<abstract>
<p>First, we recognize the valuable previous studies which model renewable energy growth with complete termination of fossil fuels along with assumptions of the remaining carbon budgets to reach IPCC warming targets. However, these studies use very complex combined economic/physical modeling and commonly lack transparency regarding the sensitivity to assumed inputs. Moreover, it is not clear that energy poverty with its big present impact in the global South has been eliminated in their scenarios. Further, their CO<sub>2</sub>-equivalent natural gas emission factors are underestimated, which will have significant impact on the computed greenhouse gas emissions. Therefore, we address this question in a transparent modeling study: can the 1.5 ℃ warming target still be met with an aggressive phaseout of fossil fuels coupled with a 100% replacement by renewable energy? We compute the continuous generation of global wind/solar energy power along with the cumulative carbon dioxide equivalent emissions in a complete phaseout of fossil fuels over a 20 year period. We compare these computed emissions with the state-of-the-science estimates for the remaining carbon budget of carbon dioxide emissions consistent with the 1.5 ℃ warming target, concluding that it is still possible to meet this warming target if the creation of a global 100% renewable energy transition of sufficient capacity begins very soon which will likely be needed to power aggressive negative carbon emission technology. The latter is focused on direct air capture for crustal storage. More efficient renewable technologies in the near future will make this transition easier and promote the implementation of a global circular economy. Taking into account technological improvements in 2<sup>nd</sup> law (exergy) efficiencies reducing the necessary global energy demand, the renewable supply should likely be no more than 1.5 times the present level, with the capacity to eliminate global energy poverty, for climate mitigation and adaptation.</p>
</abstract>
Czech Building Stock: Renovation Wave Scenarios and Potential for CO2 Savings until 2050
