Articles

Biofuel prices depend on related commodities—such as corn, sugar cane and palm oil—but their connection to other non-feedstock commodities is less well explored. Filip et al. analyse a data set of 33 commodities and assets and examine their relationships to biofuels in Brazil, the US and Europe.

Intermittent renewable sources provide an ever-greater share of electricity, which changes the variability of the net load. This study models different renewables combinations over different timescales for the Nordic power system and shows how the optimal mix depends on the frequency band of the fluctuations.

Electricity is a fundamental aspect of socio-economic development. Urpelainen et al. survey 8,568 households in rural India and find that the average hours of available electricity is an important factor in household satisfaction with supply, whereas reliability and voltage stability are less important.

Luminescent solar concentrators can be used to harvest sunlight over large areas at low cost, and are promising for building-integrated photovoltaics. Li et al. fabricate such devices from silica-coated colloidal quantum dots having internal quantum efficiencies over 10% on tens of centimetres.

More efficient, noble metal-free catalysts are sought to generate hydrogen from aqueous solutions using light. Liu et al. achieve high quantum efficiencies using a system where the co-catalyst is proposed to consist of small NiS_x particles that are not anchored to the Cd_0.5Zn_0.5S photocatalyst.

Defects affect the performance of photovoltaic devices, but their exact role is still under scrutiny. Luria et al. use 3D imaging of current pathways in a working CdTe solar cell with nanoscale resolution and observe electrically active defects, which contribute to conduction.

Controlling the crystallization process of perovskite films is crucial to obtaining high efficiency in perovskite solar cells. Bi et al. propose the use of poly(methyl methacrylate) as a template for the controlled nucleation and growth of perovskite crystals achieving efficiency of 21.6%.

Solar thermoelectric generators are a promising technology for converting solar energy into electricity, however their efficiency has been limited to 5.2%. Kraemer et al. report a solar thermoelectric generator with an efficiency of 9.6%, resulting in 7.4% efficiency in a concentrating solar thermoelectric system.

Strategies to improve energy access in developing countries are urgently needed. Szabó et al. propose an approach to achieve wider access to electricity in sub-Saharan Africa that depends on existing under-utilized energy infrastructure such as dams, non-hybridized gensets and biomass cofiring.

The performance of inverted perovskite solar cells has so far lagged behind that of their normal-structure counterparts. Wu et al. fabricate an inverted perovskite–fullerene solar cell with a graded heterojunction that achieves a certified efficiency of over 18% for a cell area of 1 cm².

Metal-free doped-graphene materials are emerging as electrocatalysts for energy conversions, but their activity remains low. Here, Jiao et al. explore the origins of catalytic activity for hydrogen evolution, suggesting pathways to metal-free catalysts with activity to rival metal-containing benchmarks.

Energy harvesting from the environment by portable and flexible power sources can power a variety of devices sustainably. Chen et al. report a hybrid power textile with solar cells and triboelectric nanogenerators that can simultaneously harvest solar and mechanical energy.

Although heating and cooling consume a large fraction of global energy, current technologies are not energy efficient. Tušek et al. report an elastocaloric heat pump with active regeneration that can outperform other caloric-based cooling and heat-pumping devices.

Silicon has long been recognized as a high-energy battery electrode but its commercialization faces significant barriers. Here the authors report scalable synthesis of silicon-nanolayer-embedded graphite electrodes that display cycling stability at the industrial electrode density.

High-performing positive electrode materials are crucial for the development of aqueous Zn-ion batteries. Here the authors report a battery based on reversible intercalation of Zn ions in a layered Zn_0.25V₂O₅⋅nH₂O-based positive electrode, which exhibits high-capacity and long-term cycling stability.

Aqueous Li-ion batteries have considerably lower energy density than their non-aqueous counterparts. Here the authors report a room-temperature hydrate metal salt electrolyte that, when coupled with a spinel Li₄Ti₅O₁₂ electrode, displays an energy density of 130 Wh kg⁻¹.

There is intensive research underway into the development of fuel cells. Here, the authors present a proton exchange membrane fuel cell based on quaternary ammonium-biphosphate ion pairs, offering promising performance under a wide range of conditions that are unattainable with conventional technologies.

Solar energy can be used to evaporate water and generate steam, however this usually requires expensive optical concentrators. Ni et al. demonstrate a low-cost solar receiver based on thermal concentration that generates steam at 100 ^∘C without the need for optical concentration.

Carrier recombination in organic solar cells usually limits their optoelectronic performance, in particular their fill factor. Gasparini et al show that adding an ordered polymer to a ternary blend reduces carrier recombination, achieving a fill factor of 77%.

Large-scale adoption of electric vehicles will only occur if the needs of individual drivers are met. Here the authors present a model of the energy consumption of personal vehicles in the USA, allowing an evaluation of the adoption potential of electric vehicles.