Limitations to sustainable renewable jet fuels production attributed to cost than energy-water-food resource availability.

Renewable jet fuel (RJF) is often touted as the only viable sustainable energy source for the aviation sector, given the difficulties faced by other low-carbon energy sources in overcoming technological barriers. Despite that, the sustainability of RJF is still in dispute due to the conflicting requirements in natural resource for producing the fuels. We introduce a holistic 25-indicator sustainability index encompassing the four domains of energy-water-food nexus and governance, that measures the potential impact of RJF production on 154 countries (and territories) through the oil-to-jet, alcohol-to-jet and gas-to-jet conversion methods. Countries and territories are ranked according to the composite index scores of the four domains. The sustainability index model provides insights on how RJF affords the aviation sector a clean slate in determining the manner of development in a sustainably and equitable way, while also marching towards the long-term goal of carbon neutrality, in alignment with the Sustainable Development Goals.

Post COVID-19 ENERGY sustainability and carbon emissions neutrality.

This review covers the recent advancements in selected emerging energy sectors, emphasising carbon emission neutrality and energy sustainability in the post-COVID-19 era. It benefited from the latest development reported in the Virtual Special Issue of ENERGY dedicated to the 6th International Conference on Low Carbon Asia and Beyond (ICLCA'20) and the 4th Sustainable Process Integration Laboratory Scientific Conference (SPIL'20). As nations bind together to tackle global climate change, one of the urgent needs is the energy sector's transition from fossil-fuel reliant to a more sustainable carbon-free solution. Recent progress shows that advancement in energy efficiency modelling of components and energy systems has greatly facilitated the development of more complex and efficient energy systems. The scope of energy system modelling can be based on temporal, spatial and technical resolutions. The emergence of novel materials such as MXene, metal-organic framework and flexible phase change materials have shown promising energy conversion efficiency. The integration of the internet of things (IoT) with an energy storage system and renewable energy supplies has led to the development of a smart energy system that effectively connects the power producer and end-users, thereby allowing more efficient management of energy flow and consumption. The future smart energy system has been redefined to include all energy sectors via a cross-sectoral integration approach, paving the way for the greater utilization of renewable energy. This review highlights that energy system efficiency and sustainability can be improved via innovations in smart energy systems, novel energy materials and low carbon technologies. Their impacts on the environment, resource availability and social well-being need to be holistically considered and supported by diverse solutions, in alignment with the sustainable development goal of Affordable and Clean Energy (SDG 7) and other related SDGs (1, 8, 9, 11,13,15 and 17), as put forth by the United Nations.

Co-pyrolysis of microalgae and other biomass wastes for the production of high-quality bio-oil: Progress and prospective.

Microalgae are the most prospective raw materials for the production of biofuels, pyrolysis is an effective method to convert biomass into bioenergy. However, biofuels derived from the pyrolysis of microalgae exhibit poor fuel properties due to high content of moisture and protein. Co-pyrolysis is a simple and efficient method to produce high-quality bio-oil from two or more materials. Tires, plastics, and bamboo waste are the optimal co-feedstocks based on the improvement of yield and quality of bio-oil. Moreover, adding catalysts, especially CaO and Cu/HZSM-5, can enhance the quality of bio-oil by increasing aromatics content and decreasing oxygenated and nitrogenous compounds. Consequently, this paper provides a critical review of the production of bio-oil from co-pyrolysis of microalgae with other biomass wastes. Meanwhile, the underlying mechanism of synergistic effects and the catalytic effect on co-pyrolysis are discussed. Finally, the economic viability and prospects of microalgae co-pyrolysis are summarized.

Impacts of COVID-19 pandemic on the global energy system and the shift progress to renewable energy: Opportunities, challenges, and policy implications.

Being declared a global emergency, the COVID-19 pandemic has taken many lives, threatened livelihoods and businesses around the world. The energy industry, in particular, has experienced tremendous pressure resulting from the pandemic. In response to such a challenge, the development of sustainable resources and renewable energy infrastructure has demonstrated its potential as a promising and effective strategy. To sufficiently address the effect of COVID-19 on renewable energy development strategies, short-term policy priorities should be identified, while mid-term and long-term action plans should be formulated in achieving the well-defined renewable energy targets and progress towards a more sustainable energy future. In this review, opportunities, challenges, and significant impacts of the COVID-19 pandemic on current and future sustainable energy strategies were analyzed in detail; while drawing from experiences in identifying reasonable behaviors, orientating appropriate actions, and policy implications on the sustainable energy trajectory were also mentioned. Indeed, the question is that whether the COVID-19 pandemic will kill us or provide us with a precious lesson on future sustainable energy development.

Acid-based lignocellulosic biomass biorefinery for bioenergy production: Advantages, application constraints, and perspectives.

The production of chemicals and fuels from renewable biomass with the primary aim of reducing carbon footprints has recently become one of the central points of interest. The use of lignocellulosic biomass for energy production is believed to meet the main criteria of maximizing the available global energy source and minimizing pollutant emissions. However, before usage in bioenergy production, lignocellulosic biomass needs to undergo several processes, among which biomass pretreatment plays an important role in the yield, productivity, and quality of the products. Acid-based pretreatment, one of the existing methods applied for lignocellulosic biomass pretreatment, has several advantages, such as short operating time and high efficiency. A thorough analysis of the characteristics of acid-based biomass pretreatment is presented in this review. The environmental concerns and future challenges involved in using acid pretreatment methods are discussed in detail to achieve clean and sustainable bioenergy production. The application of acid to biomass pretreatment is considered an effective process for biorefineries that aim to optimize the production of desired products while minimizing the by-products.

Valorisation of medical waste through pyrolysis for a cleaner environment: Progress and challenges.

The COVID-19 pandemic has exerted great shocks and challenges to the environment, society and economy. Simultaneously, an intractable issue appeared: a considerable number of hazardous medical wastes have been generated from the hospitals, clinics, and other health care facilities, constituting a serious threat to public health and environmental sustainability without proper management. Traditional disposal methods like incineration, landfill and autoclaving are unable to reduce environmental burden due to the issues such as toxic gas release, large land occupation, and unsustainability. While the application of clean and safe pyrolysis technology on the medical wastes treatment to produce high-grade bioproducts has the potential to alleviate the situation. Besides, medical wastes are excellent and ideal raw materials, which possess high hydrogen, carbon content and heating value. Consequently, pyrolysis of medical wastes can deal with wastes and generate valuable products like bio-oil and biochar. Consequently, this paper presents a critical and comprehensive review of the pyrolysis of medical wastes. It demonstrates the feasibility of pyrolysis, which mainly includes pyrolysis characteristics, product properties, related problems, the prospects and future challenges of pyrolysis of medical wastes.

The COVID-19 pandemic face mask waste: A blooming threat to the marine environment.

Recently, the COVID-19 disease spread has emerged as a worldwide pandemic and cause severe threats to humanity. The World Health Organisation (WHO) releases guidelines to help the countries to reduce the spread of this virus to the public, like wearing masks, hand hygiene, social distancing, shutting down all types of public transports, etc. These conditions led to a worldwide economic fall drastically, and on the other hand, indirect environmental benefits like global air quality improvement and decreased water pollution are also pictured. Currently, use of face masks is part of a comprehensive package of the prevention and control measures that can limit the spread of COVID-19 since there is no clinically proven drugs or vaccine available for COVID-19. Mostly, face masks are made of petroleum-based non-renewable polymers that are non-biodegradable, hazardous to the environment and create health issues. This study demonstrates the extensive use of the face mask and how it affects human health and the marine ecosystem. It has become a great challenge for the government sectors to impose strict regulations for the proper disposal of the masks as medical waste by the public. Neglecting the seriousness of this issue may lead to the release of large tonnes of micro-plastics to the landfill as well as to the marine environment where mostly end-up and thereby affecting their fauna and flora population vastly. Besides, this study highlights the COVID-19 spread, its evolutionary importance, taxonomy, genomic structure, transmission to humans, prevention, and treatment.

Microwave pyrolysis valorization of used baby diaper.

Used baby diaper consists of a combination of decomposable cellulose, non-biodegradable plastic materials (e.g. polyolefins) and super-absorbent polymer materials, thus making it difficult to be sorted and separated for recycling. Microwave pyrolysis was examined for its potential as an approach to transform used baby diapers into value-added products. Influence of the key operating parameters comprising process temperature and microwave power were investigated. The pyrolysis showed a rapid heating process (up to 43 °C/min of heating rate) and quick reaction time (20-40 min) in valorizing the used diapers to generate pyrolysis products comprising up to 43 wt% production of liquid oil, 29 wt% gases and 28 wt% char product. Microwave power and operating temperature were observed to have impacts on the heating rate, process time, production and characteristics of the liquid oil and solid char. The liquid oil contained alkanes, alkenes and esters that can potentially be used as chemical additives, cosmetic products and fuel. The solid char contained high carbon, low nitrogen and free of sulphur, thus showing potential for use as adsorbents and soil additives. These observations demonstrate that microwave pyrolysis has great prospect in transforming used baby diaper into liquid oil and char products that can be utilised in several applications.

Pyrolysis production of fruit peel biochar for potential use in treatment of palm oil mill effluent.

Fruit peel, an abundant waste, represents a potential bio-resource to be converted into useful materials instead of being dumped in landfill sites. Palm oil mill effluent (POME) is a harmful waste that should also be treated before it can safely be released to the environment. In this study, pyrolysis of banana and orange peels was performed under different temperatures to produce biochar that was then examined as adsorbent in POME treatment. The pyrolysis generated 30.7-47.7 wt% yield of a dark biochar over a temperature ranging between 400 and 500 °C. The biochar contained no sulphur and possessed a hard texture, low volatile content (≤34 wt%), and high amounts of fixed carbon (≥72 wt%), showing durability in terms of high resistance to chemical reactions such as oxidation. The biochar showed a surface area of 105 m2/g and a porous structure containing mesopores, indicating its potential to provide many adsorption sites for use as an adsorbent. The use of the biochar as adsorbent to treat the POME showed a removal efficiency of up to 57% in reducing the concentration of biochemical oxygen demand (BOD), chemical oxygen demand COD, total suspended solid (TSS) and oil and grease (O&G) of POME to an acceptable level below the discharge standard. Our results indicate that pyrolysis shows promise as a technique to transform banana and orange peel into value-added biochar for use as adsorbent to treat POME. The recovery of biochar from fruit waste also shows advantage over traditional landfill approaches in disposing this waste.