Volume 4 Issue 2, February 2019

Energy return on investment (EROI) is a critical measure of the comparative utility of different energy carriers, including fossil fuels and renewables. However, it must not be used to compare carriers that cannot be put to similar end-use. In addition, combining carriers to arrive at estimates of ‘average’ or ‘minimum’ EROIs can be problematic.

In contrast to lithium-ion batteries where lithium ions carry the charge, a proton battery, making use of a hydrated Prussian blue analogue electrode, is shown to be able to transmit charges in the fashion of the Grotthuss mechanism, displaying ultrafast-rate and ultralong-life properties.

Control of electron and hole concentrations in semiconductors is a longstanding challenge. Now, by managing defect populations, a p–n homojunction solar cell has been fabricated, opening a new avenue for metal halide perovskite devices.

The answer to seasonal energy storage and security to support highly renewable power systems could lie deep under the seabed, where compressed air energy storage offers a route to long-term storage at large scales. Now, research models the potential for this in porous rock and finds a large capacity in saline aquifers offshore in the UK.

Although controversial for some, the Joint Comprehensive Plan of Action — also known as the Iran deal — offered a legal arrangement to curb Iran’s nuclear activities and limit its ability to build weapons. This Review examines the deal’s technical basis and how it could be applied in other contexts.

Integrating electrocatalytic H₂ production with biological H₂-fed systems for CO₂ upgrading requires H₂ generation to occur in biocompatible media—typically with neutral pH. Here, the authors design multi-site H₂ evolution catalysts that minimize the water dissociation barrier and promote hydride coupling in neutral media.

Metal–organic frameworks (MOFs) are increasingly being explored as electrocatalysts for the oxygen evolution and reduction reactions, which are important processes in electrolysers and fuel cells. Here, the authors increase the activity of MOFs for these reactions by introducing strain into the lattice using UV light illumination.

This Article presents a battery with protons as the charge carrier, as opposed to Li-ion batteries, which rely on the transport of Li-ions. Protons are conducted by means of the Grotthuss mechanism in a hydrated Prussian blue analogue electrode, offering potential for ultrafast rate and long-life batteries.

Compressed-air energy storage could be a useful inter-seasonal storage resource to support highly renewable power systems. This study presents a modelling approach to assess the potential for such storage in porous rocks and, applying it to the UK, finds availability of up to 96 TWh in offshore saline aquifers.

Blockchain-based distributed management of electricity systems is an important step towards making these systems more resilient. Although there are many implementations, here the researchers formalize a basic template for smart contracts that can be built upon for distributed electricity systems management.

Carrier recombination limits the power conversion efficiency of perovskite solar cells. Here the authors construct a planar p–n homojunction perovskite solar cell to promote the oriented transport of carriers and reduce recombination, thus enabling power conversion efficiency of 21.3%.

Electric aircraft offer an aviation decarbonization pathway and attract increasing attention owing to the rapid development of batteries. Here Andreas Schäfer and colleagues analyse the potential technological, economic and environmental viability of battery-electric commercial aircraft.