Reviews & Analysis

The conversion of low-grade waste heat into electrical energy is an attractive opportunity to harvest a sustainable energy resource. A thermo-osmotic energy conversion process that uses Earth-abundant materials has now been shown to convert waste heat into electrical energy from sources at temperatures as low as 40 °C.

Persistent and significant curtailment has cast concern over the prospects of wind power in China. A comprehensive assessment of the production of energy from wind has identified grid-integrated wind generation potential at 11.9–14% of China's projected energy demand by 2030.

Energy storage offers potential to support a changing electricity sector, but investors remain uncertain about its attractiveness. Analysis now shows that this can be overcome for battery technology by providing more than one storage service in a single facility.

Coupling high ionic and low electronic conductivity in the electrolyte of low-temperature solid-oxide fuel cells remains a challenge. Now, the electronic conductivity of a perovskite electrolyte, which has high proton conductivity, is shown to be heavily suppressed when exposed to hydrogen, leading to high fuel cell performance.

Combatting climate change is often considered to bring about security of energy supply by reducing reliance on imports. By modelling the impact of pursuing energy security policies, a study now finds that the inverse situation is less advantageous for the global climate.

Redox mediators facilitate the oxidation of the highly insulating discharge product in metal–oxygen batteries during recharge and offer opportunities to achieve high reversible capacities. Now a design principle for selecting redox mediators that can recharge the batteries more efficiently is suggested.

China has the largest installed capacity of wind farms, yet its wind energy electricity output is lower than that of other countries. A new analysis of the relative contributions of the factors influencing China's wind sector could help policy makers prioritize solutions.

Economic agents have varying expectations on oil price fluctuations that play an important role in determining the timing and magnitude of oil price shocks. A study now shows that heterogeneous expectations should be included when modelling oil price shocks to grasp their impact on macroeconomic outcomes and energy policies.

Oxygen reduction at the cathode of fuel cells typically requires a platinum-based material to catalyse the reaction, but lower-cost, more stable catalysts are sought. Now, an intrinsically conductive metal–organic framework based on cheaper elements is shown to be a durable, structurally well-defined catalyst for this reaction.

Rechargeable aqueous batteries are attractive energy storage technologies owing to their low cost and high safety, but suffer from poor electrochemical performance. Now, an aqueous mild-acid-based Zn/MnO₂ battery that operates via a conversion mechanism is shown to have a long-term cycling stability.

The resilience of distribution power grids is put to the test by daily operations as well as by extreme weather events such as hurricanes. An analysis of blackout data in upstate New York now reveals that larger blackouts have a disproportionate effect on grid reliability.

Doping graphitic materials is desirable to enhance their performance for energy conversion and storage applications, but achieving high dopant concentrations remains a challenge. Researchers now demonstrate synthesis of such materials with very high doping levels and facile tunability.

Public investment in science and technology is critical for meeting future energy needs, although understanding its impact has remained unclear. Now, an analysis of publications resulting from government funding sheds light on its outcomes and the timescales required to see them.

Materials with high ionic conductivity are urgently needed for the development of solid-state lithium batteries. Now, an inorganic solid electrolyte is shown to have an exceptionally high ionic conductivity of 25 mS cm⁻¹, which allows a solid-state battery to deliver 70% of its maximum capacity in just one minute at room temperature.

Waste heat can be converted to electricity by thermoelectric generators, but their development is hindered by the lack of cheap materials with good thermoelectric properties. Now, carbon-nanotube-based materials are shown to have improved properties when purified to contain only semiconducting species and then doped.

The chemistry of the discharge products of metal–oxygen batteries is related to the battery's efficiency but knowledge of their formation mechanism is incomplete. Now, the initial discharge product in sodium–oxygen batteries is shown to be sodium superoxide, which undergoes dissolution and then transforms to sodium peroxide dihydrate.

The oxidation of water is essential to the sustainable production of fuels using sunlight or electricity, but designing active, stable and earth-abundant catalysts for the reaction is challenging. Now, a complex containing five iron atoms is shown to efficiently oxidize water by mimicking key features of the oxygen-evolving complex in green plants.

The transport sector must undergo radical changes if it is to reduce its carbon emissions, calling for alternative vehicles and fuel types. Researchers now analyse the expectation cycles for different fuel technologies and draw lessons for the role of US policy in supporting them.

The performance of CdTe solar cells — cheaper alternatives to silicon photovoltaics — is hampered by their low output voltages, which are normally well below the theoretical limit. Now, record voltages of over 1 V have been reported in single-crystal CdTe heterostructure solar cells, which are close to those of benchmark GaAs cells.

Micrometre-sized silicon particles are attractive negative-electrode materials for lithium-ion batteries but are prone to mechanical failure during electrochemical cycling. Now, graphene cages grown conformally around the micro-silicon particles are shown to improve their cycling stability.