The conversion of biomass by thermochemical means is very promising for the substitution of fossil materials in many energy applications. Given the complexity of biomass the main challenge in its use ...is to obtain products with high yield and purity. For a better understanding of biomass thermochemical conversion, many authors have studied in TG analyzer or at bed scale the individual pyrolysis of its main constituents (i.e. cellulose, hemicelluloses and lignin). Based on these studies, this original work synthesizes the main steps of conversion and the composition of the products obtained from each constituent. Pyrolysis conversion can be described as the superposition of three main pathways (char formation, depolymerization and fragmentation) and secondary reactions. Lignin, which is composed of many benzene rings, gives the highest char yield and its depolymerization leads to various phenols. The depolymerization of the polysaccharides is a source of anhydro-saccharides and furan compounds. The fragmentation of the different constituents and the secondary reactions produce CO, CO2 and small chain compounds. For temperature higher than 500°C, the residues obtained from the different constituents present a similar structure, which evolves towards a more condensed polyaromatic form by releasing CH4, CO and H2. As the aromatic rings and their substituent composition have a critical influence on the reactivity of pyrolysis products, a particular attention has been given to their formation. Some mechanisms are proposed to explain the formation of the main products. From the results of this study it is possible to predict the reactivity and energy content of the pyrolysis products and evaluate their potential use as biofuels in renewable applications.
The uncontrolled discharge of large amounts of food waste (FW) causes severe environmental pollution in many countries. Within different possible treatment routes, anaerobic digestion (AD) of FW into ...biogas, is a proven and effective solution for FW treatment and valorization. The present paper reviews the characteristics of FW, the principles of AD, the process parameters, and two approaches (pretreatment and co-digestion) for enhancing AD of food waste. Among the successive digestion reactions, hydrolysis is considered to be the rate-limiting step. To enhance the performance of AD, several physical, thermo-chemical, biological or combined pretreatments are reviewed. Moreover, a promising way for improving the performance of AD is the co-digestion of FW with other organic substrates, as confirmed by numerous studies, where a higher buffer capacity and an optimum nutrient balance enhance the biogas/methane yields of the co-digestion system.
Dynamic stabilization of an array Large-scale systems comprising one-dimensional chains and two-dimensional arrays of excited atoms held in a programmable optical lattice are a powerful platform with ...which to simulate emergent phenomena. Bluvsteinet al.built an array of up to 200 Rydberg atoms and subjected the system to periodic excitation. Under such driven excitation, they found that the array of atoms stabilized, freezing periodically into what looked like time crystals. Understanding and controlling the dynamic interactions in quantum many-body systems lies at the heart of contemporary condensed matter physics and the exotic phenomena that can occur. Science, this issue p.<related-article issue='6536' page='1355' related-article-type='in-this-issue' vol='371'>1355</related-article>
Combustion of fuels to generate energy is integral to various human activities, both domestic and industrial. However, the predominance of hydrocarbon fuel usage produces emissions containing ...pollutants that cause multiple environmental complications and risks to human health. Therefore, replacement of conventional fuels to achieve zero carbon emission is of utmost importance. In terms of carbon-free fuel, ammonia offers several advantages over hydrogen. However, its low burning velocity and high fuel NOx emissions inhibit large-scale usage. Hence, hydrogen and methane have been studied in this review as possible secondary fuels to aid ammonia combustion and address the aforementioned issues. This review starts from the suitability of ammonia fuel as energy vector in terms of physicochemical and combustion characteristics, moving through the kinetics and mechanisms of ammonia-based and ammonia-fuel combustion. The impacts and limitations of each system are also addressed, thus providing a comparison on each system. Particularly, this review assesses and discusses the advantages and mechanisms involved with secondary fuel addition to the ammonia combustion, presenting the role of key reaction differences and the change in key reaction mechanism under different conditions at the level of reaction mechanisms. Finally, this review covers future perspectives and challenges on the usage and development of ammonia-based fuels, emphasizing the maturity of ammonia-based and ammonia-fuel combustion kinetics. Herein, this work summarizes the principles of the combustion reactions of ammonia-based and ammonia-fuel systematically and serves as a theoretical reference of ammonia-fuel combustion kinetics for transitioning into future practical applications where ammonia is an important energy vector.
•Physicochemical and combustion characteristics of ammonia are summarized in detail.•Hydrogen/methane addition to ammonia combustion is discussed.•Effects on combustion speed, NOx generation and reaction kinetics are discussed.•Both hydrogen and methane are effective in improving ammonia combustion.•Future development of ammonia-based fuels is prospected.
for reducing GHG emissions and the challenges of climate change, such as “green finance”, have emerged as an approach that combines financial services and products that confront a wider range of ...sustainability issues, such as commercial pollution reduction, environmental management, improved sanitation, and environmental conservation. Therefore, our study aimed to investigate how green financing and renewable energy sources in China contribute to sustainable development. This study employs a unique methodology called panel cointegration and causality modelling to analyse the factors that led to the growth of renewable energy in China between 2005 and 2020. The results demonstrate the value of green finance development and private sector participation in localised and worldwide growth. Trademark registrations will increase by 0.487% and financial development filings by 0.144% for every 1% increase in renewable energy sources. When private sector participation is enhanced by 0.032%, trademarks and patents increase by 0.057%. Investment, trade, and human development calm these relationships. Several robustness tests support our findings. The study's empirical evidence, policymakers and environmentalists now have helpful knowledge for creating and implementing environmental projects with long-term financial advantages.
•Nexus among green finance and renewable energy were studied.•Green finance positively impacted on RE development.•Financial inclusion raised renewable energy development.•Several robustness tests were performed.
Global warming is now the most serious environmental challenge. In the most recent Paris accord, authorities opted to reduce global emissions to a certain level and voiced significant concern for ...China, the world's largest CO2 emitter, accounting for around 29.4% of total emissions. In contrast, coal accounts 65% of the majority of China's energy mix in 2019. Therefore, it is critical to analyze the environmental factors influencing China's CO2 emissions. Hence, the research examines fossil fuel energy, renewable energy, and GDP between 1980 to 2018 using novel dynamic ARDL simulations and Frequency Domain Causality (FDC) models. The empirical findings show that fossil fuel energy intensely boosts CO2 emissions long and short term. On the other hand, GDP increases carbon emissions in the long term but has a significant adverse effect on China's environment in the short run. While renewable energy usage has a short-term detrimental impact on CO2 emissions. The FDC also supports the long-, medium-and short-term causality hypotheses. Overall, our results imply that renewable energy consumption is crucial for achieving sustainable environmental goals and discourages fossil fuel use in the energy mix. We recommend that China consider empirical evidence and initiate long-term strategies to diminish carbon emissions for a sustainable environment.
Transportation electrification is one of the main research areas for the past decade. Electric vehicles (EVs) are taking over the market share of conventional internal combustion engine vehicles. The ...increasing popularity of EVs results in higher number of charging stations, which have significant effects on the electricity grid. Different charging strat2egies, as well as grid integration methods, are being developed to minimize the adverse effects of EV charging and to strengthen the benefits of EV grid integration. In this paper, a comprehensive review of the current situation of the EV market, standards, charging infrastructure, and the impact of EV charging on the grid is presented. The paper introduces the current EV status, and provides a comprehensive review on important international EV charging and grid interconnection standards. Different infrastructure configurations in terms of control and communication architectures for EV charging are studied and evaluated. The electric power market is studied by considering the participation roles of EV aggregators and individual EV owners, and different optimization and game based algorithms for EV grid integration management are reviewed. The paper specially presents an evaluation on how the future EV development, such as connected vehicles, autonomous driving, and shared mobility, would affect EV grid integration as well as the development of the power grid moves toward future energy Internet and how EVs would affect and benefit the development of the future energy Internet. Finally, the challenges and suggestions for the future development of the EV charging and grid integration infrastructure are evaluated and summarized.
•An overview of the current situation and future development trend of the EV market.•A detailed review of standards associated with EVs and EV grid integration.•An in-depth evaluation of EV charging and grid integration infrastructure.•A summary of limitations and suggestions on EV charging and grid integration.•An assessment of the importance and role of EVs in the future energy internet with the development of automobile industry.
Lignocelluloses are often a major or sometimes the sole components in different waste streams from various sources such as industries, forestry, agriculture and municipalities. It represents an ...as-of-yet untapped source of fermentable sugars for significant industrial use. Many physico-chemical, structural and compositional factors hinder the hydrolysis of components present in the biomass to sugars and other organic compounds that can later be converted into fuels. During the past few years, a large number of chemical pretreatment methods including lime, acid, steam explosion, sulfur dioxide explosion, ammonia fiber explosion, ionic liquid and others have been developed for efficient pretreatment of biomass. Many pretreatment methods have shown high sugar yields i.e. more than 90% of the theoretical yield from lignocelluloses. In this review, we discuss various chemical pretreatment processes, feasibility of the processes at industrial scale in terms of the mechanisms involved, advantages, disadvantages and economic assessment. It is not possible to define the best pretreatment method as it depends on many factors such as type of lignocellulosic biomass, process parameters, environmental impact, economical feasibility, etc. However, some of these chemical pretreatments have disadvantages such as formation of inhibitory compounds especially furfural and 5-hydroxyl methyl furfural (HMF).
The increasing prices and environmental impacts of fossil fuels have made the production of biofuels to reach unprecedented volumes over the last 15 years. Given the increasing land requirement for ...biofuel production, the assessment of the impacts that extensive biofuel production may cause to food supply and to the environment has considerable importance. Agriculture faces some major inter-connected challenges in delivering food security at a time of increasing pressures from population growth, changing consumption patterns and dietary preferences, and post-harvest losses. At the same time, there are growing opportunities and demands for the use of biomass to provide additional renewables, energy for heat, power and fuel, pharmaceuticals and green chemical feedstocks. Biomass from cellulosic bioenergy crops is expected to play a substantial role in future energy systems. However, the worldwide potential of bioenergy is limited, because all land is multi-functional and land is also needed for food, feed, timber, and fiber production, and for nature conservation and climate protection. Furthermore, the potential of bioenergy for climate change mitigation remains unclear due to large uncertainties about future agricultural yield improvements and land availability for biomass plantations. Large-scale cultivation of dedicated biomass is likely to affect bioenergy potentials, global food prices and water scarcity. Therefore, integrated policies for energy, land use and water management are needed. As biomass contains all the elements found in fossil resources, albeit in different combinations, therefore present and developing technologies can lead to a future based on renewable, sustainable and low carbon economies. This article presents 1 risks to food and energy security 2 estimates of bioenergy potential with regard to biofuel production, and 3 the challenges of the environmental impact.