Articles in 2016

The elastocaloric effect can be exploited in solid-state cooling technologies as an alternative to conventional vapour compression. Now, an elastocaloric device based on the concept of active regeneration achieves a temperature lift of 15.3 K and efficiencies competitive with other caloric-based approaches.

Political divisions are important in understanding public perceptions of unconventional oil and natural gas development, but so is proximity to drilling activities. New research highlights that, as geographical distance from development areas increases, political ideology becomes more influential in explaining diverging perceptions.

The US plays a key role in shoring up European energy security and this is unlikely to change dramatically after the November 2016 elections. However, the outcome could compound longer term risks to an internationally engaged US energy policy, affecting European energy security and diplomacy.

In terms of energy policy, the Trump presidential campaign is largely aligned with mainstream Republican positions, evoking independence and deregulation. However, Trump's rhetoric and personality might inject uncertainties into long-term energy policies, increasing the risk inherent in energy related businesses.

Technology breakthroughs will tilt the long-term balance between oil demand and the resource base of oil and gas. According to Amy Myers Jaffe, energy markets will be characterized by the growing tension between low carbon efforts led by the US and the strategies of large oil exporting countries.

Hillary Clinton's campaign has stressed her continuity with Obama's energy policy on key aspects such as decarbonization of the US economy, technological innovation and global cooperation. However, policy reforms to deliver long-term climate goals might be out of reach in a highly divided Congress.

Combining silicon and other materials in tandem solar cells is one approach to enhancing the overall power conversion efficiency of the cells. We argue that top cell partners for silicon tandem solar cells should be selected on the basis of their spectral efficiency — their efficiency resolved by wavelength.

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.

Lower-cost alternatives to platinum electrocatalysts are being explored for the sustainable production of hydrogen, but often trial-and-error approaches are used for their development. Now, principles are elucidated that suggest pathways to rationally design efficient metal-free electrocatalysts based on doped graphene.

Further global deployment of wind energy, both onshore and offshore, will depend on its future costs. Wiser et al. report the results of a survey of 163 leading experts on the possibilities of cost reduction and technological advancements by 2050.

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.

The US National Labs will continue to play a crucial role in developing energy science and technology, yet their operation is not without its problems. Anadon et al. discuss the challenges faced by the Labs and propose changes that can help them to better meet their goals.