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In order to achieve the Paris Agreement goals of keeping the temperature rise well below 2 °C or even 1.5 °C, all countries would need to make fair and ambitious contributions to reducing emissions. A vast majority of countries have adopted reduction targets by 2030 in their Nationally Determined Contributions (NDCs). There are many alternative ways to analyze the fairness of national mitigation contributions. This article uses a model framework based on six equity principles of effort-sharing, to allocate countries’ reduction targets under global emissions scenarios consistent with meeting the Paris climate goals. It further compares these allocations with the NDCs. The analysis shows that most countries need to adopt more ambitious reduction targets by 2030 to meet 2 °C, and even more for 1.5 °C. In the context of 2 °C, the NDCs of the United States of America and the European Union lack ambition with respect to the approaches that emphasize responsibility; China's NDC projection falls short of satisfying any approach in 2030. In the context of 1.5 °C, only India, by implementing its most ambitious efforts by 2030, could be in line with most equity principles. For most countries, the NDCs would use most of their allowed emissions space for the entire 21 st century by 2030, posing a major challenge to transform to a pathway consistent with their fair contributions in the long-term.

In cold regions, the occurrence of frozen ground has a fundamental control over the character of the water cycle. To investigate the impact of changing ground temperature conditions on hydrological processes in the context of climate change, a distributed hydrological model with an explicit frozen ground module was applied to an alpine watershed in the upstream area of the Hei'he River in the Qilian Mountains, northwest China. After evaluating the base model, we considered scenarios of frost-free ground and climate change. Results showed that the base model with a frozen ground module successfully captured the water balance and thermal regimes in the basin. When the frozen ground module was turned off, the simulated groundwater recharge and base flow increased by a factor of two to three because surface runoff caused by exceeding infiltration capacities at high elevations, which occurred in the base model, was eliminated. Consequently, the river hydrograph became smoother and flatter, with summer flood peaks delayed and reduced in volume. The annual mean depth where subsurface runoff was generated, was about 2.4m compared to 1.1m in the base model. For a warming climate, a combination of increasing evapotranspiration and reducing permafrost area results in smoother and flatter hydrographs, and a reduction in total river discharge. Although our analysis using numerical models has its limitations, it still provides new quantitative understanding of the influences of frozen ground and climate change on hydrological processes in an alpine watershed.

Waste management is one of the biggest environmental challenges worldwide. Biomass-derived hard carbons, which can be applied to rechargeable batteries, can contribute to mitigating environmental changes by enabling the use of renewable energy. This study has carried out a comparative environmental assessment of sustainable hard carbons, produced from System A (hydrothermal carbonization (HTC) followed by pyrolysis) and System B (direct pyrolysis) with different carbon yields, as anodes in sodium-ion batteries (SIBs). We have also analysed different scenarios to save energy in our processes and compared the biomass-derived hard carbons with commercial graphite used in lithium-ion batteries. The life cycle assessment results show that the two systems display significant savings in terms of their global warming potential impact (A1: −30%; B1: −21%), followed by human toxicity potential, photochemical oxidants creation potential, acidification potential and eutrophication potential (both over −90%). Possessing the best electrochemical performance for SIBs among our prepared hard carbons, the HTC-based method is more stable in both environmental and electrochemical aspects than the direct pyrolysis method. Such results help a comprehensive understanding of sustainable hard carbons used in SIBs and show an environmental potential to the practical technologies. This article is part of the theme issue ‘Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)’.

Artículos en revistas Energy transportation costs typically make up a quarter of consumers? electricity bills, and most of this amount (90% in the United Kingdom, 75% in Brazil and Spain, and 60% in India, for example) is due to energy transportation through the distribution network. This cost could escalate over the next few decades as distributed energy resources are expected to grow substantially in response to the financial incentives many governments have created for renewable and efficient generation to meet their CO2 reduction targets. info:eu-repo/semantics/publishedVersion

Due to the intermittency and uncertainty natures of wind power, electrical energy storages (EESs) are often equipped in the power systems to reduce the side-effect of wind power fluctuations, and adiabatic compressed air energy storage (A-CAES) is one of EES technologies to smooth the power fluctuation of wind farms (WFs). This paper proposes a coordinated control framework of WF and A-CAES station to achieve frequency response, and discusses the active power distribution scheme among wind turbines (WTs) and A-CAES units during frequency regulation. Firstly, the models of WT and A-CAES used in frequency regulation are presented. Then, considering that the power distribution might go through a long iteration process when the number of WTs in WF is quite large, these WTs are clustered into several groups using a comprehensive multi-view grouping indicator. On the basis of the WTs grouping result and with a defined generalized energy increment (GEI), this paper proposes a discrete consensus based tri-level coordinated frequency control method, which divides the control into three levels, i.e., group level, wind farm level and coordinated level. Through the three levels’ control, the method can reasonably and rapidly distribute the frequency regulation powers among WTs and A-CAES units without being limited by the scale of WF, and the coordination of WF and A-CAES station during frequency regulation is achieved. To demonstrate the effectiveness of the proposed method, a modified WF in Inner Mongolia of China is utilized for case study. Simulation results show that the proposed method is valid in various frequency events and can reach consensus within 4 s in the studied cases, and it is well-performed with different capacities of wind powers and A-CAESs in the power systems. The common communication failures have few influences on the methods, and the frequency nadirs fluctuate lower than 0.1 Hz with time delays in the communications. Compared with centralized and multi-machine equivalent methods, the proposed distributed method can balance the computational speed and the solution accuracy, and thus is beneficial to improve the system frequency nadirs when frequency drops.

In this work, supported amine sorbents were prepared by physical impregnation of silica and polymethylmethacrylate (PMMA) with tetraethylenepentamine (TEPA) and studied for post-combustion CO2 capture purposes in a lab scale circulating fluidized bed (CFB) reactor. Sorbent amine loading and support pore size effects were investigated by thermal gravimetric analysis (TGA). The sorbent CO2 capacity was found to be a strong function of amine loading and pore volume. Significant improvement of the sorbent CO2 adsorption capacity (3.5 mol kg−1) was achieved by tuning these variables. From preliminary testing of the fluidization behavior of PMMA based sorbent particles, it was found that, at high desorber temperatures, these sorbent particles formed aggregates plugging the reactor. This underlines the importance of not only evaluating sorbent capacity but also fluidization behavior in an early stage of process development. Continuous CO2 capture was demonstrated applying the developed silica based sorbent particles in the CFB reactor. Here, CO2 was captured from dry simulated flue gas applying a temperature difference of only 70 °C between the adsorber column (40 °C) and the desorber column (110 °C). To the best of our knowledge this was the first time, a high (90%) purity CO2 product gas was produced at the regenerator outlet in continuous mode using these supported amine sorbents

In this paper, a new methodology to unleash the potential of demand response (DR) in real-time is presented. Customers may tend to apply their DR potential in the real-time market in addition to their scheduled potential in the day-ahead stage. Thus, the proposed method facilitates balancing the real-time market via DR aggregators. It can be vital, once the stochastic variables of the network such as production of wind power generators do not follow the forecasted production in real-time and have some distortions. Two-stage stochastic programming is employed to schedule some DR options in both day-ahead and real-time markets. DR options in real-time are scheduled based on possible scenarios that reflect the behaviors of wind power generation and are generated through Monte-Carlo simulation method. The merits of the method are demonstrated in a 6-bus case study and in the IEEE RTS-96, which shows a notable reduction in total operation cost.

This study proposed an efficient way of direct sewage pre-concentration by a combined coagulation microfiltration (CCM) system and an optimal operational strategy of aeration. Compared to two typical technologies for sewage pre-concentration, i.e. direct sewage microfiltration (DSM) and continuous aerated sewage microfiltration (ASM), the CCM system under optimal aeration strategy showed higher concentration efficiency and slower permeability decline (i.e. better control of membrane fouling), and easier collection of retained organic matter (OM). A lab-scale CCM reactor was running continuously for 295 h, and a concentrate of about 16,000 mg COD/L was produced at an average net flux of 13.3 L/(m2 h) and an influent OM recovery of nearly 70%, which was higher than the concentrate produced by a high-loaded membrane bioreactor (MBR) with one day solids retention time. The use of chemical coagulant was found to have little impact on the following anaerobic digestion (AD) process, for anaerobic biodegradability of the concentrate is 56.5% (close to the typical value for blackwater). The integration of the CCM and AD processes could achieve a net energy production of 0.0098 kW h/m3 after deduction of 0.0919 kW h/m3 required for the operation of the CCM system, thus showing promise as an effective OM concentration method for energy recovery from sewage.