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Abstract This paper presents a novel multi-time-stage input–output-based modeling framework for simulating the dynamics of bioenergy supply chains. One of the key assumptions used in the model is that the production level at the next time-stage of each segment of the energy supply chain adjusts to the output surplus or deficit relative to targets at the current time period. Furthermore, unlike conventional input–output models, the technology matrix in this approach need not be square, and thus can include coefficients denoting flows of environmental goods, such as natural resources or pollutants. Introducing a feedback control term enables the system to regulate the dynamics, thus extending the model further. This is an important feature since the uncontrolled dynamic model exhibits oscillatory or unstable behavior under some conditions; in principle, the control term allows such undesirable characteristics to be suppressed. Numerical simulations of a simple, two-sector case study are given to illustrate dynamic behavior under different scenarios. Although the case study uses only a hypothetical system, preliminary comparisons are made between the simulation results and some broad trends seen in real bioenergy systems. Finally, some of the main policy implications of the model are discussed based on the general dynamic characteristics seen in the case study. In particular, insights from control theory can be used to develop policy interventions to impart desirable dynamic characteristics to nascent or emerging biofuel supply chains. These interventions can be used to guide the growth of bioenergy supplies along final demand trajectories with minimal fluctuation and no instability.

Yard waste is either dumped or is being openly burned to get rid of it, instead of using it as a valuable renewable energy source. In this study, hydrothermal carbonization of yard waste was conducted to valorize it as a solid bio fuel, using a batch reactor. The effect of process parameter on yield, energy and physicochemical properties of the valorized solid bio fuel (hydrochar) was examined in this study by varying reaction temperature (160-200 °C for 2 h) and reaction time (2-24 h at 200 °C). The calorific value of hydrochar was within a range of 17.72-24.59 MJ/kg as compared to 15.37 MJ/kg for untreated yard waste. Hydrochar mass yield decreased from 78.6% at operating temperature - time of 160 °C -2 h to 45.6% at 200 °C -24 h. The plot of atomic ratios (H/C and O/C) demonstrates improvement in the coalification process which was mainly governed by decarboxylation and dehydration reactions. The grindability of the prepared hydrochar was comparable to that of coal. Hydrochar produced at lower reaction condition (160-200 °C at 2 h) have better flowability as compared to that produced at higher reaction condition (4-24 h at 200 °C). The reaction time longer than 12 h has a minimal effect on the yield, energy and physicochemical properties of hydrochar. Increasing reaction time and temperature improved the ignition and burnt temperature of hydrochar. All reaction condition has an energy ratio (energy output to energy input) of more than one making HTC process a net energy producer.

Net primary production (NPP), the difference between CO2 fixed by photosynthesis and CO2 lost to autotrophic respiration, is one of the most important components of the carbon cycle. Our goal was to develop a simple regression model to estimate global NPP using climate and land cover data. Approximately 5600 global data points with observed mean annual NPP, land cover class, precipitation, and temperature were compiled. Precipitation was better correlated with NPP than temperature, and it explained much more of the variability in mean annual NPP for grass- or shrub-dominated systems (r2 = 0.68) than for tree-dominated systems (r2 = 0.39). For a given precipitation level, tree-dominated systems had significantly higher NPP (approximately 100-150 g C m(-2) yr(-1)) than non-tree-dominated systems. Consequently, previous empirical models developed to predict NPP based on precipitation and temperature (e.g., the Miami model) tended to overestimate NPP for non-tree-dominated systems. Our new model developed at the National Center for Ecological Analysis and Synthesis (the NCEAS model) predicts NPP for tree-dominated systems based on precipitation and temperature; but for non-tree-dominated systems NPP is solely a function of precipitation because including a temperature function increased model error for these systems. Lower NPP in non-tree-dominated systems is likely related to decreased water and nutrient use efficiency and higher nutrient loss rates from more frequent fire disturbances. Late 20th century aboveground and total NPP for global potential native vegetation using the NCEAS model are estimated to be approximately 28 Pg and approximately 46 Pg C/yr, respectively. The NCEAS model estimated an approximately 13% increase in global total NPP for potential vegetation from 1901 to 2000 based on changing precipitation and temperature patterns.

A brief review of energy use patterns in three economic sectors; namely, residential, industrial and transport sectors is provided in this paper. The transport sector is the largest energy-consuming sector in Thailand, followed by the industrial and residential sectors, respectively. In order to reduce both imported energy and environmental emissions, energy conservation programs would be implemented. This paper forecasts the growth in energy demand and corresponding emissions to the year 2020 for those three sectors by using a model based on the end-use approach. The energy savings from the energy conservation strategies, such as energy efficiency improvement and energy demand management, are assessed and also the implications on electricity generation expansion planning are examined. The integrated resource planning (IRP) model is used to find the least-cost electricity generation expansion plans. Energy conservation options, including energy efficiency improvement programs, are introduced in the residential and industrial sectors. Public transportation and engine technology improvements are introduced in the transport sector. The effects of energy conservation options are analyzed using a scenario-based approach. The results of analysis reveal that the improvement of public transportation can reduce future energy requirements and CO2 emissions in 2020 by 635 thousand ton of oil equivalent (toe) and 2024 thousand ton of CO2 equivalent, respectively. If all options are simultaneously implemented, the potential of energy savings and CO2 mitigation in 2020 are estimated to be 1240 thousand toe and 3622 thousand ton of CO2 equivalent, respectively.

AbstractThe presented synthesis of the title compounds (II), (IV), (VI) and (VIII) is extremely simple and highly efficient without the use of any chromatographic purification.

Abstract Hybrid energy storage is a multi-modal approach to store and supply different forms of energy (electricity, heat, cold) simultaneously. This is an important sector coupling approach and enables large scale flexibility for a deep decarbonization of energy systems. Two different proposed energy storages – power-to-heat-to-X energy storage (PHXES) and pumped thermal energy storage (PTES) – are investigated in detail in this work towards their potential towards a hybrid deployment. The techno-economic analysis includes thermodynamic flowsheet simulations and unified cost estimations based on the used equipment. It is shown that the main input data set (e.g. working fluid selection, turbomachinery efficiency, pinch temperatures) has a strong influence on storage roundtrip efficiency in the thermodynamic simulations, but also on storage costs. Cost decrease and performance increase can be conflicting development targets, and it is not clear if future energy systems rather require technologies with the highest storage efficiencies or if low cost is an important prerequisite. PHXES and three variants of PTES are implemented into a simplified energy system model of the city of Hamburg that comprises the electric load and heat demand of the district heating system. Two scenarios (fossil benchmark and 80% decarbonization) are used to select the technologies and their capacities that allow the most cost-effective energy supply solution by a linear-programming optimization procedure. Large scale renewable power generation and hybrid energy storage play the major roles in the decarbonization scenario. PHXES with a storage capacity of 69 GWh, hot water storage (3.6 GWh) and a battery system (430 MWh) are part of the cost-optimal solution. A cost sensitivity analysis shows that a total cost reduction of 60–80% is required for PTES to become competitive in this model scenario.

Abstract This paper studied the yield and release of ClO 2 from NaClO 2 under various conditions by ultraviolet–visible spectrophotometer (UV–Vis), the existing form of HA-Na under various conditions by Fourier transform infrared spectroscopy (FT-IR), and the reactivity of chlorite/humate (NaClO 2 /HA-Na) in removal of SO 2 , NO and Hg 0 under various conditions. The investigated factors included the temperature, the pH, the standing time, the coexistence gases and the anions. The results indicated that the yield and release of ClO 2 were significantly affected by the cooperative effects of pH/temperature and pH/standing time. ClO 2 was confirmed as an effective oxidant in the removal of NO and Hg 0 , and dominated the distribution of Hg 2+ in NaClO 2 and KCl. SO 2 and NO were characterized as the promoters for oxidizing Hg 0 and stabling Hg 2+ . The addition of Cl − decreased the removal efficiencies of SO 2 and NO, but slightly increased the Hg 0 removal efficiency. The best removal efficiencies of SO 2 , NO and Hg 0 were 100%, 95.3% and 100% respectively. Based on the characterization results by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS), the removal products were determined as NaCl, humic (HA), Na 2 SO 4 , NaNO 3 , HgSO 4 , Hg(NO 3 ) 2 and HgCl 2 . The reaction mechanism was proposed finally.

Abstract A requirement for the development of a viable biomass conversion technology for clean energy production is the efficient cleaning of the gas fraction. The aim of this work was to use fly ash (AF) to develop cheap and efficient catalysts in removing tar. FA was separated in two fraction, oxide fly ash (OFA) and unburned carbon (UCFA) and both were used for catalysts preparing. The toluene was used as a tar model and a fixed-bed reactor for testing. The calcined oxide fly ash (COFA) showed a steady decrease in catalytic activity, the removal efficiency was reduced by 13.52% after 3 h. Reduced catalyst (RCOFA) and activated and reduced catalyst (AROFA) showed a higher activity than COFA catalyst and were able to maintain their performance. The RCOFA catalytic activity decreased suddenly when the steam was present, and tar removal efficiency descended to 57.32% after only 3 h and to 49.03% after 5hrs, respectively. Results showed that the catalysts obtaining by mixing RCOFA/AROFA with UCFA led to high effective toluene conversion in a reforming environment, over 90% and their catalytic activity remained constant after 12 h, because the unburned carbon presence kept the iron in its reduced form, much more catalytically active.

The crucial role evaluation can play in the co-development of project design and its implementation will be addressed through the analysis of a case study, the Green Communities (GC) project, funded by the Italian Ministry of Environment within the EU Interregional Operational Program (2007-2013) "Renewable Energy and Energy Efficiency". The project's broader goals included an attempt to trigger a change in Italian local development strategies, especially for mountain and inland areas, which would be tailored to the real needs of communities, and based on a sustainable exploitation and management of the territorial assets. The goal was not achieved, and this paper addresses the issues of how GC could have been more effective in fostering a vision of change, and which design adaptations and evaluation procedures would have allowed the project to better cope with the unexpected consequences and resistances it encountered. The conclusions drawn are that projects should be conceived, designed and carried out as dynamic systems, inclusive of a dynamic and engaged evaluation enabling the generation of feedbacks loops, iteratively interpreting the narratives and dynamics unfolding within the project, and actively monitoring the potential of various relationships among project participants for generating positive social change.