Roadmaps to net-zero emissions systems: Emerging insights and modeling challenges

Abstract

<h2>Summary</h2> Understanding economic and technical characteristics of net-zero emissions energy systems is important, given the growing number of national, subnational, and company net-zero targets. Emerging modeling studies examine how to achieve these net-zero goals, but differences across countries, model structures, and input assumptions make comparisons difficult. This perspective reviews insights from country-level studies on net-zero emissions systems. There is robust agreement on near-term "low regrets" strategies: rapid reduction of coal generation and expansion of renewables in the power sector; lower fossil fuel use; end-use efficiency improvements; electrification of end uses especially in transportation; and research, development, and deployment to buy down learning curves for emerging technologies that might be valuable for deeper decarbonization. However, although nearer-term trends are qualitatively similar, studies exhibit variation in decarbonization strategies, especially as net-zero goals are approached. Net-zero emissions targets lead to shifts toward clean electricity and declines in fossil fuel use, though magnitudes of these changes vary considerably across countries, models, and scenarios. This work also highlights modeling and analysis needs moving forward, including ways to provide more actionable information for stakeholders and research gaps where collaborations are increasingly valuable.