Research on 100% renewable energy systems is a relatively recent phenomenon. It was initiated in the mid-1970s, catalyzed by skyrocketing oil prices. Since the mid-2000s, it has quickly evolved into a prominent research field encompassing an expansive and growing number of research groups and organizations across the world. The main conclusion of most of these studies is that 100% renewables is feasible worldwide at low cost. Advanced concepts and methods now enable the field to chart realistic as well as cost- or resource-optimized and efficient transition pathways to a future without the use of fossil fuels. Such proposed pathways in turn, have helped spur 100% renewable energy policy targets and actions, leading to more research. In most transition pathways, solar energy and wind power increasingly emerge as the central pillars of a sustainable energy system combined with energy efficiency measures. Cost-optimization modeling and greater resource availability tend to lead to higher solar photovoltaic shares, while emphasis on energy supply diversification tends to point to higher wind power contributions. Recent research has focused on the challenges and opportunities regarding grid congestion, energy storage, sector coupling, electrification of transport and industry implying power-to-X and hydrogen-to-X, and the inclusion of natural and technical carbon dioxide removal (CDR) approaches. The result is a holistic vision of the transition towards a net-negative greenhouse gas emissions economy that can limit global warming to 1.5°C with a clearly defined carbon budget in a sustainable and cost-effective manner based on 100% renewable energy-industry-CDR systems. Initially, the field encountered very strong skepticism. Therefore, this paper also includes a response to major critiques against 100% renewable energy systems, and also discusses the institutional inertia that hampers adoption by the International Energy Agency and the Intergovernmental Panel on Climate Change, as well as possible negative connections to community acceptance and energy justice. We conclude by discussing how this emergent research field can further progress to the benefit of society.

Among existing and emerging technologies to recycle spent lithium-ion batteries (LIBs) from electric vehicles, pyrometallurgical processes are commercially used. However, very little is known about their environmental and energy impacts. In this study, three pyrometallurgical technologies are analyzed and compared in terms of global warming potential (GWP) and cumulative energy demand (CED), namely: an emerging direct current (DC) plasma smelting technology (Sc-1), the same DC plasma technology but with an additional pre-treatment stage (Sc-2), and a more commercially mature ultra-high temperature (UHT) furnace (Sc-3). The net impacts for the recovered metals are calculated using both “open-loop” and “closed-loop” recycling options. Results reveal that shifting from the UHT furnace technology (Sc-3) to the DC plasma technology could reduce the GWP of the recycling process by up to a factor of 5 (when employing pre-treatment, as is the case with Sc-2). Results also vary across factors, for example, different metal recovery rates, carbon/energy intensity of the electricity grid (in Sc-1 and Sc-2), rates of aluminum recovery (in Sc-2), and sources of coke (in Sc-3). However, the sensitivity analysis showed that these factors do not change the best option which was determined before (as Sc-2) except in a few cases for CED. Overall, the research methodology and application presented by this life cycle assessment informs future energy and environmental impact assessment studies that want to assess existing recycling processes of LIB or other emerging technologies. This article met the requirements for a gold–silver JIE data openness badge described at http://jie.click/badges.