Air pollution is one of the major causes of health risks as it leads to widespread disease and death each year. Countries have invested heavily in fighting air pollution, arguably without convincing results. The outbreak of the highly infectious disease COVID-19 in December 2019 has been declared a pandemic and a worldwide health crisis by World Health Organization (WHO). Countries resorted to city lockdowns that sternly curtailed personal mobility and economic activities to control the spread of this deadly coronavirus disease. This paper examines the impact of Covid-19 city lockdowns on air quality. The researchers adopted a comprehensive interpretative document analysis for this study, which guided the careful but rigorous examination of air quality and coronavirus data. This method affirmed the authenticity of the information examined and interpreted in the US, Italy and China, the study areas. The study found that Covid-19 city lockdowns have contributed to a significant improvement in air quality within the first four months of the outbreak of Covid-19. National Aeronautics and Space Administration (NASA) had reported that NO2 concentrations in the study areas had reduced significantly using evidence from their Sentinel-5P instrument. Air quality in Covid-19 cities' lockdowns also improved because of the enforcement of other types of measures enacted to battle the virus. WHO still believes that the amount of NO2 concentration in the atmosphere is still high per their standards and regulations. Based on this, the researchers recommend that governments and other stakeholders put in much effort in terms of legislation to "win the war" against air pollution.
Abstract The window for limiting global warming to 1.5°C is rapidly closing, necessitating immediate climate action which some have proposed includes deploying carbon dioxide removal (CDR) at scale. However, CDR is characterized by varying trade-offs and spill-over effects, and an excessive reliance on them to reach climate milestones could affect global Earth system negatively. This study quantitatively investigates the impacts associated with different levels of reliance on negative emissions for Asia’s net zero ambitions. We employ a technology-rich integrated assessment model, i.e., GCAM-TJU, a modified version of the Global Change Assessment Model (GCAM) with the capability of deploying six different CDR approaches. Different levels of CDR reliance are modeled by varying CDR deployment times, availability, and removal capacities. Key findings are that deploying tens of gigaton scale of negative emissions by mid-century will perpetuate fossil fuel reliance, slow energy transitions and push back net zero timelines. High reliance on CDR also reduces building efficiency improvements and transport electrification rates significantly. Furthermore, timing of net zero for multiple Asian countries is advanced under lower availability of CDR, resulting in lower residual emissions with significant health co-benefits. Regarding land and food, high reliance on CDR leads to significant changes in land use with a severe reduction in cropland. There are potential concerns related to water demands and fertilizer needs under excessive reliance on CDR. Overall, our results show that tens of gigaton scale of negative emissions by mid-century could seriously impede climate goals. Prioritizing non-CDR mitigation strategies through rapid electrification, carbon-neutral/negative fuels (e.g., hydrogen), and efficiency mainstreaming could accelerate decarbonization. We must strive to pursue emission cuts maximally before utilizing negative emissions. While CDR is necessary for delivering the "net" in "net-zero emissions", it is worth exploring strategies that reduce the need for excessive reliance on CDR, while also capitalizing on its advantages when it is most viable.
Abstract Environmental pollution and depletion of resources from the combustion of fossil fuels have necessitated the need for biofuels in recent years. Oxygenated fuels such as low carbon alcohols have received significant attention from the scientific community in the last two decades as a strategy to decarbonize the transport sector. However, a documentation of the progress, paradigm, and trend of this research area on a global scale is currently limited. In the current study, the bibliometric analysis is adopted to analyze the global transition of automotive fuels from conventional oils to low carbon alcohols in the 21st century. A dataset of 2250 publications was extracted from the Web of Science Core database and analyzed with CiteSpace, Biblioshiny, and Bibexcel. Interest in methanol and ethanol combustion research as transportation fuels is increasing, with a 70% estimated growth by the end of the next decade compared to current levels. China, India, and USA have been the major players in the research field, with Tianjin University being the most influential institution. Research has primarily centered on the combustion, performance, and emission characteristics of ethanol fuel. Alternative fuels to compete actively with low carbon fuel in the near foreseeable future are green hydrogen and biodiesel. Advanced combustion technologies and artificial intelligence are sure to increase in this research area in the coming decades.
Hydrogen fuel offers promising decarbonization solutions for hard-to-abate transport sectors. In this review, we investigate the research trends and evolution in hydrogen-fuelled internal combustion engines (ICEs) over the last decade.
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