. Building a comparable system for other countries would be similar.