Ideal photoelectrochemical systems for hydrogen production should be highly efficient, stable and scalable. Here the authors report that a perovskite-based system with promising efficiency and stability can be scaled to cells of several square centimetres in area as well as formed into mini-modules with overall area >100 cm².

Geologic formations could be used for hydrogen storage and conversion to methane, yet technical feasibility is unclear as field-scale data are lacking. Here the authors perform field tests demonstrating that hydrogen can be stored and microbially converted to methane in a depleted underground hydrocarbon reservoir.

Development ramifications of global decarbonization efforts for fossil fuel-producing low and lower–middle income countries remain underexplored. This Perspective suggests three transition pathways for navigating these ramifications.

Decision makers need sector-specific, policy-focused, dynamic economic models with rich representations of technological progress. These allow them to understand how the energy transition is likely to unfold with different policies and what its impacts might be. A new generation of models is emerging to meet these demands, but more action is needed.

Aqueous batteries, such as iodide/iodate-based ones, confront challenges due to their low energy densities. Here the authors utilize hetero-halogen electrolytes to enable fast multielectron transfer, yielding high-energy-density aqueous batteries.

A new study considers how disruption to energy systems is experienced and takes on meaning. On the basis of workshop data, the study finds that public views of heat decarbonization in the United Kingdom are shaped by relationships to family, cultural expectations, housing and financial position.

Wind farms would benefit from optimization of their design and operation. Harrison-Atlas et al. report an artificial intelligence-aided optimization approach that shows the potential of wake steering strategies to minimize land requirements and costs.

A new study assesses global small-scale nuclear power reactor deployment suitability, finding that reactors in the 1–50 MWe range could serve 70.9% of the population living in regions without night-time light. However, governance and economic issues eliminate 95% of the potential market.

Organic solar modules suffer from poor electrical contacts. Lu et al. embed the silver electrode into a polymer matrix and add chromium to enhance its electrical contact, achieving improved stability and a 14.04% efficiency on flexible modules with an active area of 41 cm².

Demonstration of high performance, upscaling and integration of ultra-lightweight perovskite solar cells are still rare. Hailegnaw et al. develop 2D perovskite solar cells based on methylbenzyl ammonium iodide with improved specific power and stability, showing scalability and integration in drones.

Annemarie Purmer discusses the importance of a sharing and inclusive safety culture in the hydrogen sector.