Understanding energy transitions

Transitions to cleaner, renewable energy are at the heart ofpolicies in many countries. The focus on renewables has, ifanything, become greater recently as uncertainty growsabout the viability and acceptability of alternatives toachieve low-carbon growth, including nuclear power andcarbon capture and storage (REN21 2010). The Fukushimaaccident has forced many governments to rethink theirnuclear energy plans—Japan has just shutdown their lastnuclear power plant, and Germany announced last year itwill be nuclear free by 2022. But transitions away fromfossil fuel-based energy systems have proven slow despitethe potential of renewable energy sources and advancingtechnologies to utilize them.Recent research in ‘Transitions Studies’ argues thattransitions will not be a technological fix but will requiresome combination of economic, political, institutional andsocio-cultural changes (Berkhout et al. 2009; Cohen et al.2010; Stephens et al. 2008). Without doubt, these transi-tions must be guided by an ethics that brings togethertechnology and sustainability. In the introductory messageto this special issue, Jean-Louis Armand calls for such anethic of long-range responsibility—one that is properlyembedded in sustainability science as a guide for ourfuture.In response to this complex issue, Sustainability Sciencehas organized a special issue on two related themes—thecosts of mitigating greenhouse gas (GHG) emissions andthe diffusion of clean energy technologies. The first fourpapers model abatement costs for world regions andsectors with a focus on medium term GHG emissiontargets (2020 and 2030)—a key step in stabilizing long-term climate change under the United Nations FrameworkConvention on Climate Change (UNFCCC). These studiesfind that transitions toward a low-carbon society are notan extension of the current trends, and far greater GHGreductions—both on national and global scales—arerequired in the mid-term. A further five papers explore thebarriers and opportunities of energy transitions on theground, using transition management theories to explainempirical cases in India, Japan, Malaysia and the UnitedStates.Hanaoka and Kainuma conduct a comparison of GHGmarginal abatement cost (MAC) curves from 0 to200 US $/tCO