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Abstract Despite a significant progress in electrification over the last decade, more than 1 billion people have no access to electricity, and about 3 billion use solid fuel or kerosene for cooking and heating purposes. More than 95 % of them live in sub-Saharan Africa or developing Asia, and around 80 % are situated in rural areas. Conventional approach to power supply such as transmission grid extension is not economical due to high investment and connection costs. Technological progress has shifted down capital costs of renewable off-grid solutions. However, in the most cases, it is not enough to reach feasibility of these solutions due to weak investment conditions and weak purchasing power of the local population in these areas. The choice of business model can have a vital role in bringing electrification and connectivity to rural areas, providing flexibility and adaptability of the technology to the market conditions. Analysis of existing literature on business models for off-grid solutions concludes that the model for rural areas in developing countries should be more service oriented, be scalable to various use case scenarios, should provide good risk balance between customer and provider, and should enable transparency and quality of service. This paper analyses recent developments in off-grid system solutions for sub-Saharan Africa and provides classification of business model innovations. Based on the analysis, the paper proposes an innovative business model for Fusion Grid project, scalable mini-grid integrated with connectivity solution. Feasibility of the project is tested for three different cases, depending on the type of the rural community. Results suggests that combining micro-grid based power supply and internet connection as one service can contribute to a viability of the project, and, furthermore, can contribute to achieving global electrification goal. [ABSTRACT FROM AUTHOR]

Abstract The results of an optimized design of grid-connected renewable energy system for University building are presented in this paper. Integrated modelling, simulation, optimization and control strategies are used to test the performance and select the best hybrid renewable power system. The main objective is to design a grid connected renewable energy system to meet the electric load of the building with high penetration of renewable energy, low greenhouse gas emissions, and low cost of energy. Hourly simulations, modelling and optimization were performed to determine the performance and cost of the hybrid power system configurations using load following and cycle charging control strategies. The results show that the grid-tied solar PV/fuel cell hybrid power system offers a good performance for the tested system architectures. With a solar PV capacity of 500 kW and fuel cell capacity of 100 kW integrated with the grid, the total energy generated from grid-tied renewable energy system to meet the desired load is 26% from the grid (purchase), 42% produced from the solar PV, and 32% from the fuel cell. From the total annual power produced, 95% is used to meet the AC primary load of the building and 5% is the sellback to the grid. The daily performance and electricity generation from the proposed grid-tied solar PV/Fuel cell power system is also presented in this paper. The proposed grid-tied solar PV/fuel Cell hybrid power system with the sale of electricity back to the grid has a high renewable fraction (40.4 %), low levelized cost of energy (71 $/MWh), and low carbon dioxide emissions (133 kg CO 2 /MWh). [ABSTRACT FROM AUTHOR]

Abstract Nowadays different kinds of renewable energy resources have got rapid development. For renewable energy planning, it is meaningful to assess the comprehensive performance of different candidate renewable energy schemes and distinguish the optimal. In view of this, based on data envelopment analysis(DEA), this paper presents a comprehensive evaluation method of renewable energy technical plans. Firstly, multiple indexes from different aspects are taken into consideration to establish the index system. And in the index processing stage, intuitionistic fuzzy number theory is adopted to describe the fuzziness and ambiguity in qualitative index and convert it into quantitative calculation. Then, super-efficiency DEA model is used to determine the relative ranking of different plans based on the concept of relative efficiency. Finally, a real case of renewable energy development in 2020 from a province in China is used to illustrate the feasibility and effectiveness of the proposed method in this paper. Results show that this proposed method can overcome the shortcoming of traditional basic DEA model and get more objective evaluation results and provide beneficial references for renewable energy planning and development. [ABSTRACT FROM AUTHOR]

Abstract Renewable energy can reduce greenhouse gas emissions by providing renewable electricity, heating, cooling and transportation. The main disadvantage of renewable energy supply is that once it reached a high share in electricity generation, the intermittency caused by renewable energy sources makes balancing of the energy system challenging. This study answers the question "What is the impact of renewable energy on public investment in R&D of energy storage technologies?" Empirical literature studying investments in renewable energy technologies is abundant, however empirical literature studying investments in energy storage technologies is highly limited. Using annual panel data from 28 OECD countries over the period 1990-2014 this paper provides an empirical evidence on the role of renewable energy deployment on public investments in energy storage technologies. The results of fixed effects estimation provide an empirical evidence that governments from countries with greater share of renewable energy invest more in energy storage technologies. Drawing from the empirical results, this paper provides policy recommendations on the need in investments in energy storage technologies due to a growing supply of renewable energy. Although this paper provides lessons from countries which experienced problems with high share of renewable energy and started to promote energy storage alongside with renewable energy, the results will be useful for policy-makers from developing countries with a growing share of renewable energy in total electricity. [ABSTRACT FROM AUTHOR]

Abstract Rural areas in developing countries have constantly been plagued by poor sanitation and energy shortages. A key issue has been the decentralized nature of waste generation and energy consumption, leading to farmers burning crop stocks, lumber, and other agricultural waste. As 1.9 billion people lack access to waste collection services [1], untreated solid and liquid refuse hamper the health of many and irreversibly damage the local ecosystem. Considering the scattered nature of agricultural waste generation and centralized treatment difficulties, this study examines the feasibility of adopting decentralized blockchain system in trading biomass energy and agricultural products across the waste-to-energy ecosystem. A case study is conducted based on the Yitong system in Changzhi City, Shanxi Province, China. This plant collects and transports agricultural wastes (crop straw and animal residue), and converts them to clean energy and agricultural by-products like briquettes, fertilizer, and animal feedstock. This paper presents how a digital coupon or cryptocurrency can be introduced to trade the wastes, energy and by-products among the farmers and entrepreneurs. It argues that this system could maximize the use of agriculture wastes by incentivizing farmers and enterprises to work together. This paper covers three key areas: 1) Literature review, methodology preparation, and field assessment for introducing digital incentive mechanism to enhance rural wastes management. 2) Design of a prototype of blockchain-based model: (a) how the waste-to-energy plant managers collect the segregated waste from individual farmers through trucks connected to blockchain-based smart meters; (b) how systems on each of the trucks register the quantity of waste received onto a universal ledger when collecting. This quantity received will be translated into a certain amount of energy and products like fertilizer that the waste-to-energy plant owes each farm; and (c) how the farmers will receive digital coupons corresponding to the quantity of energy and agricultural products that they should receive. 3) Evaluation of the feasibility of blockchain-based model (technical and economic): (a) data collection on the total quantity of waste produced and the processing capabilities and availability of Waste to Energy plants; (b) assessing readiness of digital infrastructure (cyber-security and communications); and (c) economic evaluation of the incentives and responsibilities associated with the key stakeholders from the farmers to enterprises. [ABSTRACT FROM AUTHOR]

Abstract Climate change and global warming are currently the biggest threat to human society. In Iranian households, buildings expend 33% of the yearly energy consumption. The potential of renewable energy sources in Iran is high and Iranian government is taking steps to increase the use of renewable energy sources. This paper examines the use of renewable energy in two major city buildings in Iran. In this paper, solar radiation in two cities (Tehran and Yazd) is analysed. The average annual sum of solar irradiation in Yazd is 2200 kWh/m2 and in Tehran, the amount is 2000 kWh/m2 [1]. The major task in this paper is to quantify the impact of geographical region and to evaluate the viability of implementing renewable systems in buildings in Iran. To reach this end, the annual average solar radiation is calculated in each city. Hourly Analysis Program is used to design each building and calculate their respective heating and cooling loads. Photovoltaic solar systems and solar-thermal systems are designed for both of the buildings. It is seen that, although Yazd has hot and arid climate compared to Tehran, the cooling and heating load in the building in Tehran is higher, and the higher solar radiation in Yazd reduces the number of solar panels required for the designed building. However, the difference is not significant. It is assessed that in order to have more efficient systems, the grid infrastructure in Iran should be upgraded to enable applying large-scale renewable energy systems for buildings in a neighbourhood. [ABSTRACT FROM AUTHOR]

In this paper a 2kWe small scale Organic Rankine Cycle system coupled with a concentrated solar linear Fresnel lens collector is investigated using a simulation analysis. Coupling small scale solar technologies with ORC system is a well-known solution in low temperature ranges. Efforts exist to achieve higher temperatures and overall efficiencies but at present such systems represent a challenge at small scale. This work is part of the EU funded Innova MicroSolar project about development and optimization of a solar linear Fresnel lens concentrator coupled with 2kWe Organic Rankine Cycle plant and with a PCM thermal storage system for residential applications. In this paper a preliminary assessment of the performance of two of the main components of such system (i.e. solar linear Fresnel lens collector and ORC) is presented. A dynamic analysis of the system is performed by varying the operating conditions. In particular the influence of the system configuration and working temperatures on the ORC overall efficiency is evaluated. The final aim of the work indeed is to assess the best working conditions for such micro-CHP to be integrated in residential buildings. [ABSTRACT FROM AUTHOR]

The paper uses system dynamics modelling to analyse the development of bioenergy; economic system that uses biotechnology instead of conventional technology. The research is directed towards the use of biomass in the production of higher added value bioproducts in the forestry and agricultural sectors. This paper emphasizes and evaluates the energy sector, which uses low quality wood. The main aim for this research study was to build a framework to analyse the development options for wood pellet production. A system dynamics model was created of energy wood supply, processing and consumption. Production capacity, energy consumption, technology efficiency, required labour, the price of wood, energy and labour are all taken into account. Validation and verification tests with available data and information have been carried out. These indicate that the model constitutes a viable dynamic hypothesis. [ABSTRACT FROM AUTHOR]

Abstract: This paper links energy and climate change with disadvantage in Australia and explores the dual disadvantage of steeply rising electricity prices and increasing climate change impacts. It reviews the potential of energy policy and climate policy to alleviate disadvantage, over the short and longer term, and suggests that renewable energy in particular has a role to play. However, the prospect of renewable energy policy advances in Australia is constrained, it is found, by the politicised nature of climate policy more broadly, the influence of the fossil fuel lobby, and the predisposition of current governmental policy. Drawing upon the policy streams and advocacy coalition theories of policy change, the paper assesses the political and ideological bases of this constraint, and the prospects for improved policy that could alleviate energy disadvantage. It finds that, whilst renewable energy does have an important role to play in achieving energy affordability, it needs to be supported politically, and complemented, in practical terms, by a range of policies and measures at all levels of government. [ABSTRACT FROM AUTHOR]

Rural electrification by using mini-grids has been the objective of many development policies over the past years. Most mini-grid projects turned out as failures because of poor suitability to user needs, local conditions and expectations of investors and several other risks. In order to shed light on the principles and processes involved in determining a mini-grid risk rating this paper develops and elaborates a risk rating model based on a standardized risk management procedure (SRMP). Five key criteria were outlined and explained in detail using an empirical case study on a mini-grid located in India. Ultimately, this paper aims to have shown how a methodology to achieve a risk rating for a mini-grid could be structured. In this sense a mini-grid rating is a decision supporting tool to enable sound investment decisions for debtholders and shareholders in a mini-grid and to contribute for de-risking renewable energy investments. The proposed standardized risk management procedure (SRMP) for mini grids should be considered as an educated, systematic attempt at measuring current and future development of a mini-grid's capability to fulfill future payment obligations and profitability expectations. [ABSTRACT FROM AUTHOR]

Climate change is an increasingly important global concern at this moment. Fossil fuels meet a majority of world energy needs and because buildings are large energy consumers, they are also a major contributor to global carbon emissions and greenhouse gas (GHG) production. It's important for the European Union, including Romania to avoid these problems. Buildings are responsible for 40% of energy consumption and 36% of CO 2 emissions in the EU, according to United Nations Environment Programme (UNEP). The construction sector is developing since 2013 so in the future the energy consumption will increase very fast. As a result, renewable energy sources represent one of the main directions in reducing conventional energy consumption in buildings. In this paper the authors analyze solutions for decreasing the energy consumption required by the air-conditioning system in an office building of 6466m2, located in Bucharest. The current air conditioning solutions are the classical ones, based on either fan coils, supplied with chilled water of 12/7 °C, or air-coolers, as part of an Air Handling Unit (AHU). In the latter case, the cooled water is prepared by a vapor compression refrigeration unit chiller of 190 kW cooling capacity, working with R22. The solutions analyzed in this paper consider each of the following alternatives: a. Heat recovery from the exhausted air by using a heat exchanger integrated in the AHU; b. Replacement of the vapor compression refrigeration unit chiller with an one stage lithium bromide/water absorption refrigeration unit driven bysolar energy; c. Coupling the above mentioned solutions. All these solutions are discussed and analyzed from both technical and economical points of view. [ABSTRACT FROM AUTHOR]

Climate change is an increasingly important global concern at this moment. Fossil fuels meet a majority of world energy needs and because buildings are large energy consumers, they are also a major contributor to global carbon emissions and greenhouse gas (GHG) production. It's important for the European Union, including Romania to avoid these problems. Buildings are responsible for 40% of energy consumption and 36% of CO2 emissions in the EU, according to United Nations Environment Programme (UNEP). The construction sector is developing since 2013 so in the future the energy consumption will increase very fast. As a result, renewable energy sources represent one of the main directions in reducing conventional energy consumption in buildings. In this paper the authors analyze solutions for decreasing the energy consumption required by the airconditioning system in an office building of 6466 m², located in Bucharest. The current air conditioning solutions are the classical ones, based on either fan coils, supplied with chilled water of 12/7 °C, or air-coolers, as part of an Air Handling Unit (AHU). In the latter case, the cooled water is prepared by a vapor compression refrigeration unit chiller of 190kW cooling capacity, working with R22. The solutions analyzed in this paper consider each of the following alternatives: a. Heat recovery from the exhausted air by using a heat exchanger integrated in the AHU; b. Replacement of the vapor compression refrigeration unit chiller with an one stage lithium bromide/water absorption refrigeration unit driven by solar energy; c. Coupling the above mentioned solutions. All these solutions are discussed and analyzed from both technical and economical points of view. [ABSTRACT FROM AUTHOR]

Potential energy from fluid flow of small rivers or irrigations could be extracted become electricity by using screw turbine. This turbine is promising because the advantages of ultra-low head and fish friendly.Experimental performance of screw turbine for ultra-low head hydro resource is presented in this paper. The screw turbine with anoutside diameter of 142 mm and the water flowrate of 1.2 l/s with the head of 0.25 m, can produce maximum power 1.4 W with 49% efficiency at 22 o angle of inclination. This turbine has one blade screw and screw turbine experiment apparatus is made by using locally available materials. The screw turbine has shown good potential to be used for low head micro hydro-electric installations. This paper reports on a performance analysis based on the experimental data collected from different performance tests carried out on some inclination angle position of screw turbine prototype. [ABSTRACT FROM AUTHOR]

The MENA region is facing economic and social challenges such as creating job opportunities especially for the youth. It also exhibits vast potential for renewable energy and energy efficiency (RE&EE) and tapping this potential can create economic benefits and jobs. This paper analyses the economic impacts of RE&EE support for Tunisia. In Tunisia, RE&EE legislation is in force since 2009 with the Tunisian Solar Plan (PST). For the economic impact analysis of the PST, a team of German and Tunisian researchers developed an economic model based on Tunisian statistical data and in sync with the methodology suggested by international agencies such as IRENA or IEA-RETD. The approach is based on Input-Output-Analysis, which allows for an analysis of impacts in different sectors e.g. machinery, metal industry etc. The paper will present the methodology and give an outlook on new results from an ongoing update. [ABSTRACT FROM AUTHOR]

In Uganda the low national electrification rate of around 15% and a very poor rate of progress in rural electrification, from an estimated 1% in 2001 to around 7% in 2013 are identified as major challenges for economic development and poverty reduction. In this context, the objective of this scientific paper is to analyze the economic feasibility of mini-grids based on renewable energies in the context of the Ugandan energy market as an off-grid electrification solution. In doing so, financial feasibility of mini-grids is also taken into consideration from macro-economic perspectives and risk management aspects. It acknowledges that off-grid electrification can be seen as mandatory to reach the ambitious national electrification targets and offering a huge opportunity in a so far almost untapped market, while at the same time still facing various financing- and market barriers in Uganda. By an executed case study, the paper simulates the level of subsidies required to reach economic feasibility, revealing that it can only be achieved with high level of subsidies involved due to the currently difficult financing conditions. Therefore, innovative financing recommendations are given by suggesting a layered fund as a multi-level financial support mechanism. Given the appropriate incentives, it can facilitate a subsidy phase-out for mini-grids in regards to a sustainable public sector engagement until self-sustaining market conditions are reached. It could attract investors by offering eligible investment conditions such as appealing return rates on decipherable risks by a reallocation between different shareholder layers, including public sector funding as a safety caution, while at the same time gradually transferring grant funding to revolving funding support step by step. [ABSTRACT FROM AUTHOR]

The use of ORCs is growing in importance the last years, because this type of cycles permits to exploit energy sources which are characterized by low enthalpies (waste heat, low temperature geothermal, low concentration solar plants, etc.) and low installed power sizes (up to 50-100 kW). In this size range, volumetric machines are very attractive devices because they show better efficiencies than turbines. Volumetric expansion devices flow rate is not continuous as in turbines but on the contrary has a pulsating behavior and the effective flow area of the intake and exhaust ports plays an important role in determining the efficiency of such devices. In this paper an analysis regarding the influence of the intake and exhaust valves features on the performances of a rotary expansion device for micro generation derived from a Wankel engine is presented. The analysis which is presented in this paper was carried out by means of both numerical and experimental techniques. CFD simulations of two different types of valves were performed to obtain the values of discharge coefficient and, subsequently, the results were validated at the fluid dynamic test bench. These solutions were also evaluated by testing the prototype using compressed air as working fluid under various operating conditions (pressure ratio, rotating speed). The delivered torque, the air mass flow rate and the indicated cycle were taken into account for the evaluation of the influence of the valves shape and timing on the device performances. [ABSTRACT FROM AUTHOR]

The growth in population, technology, and economy are resulting in the rapid increase of Municipal Solid Waste (MSW), which has a significant direct impact to the environment. MSW is generally disposed by landfill, which requires a lot of land space. Moreover, it is considered as a non-sustainable solution, by which only decomposable material is decayed where plastic and paper still remain inside. In order to provide the land space for recently large amount of waste, the old MSW need to be reclaimed and used as alternative fuel for sustainable disposal and converted into green and clean energy through gasification process. However, using an as-receive reclaimed product faces the challenges of combustion behaviour because it is non-homogeneous and loosens. This study discusses the improvement of the characteristics of the as-received reclaimed product by converting it into high density Refuse Derived Fuel (RDF). The surrogate reclaimed landfill RDF used has been made of waste plastic (polyethylene) and paper with a ratio of 75:25%-wt. After densification by extrusion, RDF-5 has a density higher than 600 kg/m 3 . The experiment was conducted in a laboratory scale downdraft gasifier by feeding surrogate RDF 10 kg/hr with the air flow rate 12, 15 and 18 Nm 3 /hr, respectively. Charcoal was added as an additive at the same weight of RDF in order to increase the fraction of fixed carbon and improve concentration of producer gas. The influences of the additive on the producer gas concentration and combustion characteristics were investigated. Results showed highest CO% and LHV were affected by air flow rate of 12 Nm 3 /hr at 22.02%-vol and 4.39 MJ/Nm 3 , respectively, whereas highest H 2 % was obtained with air flow rate of 15 Nm 3 /hr. It was found that the densification of the reclaimed landfill and the mixing of the additive optimized the combustion behavior in terms of temperature distribution along the gasifier height and improved the producer gas quality. [ABSTRACT FROM AUTHOR]

Regulatory uncertainties have often posed a business risk to renewable energy investors. Energy regulations in Spain were recently revised in June 2014. The objective of this study is to analyze the 50 MW wind power project under revised framework. The project is evaluated using NPV with risk and real options method through Monte Carlo simulations. As a part of this study, five scenarios were evaluated. The base scenario, “Business As Usual (BAU)” consist of recent framework that was into place, just before the new regulation was announced. The other scenarios (including newly introduced framework) were compared to the BAU. We have focused on “delay” option for the current scope. The overall results of the study suggest a negative NPV under the revised framework, with significantly higher delay value. From the results, it is advisable to delay the project. The paper presents the policy implications under scenarios selected in the papers. The article also presents the policy implication for developing countries. The study also served as the learning for developing nations from European Union states. [ABSTRACT FROM AUTHOR]

The paper analyses possibilities for CO 2 emission reduction into the centralized district heating system by using the index decomposition analysis: Kaya identity equation. The classical Kaya equation is complemented with an energy efficiency indicator of a district heating system. The paper focuses on the impact of the Kaya equation components on the CO 2 emission reduction. The elaborated methodology is tested in order to analyze possibilities for CO 2 emission reduction at district heating systems in Latvia. 3 scenarios were formed for the forecast of the CO 2 emission reduction. In case the current model for the state development is continued (scenario1) CO 2 emissions will be reduced for 13%; however, in the scenario of orderly and balanced DH systems they will reduce for 29% by 2020 as compared to 2012. [ABSTRACT FROM AUTHOR]

The paper analyses possibilities for CO 2 emission reduction into the centralized district heating system by using the index decomposition analysis: Kaya identity equation. The classical Kaya equation is complemented with an energy efficiency indicator of a district heating system. The paper focuses on the impact of the Kaya equation components on the CO 2 emission reduction. The elaborated methodology is tested in order to analyze possibilities for CO 2 emission reduction at district heating systems in Latvia. 3 scenarios were formed for the forecast of the CO 2 emission reduction. In case the current model for the state development is continued (scenario1) CO 2 emissions will be reduced for 13%; however, in the scenario of orderly and balanced DH systems they will reduce for 29% by 2020 as compared to 2012. [ABSTRACT FROM AUTHOR]

In many Japanese cities, a significant amount of CO 2 is emitted by private vehicles since modern lifestyles are highly reliant on them. In order to develop low-carbon cities, the establishment of a sustainable mobility system is essential. Meanwhile, local cities are facing a serious decline in social vitality, due to rapid ageing and economic deterioration. This paper examines a new approach for local city revitalization by introducing a “low-speed electric community bus” as a low-carbon transportation system. The bus was developed by the university–government, –industry, –education board, and –NPO collaborations. The test project was conducted in Kiryu city of Gunma prefecture as one of the projects of the JST-RISTEX's environment-energy program. In this paper, we report the co-design and co-development of a “low-speed electric community bus” for the establishment of low-carbon transportation systems. [ABSTRACT FROM AUTHOR]

Abstract: The security of supply and climate change issues and the linked recent growth of the local power generation by means of renewable energies technologies are providing real opportunities for the development of small scale biomass gasification systems. The present paper reports the state of art of the small scale gasification power plants. Initial attention has been given to the different biomass feedstock suitable for gasification, focusing on residues with low cost and low environmental impact. Then the two major typologies of gasifiers (fixed and fluidized bed) have been analyzed in terms of raw gas yield, composition and tar and particulate content. The different cold and hot raw gas conditioning systems, highlighting their compatibility with the different gasification system, are described. High efficiency examples of power production by means of internal combustion engine, micro gas turbine, Solid Oxide Fuel Cell or a mix of them, both as realized plants and process simulated ones, have been then reported. The paper provides an overview of the different power plants in terms of efficiency, reliability and cost. [Copyright &y& Elsevier]

Abstract: The Self Excited Induction Generator (SEIG) is an isolated power source whose terminal voltage and frequency are controlled by the excitation of the capacitance or the load impedance. This paper presents a method for calculating the minimum excitation capacitance using the equivalent circuit approach for analyzing the steady state operation of SEIG. A new strategy based on an active power filter (APF) for controlling the current and power quality of the self excited induction generator (SEIG) is also presented in this paper. The shunt active power filter was implemented using a three phase PWM current controlled voltage source inverter (VSI) and connected to the wind generator and loads in order to compensate the current harmonics and reactive power. The PWM-VSI gate control signals are derived from hysteresis band current controller. The proposed active filter proved to play an important role and give good dynamic response and robust behavior upon changes in load parameters. This investigation demonstrated that power average control strategy can facilitate the improvement of the power quality. The proposed control method extracts fundamental (reference) components of the source current for the shunt active power line conditioners for nonlinear and unbalanced loads. The Power average approach additionally maintains the voltage of the capacitor (of the PWM inverter) nearly constant without any external control circuit. The shunt APF in conjunction with the proposed controller performs perfectly under different steady state and transient conditions. The simulation results with nonlinear loads and unbalanced loads have showed the effectiveness of the proposed scheme for harmonic reduction in Wind based Power Generation. [Copyright &y& Elsevier]

Abstract: This paper shows the topology of grid-connected green power system and the performances of the front-end threephase power inverter by applying an advanced state feedback control. The proposed topology benefits a common DCAC inverter which injects the generated power into the grid. The control structure of the power inverter is of vector control type, in synchronous reference frame, and it uses the power balance concept. The solution presented in this paper adds supplementary benefits to the power system beside to the conventional state feedback control: the designed input filter assures zero steady state error and an adequate component is added for dynamic rejection of the load disturbance. The obtained experimental results are shown. [Copyright &y& Elsevier]

Abstract: Renewable energies are growing fast and have occupied great percentage in power generation. However, one major drawback of most renewable energies is the variability due to the stochastic nature of wind speed, solar irradiation, and etc. It is important to integrate the risk of wind power''s uncertainty into profitability assessments for investors. In this paper, certain effective ideas from portfolio theory in financial engineering field are exploited to deal with renewable energies as risky assets to be invested. It''s a systematic way to neutralize risks as well as maximize return values. To adjust these financial tools used to solve renewable energy''s problem, some other financial models and concepts are introduced. Time Series models, ARMA (autoregressive moving average), GARCH (generalized autoregressive conditional heteroscedasticity) and PSO (particle swarm optimization) algorithm are utilized to modify data to be real-time effective. Utility function is introduced to evaluate different energy resources. This paper is abundant with interdisciplinary ideas using advanced risk management methods on renewable energy issues. The proposed approach is also applied in real world problem to provide consulting evidence for power system planning and dispatching in Gansu province, northwest of China. [Copyright &y& Elsevier]

Abstract: With the economic development, the demond for energy is growing in China, and the traditional non-renewable energy makes the energy transformation is imminent.In this paper, based on the fully understanding of our existing energy structure, and from the perspective of supply and demand, the author analysis the changes in the structure of future energy and gives the suggestion.The paper argues that China''s energy structure will gradually turn to be comprehensive and diverse, but the cost and market constraints will obstruct the promotion of renewable energy sources.Therefore, the traditional high-carbon energy is still the main form of domestic energy consumptionin a very long period of time.Only by improving technology and using of the macro-control can reduce the costs and regulate the import and export, which can achieve sustainable development of changing from a high-carbon energy to low carbon. [Copyright &y& Elsevier]

In the present paper, a new approach to the management of energy resources in the Research and Technology Centre of Energy (CRTEn -Tunisia) is proposed and evaluated by the monitoring of a PV installation realized for the cooperation project DE.DU.ENER.T, using renewable energy and economic criteria. The aim of this project is to improve energy efficiency order to minimize the electricity cost consumed at the CRTEn laboratory. According to the bills of electricity received, we noticed that there is a high consumption of electrical current. So, we targeted to install a photovoltaic field of 12KWc to reduce these bills by using the sustainable, green and clean sources. A theoretical study of the PV system sizing realized in order to know in the first hand the compatibility between the different equipment of this installation and to compare the results with those found by the SMA Sunny Design and PV*SOL software in the second hand. The experimental results show that the performance factor of the proposed system is 84.6%. Meanwhile, the cost of the energy generated by the proposed system is 0.045 USD/kWh, which means that the payback period, is about 11 years. The conclusion from this study is that the price of energy generated by PV systems in Tunisia is lower than the subsidized price of energy generated by fossil fuel. [ABSTRACT FROM AUTHOR]

In recent years, net zero or plus-energy buildings (PEB) have been widely analyzed and discussed for their benefits of increasing energy savings and reducing greenhouse gas emissions. A successful transition to energy-efficient buildings must, however, develop an efficient method that examines technical, economic, environmental and social criteria. In this paper, a method for design optimization based on spatial analysis combined with multi-criteria decision-making was proposed for achieving plus-energy buildings in Algeria. To apply the proposed method, a single family residential building was chosen. First, the annual energy consumption of the building at 40 locations was evaluated and the results are then interpolated for the whole country. The best energy efficiency measures and renewable energy are then chosen using the Analytic Hierarchy Process (AHP) method. Finally, energy balance and spatial analysis were carried out based on the geographical information system. The results showed the energy plus target was achieved in large parts of the country using a high-performance envelope, more efficient appliances and solar energy (solar photovoltaic and thermal). In addition, the southern provinces, mainly Adrar, Tindouf, Bechar, Ouargla, and Illizi, have identified the most suitable areas for setting up new buildings with an energy-plus target. In addition, applying the method will reduce the overall energy demand by 43 % and reduce GHG emissions in the country by around 23 % by 2030. Therefore, the method will have a significant impact on sustainability locally and worldwide. [ABSTRACT FROM AUTHOR]

Abstract This article summarizes the design, the manufacturing and the testing of a small scale Organic Rankine Cycle using Concentrated Solar Power as the heat source. First, the choice of the nominal point of the cycle is detailed, including the operating environment of the ORC (characteristics of the solar field and ambient temperature) and the constraints of operation. The paper presents the design of a radial turbine with a power of 3 kW and the numerical simulations of flow in the fluidic part of the turbine (nozzle, wheel etc). It also deals with system engineering, the calculation and the selection methodology of main components such as exchangers, pumps, and sensors. In the second part, the results of the laboratory tests is presented. The experiment was performed using as hot source, a thermal oil boiler. The analysis of the results shows isentropic efficiency around 40% on a rather large range of pressure drop, and a cycle efficiency of 5 % which, is encouraging in view of the first test conditions. [ABSTRACT FROM AUTHOR]

Abstract Integration of renewable energy source (RES) generation to displace diesel generation can present clear economic, environmental and social benefit. While low level RES integration is relatively easy to achieve, both the cost and complexity escalate as systems target increasing RES penetration. A key barrier to greater RES penetrations remains the inefficiency of diesel generation to operate at low or partial loading. To achieve low or partial loading, conventional fixed speed diesel technologies must rely on prescribed purge routines, which serve to increase emissions intensity and fuel consumption. Fixed speed constraint remains the primary barrier to increased engine flexibility and improved partial load efficiency. This paper investigates redesign of the diesel generator to achieve variable speed operation. A suitable design basis is developed, with laboratory testing used to validate unit performance, ahead of economic evaluation. Economic modelling is presented to explore the improve engine flexibility, required of hybrid diesel applications. Variable speed application is shown to reduce diesel fuel consumption by up to 40 % in comparison to conventional hybrid diesel applications. [ABSTRACT FROM AUTHOR]

Abstract In Saudi Arabia, the current production of electric power is mainly relying on crude oil which causes a high percentage of carbon dioxide emissions and no power is generated from any renewable sources. However, recently Saudi Government has announced a development plan 'The Saudi Vision 2030' where the target is 20% of the production of power from the renewable sources mainly from solar and wind. Like other countries e.g., China, India, US and UK that produce a significant amount of their electric power from renewable sources. Saudi Arabia has a vast land area where there is a plenty of prospect to install renewable power plants (solar and wind farm) to generate a significant amount of electric power to meet their 2030 target. This paper analyses past 10 years wind data in various location of Saudi Arabia to investigate the feasibility to generate power. This study also recommends the potential locations that are suitable for wind power generation including suggestions of the wind turbine specifications. [ABSTRACT FROM AUTHOR]

Abstract With the advent of human-induced climate change, an effort towards reducing greenhouse gas emissions has been a priority for many communities and households. Pool heating is highly energy intensive and it accounts for major part of energy bills and a large carbon footprint. It is important to investigate the possible ways of reducing the energy consumption of the heated pools. The pool selected for this study is a 25 × 18-metre swimming pool located at Central Queensland University Community Sports Centre, Rockhampton, Queensland, Australia. The pool maintained at a temperature of 28 °C during the winter months by burning natural gas which causes excessive energy bill and ramps up the emissions of the university's operations. A mathematical model of the swimming pool incorporating the weather data files and various heating options is developed using the software TRNSYS, adopting relevant Australian Standards. The model is to be used to study the various heating options such as flat plate solar collectors, evacuated tube collectors, photovoltaic systems, electricity-driven heat pumps, natural gas heat pumps. With the use of this model, this paper investigates the amount of natural gas cost that is reduced when applying alternative heating concepts that exploit renewable energy or higher coefficients of performances. [ABSTRACT FROM AUTHOR]

Abstract As the demand for renewable energy is increasing, China has gradually formed two-level power market mode with inter and inner provincial market. The traditional market model cannot reduce the risk of real-time operation caused by the intermittency of renewable energy, and cannot further promote the consumption of renewable energy. This paper introduces the model of China's two-level market, and proposes a segment bidding mechanism based on the minimum dispatchable interval (MDI). Finally, the mechanism is proved to reduce the risk of real-time operation and demonstrate the effectiveness of renewable energy consumption. [ABSTRACT FROM AUTHOR]

Abstract Renewable and smart grid technologies play a key role in delivering a sustainable energy future for non-interconnected islands. In this context, societal acceptance of proposed interventions manifests itself as a major determinant of planned transitions. With extant scholarship on public acceptability of sustainable energy technologies focusing on local opposition to wind farms, this paper presents timely survey data from the island of Tilos to provide a better understanding of energy-users' perceptions vis-à-vis novel smart island proposals. Against stultifying narratives highlighting the lack of community acceptance for local interventions, we uncover: a) the widespread acceptance of sustainable and smart energy solutions, and b) the willingness of a large proportion of locals to play their part, as engaged energy prosumers, in a green energy transition. In turn, these findings form the basis for future academic and technical interventions on the island, and inform broader conclusions on public engagement around energy. [ABSTRACT FROM AUTHOR]

Abstract In contributing towards the realisation of plans to transform the Aegean into a "green" archipelago, the internationally acclaimed TILOS research consortium seeks to transfer tacit knowledge of smart micro-grids beyond the island of Tilos. However, research on public acceptability of sustainable energy technologies suggests that local opposition might undermine such plans. In order to minimize the problems of technological transfers it is, thus, imperative to embark on an early-stage exploration of public attitudes towards proposed interventions. In this paper, we draw on survey data from across the Aegean to uncover the widespread acceptability of green energy solutions. Simultaneously, though, we uncover how broad acceptability does not always translate into actual acceptance of the TILOS energy model, especially with respect to solutions that affect the end-user. In turn, we argue that these findings should inform future interventions with the ultimate aim of securing public support to "green" the Aegean. [ABSTRACT FROM AUTHOR]

Abstract As high penetration of uncertain wind and solar energy into power system, spatio-temporal correlation of wind and solar energy is of great necessity for planning and operation of wind farms and PV plants. A Copula function and first order Markov process based Monte Carlo simulation method of multivariate wind speed and PV power spatio-temporal series is proposed in this paper. In the proposed approach, either spatial correlation or temporal correlation of wind speed and PV power series is considered including cross-correlation between all series and self-correlation of every series. The results of case study based on National Renewable Energy Laboratory (NREL) of the U.S. Department of Energy are analyzed, which verify the scientific and feasibility of the proposed approach. [ABSTRACT FROM AUTHOR]

Abstract Communities situated in distant areas are deemed as 'remote' and have either very limited or no access to power grid lines. Therefore, most of these communities greatly depend on diesel-burning for power and heat provision at all times. Nonetheless, nearly 30% of the energy associated with the diesel burning and power generation process is dissipated as heat through the exhaust streams of diesel generators. The waste heat in the exhaust stream is usually recovered during the winter season and directly used as a heat source when the communal heat demand is peaked. However, recovery of this energy potential is usually discarded during the summer period due to the low demand. Seasonal thermal storage on rock piles is a developing concept that can be a low-cost solution to resolve this issue. This paper proposes utilization of the heat wasted through the exhaust stream of diesel generators on rock piles as temporary storage during low demand times. In this sense, a remote cold climate community, such as those of Canada and Norway, is selected and potentiality of the seasonal rock pile thermal storage is investigated and presented. [ABSTRACT FROM AUTHOR]

Abstract Global inclination towards renewable energy projects, facilitates deployment of alternative energy systems in various scales. However, due to the noise in usable energy generation and fluctuations in the source availability, battery units are deemed as an integral part of any mini-grid energy generation system. Although, sharp turns in battery prices have taken place over the last few years, batteries are still one of the largest capital components of such systems. On the other hand, like many other heavy industries, mining industry is also closely interested in renewable energy generation on site because of certain environmental and financial reasons. Nonetheless, the size of feasible energy generation and attached storage units are still forcing mining companies to reconsider. In this regard, renewable energy based coolth storage systems can help mining companies to enhance the financial outcomes of mine air-conditioning projects where heavy refrigeration is demanded. This paper promotes power generation via renewable energy systems and proposes coolth/energy storage by analyzing two options. The financial impact of substituting battery storage units and downsizing the refrigeration plant size by storing the peak demand as coolth was also studied. [ABSTRACT FROM AUTHOR]

Abstract This paper employs a panel quantile regression method to study the impacts of economic growth, renewable energy, and development of patents on carbon emissions. Panel quantile regression is more useful method compared to the ordinary least squared (OLS) method because both individual heterogeneity and distributional heterogeneity are considered in a panel quantile regression, which provides comprehensive information of the relationship between carbon emissions per capita and different variables. To be specific, for economic growth, its impact on carbon emissions per capita is significant and positive, but its impact decreases for fast-increase emission countries. The results do not support the Environmental Kuznet Curve hypothesis. As for renewable energy, its impacts on carbon emission show an inverted U-shaped trend at different quantile levels. As for the development of patents, its effect is non-significant and positive at different quantile levels. Based on the results, we propose some policy recommendations to control carbon emissions per capita. [ABSTRACT FROM AUTHOR]

Abstract With the advanced ICT (information and communication technology) support, the local energy trading rapidly develops and plays an important role in energy supply in recent years. Because the demand and supply directly occurs at local level, the transmission cost saves a lot and the distributed renewables energy resources are capable to be used in energy supply. This paper presents a multi-supplier trading system for the local power market, which is formulated as a non-cooperative Cournot game. In this model, four types of providers: thermal power plant, wind power plant, PV power generation and customer-operated storage electricity supplier are considered separately. Their cost functions have been extensively formulated. A unique Nash equilibrium (NE) exists and the optimum strategies can be derived as demonstrated in a typical local market. The proposed approach can effectively model local energy trading of different types of energy providers. [ABSTRACT FROM AUTHOR]

Abstract This paper evaluated the economic implications of developing net-zero energy buildings (NZEBs) for four types of residential houses (i.e. flat, terraced house, semi-detached house, and detached house), across different locations in the UK. Models specific to different locations and loads were created with varying combinations of renewable energy technologies. Houses were further classified as existing ones and new ones, and the latter had an 55% improvement in energy (heat) efficiency compared to the former. A cost-benefit analysis was conducted for each of the potential NZEB designs. Without energy storage, income from renewable technology in existing households can produce a mean net profit between 5-51% of the overall expenditure for NZEB designs. The results will enable policymakers to make informed decisions for the fulfilment of NZEBs in the UK which can potentially play an important role in mitigating greenhouse gas (GHG) emissions and help the UK achieve its climate change targets. [ABSTRACT FROM AUTHOR]

Abstract The rapid increase in application of intermittent renewable energy generation has stimulated the development of energy storage system to guarantee a stable supply in electricity grid. As a large-scale storage technology, Liquid Air Energy Storage (LAES) technology has attracted many attractions in recent years due to it offers many unique advantages including high energy density, mature technologies based and geographical-constraint free. However, current LAES has relatively low round trip efficiency (less than 60%) and still needs improvement. In the LAES, the recovered cold energy from the liquid air is insufficient to cool the compressed air to the lowest temperature with the shortage of ~18% and liquid air yield does not achieve the maximum in the charging process; external free cold sources would be needed to further increase the liquid air yield, and the round trip efficiency could easily break through 60%. This paper proposes an innovative LAES system integrated with LNG regasification process, the objectives in this established work are to improve the product yield of liquid air and enhance the overall roundtrip efficiency. Sensibility analysis and exergy efficiency analysis of charging process and discharging process at LAES are discussed. Meanwhile, the comparisons of system performance are made between traditional LAES system and LAES with LNG regasification system (LAES-LNG) at same operating parameters. Through the LAES-LNG system, more liquid air is generated. Results show that relatively higher round trip efficiency could be obtained, with 15-35% enhancement compared with the current LAES. Also, liquid air yield obtains a significant improvement to 0.87. [ABSTRACT FROM AUTHOR]

Abstract Direct usage of low-to-medium enthalpy geothermal energy can provide clean and renewable energy for heating purposes. Optimum geothermal extraction strategies improve the efficiency and effectiveness supplying heat energy, which calls for a comprehensive and integrated study on geothermal reservoir development. In this paper, an integrated modeling workflow considering surface energy demands is presented to analyze the heat extraction process in a sedimentary geothermal reservoir. Effects of surface demands, well positioning, heat production rates, and number of geothermal wells on heat extraction efficiency are thoroughly studied. Results indicate that surface energy demands, well positioning, and heat production rates jointly decide the heat extraction effectiveness and the number of geothermal wells required. Neglecting surface energy demands decreases the effectiveness of heat extraction strategy planning. For the 27 surface energy demand cases studied in this work, the geothermal project can sustainably meet the surface demands in certain cases for up to 30 years, while in some cases, the project can only meet the surface demands for 4 years. In addition, the well spacing of 300m can maintain the heat production temperature at its initial level regardless of the heat production rates. [ABSTRACT FROM AUTHOR]

Abstract The energy system's operation strategy has a significant influence on the system efficiency. The determination of the optimal operation strategy requires the effective application of a substantial amount of data accumulated from the operation or even forecasting process. However, data processing, which is not obtained based on the physical mechanism, may fail to explain, under certain boundary conditions. Therefore, using E-CPS to combine data mining and physical model to build a more efficient and accurate model or even a real-time model is vital and has received more attention in practical applications. This paper proposes a general process for constructing E-CPS and applies it to the simulation of building energy systems. The E-CPS results in a 70% reduction in the renewable energy waste rate of the building's energy system and a 57% reduction in the purchase of electricity. Finally, it is concluded that the use of intelligent algorithm-based data mining combined with physical models to build E-CPS is practical and effective. [ABSTRACT FROM AUTHOR]

Abstract The paper introduced a smart renewable energy based microgrid system which is composed of three subsystems: solar photovoltaic subsystem, air source heat pump subsystem and energy storage subsystem. This microgrid system was applied to the demonstration project located in Xining City, Qinghai Province, China. The energy performance of the smart renewable energy based microgrid system was evaluated and compared with that of traditional energy supply system which totally depends on the electricity grid and natural gas. The comparison study demonstrates that the proposed hybrid energy supply system is superior to traditional system, significantly decreasing additional energy consumption for buildings and reducing pollutant emissions. [ABSTRACT FROM AUTHOR]

Abstract Due to the obvious different characteristics of multi-energy power sources, it is necessary to take into account the economic and safety requirements of the power grid at the same time to achieve optimal operation strategy (OOS). This paper focuses on the OOS of multi-energy power system (MEPS), which contains wind power, cascade hydropower, thermal power, and pumped-storage power. Considering the complementary coordinationc characteristics of different types of energy, a completed set of day-ahead coordinated and optimized operating models of MEPS is established, with multiple optimization objectives of maximizing the safety, economy and renewable energy consumption. In order to solve this complex multi-objective problem, a three-stage solution method based on Benders decomposition is proposed. Through decoupling the safety object and economic object of MEPS, efficient solution of the OOS is achieved. The digital simulation discusses the influence of factors such as the diversity of natural scenarios and the safety requirements of the system operation, and simulation results verify the effectiveness of proposed strategy. [ABSTRACT FROM AUTHOR]

Abstract Most of isolated resident islands rely largely on imported fresh water and fossil energy. Generally, the cost of transport these basic necessities is expensive and therefore limit the human activities on these islands. This paper proposes a model which uses renewable energy (solar and wind energy) to produce both electricity and fresh water for a 5.6 km2 island in the South China Sea. To mitigate the intermittency of natural renewable energy, the water desalination system was regarded as an energy storage facility. In order to make the energy-fresh water coupling system operating smoothly, a central control system was formulated. Reverse osmosis desalination method was used to produce fresh water. In order to figure out the most appropriate configuration of the system, HOMER model which was developed by NREL was used. The simulation results show that local solar power combined with near sea offshore wind power are sufficient to make energy and fresh water self-dependent of the target island. This study also reveal that energy storage facility is the most critical components of the system. [ABSTRACT FROM AUTHOR]

Abstract Combined heat and power plants driven by renewable energy sources (RES) are becoming more and more popular, given the energy transition towards the integration of more renewable energy sources in the power generation mix. In this paper an innovative micro-solar 2kWe/18kWth Organic Rankine Cycle system, which is being developed by the consortium of several Universities and industrial organizations, with the funding from EU under the Innova MicroSolar project, is considered. In particular, its application to supply electricity and thermal energy for Domestic Hot Water (DHW) in a residential building is investigated by means of simulation analysis. Different Domestic Hot Water supply plant configurations are evaluated and the design parameters are varied in order to determine the best configuration to recover as much energy as possible from the ORC, while maintaining the final users' comfort. It was found out that with the considered plant around 67% of the Domestic Hot Water energy demand of 15 apartments can be satisfied with a water storage tank of 10'000 liters. However, in order to always guarantee the supply water temperature, a back-up boiler, which serves directly the final users when needed, is requested. [ABSTRACT FROM AUTHOR]

Abstract The combined operation of renewable energy and seawater desalination equipment will be the directions of the cleaner freshwater producing technology in the future. A CCHP system that includes wind turbine, photovoltaic, combined heating and power (CHP) and seawater desalination is built in the paper. Based on load characteristics of seawater desalination devices and other critical equipment and characteristics of renewable energy, the optimal planning and operation strategies of CCHP system is discussed by considering economical and environmental benefits, the electric cooling ratio and the capacity of critical equipment are optimized by considering capital cost, operation cost and maintenance cost, energy cost and equivalent carbon tax. Simulation and analysis result verifies the feasibility of the proposed planning and operation strategies that the total cost and CO2 emission reduced. [ABSTRACT FROM AUTHOR]

Abstract With the rapid development of economy, the lack of freshwater resources has become increasingly urgent in many areas of China. Desalination can ease some of the pressure on freshwater supply, especially in coastal areas and isolated islands. The micro energy network is an efficient distributed energy supply system that can be used to supply electricity, cooling, heat and freshwater simultaneously. In this paper, wind turbine, photovoltaic(PV), combined cooling, heating and power(CCHP) system and desalination unit are integrated into the micro energy network. A multi-objective optimization research is conducted on the key equipment capacity and the operation of the desalination unit, with the goal of optimizing the life cycle cost and annual CO2 emissions simultaneously. And through the study of cases, the impact of the operation of desalination unit on the planning solutions of micro energy network is researched. [ABSTRACT FROM AUTHOR]