It is assumed that women prefer clean cooking fuels due to the associated health benefits, but adoption is limited by fuel costs. Through qualitative analysis of focus group discussions, Malakar and Day find that women who use liquefied petroleum gas for cooking and those who use firewood both believe their cooking fuel supports their well-being in different ways, thus suggesting more complex trade-offs.

See Malakar et al.

Outdoor testing is key to the electrical characterization of solar cells as their performance in the field could differ to that under laboratory conditions. After extensive tests in a hot and sunny climate, Aydin et al. show that the bandgap of the perovskite absorber that maximizes the efficiency of perovskite/silicon tandems in the field is lower than that determined in the lab.

See Aydin et al.

Current collectors are needed to support electrodes and collect electrical energy from them in Li-ion batteries, however they do not contribute to the battery’s energy output. Cui et al. report a polymer-based current collector that not only makes batteries store more energy, but is safer than conventional current collectors.

See Cui et al.

Recovery in fuel demand after the COVID-19 slowdown continues to depend on healthcare and economic indicators, and shows extreme uncertainty. Ou et al. combine healthcare scenarios and cellphone mobility data in a machine-learning model to predict short-term gasoline demand in the United States and foresee a slow recovery.

See Ou et al.

Offshore wind power has been declining in price but is still considered expensive compared to other non-renewable and renewable energy sources. Jansen et al. use extensive energy auction data from five European countries to show that offshore wind energy may now be cheaper than fossil energy in many cases without subsidy.

See Jansen et al.

Building batteries with energy-dense metallic anodes requires compatible electrolytes. Yu et al. develop electrolytes with single-solvent and single-salt components through molecular design, offering promise for high-energy and long-cycle-life lithium metal batteries.

See Yu et al.

Photosynthetic and catalytic machineries from living cells can be coupled to produce hydrogen outside the cell using solar energy, though the production is short-lived. Now, Appel et al. rewire cyanobacteria to fuse these machineries in the cell, allowing the cell’s maintenance and replication mechanisms to support lasting hydrogen production.

See Appel et al. and News and Views by Lenz

Defects are normally detrimental to the power conversion efficiency of solar cells. Du et al. show that in quantum-dot-sensitized solar cells charge-trapping defects assist photoconversion and increase efficiency by supporting charge transfer to the electrodes.

See Du et al.

Cities around the world are either putting in place or considering mandatory audit laws for monitoring building energy efficiency. Using data from the application of New York’s pioneering Local Law 87, Kontokosta et al. document the impact of mandatory audits on energy use in buildings.

Kontokosta et al.

Energy use occurs in homes, workplaces and communities in which complex webs of social relations already exist, and social interactions routinely occur. This Focus issue explores how these social relations and interactions shape and are shaped by energy behaviour across a range of contexts.

Climate-induced extreme weather events can cause unexpected disruptions in the operation of all kinds of energy systems, from infrastructure all the way to finance. This Focus issue explores how extreme events, from high energy demand in heat waves to financial crashes, reverberate through various energy systems and how we can better prepare for them.

Perovskite solar cells based on formamidinium and caesium lead iodide alloys are limited in their power conversion efficiency because of their high defect density. Hao et al. show a method to increase device efficiency and stability for perovskite quantum dot solar cells by varying the concentration of ligand molecules binding to the quantum dots during alloy formation.

Hao et al.