Moral hazard in fossil-energy-reliant markets delays early adoption of net-zero technologies.

We use an analytical real option approach to conceptualize and formalize the interaction between long-term climate policies, such as the IRA, and short-term policies intended to protect consumers from volatile fossil-energy prices. An example of the latter is the US releasing strategic oil reserves to lower gas prices. The framework we develop suggests that those short-term policies, which effectively counter incentives created by long-term climate policies, create a moral hazard in fossil-energy-reliant markets. This, in turn, causes early adopters of net-zero technologies to delay their investment. Ultimate adopters, however, do not change their investment decision. The result of this asymmetric reaction to policies is an intensified gradient of the adoption curve of technology, which potentially puts pressure on various supply chains, the financial system, and ultimately government finances. This work is conceptual and does not include an empirical case study since data are too limited in time.

Uncovering the differentiated impacts of carbon neutrality and clean air policies in multi-provinces of China.

Ambitious action plans have been launched to address climate change and air pollution. Through coupling the IMED|CGE, GAINS, and IMED|HEL models, this study investigate the impacts of implementing carbon neutrality and clean air policies on the energy-environment-health-economy chain in the Beijing-Tianjin-Hebei-Henan-Shandong-Shanxi region of China. Results show that Shandong holds the largest reduction in energy consumption and carbon emissions toward the 1.5°C target. Shandong, Henan, and Hebei are of particularly prominent pollutant reduction potential. Synergistic effects of carbon reduction on decreasing PM2.5 concentration will increase in the future, specifically in energy-intensive regions. Co-deployment of carbon reduction and end-of-pipe technologies are beneficial to decrease PM2.5-related mortalities and economic loss by 4.7-12.9% in 2050. Provincial carbon reduction cost will be higher than monetary health benefits after 2030, indicating that more zero-carbon technologies should be developed. Our findings provide scientific enlightenment on policymaking toward achieving carbon reduction and pollution mitigation from multiple perspectives.

Mapping carbon reduction: A cross-continental study of alliance strategies.

Addressing the equitable distribution of global carbon emission rights is critical for sustainable development. Our research develops a detailed framework for a Global Carbon Reduction Alliance based on regional cooperation strategies, identifying key modes of intracontinental proximity and intercontinental distance collaboration. It emphasizes alliances formed among high carbon emission right countries and leadership-driven models propelling low carbon emission right countries, offering insights for optimizing emission reduction efforts. The analysis highlights the strategic role of developing nations in Africa and Asia, as well as developed regions in Europe and North America, advocating for the adoption of clean energy, enhancement of forest economic value, acceleration of urbanization, and an increased contribution of the service sector to the economy as essential pathways to achieving net-zero emissions. Our approach advocates for a comprehensive model of global carbon reduction cooperation, aiming at the equitable distribution of carbon emission rights and supporting the sustainable development goals.

Data-driven models and digital twins for sustainable combustion technologies.

We highlight the critical role of data in developing sustainable combustion technologies for industries requiring high-density and localized energy sources. Combustion systems are complex and difficult to predict, and high-fidelity simulations are out of reach for practical systems because of computational cost. Data-driven approaches and artificial intelligence offer promising solutions, enabling renewable synthetic fuels to meet decarbonization goals. We discuss open challenges associated with the availability and fidelity of data, physics-based numerical simulations, and machine learning, focusing on developing digital twins capable of mirroring the behavior of industrial combustion systems and continuously updating based on newly available information.

Forging a sustainable sky: Unveiling the pillars of aviation e-fuel production for carbon emission circularity.

In 2021, airplanes consumed nearly 250 million tons of fuel, equivalent to almost 10.75 exajoules. Anticipated growth in air travel suggests increasing fuel consumption. In January 2022, demand surged by 82.3%, as per the International Air Transport Association. In tackling aviation emissions, governments promote synthetic e-fuels to cut carbon. Sustainable aviation fuel (SAF) production increased from 1.9 million to 15.8 million gallons in six years. Although cost of kerosene produced with carbon dioxide from direct air capture (DAC) is several times higher than the cost of conventional jet fuel, its projected production cost is expected to decrease from $104-$124/MWh in 2030 to $60-$69/MWh in 2050. Advances in DAC technology, decreasing cost of renewable electricity, and improvements in FT technology are reasons to believe that the cost of e-kerosene will decline. This review describes major e-kerosene synthesis methods, incorporating DAC, hydrogen from water electrolysis, and hydrocarbon synthesis via the Fischer-Tropsch process. The importance of integrating e-fuel production with renewable energy sources and sustainable feedstock utilization cannot be overstated in achieving carbon emission circularity. The paper explores the concept of power-to-liquid (PtL) pathways, where renewable energy is used to convert renewable feedstocks into e-fuels. In addition to these technological improvements, carbon pricing, government subsidies, and public procurement are several policy initiatives that could help to reduce the cost of e-kerosene. Our review provides a comprehensive guide to the production pathways, technological advancements, and carbon emission circularity aspects of aviation e-fuels. It will provide a valuable resource for researchers, policymakers, industry stakeholders, and the general public interested in transitioning to a sustainable aviation industry.

Elucidation of temperature-induced water structuring on cellulose surfaces for environmental and energy sustainability.

Optimizing drying energy in the forest products industry is critical for integrating lignocellulosic feedstocks across all manufacturing sectors. Despite substantial efforts to reduce thermal energy consumption during drying, further enhancements are possible. Cellulose, the main component of forest products, is Earth's most abundant biopolymer and a promising renewable feedstock. This study employs all-atom molecular dynamics (MD) simulations to explore the structural dynamics of a small Iß-cellulose microcrystallite and surrounding water layers during drying. Molecular and atomistic profiles revealed localized water near the cellulose surface, with water structuring extending beyond 8 Å into the water bulk, influencing solvent-accessible surface area and solvation energy. With increasing temperature, there was a ∼20 % reduction in the cellulose surface available for interaction with water molecules, and a ∼22 % reduction in solvation energy. The number of hydrogen bonds increased with thicker water layers, facilitated by a "bridging" effect. Electrostatic interactions dominated the intermolecular interactions at all temperatures, creating an energetic barrier that hinders water removal, slowing the drying processes. Understanding temperature-dependent cellulose-water interactions at the molecular level will help in designing novel strategies to address drying energy consumption, advancing the adoption of lignocellulosics as viable manufacturing feedstocks.

Digital inclusion to enhance energy sustainability: public participation and environmental governance in the new media era to achieve energy sustainable goals.

Renewable energy not only helps to safeguard the environment and slow down climate change but also supports economic growth and energy security. The significance of renewable energy sources is expanding as more people throughout the globe understand how important it is to switch to clean energy sources. Therefore, empirics are in search of the factors that can promote renewable energy production. This analysis investigates some of the novel determinants of renewable energy production, such as digital inclusion, public participation, and environmental governance, which have not been examined previously in any study. For empirical analysis, the study employs the ARDL and QARDL estimation techniques using Chinese data from 1998Q1 to 2021Q4. The analysis findings confirm that digital financial inclusion, ICT, and GDP are vital in boosting both short and long-run renewable production. Green investment, environmental governance, and carbon emissions also significantly and favourably impact long-run renewable energy production. In the Quantile ARDL model, digital financial inclusion is positively linked to renewable energy production at most of its quantiles in the short and long run, while the ICT, GDP, environmental governance, and carbon emissions are positively linked to renewable energy in most quantiles in the long-run only. The Wald test confirms the asymmetric impact for all variables in the long run, which implies that policymakers should consider the positive and negative changes in these factors while devising policies for enhancing renewable energy production.

Solar-driven thermochemical conversion of H2O and CO2 into sustainable fuels.

Solar-driven thermochemical conversion of H2O and CO2 into sustainable fuels, based on redox cycle, provides a promising path for alternative energy, as it employs the solar energy as high-temperature heat supply and adopts H2O and CO2 as initial feedstock. This review describes the sustainable fuels production system, including a series of physical and chemical processes for converting solar energy into chemical energy in the form of sustainable fuels. Detailed working principles, redox materials, and key devices are reviewed and discussed to provide systematic and in-depth understanding of thermochemical fuels production with the aid of concentrated solar power technology. In addition, limiting factors affecting the solar-to-fuel efficiency are analyzed; meanwhile, the improvement technologies (heat recovery concepts and designs) are summarized. This study therefore sets a pathway for future research works based on the current status and demand for further development of such technologies on a commercial scale.

India's photovoltaic potential amidst air pollution and land constraints.

India aims for ambitious solar energy goal to fulfill its climate commitment but there are limited studies on solar resource assessment considering both environmental and land availability constraints. The present work attempts to address this issue using satellite-derived air pollution, radiation, and land use data over the Indian region. Surface insolation over India has been decreasing at a rate of -0.29 ± 0.19 Wm-2 y-1 between 2001 and 2018. Solar resources over nearly 98%, 40%, and 39% of the Indian landmass are significantly impacted by aerosols, clouds, and both aerosols and clouds respectively. Only 29.3% of the Indian landmass is presently suitable for effective solar photovoltaic harnessing, but this is further declining by -0.21% annually, causing a presumptive loss of 50 GW solar potential, translating 75 TWh power generation. Lowering two decades of aerosol burden can make 8% additional landmass apt for photovoltaic use. Alleviating aerosol-induced dimming can fast-track India's solar energy expansion.

Small wind turbines and their potential for internet of things applications.

Wind energy is crucial for meeting climate and energy sustainability targets. Small wind turbines (SWTs) have gained significant attention due to their size and adaptability. These turbines have potential for Internet of Things (IoT) applications, particularly in powering large areas and low-power devices. This review examines SWTs for IoT applications, providing an extensive overview of their development, including wind energy rectifiers, power generation mechanisms, and IoT applications. The paper summarizes and compares different types of wind energy rectifiers, explores recent advancements and representative work, and discusses applicable generator systems such as electromagnetic, piezoelectric, and triboelectric nanogenerators. In addition, it thoroughly reviews the latest research on IoT application scenarios, including transportation, urban environments, intelligent agriculture, and self-powered wind sensing. Lastly, the paper identifies future research directions and emphasizes the potential of interdisciplinary technologies in driving SWT development.

Machine learning approaches reveal highly heterogeneous air quality co-benefits of the energy transition.

Estimating health benefits of reducing fossil fuel use from improved air quality provides important rationales for carbon emissions abatement. Simulating pollution concentration is a crucial step of the estimation, but traditional approaches often rely on complicated chemical transport models that require extensive expertise and computational resources. In this study, we develop a machine learning framework that is able to provide precise and robust annual average fine particle (PM2.5) concentration estimations directly from a high-resolution fossil energy use dataset. Applications of the framework with Chinese data reveal highly heterogeneous health benefits of avoiding premature mortality by reducing fossil fuel use in different sectors and regions in China with a mean of $19/tCO2 and a standard deviation of $38/tCO2. Reducing rural and residential coal use offers the highest co-benefits with a mean of $151/tCO2. Our findings prompt careful policy designs to maximize cost-effectiveness in the transition toward a carbon-neutral energy system.

Exploring carbohydrate extraction from biomass using deep eutectic solvents: Factors and mechanisms.

Deep eutectic solvents (DESs) are increasingly being recognized as sustainable and promising solvents because of their unique properties: low melting point, low cost, and biocompatibility. Some DESs possess high viscosity, remarkable stability, and minimal toxicity, enhancing their appeal for diverse applications. Notably, they hold promise in biomass pretreatment, a crucial step in biomass conversion, although their potential in algal biomass carbohydrates extraction remains largely unexplored. Understanding the correlation between DESs' properties and their behavior in carbohydrate extraction, alongside cellulose degradation mechanisms, remains a gap. This review provides an overview of the use of DESs in extracting carbohydrates from lignocellulosic and algal biomass, explores the factors that influence the behavior of DESs in carbohydrate extraction, and sheds light on the mechanism of cellulose degradation by DESs. Additionally, the review discusses potential future developments and applications of DESs, particularly extracting carbohydrates from algal biomass.

Fundamentals, rational catalyst design, and remaining challenges in electrochemical NOx reduction reaction.

Nitrogen oxides (NOx) emissions carry pernicious consequences on air quality and human health, prompting an upsurge of interest in eliminating them from the atmosphere. The electrochemical NOx reduction reaction (NOxRR) is among the promising techniques for NOx removal and potential conversion into valuable chemical feedstock with high conversion efficiency while benefiting energy conservation. However, developing efficient and stable electrocatalysts for NOxRR remains an arduous challenge. This review provides a comprehensive survey of recent advancements in NOxRR, encompassing the underlying fundamentals of the reaction mechanism and rationale behind the design of electrocatalysts using computational modeling and experimental efforts. The potential utilization of NOxRR in a Zn-NOx battery is also explored as a proof of concept for concurrent NOx abatement, NH3 synthesis, and decarbonizing energy generation. Despite significant strides in this domain, several hurdles still need to be resolved in developing efficient and long-lasting electrocatalysts for NOx reduction. These possible means are necessary to augment the catalytic activity and electrocatalyst selectivity and surmount the challenges of catalyst deactivation and corrosion. Furthermore, sustained research and development of NOxRR could offer a promising solution to the urgent issue of NOx pollution, culminating in a cleaner and healthier environment.

A systematic review on tannery sludge to energy route: Current practices, impacts, strategies, and future directions.

The growing amount of tannery sludge (TS) generated from leather processing often undergoes uncontrolled landfilling, or open dumping, releasing a significant volume of harmful pollutants, including carcinogenic chromium (Cr) into the air, water, and soil. Therefore, the sustainable TS management through advanced valorization technologies becomes vital to align with the Sustainable Development Goals (SDGs) and mitigate the adverse environmental, health, and social impacts. Moreover, TS, as biomass, can be considered a renewable energy source for bioenergy generation, which could be a viable solution for meeting contemporary environmental standards and expediting transition towards a circular economy. However, TS valorization is sensitive and critical due to the potential risk of transforming Cr(III) to Cr(VI) during the valorization process. Therefore, there is an urgency to consider efficient and holistic TS valorization technologies in the design, implementation, and operations phases to avoid any environmental and health hazards. In pursuit of this goal, this systematic literature review (SLR) comprehensively and critically analyzes the existing TS valorization processes to develop sustainable energy recovery solutions from TS. This SLR contributes uniquely to the existing literature in different ways. Firstly, it provides a critical evaluation of the current TS valorization technologies identifying the available waste-to-energy recovery options. Secondly, the review encompasses extensive research from three reputed databases such as Scopus, Web of Science, and ScienceDirect, without temporal restrictions to offer a comprehensive understanding of current TS management practices and available valorization techniques. Moreover, the review categorized 124 published papers into distinct groups, revealing promising avenues for future research in this field. The findings indicated that most of the work concentrating on Chrome (Cr) recovery, pyrolysis, anaerobic co-digestion, and solidification while gasification and biodiesel or biofuel production from TS remained largely unexplored. Additionally, vital aspects such as process optimization, life cycle assessment of different valorization techniques, environmental, economy, energy, emergy, and exergy (5E) analysis, life cycle energy balance, and techno-economic analysis including exergoeconomic and exergoenvironmental are completely absent in the literature. Future studies need to concentrate on process optimization, exergy and energy analysis, and techno-economic assessment including exergoeconomic and exergoenvironmental analysis to understand the feasibility and environmental benefits of various TS valorization technologies and to develop industry-scale valorization plants for TS management in an economically and ecologically sustainable manner. Moreover, the review will serve as a comprehensive guide for scholars, authorities, and stakeholders to advance research in this field and formulate policies for the eco-friendly management of TS, paving the way towards clean energy solutions.

Life Cycle Assessment of Closed-Loop Pumped Storage Hydropower in the United States.

The United States has begun unprecedented efforts to decarbonize all sectors of the economy by 2050, requiring rapid deployment of variable renewable energy technologies and grid-scale energy storage. Pumped storage hydropower (PSH) is an established technology capable of providing grid-scale energy storage and grid resilience. There is limited information about the life cycle of greenhouse gas emissions associated with state-of-the-industry PSH technologies. The objective of this study is to perform a full life cycle assessment of new closed-loop PSH in the United States and assess the global warming potential (GWP) attributed to 1 kWh of stored electricity delivered to the nearest grid substation connection point. For this study, we use publicly available data from PSH facilities that are in the preliminary permitting phase. The modeling boundary is from facility construction to decommissioning. Our results estimate that the GWP of closed-loop PSH in the United States ranges from 58 to 530 g CO2e kWh-1, with the stored electricity grid mix having the largest impact, followed by concrete used in facility construction. Additionally, PSH site characteristics can have a substantive impact on GWP, with brownfield sites resulting in a 20% lower GWP compared to greenfield sites. Our results suggest that closed-loop PSH offers climate benefits over other energy storage technologies.

In-depth understanding of boosting salinity gradient power generation by ionic diode.

Ionic diodes constructed with asymmetric channel geometry and/or charge layout have shown outstanding performance in ion transport manipulation and reverse electrodialysis (RED) energy collection, but the working mechanism is still indistinct. Herein, we systematically investigated RED energy conversion of straight nanochannel-based bipolar ionic diode by coupling the Poisson-Nernst-Planck and Navier-Strokes equations. The effects of nanochannel structure, charging polarity, and symmetricity as well as properties of working fluids on the output voltage and output power were investigated. The results show that as high-concentration feeding solution is applied, the bipolar ionic diode-based RED system gives higher output voltage and output power compared to the unipolar channel RED system. Under optimal conditions, the voltage output of the bipolar channel is increased by ∼100% and the power output is increased by ∼260%. This work opens a new route for the design and optimization of high-performance salinity energy harvester as well as for water desalination.

Temperature-adaptive rooftop covering with synergetic modulation of solar and thermal radiation for maximal energy saving.

The energy consumption for maintaining desired indoor temperature accounts for 20% of primary energy use worldwide. Passive rooftop modulation of solar/thermal radiation without external energy input has a great potential in building energy saving. However, existing passive rooftop modulation techniques failed to simultaneously modulate solar/thermal radiation in response to rooftop surface temperature which is closely related to the building thermal loads, leading to limited or even counter-productive overall energy saving. Here, we report the development of a surface temperature-adaptive rooftop covering with synergetic solar and thermal modulations. The covering, made of a scalable metalized polyethylene film, demonstrated excellent solar absorptance modulation (72.5%) and thermal emissivity modulation (79%) in response to its temperature change from 22°C (indoor heating setpoint) to 25°C (indoor cooling setpoint), and vice versa. Building energy simulations demonstrate that the proposed rooftop covering can achieve all-season energy savings across all climate regions.

Cost, energy, and carbon footprint benefits of second-life electric vehicle battery use.

The manuscript reviews the research on economic and environmental benefits of second-life electric vehicle batteries (EVBs) use for energy storage in households, utilities, and EV charging stations. Economic benefits depend heavily on electricity costs, battery costs, and battery performance; carbon benefits depend largely on the electricity mix charging the batteries. Environmental performance is greatest when used to store renewable energy such as wind and solar power. Inconsistent system boundaries make it challenging to compare the life cycle carbon footprint across different studies. The future growth of second-life EVB utilization faces several challenges, including the chemical and electrical properties and states of health of retired EVBs, the rapidly decreasing costs of new batteries, and different operational requirements. Measures to mitigate these challenges include the development of efficient diagnostic technologies, comprehensive test standards, and battery designs suitable for remanufacturing. Further research is needed based on real-world operational data and harmonized approaches.

Geographical balancing of wind power decreases storage needs in a 100% renewable European power sector.

To reduce greenhouse gas emissions, many countries plan to massively expand wind power and solar photovoltaic capacities. These variable renewable energy sources require additional flexibility in the power sector. Both geographical balancing enabled by interconnection and electricity storage can provide such flexibility. In a 100% renewable energy scenario of 12 central European countries, we investigate how geographical balancing between countries reduces the need for electricity storage. Our principal contribution is to separate and quantify the different factors at play. Applying a capacity expansion model and a factorization method, we disentangle the effect of interconnection on optimal storage capacities through distinct factors: differences in countries' solar PV and wind power availability patterns, load profiles, as well as hydropower and bioenergy capacity portfolios. Results indicate that interconnection reduces storage needs by around 30% in contrast to a scenario without interconnection. Differences in wind power profiles between countries explain around 80% of that effect.

Multi-criteria decision analysis for the evaluation and screening of sustainable aviation fuel production pathways.

The aviation sector, a significant greenhouse gas emitter, must lower its emissions to alleviate the climate change impact. Decarbonization can be achieved by converting low-carbon feedstock to sustainable aviation fuel (SAF). This study reviews SAF production pathways like hydroprocessed esters and fatty acids (HEFA), gasification and Fischer-Tropsch Process (GFT), Alcohol to Jet (ATJ), direct sugar to hydrocarbon (DSHC), and fast pyrolysis (FP). Each pathway's advantages, limitations, cost-effectiveness, and environmental impact are detailed, with reaction pathways, feedstock, and catalyst requirements. A multi-criteria decision framework (MCDS) was used to rank the most promising SAF production pathways. The results show the performance ranking order as HEFA > DSHC > FP > ATJ > GFT, assuming equal weight for all criteria.