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Abstract The eddy covariance method was used to investigate carbon fluxes and evapotranspiration (ET) from a high biomass forage sorghum ( Sorghum bicolor L.) field in the Southern U.S. Great Plains for three growing seasons (2013–2015). Above normal precipitation and narrow row spacing (50 cm) led to higher biomass production (25 Mg ha −1 ) and leaf area index (LAI = 7.2) development in 2014. This also resulted in higher carbon uptake or net ecosystem production (NEP) and ET during that year. Early and late season precipitation enhanced ecosystem respiration (R eco ) resulting in lower NEP in 2015. Shorter growing season (119 days) also contributed to lower cumulative NEP in 2015. Estimated gross primary production (GPP) in 2014 (1780 g m −2 ) was 10% higher than the GPP in 2013 (1591 g m −2 ) and 24% higher than the GPP in 2015 (1353 g m −2 ). During all growing seasons, the site was a source of carbon (negative NEP) at the beginning and transitioned to a sink (positive NEP) later in the season. Biomass-GPP relationship indicated that approximately 65% of total GPP was allocated to above ground biomass (AGB). Average monthly ecosystem WUE (expressed as gross carbon gain per unit of ET) ranged from 1.7 g mm −1 to 4.2 g mm −1 . Results from our study indicate that weather conditions, growing season length and crop management are important factors in determining the magnitude of carbon uptake and release, and ET of this cellulosic biofuel feedstock crop in the Southern U.S. Great Plains.

Abstract Even though renewable energy development has gained momentum in China, thermal power generation still accounts for approximately 70% of the county's total power generation serving as the major source of carbon dioxide (CO2) emissions in China. Facing the challenges of meeting 2030 peak target of CO2 emission and realizing the coordinated development of thermal power generation in Beijing-Tianjin-Hebei region, this paper applies generalized Divisia Index Method (GDIM) to decompose the dynamics in the relevant CO2 emission. The effects of five factors including electricity demand, energy consumption, technology, energy efficiency and energy-mix are considered. The decomposition suggests that electricity demand is the primary factor driving the CO2 emission up, whereas technology effect decreases CO2 emission the most. Given the significant roles of technology, energy-mix and energy efficiency in CO2 emissions reduction, seven scenarios are designed to identify the optimal coordinated development pathway for thermal power generation in Beijing-Tianjin-Hebei region. Through upgrading energy structure and/or enhancing energy efficiency, the thermal power generation in Beijing-Tianjin-Hebei region can achieve coordinated development and realize the 2030 peak target under four scenarios. The detailed development pathways for CO2 emissions and specific policy implications for Beijing, Tianjin and Hebei are provided to further govern CO2 emissions and maintain sustainable development.

The present paper considers the evaluation of temperature regulated and unregulated charging strategies to select the appropriate one to ensure extended battery life with reduced charging time. Temperature regulated pulse charging (TRPC) and temperature regulated reflex charging (TRRC) are compared with the Constant current-constant voltage (CC-CV) charging strategy. In the case of CC-CV charging temperature of the battery rises with the magnitude of the current being injected and cannot be regulated without any external cooling arrangement. Impact on the State of health (SOH) and the expected lifespan of the battery are considered as the parameters of evaluation. Temperature regulated strategies are implemented through a discrete electro-thermal model, which acts as a temperature estimator. The co-efficient of the estimators corresponds to the battery parameters such as internal resistance and thermal time constants, entropy, etc. Temperature regulation is ensured in the three identified sections of charge deposited vs magnitude of the injected current. Three sections are identified as sections where the injected current is not sufficient to raise the battery temperature to set limit or not and the level of charge submitted as compared to normal charging. Experimentation is carried with 12 V, 26 Ah Valve regulated lead-acid battery to justify that increase in temperature reference of regulation allows submission of higher charge for the same charging rate. It is demonstrated that TRPC results in a significant reduction (≈60%) in charging time as compared to CC-CV and TRRC. For the same charging time as achieved with TRPC, TRPC results in almost double the expected life of operation and better SOH as compared to CC-CV and TRRC.

The study aims to comprehensively assess the energy and water consumption pattern in the seafood industries and suggest measures for the sustainable development of the sector. The unscrupulous usage of water and higher consumption of energy resulted in an uncontrolled generation of wastewater and enormous usage of fossil fuels. In the seafood industry, energy is primarily used for machinery and equipment handling processes such as freezing, refrigeration, heating, cooling, and drying. Similarly, a huge amount of clean water is used for cleaning machinery and plant, and for operations like washing of raw material, de-icing, defrosting, and salt splashing. As a consequence, in the energy-water nexus, additional energy is required for drawing fresh water and further processing of wastewater demands energy that results in air pollution and greenhouse gas emissions and incurring additional costs to the plant. Hence, this review mainly focuses on the significance of energy and water use optimization in the seafood industry, the existing trend of energy and water use pattern and management practices, optimization strategies, and the seafood-energy-water nexus and its environmental implications.

Abstract In this study, a multi-phase, two-dimensional model that integrates the bipolar plate (BP) and gas diffusion layer (GDL) interfacial morphology was developed to understand the effects of this interface on mass, charge and heat transport and performance of polymer electrolyte fuel cells (PEFCs). Two different case studies were performed. The first case assumes a perfect contact interface between the BP and GDL, whereas in the second case, the BP|GDL interfacial layer was incorporated as a separate domain based on the measured BP|GDL morphology. In the BP|GDL interface case, the interfacial voids were assumed to be filled with liquid water to investigate the role of the interfacial voids. For both cases, the effects of different current densities on the in-plane temperature, saturation, and oxygen concentration distribution in the GDL were investigated. Simulations indicate that the Ohmic and concentration losses are increased due to the inclusion of the realistic BP|GDL interface. The electrical contact resistance contribution of the BP|GDL interface was predicted to be 3.8 mΩcm 2 . The saturation in the GDL was found to be higher for the BP|GDL interface case, which results in higher concentration losses. The temperature was predicted to be slightly higher for the BP|GDL interface case, which could be attributed to the higher thermal contact resistance due to the fewer contact regions at the interface.

Abstract This paper provides the first estimates of China's global developmental finance institutions in general and China's policy bank lending to foreign governments for energy in particular. According to the China Global Energy Finance database, between 2000 and 2017, China Development Bank (CDB) and China Export-Import Bank (CHEXIM) provided $225.75 billion in overseas energy development finance. We find that: China's ‘policy banks’ and funds have doubled the availability of global development finance –and hold more assets than the major Western-backed MDBs operating in developing countries. With the onset of a new family of funds and multilateral development banks co-financed by China, China is poised to be the largest development lender in the world as Western-backed MDBs appear stagnated in their ability to increase their capital bases. China's global energy portfolio is heavily exposed to country, macroeconomic, climate, and social risks, however. To mitigate such risks and meet the broader sustainable development challenge for the 21st Century, China's development finance will need to shift the composition of its global energy lending in a significant manner.

A new scheme on dynamic pricing of electricity in a smart grid is proposed in this research article. Also the consumer's demand behavior and response is analyzed. With the smart grid it is possible to determine and communicate the real time prices of electricity like other market goods and evaluate the variation in demand. Utility can exploit the natural human response that is reduction in demand by increasing the prices. The user consumption behavior has modeled into utility functions as per the concepts in the micro-economics. Thus the electricity consumption of each consumer has optimized such that the aggregate utility function of all consumers is maximized. The proposed algorithm is beneficial for consumers and the utility as shown by the simulation results.

A variety of renewable electricity policies to promote investment in wind, solar, and other types of renewable generators exist across the United States. The federal renewable energy investment tax credit, the federal renewable energy production tax credit, and state renewable portfolio standards are among the most notable. Whether the benefits of promoting new technology and reducing pollution emissions from the power sector justify these policies’ costs has been the subject of considerable debate. We argue in this paper that the debate is misguided because it does not consider two important interactions between renewable electricity generators and the rest of the power system. First, the value of electricity from a renewable generators depends on the generation and investment it displaces. Second, a large increase in renewable generation can reduce electricity prices, increasing consumption and emissions from fossil generators, and offsetting some of the environmental benefits of the policies. Two policy conclusions follow. First, existing renewable electricity policies can be redesigned to promote investment in the highest-value generators, which can greatly reduce the cost of achieving a given emissions reduction. Second, subsidies financed out of general tax revenue reduce emissions less than subsidies financed by charges to electricity consumers.

This work investigates the optical performance of a textured back surface reflector (BSR) produced by a maskless solution-based wet chemical etch in Al $_\text{0.3}$ Ga $_\text{0.7}$ As for a 1.1- $\mu$ m-thick GaAs solar cell. Combining the maskless texture with the 94% reflective flat mirror resulted in a high haze in reflectance near 80% across the GaAs absorbing region. The increased diffuse reflectance from the maskless BSR provided a 19.7% increase in the integrated short-circuit current density from the base region of the 1.1- $\mu$ m GaAs solar cell with the maskless BSR compared to the simulated 1.1- $\mu$ m solar cell with no light trapping structures. Based on the principle concepts for the Fabry–Perot etalon, the lifetime enhancement factor (LEF), defined as the extended photon lifetime in an optical cavity due to light trapping, was derived for the BSR devices. The LEF for the maskless BSR device was measured to be 4.3 times greater than the single-pass photon lifetime, agreeing with the high haze in reflectance and improved photoabsorption near the GaAs band edge. This value agrees with the F factor in the analytical propagation model that fits the experimental external quantum efficiency curves and justifies using the LEF to quantitatively represent the optical performance of light trapping structures in sub- $\mu$ m thick solar cells.