Renewable energy is now a mainstream concern among businesses and governments across the world, and could be considered a characteristic preoccupation of our time. It is interesting to note that many of the energy technologies currently being developed date back to very different eras, and even predate the industrial revolution. The fuel cell was first invented as long ago as 1838 by the Swiss--German chemist Christian Friedrich Schönbein [1], and the idea of harnessing solar power dates back to ancient Greece [2]. The enduring fascination with new means of harnessing energy is no doubt linked to man's innate delight in expending it, whether it be to satisfy the drive of curiosity, or from a hunger for entertainment, or to power automated labour-saving devices. But this must be galvanized by the sustained ability to improve device performance, unearthing original science, and asking new questions, for example regarding the durability of photovoltaic devices [3].As in so many fields, advances in hydrogen storage technology for fuel cells have benefited significantly from nanotechnology. The idea is that the kinetics of hydrogen uptake and release may be reduced by decreasing the particle size. An understanding of how effective this may be has been hampered by limited knowledge of the way the thermodynamics are affected by atom or molecule cluster size. Detailed calculations of individual atoms in clusters are limited by computational resources as to the number of atoms that can studied, and other innovative approaches that deal with force fields derived by extrapolating the difference between the properties of clusters and bulk matter require labour-intensive modifications when extending such studies to new materials. In [4], researchers in the US use an alternative approach, considering the nanoparticle as having the same crystal structure as the bulk but relaxing the few layers of atoms near the surface. The favourable features of nanostructures for catalysis also recommend them for ethanol fuel cells, as demonstrated in the decoration of SnO₂-coated single-walled carbon nanotubes with platinum catalysts by researchers in Canada [5]Interest in solar power received an enormous boost in the early 1990s when Brian O'Regan and Michael Grätzel published work on a new way to maximise the amount of energy harvested by colloidal TiO₂ films with the use of a charge-transfer dye [6]. This approach captured attention across the community due to the large current densities, exceptional stability and low cost of the devices. This design has been modified since, using arrays of nanowires, where each nanowire provides a direct pathway to the collection electrode. In [7], researchers in the US investigate how arrays of vertical nanowires with controlled aspect ratios grow in solution, and how the nanowire aspect ratio affects the performance of nanowire-based dye-sensitized solar cells. A collaboration of researchers in China and Australia has considered how the cell performance could be improved by maximising the interface area between the indium-tin-oxide (ITO)-glass electrode and the oxide semiconductor. To this end, they synthesized arrays of ITO nanowires and ITO/TiO₂ core-shell nanowires creating a three-dimensional electrode [8]. Quantum dots have also been incorporated into solar cell devices as they have higher extinction coefficients than metal-organic dyes and their size-dependent spectral responses allow them to be tuned to optimize their performance. Until recently, molecular linkers have been required to attach the quantum dots to the electrode, creating a gap between quantum dot and electrode that is thought to diminish cell performance. Researchers in Spain and Japan have applied a new technique that allows the quantum dots to be adsorbed directly onto the electrode, yielding significant improvements to cell efficiency [9].Organic photovoltaic devices have also attracted considerable interest as a result of their flexibility and the ability to produce them at a low cost in large scales. While maximising cell efficiency has been the focus of widespread research, few studies have investigated in depth the issue of the durability of these devices. A hindrance to this sort of study is the timescale over which degradation of the components may be expected to occur, and the difficulty of correlating any accelerated degradation process with the rate in natural conditions. In this issue, researchers in Denmark and Israel present a systematic study of the feasibility of applying high intensity light exposure for accelerated testing of the stability of polymer solar cells [3]. They observe effects under accelerated conditions that do not occur under 1 sun illumination, indicating the complexity involved in gaining an understanding of the potential lifetime of these devices.The daily flurry of energy news coverage ranges in tone from impassioned debate to pragmatic financial analysis. But the underlying foundation for developments in the energy industry is a deepening scientific understanding of the potential of alternative energy sources. As demonstrated in studies of photovoltaic nanostructures, fuel cell devices and countless other innovations, nanotechnology is a key ingredient for advancing energy research. Nanotechnology is very pleased to dedicate its new Energy section to developments in this endeavour.References[1] Rubin M B 2001 Bull. Hist. Chem. 26 40–56[2] History of Solar Power 2008 www.historyofsolarpower.com[3] Tromholt T, Manor A, Katz E A and Krebs F C 2011 Nanotechnology 22 225401[4] Kim K C, Dai B, Johnson J K and Sholl D S 2009 Nanotechnology 20 204001[5] Hsu R S, Higgins D and Chen Z 2010 Nanotechnology 22 165705[6] O'Regan B and Grätzel M A 1990 Nanotechnology 353 737–40[7] Baxter J B, Walker A M, van Ommering K and Aydil E S 2006 Nanotechnology 17 S304–12[8] Wang H-W, Ting C-F, Hung M-K, Chiou C-H, Liu Y-L, Liu Z, Ratinac K R and Ringer S P 2009 Nanotechnology 20 055601[9] Giménez S et al 2009 Nanotechnology 20 295204