Search

Abstract: A new tar destruction technology has been developed by integrating in-situ catalytic gasification and a hot-gas cleaning system in the catalytic gasification of paper-reject sludge. Experimental results indicated that the tar yield in syngas decreased significantly from 13.64 to 10.76 g/m3, when increasing the zeolite addition during in-situ catalytic gasification. When the syngas passed through the hot-gas cleaning system, the tar concentration measured from downstream was approximately 0.22 g/m3. The hot-gas cleaning system used in this research seems to have played a significant role in reducing tar concentration of the syngas. The major tar speciation identified after hot-gas cleaning system was 1-ring or 2-ring hydrocarbons, which included benzene, toluene, xylene, styrene and naphthalene. In summary, the energy yield efficiency of syngas will be enhanced due to the tar reduction and transformation. The syngas seems to be appropriate to use as a fuel in gas engines for electricity generation. [Copyright &y& Elsevier]

The optimal capacity configuration of combined wind-storage systems (CWSSs) serves as a foundation and premise for building new electricity system. This paper proposes a novel capacity configuration model of CWSS. The model simultaneously considers economy, stability and low carbon by respectively minimizing Levelized cost of electricity (LCOE) and maximizing effective load carrying capacity (ELCC). The multi-objective optimization model is solved by Non-dominated Sorting Genetic Algorithm II (NSGA-II). And Multi-Attributive Border Approximation Area Comparison (MABAC) method is used to score the alternative solutions on the Pareto front and make decisions under different scenarios. The results of the case study show that: (1) The evaluation of the ELCC for CWSS can quantify its ability to replace the installed capacity of thermal power, thus greatly reducing the uncertainty of wind power output. (2) Under low-carbon scenario, economic scenario and standard scenario, the results of optimal capacity configuration for the CWSS show that LCOE and ELCC are negatively correlated. When the weights of ELCC and LCOE are equal, the three goals of economy, low carbon and safety and stability are achieved. (3) The results of a single sensitivity analysis on LCOE show that the sensitivity coefficient of electricity generation is the highest, exerting the greatest impact on the capacity configuration decision of the CWSS. A 20 % increase in power generation can reduce LCOE by 0.1203RMB/kWh. This paper provides energy planning recommendations for decision-makers in CWSSs, contributing to the development of a reliable new electricity system. • A multi-objective optimization of CWSSs considering ELCC and LCOE. • Multi-objective optimization model is established based on NSGA-II and MABAC. • The model of LCOE based on ELCC is proposed. • The model is presented to achieve the optimal capacity configuration of the CWSS. [ABSTRACT FROM AUTHOR]

In today's China, the reverse distribution of electricity resources and electricity demand makes large-scale and long-distance transmission of electricity inevitable, resulting in the problem of electricity allocation optimization. To address this problem in the region covered by the China Southern Grid (CSG), the paper establishes an optimized model for electricity generation and interprovincial trading strategies in southern China. Based on data from 2015, this paper simultaneously optimizes electricity generation and interprovincial trading strategies in each of the five provinces. The result shows that interprovincial trading in the CSG-served area can yield significant energy, economic, environmental and interconnection benefits. It can reduce the power supply cost and environmental pressure in Guangdong province, help make Yunnan province a hydropower base in China and a thermal power base in southern China, facilitate the completion of the "West-to-East Power Transmission" project, and partly resolve the issues raised in each province's 13th Five-Year Plan as well as the problem of optimizing electricity allocation in the region covered by the CSG. • We propose an annual total optimized model for electricity generation and interprovincial trading in Southern China. • The model optimizes the electricity trading and transmission routes across regions. • The model considers the generation cost and penalty cost of emitting CO 2 , SO 2 and NO x. • Corresponding policies and proposals are put forward for power grid and five regions in South China. [ABSTRACT FROM AUTHOR]

Abstract The paper proposes a novel improved social spider optimization algorithm (NISSO) for solving optimal power flow (OPF) problem to independently optimize electricity generation fuel cost, power loss, polluted emission, voltage deviation and L index. The proposed NISSO method is first developed in the paper by performing three modifications with intent to improve optimal solution quality and speed up convergence of conventional social spider optimization (SSO). The first and the second modifications are to focus on new solution generation by changing the movement strategy of female spiders and male spiders while the third modification is to fix the female spider rate to an appropriate ratio. The performance of the proposed method is evaluated by testing on three IEEE systems with 30, 57 and 118 buses. As a result, the proposed method has advantages over SSO such as simpler application, fewer number of control parameters, spend less time tuning control parameter values, faster convergence to optimal solutions and more stable search ability. In addition, the proposed method's results are also compared to other existing methods and the indications are that the proposed method can find better optimal solutions, use lower number of generated solutions and faster convergence. Highlights • Novel Improved Social Spider Optimization (NISSO) is first proposed in the paper. • Optimal power flow (OPF) problem is one of the most complicated problems. • NISSO is executed for OPF problem with three IEEE systems with 30, 57 and 118 buses. • NISSO can find high quality solutions of OPF problem with fast search ability. • NISSO is superior to approximately all compared methods for all study cases. [ABSTRACT FROM AUTHOR]

Abstract Tidal energy is one of the most abundant renewable energy sources. Due to its intermittent nature, the integration of tidal energy within a Microgrid (MG) requires appropriate energy management strategies. Some important considerations are tidal energy generation prediction, energy storage requirements, load profile and demand within the Microgrid, and energy pricing structures. This paper considers an MG scenario that includes a small scale tidal farm near Darwin in north of Australia. A tidal power prediction model is introduced using tidal current speed data. Then, for a fixed-size energy storage system (ESS), an optimal scheduling strategy is devised using Particle Swarm Optimization (PSO) to achieve minimum operating costs in the MG. The work presented in this paper provides a framework for the planning of MGs that include tidal generation in their energy mix. Highlights • Visibility of tidal power in the North of Australia. • Tidal power prediction based on tidal current speed observation. • Optimal scheduling for a tidal Micro-grid using Particle Swarm Optimisation. [ABSTRACT FROM AUTHOR]

Abstract Evaluating which electric power generation technologies should comprise the electricity matrix of a country has become a worldwide issue. Multiple factors should be taken into account and issues such as those to do with social, economic and environmental aspects have to be considered in the decision process. In this paper a decision model based on the FITradeoff method is proposed in order to aid multicriteria decision making in the energy planning context. The originality of the paper comes from accommodating, in the proposed model, situations in which the available information is incomplete, when evaluating electric power generation technologies. In order to illustrate the applicability of the model, eight different electrical energy technologies that form the current Brazilian electricity matrix are evaluated under four dimensions: financial, technical, environmental and socio-economic. A sensitivity analysis was performed in order to check the robustness of the results obtained. The application of the proposed model provides information that could be used in Brazil when drawing up energy policies, thus showing the potential use of the method to solve related problems. Highlights • In this paper a multicriteria model based on the FITradeoff method is proposed. • The preferences of different groups are represented by means of decision profiles. • A sensitivity analysis was conducted and this showed the results obtained are robust. • The evaluation performed could be used when drawing up energy policies. [ABSTRACT FROM AUTHOR]

Abstract A new cycle combining a heat pump-transformer and a turbine is proposed to simultaneously produce electric power and useful heat. The system was modeled using the ammonia-lithium nitrate mixture. Plots of power, useful heat, energy and exergy efficiencies are shown against the main system operating temperatures. The heat supplied to the system at a relatively low temperature was upgraded by 40 K to a higher useful level, whilst the proposed cycle was able to produce up to 300 kW of electric power at the same time depending on the operating system temperatures. The modeling showed that the overall energy and exergy efficiencies can reach values of up to 61% and 92%, respectively. Comparing the proposed system with an organic Rankine power cycle and an absorption heat transformer operating separately under the same operating conditions reductions in energy use and irreversibilities of up to 32.3% and 21.6%, respectively, could be achieved. In addition, a case study of the integration of the proposed cycle into a cogeneration pulp and paper mill is presented and it is shown that up to 25% of the gas natural supplied to the boilers could be saved together with 210 kW electric power production. Highlights • A new cycle integrating a heat-pump transformer with a turbine has been proposed. • The cycle has the capability to upgrade waste heat and produce mechanical power. • Overall energy and exergy efficiencies reached maximums of 61% and 92%, respectively. • The system can achieve up to 32.3% energy savings compared with separate heat and power cycles. • The AHPTP was integrated into a pulp and paper mill plant with considerable savings. [ABSTRACT FROM AUTHOR]

Abstract The transition to a 100% renewable energy system based on variable renewable energy raises technical but also institutional questions. The smart energy system concept integrates variable renewable energy by addressing the technical challenges through the integration of different energy sectors, but integration of variable renewable energy also entails a change in the cost structures, especially related to electricity. The effect of this change in cost structures on market prices is investigated. This is done through simulation of a 100% renewable energy system that utilises a large degree of cross-sector integration but maintaining the current electricity market structure. The paper uses a 100% renewable energy system scenario for a 2050 Danish energy system. This is reflected in the use of wind energy as the primary renewable energy source. It is concluded that the current electricity market structure is not able to financially sustain the amounts of wind power necessary for the transition to a 100% renewable energy system. Since earlier research shows that neither electricity production costs nor the total system costs is higher for the renewable path than the fossil-based alternatives, the conclusion in this paper points towards a need for reshaping the institutional structure of electricity trade. Highlights • Calculates electricity prices in a renewable energy system with current market design. • Calculates private profitability of wind power investments within such system. • The market design cannot financially sustain wind power in a renewable energy system. [ABSTRACT FROM AUTHOR]

The exploitation of renewables through energy self-consumption installations is one of the key strategies for the decarbonisation of energy systems and the promotion of distributed electricity generation. Wind and solar photovoltaic energy are two of the renewable sources commonly used to generate electricity for self-consumption. One of the key limitations in the exploitation of medium-large scale wind and solar photovoltaic installations is their compatibility with the geographical characteristics of the territory. In this paper, a method has been developed using GIS techniques to precisely identify the optimal locations that maximise the energy yield of such installations for electrical energy self-consumption. In the implementation of the method, criteria related to the topographical characteristics of the terrain (slope, orientation and shading, etc.), to the energy potential (capacity factor, etc.), and to logistical questions are jointly considered. The method is applied to a case study on the island of Gran Canaria (Spain). The results derived from the application of the method show the importance of detailed consideration of the topographical characteristics. This aspect is even more important in regions/countries with limited availability of useful territory for these types of installations, and is therefore key in the elaboration of energy planning strategies. [Display omitted] • A method using GIS techniques in the optimization of renewable energy. • Land distribution of Wind and photovoltaic plants for self-consumption. • Contribution of strategies for the development of sustainable energy policies. • A method to promote the distributed electricity generation. [ABSTRACT FROM AUTHOR]

Solar energy application in a wider spectrum has the potential for high efficiency energy conversion. However, solar cells can only absorb photon energy of the solar spectrum near the solar cell band-gap energy, and the remaining energy will be converted into thermal energy. The thermoelectric generator is a good choice to utilize this thermal energy. This paper analyses the feasibility of photovoltaic-thermoelectric (PV-TE), and reviews the current types and performance of PV-TE. Furthermore, it presents the optimization and development of PV-TE. In addition, this paper presents the challenge and efficient improvement of PV-TE in actual application. Therefore, this paper would provide a valuable reference for further research into the field of PV-TE and its applications. [ABSTRACT FROM AUTHOR]

The trend of global energy demand forecasts a continuous increase in the forthcoming years together with a diversification and differentiation of energy sources. In order to ensure the energy systems transition towards a sustainable functioning mode while avoiding early depletion of energy resources, industrial activities need to foster process improvement. Among energy efficient process design methodologies, pinch analysis and exergy analysis are two powerful methods but each one shows drawbacks. This paper introduces a new methodology that uses the Jacobian Matrix of exergy destruction as a mathematical indicator to couple the Pinch and the exergy analysis and overcome their individual limitations. In the proposed approach, exergy analysis is used not only to assess the exergy losses but also to guide the changes needed in industrial processes structures and operating conditions. And while the pinch analysis considers only heat integration, the proposed methodology allows including other recoverable exergy in a process through thermodynamic conversion. In this paper, the guidelines of the methodology are first detailed. When applied on a basic natural gas liquefaction process, the proposed approach will numerically result in a new improved process comparable to the existing, most widely used natural gas liquefaction process. The main advantage of the methodology is time saving compared to holistic operating conditions improvement as in the traditional process design methods and automatic process structure modification leading to better heat integration. [ABSTRACT FROM AUTHOR]

This paper reports the results of analysis of technical and economic parameters on the specific cost of electricity production. The use of a particular technology determines the value of the investment needed for the construction of a power plant, its energy efficiency, internal electrical load of the power plant and its annual operating time. Besides, this cost is considerably dependent on the interest rate on the capital, fuel prices and environmental charges as well as, equally importantly, their variability in time. The variability in the prices of energy carriers and their mutual relations are inevitable for a number of reasons. As shown in the paper the change of the technical parameters in the range of the possible boundaries in a particular technology cannot considerably reduce the specific cost of electricity production. The reduction of the current price relation between gas and three-times cheaper coal (calculated per specific unit of energy) can considerably improve the profitability of the use of the gas-steam technology. When the ratio of the cost of fuel in the specific cost of electricity production is small, the impact of the fuel price on its value is also insignificant. [ABSTRACT FROM AUTHOR]

Organic Rankine Cycle (ORC) is promising in utilizing low-medium thermal energy, and solar energy is widely considered as the most attractive renewable energy for the future. Consequently, electricity production by coupling ORC and solar energy can reduce the fossil fuel consumption and lower the CO 2 emissions over the world. However, the intensity of solar radiation keeps changing throughout the daytime, so it is important to study the daytime performance of solar-ORC system to guarantee a proper operation. Based on the discretized parameter model built in Dymola, dynamic performances of a small-scale power plant driven by parabolic trough collector (PTC) under clear sky and cloudy sky conditions are analyzed in this paper, respectively. The results show that degree of super heat, evaporation pressure and output power are relevant to direct normal irradiance (DNI) and follow the variation of DNI from morning to afternoon. Particularly, this paper pays attention to analyze the system's responses to the cloud blockage using the dynamic model. It shows that short period (5 min) of cloud blockage of the sun poses no severe influence, while the cloud occurring at morning can cause the system to break down easily. In addition, a conventional PID control strategy is considered for the PTC-ORC system under the weather condition of cloudy sky. The optimized system can generate 105.54 kWh and the system without control can generate 84.95 kWh. The generation can improve 24% compared to the system without control. [ABSTRACT FROM AUTHOR]

In the process of vaporizing water within the biogas-driven CCHP system based on chemical recuperation, a significant temperature disparity in heat transfer exists, leading to increased irreversible loss, and the methane conversion rate is low because the gas turbine exhaust gas is difficult to drive efficient methane conversion. This paper proposed a novel biogas-driven CCHP system based on chemical reinjection. Through the reinjection of a portion of the exhaust gas into the reactor, a self-thermal reforming reaction process is engineered, leading to a substantial enhancement in methane conversion rate. The heat matching of the heat exchange unit is optimized by the reheat air, and the power generation and cooling capacity of the system are improved. Notably, the electricity and cooling generation of the new system increased by 55.52 kW (6.20 %) and 542.49 kW (101.49 %), respectively, while the exergy efficiency increased by 8.31 %. The study delves into the influence of key parameters on the system thermal performance. During the reforming process, the exhaust gas split ratio has a significant impact on carbon deposition and methane conversion. When the methane is nearly completely converted, there is no significant change in electricity generation of the system. Excessive turbine inlet temperature is found to be unfavorable for improving the exergy efficiency of the new system from a holistic system perspective. Finally, a comprehensive comparison of the thermal performance between the new system and the reference system is conducted under various ambient temperatures. This study offer a new design scheme for the efficient utilization of biogas. • A novel biogas-driven CCHP system based on chemical reinjection is proposed. • Partial exhaust gas reinjection for self-heating of biogas reforming reaction. • The thermal efficiency and exergy efficiency increased by 28.39 % and 8.31 % in the new system. • The system is subjected to parameter analysis in combination with carbon deposition analysis. [ABSTRACT FROM AUTHOR]

This paper focuses on the determination of the optimal operating scenario of an Externally-Fired Micro-Gas turbine utilizing syngas produced by biomass gasification. Biomass exploitation can contribute to the achievement of the net-zero emissions target in 2050. This can be boosted by the advancement of externally-fired technology. In this study, a dual-objective optimization process, including a validated thermodynamic model, is combined with preliminary cost insights to assist the decision-making process. The resulting performance is compared with the actual data-based performance of a reference natural-gas-fired Micro-Gas Turbine. The performance comparison is performed through an exergetic analysis, identifying the main losses contributors. The optimization results in an externally-fired performance of 77.9 kW el electrical power and 20.3% efficiency, improved by 31.5% compared to the average current externally-fired demonstrated efficiencies. Yet, there is still room for improvement to reach natural-gas-fired Micro-Gas Turbine efficiency. The study highlights an unavoidable efficiency decrease of at least 4.0 percentage points due to the use of syngas itself instead of natural gas, which conversely increases heat recovery potential. However, compared to the state-of-the-art demonstrations, the proposed analysis is a significant step towards efficiency improvement, which can be exploited for future biomass demonstrations, attractive for electricity generation as well. • Performance of an externally-fired microturbine using biomass syngas is optimized. • Design point is determined through an optimization with preliminary cost insights. • Performance is compared with the validated data from a natural gas microturbine. • Electrical efficiency improved by 31.5% compared to average current demonstrations. • Syngas use results in an unavoidable efficiency decrease of 4.0 percentage points. [ABSTRACT FROM AUTHOR]

Deck photovoltaic (PV) system has been widely investigated on ocean-going ships to reduce oil consumption. However, its adoption on smaller ship encounters obstacles such as limited deck space, reduced energy efficiency, and cumbersome support structures. This paper explores the application of vertical PV windows on small ships as an alternative solution. By retrofitting standard glass with PV windows, the electricity generation area is expanded without occupying valuable deck space or requiring heavy brackets. Unlike deck PV system that solely generate electricity, PV windows also have the added benefit of reducing cooling load inside cabin, enhancing the overall energy-saving effect. Solar energy received by vertical surface is related to heading angles during navigation, a factor that has received scant attention in previous studies. Therefore, hybrid energy saving performance of PV window system is investigated under sailing condition by experiment and simulation methods. The electricity performance of PV window exhibits periodic fluctuations in closed-route trails, with sailing resulting in better electricity performance than mooring. Annual simulation research indicates that PV window system can generate 300.0 kWh of electricity actively, decrease 374.4 kWh of air conditioning load passively and reduce 472.0 kg of CO 2 emission. The optimal transmittance of PV window is 0.4%. • Hybrid energy saving performances of ship PV window system are researched by experiment and simulation. • The periodical changes of received solar radiation and electricity performances are observed from experiment. • The electricity generation and air conditioning load reduction are 300.0 kWh and 374.4 kWh, respectively. • The recommended transmittance of PV window is 40%. • Sailing can promote the electricity efficiency and power generation. [ABSTRACT FROM AUTHOR]

This paper investigates the challenges isolated islands face in transitioning from fossil fuel-based electricity generation to renewable energy sources. The Canary Islands serve as a case study, where photovoltaic and wind power are the primary renewables, but their variability requires a deep techno-economic analysis. The island's energy demand is predicted to rise by 100% due to economic growth, electrification and electric vehicles. However, implementing renewable systems encounters obstacles, such as limited suitable sites and protected areas. The study uses Wilks' methodology and Monte Carlo sampling to explore 59 combinations of randomly selected inputs of the uncertain variables, aiming for a 95/95% coverage and confidence level in the results. In most cases, they experience energy shortages, failing to meet electric demand. Even though a new generation mix appears to cover demand under all circumstances, the uncertainty unveils a different reality, leading to an approximate 25% increase in system costs. Surpluses in energy generation, while seemingly positive, can pose challenges. The new system's Levelized Cost of Energy increases from around 14 to 17c€/kWh. These cost increases are contingent upon future performance and the variability of uncertain parameters, leading to excesses ranging from slightly below 25% to over 40%. • Demand coverage scenario designed to meet electric demand through renewable sources. • Uncertainty analysis of a scenario for the complete electrification of the economy. • Best Estimate Plus Uncertainty analysis implementing the Wilks' methodology. • Resizing the system to cover the demand with 95% coverage and confidence levels. • Differences in using deterministic and stochastic methods for electric demand coverage. [ABSTRACT FROM AUTHOR]

Solar-driven thermoelectric generator is an enticing avenue for sustainable global electricity generation. Nevertheless, its broad adoption is impeded by two significant challenges: low efficiency and reliability. To address these challenges, a novel hybrid system that integrates angle-independent evacuated U-tube solar collector (EUSC) with inhomogeneous thermoelectric generator (ITEG) is first proposed in this paper. The power density of the hybrid system is predicted to be 26.1 W m−2 with an efficiency of 2.61% under AM 1.5, signaling considerable potential for performance enhancement. Extensive parametric studies demonstrate that raising the inlet water temperature for EUSC and the spatial inhomogeneity coefficient of ITEG, reducing external environmental temperatures and fluid flow rate within the EUSC, and optimizing the number and geometric characteristics of ITEG can improve the output performance. By optimizing the number of thermocouples in ITEG, the power density could reach 39 W m−2 when the spatial inhomogeneity coefficient of ITEG is 0.83. Gradient-based local sensitivity analyses further identify that the geometrical characteristics of ITEG and inlet water temperature of EUSC are, respectively, the most and least sensitive variables. These findings offer valuable insights into the intricate integration and operational mechanisms pivotal for achieving efficiency and stability in solar-driven thermoelectric generator power systems. • A novel photo-thermal-electric hybrid system is conceptualized and formulated. • Power density and efficiency can reach 26.1 W m−2 and 2.61%, respectively. • Influential laws of key design parameters and operation conditions are revealed. • The most and least sensitive factors are identified by local sensitivity analyses. [ABSTRACT FROM AUTHOR]

In this paper, an optimization technique based on time-varying acceleration particle swarm optimization (TVAC-PSO) is applied for optimizing economic dispatch and emission reduction problems in a system consisting of CHP units. At first algorithm is used for deterministic model that for comparison with previous works. Besides, its convergence speed is adequately high. Then Monte Carlo method is implemented to solve the stochastic model providing real situation. In the Monte Carlo simulation you have a range of values as a result, and you are able to understand the risk and uncertainty in the model. Deterministic models used for conventional economic dispatch problems are not able to address some real conditions in practical applications. Deterministic models of power system applications are incapable to express the uncertainties that come from energy demand and supply of intermittent renewable systems. Due to the presence of these various uncertain variables stochastic attitude is inevitable in practical applications. Therefore, solving economic dispatch and emission reduction problems simultaneously and stochastically that is the main objective of this paper has a great level of importance. For modeling accurately, both power transmission losses and nonlinear fuel cost function are considered. The proposed method is applied to a 7-unit test system. [ABSTRACT FROM AUTHOR]

The electricity mix in Tunisia mainly relied on conventional energy sources for over 50 years. Recently, due to fossil fuel prices oscillations and national reserves shortage, the need arose for restructuring the energy supply system. Targeting the integration of renewable energies could be a plan for satisfying the increasing demand and the supply independence. However, several macroeconomic conditions and policies present barriers for the integration of Renewable Energy Sources (RES), despite their abundance, availability and environmental benefits. This paper presents a long-term model of Tunisia electricity system, based on OSeMOSYS (Open Source energy MOdelling SYStem), aimed at unveiling potential benefits of increasing RES in electricity production. The paper first investigates peculiarities of Tunisia electricity system, arguing the necessity to include them in the electricity system model. Then, it explains the choice of OSeMOSYS and brought modifications, including peculiar system characteristics. Finally, the model is applied to two scenarios, a Business As Usual case and a 30% RES target in electricity production case, for time horizon 2010–2030. Results demonstrate the importance of system features detailed modelling. Specifically, they show that targeting RES state-invested integration in the electricity mix may allow higher energy independence to be reached, without increasing significantly system costs. [ABSTRACT FROM AUTHOR]

Kazakhstan's electricity generation depends heavily on fossil fuels. Renewables and other non-fossil resources provide potential alternatives to diversify the electricity generation system. In this paper, various potential local non-fossil fuel resources, hydro, solar, wind, biomass and uranium are reviewed and an assessment framework for prioritizing these resources is established. A multi-criteria decision making approach, analytic hierarchy process (AHP) based on expert opinion, is utilized for developing the assessment model, using four main criteria of technical, economic, social and environmental aspects and thirteen sub-criteria. The review reveal that Kazakhstan has ample potential to develop a non-fossil fuel based electricity system. Furthermore, the model shows hydro to be the most favorable resource followed by solar; wind and nuclear are ranked third and fourth, respectively while biomass is found to be the least attractive option. It is also found that each resource is inclined towards a particular criterion; hydro towards social, solar towards economic, nuclear towards technical, with biomass and wind directed towards environmental. Besides reporting the use of the AHP model for the first time in the Kazakhstan context, the assessment carried out in this paper can assist decision-makers to articulate long-term energy policy for any country. [ABSTRACT FROM AUTHOR]

This paper describes the construction and analysis of a disaggregated input-output model and its extension to a social accounting matrix (SAM) for the Spanish economy in 2013. Our focus is the specific disaggregation of the electricity industry into the generating, transmission, distribution and marketing businesses, which were decoupled in 1997 under legislation prohibiting any single company from conducting more than one of them. The multi-sectoral framework also allows disaggregation of electricity generating by production technologies (wind, nuclear, conventional thermal, hydropower, solar and other technologies). To the best of our knowledge, this is the first paper in which this information is presented in a multi-sectoral framework for the Spanish economy, which is enormously dependent on the electricity industry. The structural analysis reveals the industry's role in Spain and the importance of its activities. None of the electricity generating businesses is a Rasmussen key sector, and generating and distribution are both capital-intensive activities. Meanwhile, conventional thermal and hydropower generating together make up more than 50% of total output in value terms, while nuclear power accounts for only around 7%. Finally, imports and exports of electricity are small, and almost all demand is covered by domestic production. [ABSTRACT FROM AUTHOR]

The multi-objective thermal power dispatch (MTPLD) problem allocates power demand among the committed generating units while minimizing the operating cost and pollutant's emission objectives simultaneously, subject to physical and technological constraints. The success to find MTPLD solution relies on the decision-maker's ability to select compromised solution under uncertain/diverse conditions and the search algorithm's potential to generate non-dominated solutions. Owing to ambiguous choice of objectives, this paper presents a fuzzy surrogate worth trade-off approach to decide the preferred solution among the non-dominated solution set. The uniformity of non-dominated solution set is maintained exploiting a quality measure approach. This paper presents a novel foraging activity paradigm to generate non-dominated solutions. The presented approach comprises of fly and walk behavior of preys. The direction of turn heuristic of prey handles system's equality constraint. The search algorithm balances exploration and exploitation and handles system constraints autonomously. The performance of proposed algorithm is investigated using generalized benchmark functions and multi-fuel, medium and large power system MTPLD problems. The experimental results shows that the proposed approach is robust, depends on least parameters and retains Pareto quality in independent trials while generating non-dominated solutions in a trial run. [ABSTRACT FROM AUTHOR]

A new procedure for energy consumption characteristics of steam turbine is proposed in this paper. The heat rate index evaluates heat energy needed for electricity generation, and fluctuates greatly in real-time operation. The volume effect in the system is thus considered to modify the traditional real-time heat rate calculation. Particle swarm optimization (PSO) algorithm is inserted in the traditional Fuzzy C -means (FCM) to find the optimal initial clustering centers. Three clustering evaluating indicators are further added for the clustering number's adaptive searching. The modified clustering method is then tested to be effective by UCI datasets. The operation data from a 660 MW steam turbine system are then taken for the industrial case study, and the heat rate index values are then calculated by the proposed method with the volume effect taken into consideration. After steady working condition selection, the modified clustering method proposed in the paper is then utilized under the whole working condition. The clustering results are showed in graphs with the power output and temperature as coordinate axes, and coincide well with actual operation of the steam turbine system. The proposed procedure can be taken as a new guidance to obtain the energy consumption indexes' target condition library in steam turbine system. • A modified heat rate index calculation has been proposed with the volume effect. • The modified self-adaptive FCM has been used for working condition division. • The paper proposes a new guidance for energy consumption indexes' target condition library in the field. [ABSTRACT FROM AUTHOR]

Abstract: Two-thirds of input energy for electricity generation in the USA is lost as heat during conversion processes. Additionally, 12.5% of primary fuel and 20.3% of electricity are employed for space heating, water heating, and refrigeration where low-grade heat could suffice. The potential for harnessing waste heat from power generation and thermal processes to perform such tasks is assessed. By matching power plant outlet streams with applications at corresponding temperature ranges, sufficient waste heat is identified to satisfy all USA space and water heating needs. Sufficient high temperature exhaust from power plants is identified to satisfy 27% of residential air conditioning with thermally activated refrigeration, or all industrial refrigeration and process heating from 100 to 150 °C. Engine coolant and exhaust is sufficient to satisfy all air conditioning and 68% of electrical demands in vehicles. Overall, this study demonstrates the potential to reduce USA primary energy demand by 12% and CO2 emissions by 13% through waste heat recovery. A detailed analysis of thermal energy demand in pulp and paper manufacturing is conducted to demonstrate the methodology for improving the fidelity of this approach. These results can inform infrastructure and development to capture heat that would be lost today, substantially reducing USA energy intensity. [Copyright &y& Elsevier]

Abstract: Black liquor gasification (BLG) is currently being developed as an alternative technology for energy and chemical recovery at chemical pulp mills. This study examines how different assumptions regarding systems surrounding the pulp mill affect the CO2 emission balances for different BLG concepts. The syngas from the gasification process can be used for different applications; this study considers production of renewable motor fuels and electricity generation. Both a market pulp mill and an integrated pulp and paper mill are considered as host mill for the BLG plant. Furthermore, the consequences of limited availability of biomass are shown, i.e., increasing the use of biomass in a mill is not necessarily CO2-neutral. The results show that the potential to reduce CO2 emissions by introducing BLG is generally much higher for a market pulp mill than for an integrated pulp and paper mill. Electricity generation from the syngas is favoured when assuming high grid electricity CO2 emissions where as motor fuel production is favoured when assuming low grid electricity CO2 emissions. When considering the consequences of limited availability of biomass, the CO2 emission balances are strongly affected, in some cases changing the results from a decrease to an increase of the CO2 emissions. [Copyright &y& Elsevier]

In the present context, energy access to remote rural households through local energy generating systems has been recognized as a cost effective and extent efficient option. With increased emphasis on eco-friendly technologies and high fuel cost associated with conventional energy generation, the use of renewable energy resources (small hydro, biomass, solar, wind energy etc.) are being explored. The present paper is focused on the optimal sizing of a stand-alone Integrated Renewable Energy System (IRES) which comprises the resources of micro hydro power (MHP), biogas, biomass, solar and wind energy. Initially, a demand response (DR) strategy based on energy consumption scheduling of appliances has been suggested and modelled in the paper. This strategy aims to minimize the peak hourly energy consumption of the study area. Further, different combinations of system components without and with DR strategy were considered and optimized for power reliability criteria of 0% and 5% unmet load. It has been found that significant amount of savings in system sizes and costs are obtained with DR strategy compared to system without DR. [ABSTRACT FROM AUTHOR]

Long term peak electricity demand forecasting is a crucial step in the process of planning for power transmission and new generation capacity. This paper discusses an application of the Generalized Pareto Distribution to the modelling of daily peak electricity demand using South African data for the period 2000 to 2010. The main contribution of this paper is in the use of a cubic smoothing spline with a constant shift factor as a time varying threshold. An intervals estimator method is then used to decluster the observations above the threshold. We explore the influence of temperature by including it as a covariate in the Generalized Pareto Distribution parameters. A comparative analysis is done using the block maxima approach. The GPD model showed a better fit to the data compared to the GEVD model. Key findings from this study are that the Weibull class of distributions best fits the data which is bounded from above for both stationary and non-stationary models. Another key finding is that for different values of the temperature covariate the shape parameter is invariant and the scale parameter changes for different values of heating degree days. [ABSTRACT FROM AUTHOR]

Electricity generation from photovoltaic (PV) plants plays a major role in the decarbonization of the energy sector. The core objective of this paper is to identify the most important conditions for the future development of PV in order to achieve its greatest possible benefits of PV systems for society. This analysis is based on the documentation of the historical deployment of quantities of PV and on the lessons learned regarding cost developments. In addition, the improvements of PVs technical and environmental performance parameters are investigated. A major result is that the impact of PV feed-in on network capacities may be substantial. Hence, classical energy-based network charges are inadequate. Changes in tariff and pricing structures are needed especially on retail level. The major conclusions is that customers should also receive time-variable price signals that tells them the real-time value of electricity in the system and provides incentives for taking electricity from the grid or feed-in. In addition, the tariffs should have components for maximum power from and to the grid. Another conclusion is that on retail level grid parity already today provides sufficient incentives to purchase a PV system in many countries without additional financial support. • The 4 major Highlights of this paper are: • Grid parity has made PV systems economically attractive already in many countries. • Grid parity has reduced the need for subsidies for small decentralized systems. • Retail pricing systems providing fair conditions for all customers are needed. • Final customers tariffs should include components for power from and to the grid. [ABSTRACT FROM AUTHOR]

Urban agglomeration is identified as the important geographic units of country development while contributing immensely to carbon emission. This paper explored energy-related carbon emission characteristics of the Pearl River Delta (PRD) - the typical urban agglomeration in China, from cities and sectors perspectives. By conducting LMDI model, this paper decomposed carbon emission by sector and by cities to illustrate the key impact factors in the PRD, explored the reasons for the change of driving effects in urban agglomeration in view of regional difference. It concludes that, most cities carbon emission rebound around 2017, while carbon emission sharply decreased. There are differences in key reduction industries in different cities, while production and supply of electric power and transport sector had negative impact on reduction processes in most cities. The significant inhibition effect of energy intensity is mainly attributed to the great decrease of energy intensity in main industries reduction cities, such as Shenzhen, Guangzhou, Dongguan and Foshan. Based on the characteristics of carbon emission and social and economic development of the PRD, this paper puts forward specific suggestions and measures for differentiated emission reduction in urban agglomeration, and provides a new idea for the governance of carbon emission in urban agglomeration. • The carbon emission inventory of typical urban agglomeration was built. • Carbon emission characteristics were diagnosed from cities and sectors perspectives. • Great disparities in contribution of carbon emission variation exists sectors and cities. • Energy intensity and economic growth were key drives of PRD region carbon emission. [ABSTRACT FROM AUTHOR]

Large-scale disordered charging of electric vehicles will lead to problems such as voltage drop, increased network loss, and reduced life of transformers. In order to fully tap the dispatch potential of electric vehicles and promote more extensive participation of electric vehicle users in the orderly interaction of the power grid, this paper combines power grid optimization. The most economic lever is used in dispatching, and an optimized dispatching strategy based on the dynamic electricity price mechanism is designed. In order to fully absorb wind power, ensure the charging and discharging demand of electric vehicles and the safe operation of the distribution network, realize the power generation side and the electric vehicle user side, maximize bilateral interests. This paper verifies that the collaborative optimization scheduling strategy is an effective scheduling scheme that takes into account the interests of all aspects and realizes multi-objective optimization through an example. The optimal scheduling scheme proposed in this paper provides an example for the multi-objective optimization problem. • The dynamic electricity price mechanism is constructed to optimize the scheduling strategy. • The dynamic electricity price mechanism effectively guides the interaction between electric vehicle users and the grid. • The optimal scheduling strategy ensures the safe operation of the grid. [ABSTRACT FROM AUTHOR]

In recent years, solar energy has been considered as one of the principle renewable energy source for electric power generation. In this paper, single diode photovoltaic (PV) system and double/bypass diode based PV system are designed in MATLAB/Simulink environment based on their mathematical modeling and are validated with a commercially available solar panel. The novelty of the paper is to include the effect of climatic conditions i.e. variable irradiation level, wind speed, temperature, humidity level and dust accumulation in the modeling of both the PV systems to represent a realistic PV system. The comprehensive investigations are made on both the modeled PV systems. The obtained results show the satisfactory performance for realistic models of the PV system. Furthermore, an in depth comparative analysis is carried out for both PV systems. [ABSTRACT FROM AUTHOR]

Demand response (DR) can serve as an effective tool to better balance the electricity demand and supply in the smart grid. It is defined as "the changes in electricity usage by end-use customers from their normal consumption patterns" in response to pricing and incentive payments. This paper focuses on new opportunities for DR with electric vehicles (EVs). EVs are potential distributed energy resources that support both the grid-to-vehicle and vehicle-to-grid modes. Their participation in the time-based (e.g., time-of-use) and incentive-based (e.g., regulation services) DR programs helps improve the stability and reduce the potential risks to the grid. Smart scheduling of EV charging and discharging activities also supports high penetration of renewables with volatile energy generation. This paper proposes a novel stochastic model from the Independent System Operator's perspective for risk management and participation planning of EVs in the smart grid for DR. The risk factors considered in this paper involve those caused by uncertainties in renewables (wind and solar), load patterns, parking patterns, and transmission lines' reliability. The effectiveness of the model in response to various settings such as the area type (residential, commercial, and industrial), the EV penetration level, and the risk level has been investigated. [ABSTRACT FROM AUTHOR]

This paper introduces a novel approach that addresses the intricate challenges associated with energy hubs, focusing on diverse issues in the transmission and production of energy, particularly within the realms of gas and electricity networks. A key emphasis is placed on the profitability of energy hubs, navigating through uncertainties heightened by the presence of varied energy carriers. The proposed model features an energy hub with electrical inputs and outputs encompassing natural gas, electricity, and thermal energy. Diverse sources contribute to electricity supply, including bilateral contracts, power basin purchases, and generation via a cogeneration unit. Thermal heat is provided by a heating furnace, alongside a simultaneous cooling, heating, and power production unit. Addressing market price uncertainties, the model incorporates probabilistic considerations for the next day's electricity prices. Notably, the model encompasses the intricacies of electric vehicle rechargeable modes, treating them as a bidirectional source for both energy production and consumption, contributing to effective demand-side management. To tackle the complexity inherent in these dynamics, a novel optimization method based on crow search is proposed, enhancing local and global search capabilities. The efficacy of the proposed method is demonstrated through a comprehensive application on a micro-energy grid, considering four distinct cases on a typical summer day. The analysis reveals that Case 2, incorporating PV and WT, significantly outperforms Case 1, with a 10.8 % surplus in electricity generation. Furthermore, the proposed Crow Search Optimization algorithm exhibits a 50 % improvement over alternative methods, showcasing its efficacy in achieving optimal solutions for microgrid performance. [Display omitted] • Model explores gas-electricity networks in an energy hub. • Addresses energy hub profitability amidst uncertainties. • Introduces crow search optimization for complex models. • Models EVs as two-way energy sources. • Applies proposed method to micro-energy grid scenarios. [ABSTRACT FROM AUTHOR]

To avoid the coincidence between the tower nature frequency and rotational excitation frequency, a SEZ (speed exclusion zone) must be built for a two-blade wind turbine with a full rated converter. According to the literature, two methods of SEZ-crossing could be adopted. However, none of them have been studied in industrial applications, and their performance remains unclear. Moreover, strategies on power regulation operation are not covered. To fully investigate them, this paper develops two control systems for a two-blade WT (wind turbines) with a SEZ. Because control systems play vital roles in determining the performance of the WT, this paper focuses on comparative studies on their operation strategies and performance. In these strategies, optimal designs are introduced to improve existing SEZ algorithms. Moreover, to perform power regulation outside the SEZ, two operation modes are divided in the proposed down power regulation solutions. The developed control systems’ performance is confirmed by simulations and field tests. Two control systems present similar capabilities of power production and SEZ-bridging. Nevertheless, at the cost of significantly increased tower loads, one captures 1% more energy than the other. Overall consideration must be made for the control system selection for a WT with a SEZ. [ABSTRACT FROM AUTHOR]

Five different models for calculating solar module temperature, output power and efficiency for sunny days with different solar radiation intensities and ambient temperatures are assessed in this paper. Thereafter, modeled values are compared to the experimentally obtained values for the horizontal solar module in Nis, Serbia. The criterion for determining the best model was based on the statistical analysis and the agreement between the calculated and the experimental values. The calculated values of solar module temperature are in good agreement with the experimentally obtained ones, with some variations over and under the measured values. The best agreement between calculated and experimentally obtained values was for summer months with high solar radiation intensity. The nonlinear model for calculating the output power is much better than the linear model and at the same time predicts better the total electrical energy generated by the solar module during the day. The nonlinear model for calculating the solar module efficiency predicts the efficiency higher than the STC (Standard Test Conditions) value of solar module efficiency for all conditions, while the linear model predicts the solar module efficiency very well. This paper provides a simple and efficient guideline to estimate relevant parameters of a monocrystalline silicon solar module under the moderate-continental climate conditions. [ABSTRACT FROM AUTHOR]

The reliability of natural gas and electricity supply is a crucial aspect in many fast-growing economies, as the economic boom of these countries demands a solid energy infrastructure. In Colombia, the economy has experienced a steady increment over the last several years that have placed the country as one of the most promising economies in Latin America. However, the natural gas infrastructure lacks sufficient robustness to withstand the rate of economic growth. This paper assesses the impact on the reliability of a liquefied natural gas regasification terminal in Colombia as one potential solution to improve the reliability in the country. Contrary to other works, this paper investigates the impact of using an integrated electric and natural gas model, as there exists a strong interdependency between both sectors. This approach is more suitable since it permits evaluation of the impact of a terminal on electricity users, as they also experience the negative consequences of an unreliable natural gas supply. Numerical results show that the terminals substantially improve the reliability of both systems. Furthermore, numerical results prove that the current regulatory approach, based on a priority service queue to mitigate the negative effect of an unreliable system, would no longer be needed. [ABSTRACT FROM AUTHOR]

Capacity expansion models for the power sector are used to project future decisions over the coming decades by simulating investment and operation decisions for the use of electricity. Due to model performance constraints, these models typically do not explicitly simulate every hour within a year, but instead simulate representative time segments (groups of hours). This paper evaluates different approaches for selecting time segments across three methods: sequential, categorical, and clustering, across a wide range of time-segment quantities, for a total of 204 temporal profiles. To measure the performance of each profile's ability to accurately represent data, the root-mean-square-error of each profile's time segments are compared to the data's original hourly data. The temporal alignment across regions is also measured (i.e., how often windy days align across regions). Different spatial resolutions were applied for a subset of the temporal selection methods to investigate the impact spatial resolution has on performance. This paper provides a framework for measuring the value of different temporal selection methods and of adding more granular data to energy system models. Overall, multi-criteria clustering yields the lowest root-mean-square-error across all datasets evaluated and provides a holistic view of the intertwined relationships between renewable generation and electricity demand. • Temporal selection methods analyzed across three commonly used techniques. • Measured performance of representing model data within representative hours. • Measured temporal performance across electric load and wind and solar generation. • Clustering techniques performed better than sequential or categorical techniques. [ABSTRACT FROM AUTHOR]

Based on constructal theory, the disc-shaped solid–gas reactors combined heat and mass transfer are investigated in this paper. Radial- and branched-pattern of the discs are considered, and the two pattern discs are optimized based on entropy generation rate minimization. The results show that there exist a minimum value of the entropy generation rate and the corresponding optimal construct of the reactor. The minimum entropy generation rate increases with the increase in the radius of the first order disc; therefore, a proper radius of the first order disc should be adopted according to the practical demand of the reactor. The performance of the reactor can be improved by increasing the material amount of the integrated collector or reducing the number of elemental tributaries and the thermodynamic parameter η . The design pattern of the disc depends on the relationship of the critical radius and disc radius. Moreover, the heat transfer or mass transfer models are special cases of the heat and mass transfer model in this paper. [ABSTRACT FROM AUTHOR]

The city of Pécs in Hungary has developed an energy strategy to be implemented in the years to come which proposes structural changes in both the supply and demand sides. This paper offers a model based on the proposed system aimed at providing a basis for comparison for decision-makers. The model has been developed with the help of energy system analysis tool energyPRO, and covers the three basic sectors of heat, electricity and transport. It shows the energy system of Pécs in terms of hourly production and demand levels – and these values enable the model to analyse intermittent energy sources. The model is also validated – to ensure that it is satisfactory for the simulation of future energy systems. It analyses two scenarios – one where the city does not implement the changes proposed in the strategy, and one where it does. The paper compares the two scenarios based on sustainability, energy security and affordability. [ABSTRACT FROM AUTHOR]

In this paper, a constant-voltage power generation system based on a novel memory machine is proposed and implemented. The memory machine can offer direct and efficient air-gap flux control due to its creative integration of the memory concept and doubly-salient machine structure. By utilizing such memory machine in a direct-drive wind power generation, the resulting system can realize the constant-voltage operation under different load conditions. After addressing the memory machine design and characteristics analysis by using finite element method, this paper presents the detailed implementation and control principle of the constant-voltage power generation system. Both the numerical simulation and prototyping test are conducted to verify the validity of the proposed machine and system. [ABSTRACT FROM AUTHOR]

The paper examines the expected regional employment returns connected to the development of tidal stream and wave-based electricity generation in a UK region – Wales. New employment provides economic development opportunities and the paper demonstrates that there is a need to develop the evidence base on these regional employment impacts. It addresses how far a region which is adjacent to significant marine resources is likely to benefit from a change in the energy generation mix which could feature more wave and tidal stream technologies. [ABSTRACT FROM AUTHOR]

The paper presents a novel concept for thermodynamic evaluation of a selected energy system. The presented method has been developed by integration of the Thermo-Economic Analysis with the theory of Thermo-Ecological Cost. It can be applied as a thermodynamic evaluation method of rational resources management within any production system. It takes into account both the interrelation of irreversibility within the analyzed system and its influence on the global effects related to the depletion of non-renewable natural resources. The proposed method has been applied to evaluate the production of electricity in the process of natural gas transmission at pressure reduction stations. The expansion system is based on an existing plant integrated with a CHP module, characterized by a performance ratio of 89.5% and exergy efficiency of 49.2%. Within the paper, this expansion plant is supplied with natural gas transported from a natural deposit through a case-study transmission system with 4 compressor stations. The TEC (thermoecological cost) method was applied in conjunction with thermoeconomic analysis. As a result, TEC of the electricity generated in the expanders was determined at 2.42 kJ/kJ, TEC of electricity from the CHP module is 1.77, and the TEC of medium-pressure natural gas distributed to consumers is 1.022. [ABSTRACT FROM AUTHOR]

As the proportion of renewable energy in electricity generation continues to increase, the uncertainty of renewable energy has brought significant challenges to power system security. Traditional renewable energy dispatching methods have less research on power system failure risk analysis due to economic considerations. In this paper, a renewable energy time series regulation strategy considering N-1 faults is proposed to improve the power system economy and security. In this strategy, by researching flexible load aggregation models, the time-series regulation model of aggregation loads is determined. Then the network N-1 security analysis divided into generator detection and branch detection is conducted. Determining possible N-1 faults of the system, the scheme minimizes the operating cost and grid risk. Adopting the methods above, the most desired renewable energy time-series regulation results are obtained. The results have shown that after adopting the proposed strategy in the improved system, the solar and wind curtailment volume is reduced by 38.10%, and the operating cost is reduced by 24.60%. In a daily cycle, the maximum power of all branch power overruns at the most risky moment is reduced by 20.36%, and the sum of the total power of all branch power overruns is reduced by 40.30%. • A renewable energy time-series regulation strategy is proposed. • A time-series regulation model of aggregation loads is established. • The grid failure scenario is considered in the new energy time series forecast. • The influence of N-1 faults during power system operation is considered. • The time series regulation strategy improves system benefit and security. [ABSTRACT FROM AUTHOR]

Coal power plants are crucial in both the power sector and central heating sector and also emit large amount of carbon dioxide. Existing research on coal power plants transformation mainly focused on their role in the power sector, with insufficient attention paid to their heat and power cogeneration capabilities. To address this gap, this paper proposes a long-term expansion joint optimization model for power sector and central heating sector incorporating the competitive technologies in both sectors, which is used to obtain the optimal low-carbon transition pathway of power sector and central heating sector, and analyse the pathway of coal power plants. China is selected for a case study for its largest scale of existing coal power plants in the world and urgent need of decarbonization. Compared to the scenario only considering electricity generation function from coal power plants to power sector, another scenario also considering the heating production to central heating sectors brings less than 5% increase in their remaining capacity, whilst results in significant changes in their regional distribution. Proportion of heat and power cogeneration of coal power plants in the heat generation structure is expected to increase first to 80% in 2030 and decrease to 58% in 2055. • A long-term optimization model for sectors of power and central heating is built. • Impacts of considering heating sector on coal power plants paths are quantified. • Proportion of coal power plants in total heat production increases to 80% in 2030. • Electric heat pumps are developed rapidly for negative carbon emission constraint. [ABSTRACT FROM AUTHOR]

Ethiopia's electric grid relies mostly on hydropower for electricity generation. Compared to metropolitan regions, rural areas have only 5% access to power, and 83% of remote areas rely on traditional biomass energy for lighting and cooking. Close to 60% of the land area in Ethiopia is pastoral, and electrifying from the main grid is a major challenge due to economic, technical, and nomadic reasons. This paper explores the feasibility analysis, design, and simulation of an off-grid solar Photovoltaic system in addition to discussing the complete engagement of national energy policy and a strategic plan for electrifying a pastoral Communities' in Borena. Using solar radiation base data from the National Aeronautics and Space Administration, a case study is performed at Moyale, Yabelo, and Dire, which have 454 households, 367 households, and 379 households, respectively. Through the HOMER software simulation, the optimization determines the inverter, battery size and number, and solar array's capacity. The daily energy usage and peak power demand in the pastoral communities of Moyale, Yabelo, and Dire were 498.102 kWh/day, 447.114 kWh/day, and 454.02 kWh/day, or 36.89 kW, 35.41 kW, and 35.68 kW, respectively. Due to the country's subsidizing of all clean energy costs, off-grid solar Photovoltaic systems are more economically feasible than diesel generators, which have a level cost of electricity of 0.4 US$/kWh. National energy strategic plans and policies ultimately support the full involvement of off-grid solar Photovoltaic electrification at remote sites. • The design, simulation, and feasibility study of an off-grid solar PV system are investigated. • The inverter, battery size, number of batteries, and solar array's capacity are determined by optimization using HOMER software. • The three locations, Moyale, Yabelo, and Dire, have significant solar resource potential. • The nation subsidizing electricity prices, solar PV systems are preferred, especially for pastorals living in remote places. • Off-grid solar PV electrification for selected sites was fully supported and viable by a national strategic plan and policy. [ABSTRACT FROM AUTHOR]

Solar thermal devices with large installation areas represent technical, economic, and environmental challenges to design, construct, and operate them. Heat pump assisted with a solar thermal installation (STI) guarantee heat load supply at target temperature of a process, minimizing STI occupied area, environment impacts and associated costs. This paper deals with the design of two heat pumps, each one assisted with a STI. For designing solar network (which together the storage tank makes up the STI), lower irradiance levels than winter period are considered, guaranteeing continuous process operation. For designing each heat pump, two refrigerants with Ozone Depletion Potential of zero and Global Warming Potential of 7 (in one of them) are evaluated. This designing methodology is applied to a second-generation production of bioethanol case study. When heat is generated through a heat pump assisted with STI, the solar network absorber area is reduced by 85%, comparing with required area if only a STI produces heating. The same thing happens to generate electric power. Solar fraction value is one, 81,360 tons/year of not burned bagasse avoids 63,142 tons/year of greenhouse gases emissions. Still always guaranteeing the supply of energy to process, the impacts on environment and soil are minimized. [Display omitted] • Significant reduction of large solar thermal installation and storage system areas. • The cost of solar thermal energy is below the cost of fossil fuels. • Operation of the solar collector network under adverse irradiance conditions. • Profitable heat and power production from solar thermal energy plus heat pumps. [ABSTRACT FROM AUTHOR]

This paper studies a gas-steam combined cycle system with CO2 capture by integrating the MCFC (molten carbonate fuel cell). With the Aspen plus software, this paper builds the model of the overall MCFC-GT hybrid system with CO2 capture and analyzes the effects of the key parameters on the performances of the overall system. The result shows that compared with the gas-steam combined cycle system without CO2 capture, the efficiency of the new system with CO2 capture does not decrease obviously and keeps the same efficiency with the original gas steam combined cycle system when the carbon capture percentage is 45%. When the carbon capture percentage reaches up to 85%, the efficiency of the new system is about 54.96%, only 0.67 percent points lower than that of the original gas-steam combined cycle system. The results show that the new system has an obvious superiority of thermal performance. However, its technical economic performance needs be improved with the technical development of MCFC and ITM (oxygen ion transfer membrane). Achievements from this paper will provide the useful reference for CO2 capture with lower energy consumption from the traditional power generation system. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents high renewable electricity penetration scenarios in the United States using detailed capacity expansion modeling that is designed to properly account for the variability and uncertainty of wind and solar resources. The scenarios focus solely on the electricity system, an important sector within the larger energy sector, and demonstrate long-term visions of a U.S. power system where renewable technologies, including biomass, geothermal, hydropower, solar, and wind, contribute 80% of 2050 annual electricity, including 49–55% from wind and solar photovoltaic generation. We present the integration challenges of achieving this high penetration and characterize the options to increase grid flexibility to manage variability. Four high renewable pathways are modeled and demonstrate the robustness and diversity of renewable options. We estimate 69–82% annual greenhouse gas emission reductions and 3%–30% incremental electricity price increases associated with reaching 80%-by-2050 renewable electricity relative to reference scenarios. This paper affirms and strengthens similar analysis from the Renewable Electricity Futures study by using an improved model and updated data to better reflect investment and dispatch decisions under current outlooks for the U.S. electricity sector. [Copyright &y& Elsevier]

Abstract: In this paper we expand the work of Brandt and Dale (2011) on ERRs (energy return ratios) such as EROI (energy return on investment). This paper describes a “bottom-up” mathematical formulation which uses matrix-based computations adapted from the LCA (life cycle assessment) literature. The framework allows multiple energy pathways and flexible inclusion of non-energy sectors. This framework is then used to define a variety of ERRs that measure the amount of energy supplied by an energy extraction and processing pathway compared to the amount of energy consumed in producing the energy. ERRs that were previously defined in the literature are cast in our framework for calculation and comparison. For illustration, our framework is applied to include oil production and processing and generation of electricity from PV (photovoltaic) systems. Results show that ERR values will decline as system boundaries expand to include more processes. NERs (net energy return ratios) tend to be lower than GERs (gross energy return ratios). External energy return ratios (such as net external energy return, or NEER (net external energy ratio)) tend to be higher than their equivalent total energy return ratios. [Copyright &y& Elsevier]