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In this paper, we compare 2015 satellite-derived natural gas (gas) flaring data with the greenhouse gas reduction targets presented by those countries in their nationally determined contributions (NDC) under the United Nations Framework Convention on Climate Change (UNFCCC) Paris Agreement. Converting from flaring to utilization is an attractive option for reducing emissions. The analysis rates the potential role of reduction of gas flaring in meeting country-specific NDC targets. The analysis includes three categories of flaring: upstream in oil and gas production areas, downstream at refineries and transport facilities, and industrial (e.g., coal mines, landfills, water treatment plants, etc.). Upstream flaring dominates with 90.6% of all flaring. Global flaring represents less than 2% of the NDC reduction target. However, most gas flaring is concentrated in a limited set of countries, leaving the possibility that flaring reduction could contribute a sizeable portion of the NDC targets for specific countries. States that could fully meet their NDC targets through gas flaring reductions include: Yemen (240%), Algeria (197%), and Iraq (136%). Countries which could meet a substantial portion of their NDC targets with gas flaring reductions include: Gabon (94%), Algeria (48%), Venezuela (47%), Iran (34%), and Sudan (33%). On the other hand, several countries with large flared gas volumes could only meet a small portion of their NDC targets from gas flaring reductions, including the Russian Federation (2.4%) and the USA (0.1%). These findings may be useful in guiding national level efforts to meet NDC greenhouse gas reduction targets. Keywords: VIIRS, Gas flaring, Nightfire, Nationally determined contributions, UN climate agreement

In this study, the effect of recycling the non-condensable gases (NCG) in the catalytic pyrolysis of hybrid poplar using FCC catalyst was investigated. A 50mm bench scale fluidized bed reactor at 475°C with a weight hourly space velocity (WHSV) of 2h(-1) and a gas recycling capability was used for the studies. Model fluidizing gas mixtures of CO/N(2), CO(2)/N(2), CO/CO(2)/N(2) and H(2)/N(2) were used to determine their independent effects. Recycling of the NCG in the process was found to potentially increase the liquid yield and decrease char/coke yield. The model fluidizing gases increased the liquid yield and the CO(2)/N(2) fluidizing gas had the lowest char/coke yield. The (13)C-NMR analysis showed that recycling of NCG increases the aromatic fractions and decreases the methoxy, carboxylic and sugar fractions. Recycling of NCG increased the higher heating value and the pH of the bio-oil as well as decreased the viscosity and density.

Abstract The increasing worldwide energy demand is rising the interest on alternative power production technologies based on renewable and emission-free energy sources. In this regard, the closed-loop reverse electrodialysis heat engine is a promising technology with the potential to convert low-grade heat into electric power. The reverse electrodialysis technology has been under investigation in the last years to explore the real potentials for energy generation from natural and artificial solutions, and recent works have been addressing also the potential of its coupling with regeneration strategies, looking at medium and large energy supply purposes. In this work, for the first time, a comprehensive exergy analysis at component level is applied to a reverse electrodialysis heat engine with multi-effect distillation in order to determine the real capability of the waste heat to power conversion, identifying and quantifying the sources of exergy destruction. In particular, sensitivity analyses have been performed to assess the influence of the main operating conditions (i.e. solutions concentration and velocity) and design features (aspect ratio of the pile), characterizing the most advantageous scenarios and including the effect of new generations of membranes. Results show that the multi-effect distillation unit is the main source of exergy destruction. Also, using high-performing membranes, inlet solutions concentration and velocity of 4.5–0.01 mol/L and 0.2–0.36 cm/s, respectively, a global exergy efficiency of 24% is reached for the system, proving the high potential of this technology to sustainably convert waste heat into power.

Carbon neutrality innovation technologies are a leading research topic in sustainable development. Among these, anaerobic digestion is considered as a better choice for biowaste utilization. However, large amounts of produced biogas slurry hamper the widespread application of anaerobic digestion. The hydrothermal process is regarded as favorable to treat biogas slurry. The effects of inorganic and organic matter in processed water from the hydrothermal-treated biogas slurry were investigated in our research. The changes in inorganic elements such as P, Ca, Mg, Cu, and Zn were detected at different reaction temperatures (90, 120, 150, 180, 210, and 240 ℃) and acid catalytic conditions (0.5, 1, 2, 3, 4, 4.5, and 5 mL 5 M HCl). The changes in organic matter were analyzed using three-dimensional excitation emission matrix fluorescence spectroscopy. With the increase in the hydrothermal reaction temperatures, the quantity of total and inorganic P and the concentration of Ca initially increased and then decreased, concentration of Mg remained constant, while the concentration of Zn and Cu showed a trend of initial decrease and then increase, and the macromolecular organic matter was hydrolyzed into small, soluble molecular organic matter. With the increase in HCl, the amount of released total and inorganic P and concentrations of Ca, Mg, Zn, and Cu increased, and the macromolecular organic matter was hydrolyzed into small molecular organic matter. The hydroponic testing indicated that the processed water has a positive effect on the growth of maize. These results provide critical findings on the reuse of biogas slurry, which is useful for biowaste management and improves carbon neutrality strategy.

Abstract The pyrolysis char derived from solid waste peat was used in the removal of biomass tar. A laboratory dual-stage reactor was designed to obtain a cost-effective and eco-friendly tar removal approach using peat pyrolysis char-based catalyst. Rich pore structure of pyrolysis char can enhance the adsorption and removal performance of tar, the KOH and CO2 activation method were used to increase the pore structure of pyrolysis char. Toluene was chosen as the model compound of biomass tar for basic research. The effects of pyrolysis char and transition metal Fe on toluene removal were studied. The investigated reforming parameters were reaction temperature (700–900 °C), residence time (0.3–0.8 s) and steam-to-carbon ratio (1.5:1–4:1). The results indicated that the peat pyrolysis char-based Fe catalysts showed excellent catalytic performance (toluene conversion >89%) and gas selectivity, especially the catalyst that activated by CO2 had the best selectivity for syngas (88.1 mol%), and the waste peat catalyst was compared with other waste pyrolysis char-based catalysts. Textural characterization showed that the excellent catalytic activity and stability of the catalysts are due to the presence of FeC and FeSiO3 structures. Such the peat pyrolysis char can as a carrier be used to remove tar and produce high content syngas in pyrolysis process.

In this study, a pilot scale of 100 t/year biodiesel production system, mainly consisting of a fixed-bed and a down-stream plug-flow reactors, was setup to test different feedstock oils, especially a kind of high-acidified oil, trap grease, for their feasibility as biodiesel feedstock in China. The tested oils include three kinds of typical oil from Guangdong Province, China: rapeseed oil, Chinese wood oil, and trap grease. At the same time the optimum residence time for a plug-now reactor to perform transesterification reaction was investigated in this study. At the temperature of 65 degrees C, methanol/oil molar ratio of 6:1 and KOH load of 1.2 wt% of oil, the optimum residence time was found to be 19 min. A type of ion-exchange resin was used to fill in the fixed-bed reactor and used as the esterification catalyst for pretreating on the high-acidified oil. For the fresh catalyst, the acid value of trap grease could be reduced from 114 mg KOH/g to about 2 mg KOH/g after 13 h at temperature 75 degrees C, catalyst load of 15 wt% of oil, methanol addition of 20 wt% of oil. The lifetime test for the catalyst indicated that its life is over 30 days. The quality of biodiesel derived from three feedstock oils is compared with newly published China BD100 standard of GB/T20828-2007. A comparison of the results reveals that the biodiesel generated through this system could satisfactorily meet China BD100 standard. It indicates that the designed process in this system has a good adaptability for different kinds of oil. (C) 2009 Elsevier Ltd. All rights reserved.

Abstract This study illustrated the pyrolysis of banana peel (BP) as a potential waste management solution. Samples were characterized through Fourier transform infrared spectrometry (FTIR), elemental analysis, and high heating value (HHV) calculation. After pyrolysis experiments were performed at different heating rates (10, 20, 30, and 40 °C min−1) by using a thermogravimetric analyzer coupled with FTIR (TG-FTIR), the apparent activation energies were computed with Friedman, Kissinger–Akahira–Sunose (KAS), and Flynn–Wall–Ozawa (FWO) methods, and the evolved gaseous products were analyzed simultaneously. During pyrolysis, BP underwent three devolatilization steps accompanied by the evolution of some major gaseous products, including CO2, CH4, H2O, CH3COOH, C C, C6H5OH, HCOOH, and CH3CH2OH. Among them, C C, CH3COOH, and CO2 accounted for approximately 71.56% of the total gaseous products. Gas evolution was more significantly influenced by the pyrolysis temperature than by the heating rate. Pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) analysis confirmed the presence of some high-energy compounds and valuable chemicals containing aromatic, aldehyde, ketone, and other functional groups. In terms of preliminary energy balance, more than 70% of the total energy output was attributed to the liquid pyrolytic products followed by the solid and gaseous products. The energy recovery ratio of BP pyrolysis was superior to that of other fuel feedstocks. This work provided insights into resolving environmental problems associated with BP management by pyrolyzing BP as a potential source of renewable bioenergy.

Abstract This paper seeks to quantify the benefits of a flexible energy system in the context of enabling higher levels of variable renewable energy on the grid. We explore a nuclear hybrid energy system (NHES) consisting of a 300 MW small modular reactor, wind generation, battery storage, and a reverse osmosis desalination plant. A dispatch rule is constructed within the Risk Analysis Virtual Environment (RAVEN) to model the system. Stochastic optimization and parametric analysis are utilized to explore how increased volatility in the net demand resulting from higher levels of wind penetration affect the optimal solution, and the stability of the system’s levelized cost of electricity (LCOE). In this study, net demand is the demand minus wind generation. This work contributes multi-objective analysis implemented through a supply-demand mismatch penalty to illustrate the financial stability and operational reliability benefits of the flexible energy system. In this context, we find that the additional up front cost of flexible loads and energy storage result in greater stability in LCOE as volatility in the demand increases. Additionally, the flexibility results in increased reliability in terms of meeting the demand. Although the analysis is conducted on a NHES, we emphasize the flexibility of the method applied here, in that the RAVEN platform and the multi-objective strategy are widely applicable to the analysis of energy systems faced with uncertainties in supply and demand.