Analyses

Published energy-return-on-investment ratios for fossil fuels have not always been estimated at the final point of use. By including all energy required for processing and the supply chain, Brockway et al. find that fossil fuels might have final energy return close to renewables and susceptible to rapid further decline in the near future.

The Beijing Municipality has implemented a programme that subsidizes electric heat pumps and electricity, and bans coal. This study estimates the programme’s impact on household energy use and expenditure, well-being and indoor environment quality.

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.

Multilateral development banks are known to finance a significant number of new power plants in low-income countries, and have been pushing for more renewables. Here, researchers build a bottom-up dataset of more than 800 projects from 10 banks to quantify the extent to which these banks have greened their portfolios.

Although rigid silicon panels dominate the solar power market, they are unsuitable for niche applications such as portable charging or drones, where thin-film and flexible technologies would be advantageous. This Analysis examines the needs of niche markets and the packaging weights that would be required to enable such photovoltaic devices to enter them.

Germany is the first major country to pursue an energy transition based on decentralized renewables. This Analysis finds that news media coverage of the ‘Energiewende’ in the United Kingdom, Finland and Hungary focuses on techno-economics, but normative assessments reflect local visions of a good society.

Understanding the water–energy nexus requires a detailed picture of how the two resources are linked. Towards this end, Chini et al. combine concepts of virtual water transfers with water-usage data for electricity generation to visualize and analyse the virtual water transfers for the US electricity grid from 2010–2016.

In the Middle East, new solar projects are being launched where developers have agreed to provide solar energy at record-low costs to utilities. Here, researchers analyse the key factors contributing to the low cost, showing that it is possible to replicate similar costs in other parts of the world.

Achieving sustainable development goals while meeting the 1.5 °C climate target requires radical changes to how we use energy. A scenario of low energy demand shows how this can be done by down-sizing the global energy system to enable feasible deployment rates of renewable energy resources.

Predictability of energy quantities such as natural gas price and oil production is important for planning and finance not just in energy markets but national economies. Here, researchers show that the energy industry was more volatile and harder to predict in the last decade than previous decades.

Energy systems are transitioning from fossil fuel sources to renewable sources with lower net energy generation. Using the concept of energy return on investment, this study finds that net energy per capita is likely to greatly decrease without more efficiency savings or energy infrastructure.

Governments give a variety of subsidies to fossil fuel companies, but G20 nations have committed to phasing these out. Erickson et al. analyse subsidies provided to new crude oil fields in the US and find that, at current oil prices, nearly half of them depend on these subsidies to proceed.

Clean energy sources bring environmental and health benefits by reducing traditional electricity sources. Millstein et al. analyse data from 2007–2015 on the expansion of solar and wind power in the US to explore impacts in terms of air pollution, avoided emissions and associated premature mortality.

Electrical energy storage is expected to be important for decarbonizing personal transport and enabling highly renewable electricity systems. This study analyses data on 11 storage technologies, constructing experience curves to project future prices, and explores feasible timelines for their economic competitiveness.

Concentrating solar power with thermal storage offers dispatchable renewable power but has enjoyed less support than photovoltaics. This study of global concentrating solar power projects finds a learning rate of 20%, which should be sustained if policy support and industrial development continue.

Reforms of energy markets are necessary to face the low carbon transition but are problematic to measure. New data evaluate implicit taxes and subsidies for gasoline in almost all countries at monthly intervals showing mixed results that highlight the difficulty in implementing effective policy tools.

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.

Climate policies are frequently argued to achieve energy independence as an additional benefit. Jewell et al. use five energy-economy models to show that the opposite is not true: constraining energy imports is much cheaper than climate change mitigation but would not significantly reduce emissions.

Several factors, such as wind power curtailment and quality of turbines, cause a reduced capacity of wind energy production in China compared with the US. The authors quantify the relative weight that these factors have in limiting the wind power output in China, and provide policy recommendations.

Alternative fuel technologies are crucial to decarbonize transport, but attention has shifted among options over time. This study presents an analysis of media, innovation and funding data for these different options and recommends actions to help move beyond hype to support technology adoption.