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Abstract The present paper presents the methodology and development of a planning tool for the installation of marine renewable energy systems, which enables the identification of suitable areas for this purpose. The marine spatial planning is one of the challenges of the offshore renewable energies. This is one of the reasons to write this paper, because there are areas where the energy potential is great but with real limitations for installing an offshore renewable energy farm. This methodology is based on the development of automated and interactive GIS tools in order to enable the user to change inputs according to his research objectives. The developed tools are applied to a case study referring to the Portuguese coast and the obtained results enable the identification of several areas, suitable for the development of marine renewable energies projects. The methodology and the developed tools intend to be a contribution for the Maritime Spatial Planning of the Portuguese coast and can be applied to other countries as well whenever the necessary information is available. Highlights • Methodology and development of a planning tool for marine renewable energy. • Identification of suitable areas of installing. • GIS tools to change inputs according to his objectives. • Maritime Spatial Planning of the Portuguese coast. • Results identify suitable areas for marine renewable energies. [ABSTRACT FROM AUTHOR]

Abstract Wind turbines are emerging as one of the most promising and cost-effective renewable energy sources, due to their economical merits and technical maturity. It is important to accurately predict the aerodynamic performance of rotor blades for efficient design of wind turbine. Among the various numerical approaches, the vortex lattice method (VLM) is one of the most suitable models for wind turbine aerodynamics because the wind turbine mostly operates in the subsonic flow. However, it inherently cannot predict the nonlinear aerodynamic characteristics at a high angle of attack. In the current paper, a nonlinear vortex lattice method (NVLM) has been suggested to extend the existing VLM for handling the nonlinear stall and post-stall behaviors. This can be possible by finding a control point in the airfoil where the effective angle of attack is applied. This paper mainly discusses the development and validation of the NVLM for predicting the aerodynamic performances and the wake geometry against the measurements on the MEXICO rotor model. The comparison results show that the aerodynamic loads and tip vortex trajectories computed by NVLM are in significantly good agreement with the measured data. In addition, the complicated and unsteady wake structures are also analyzed using vortex particle method. Highlights • The nonlinear vortex lattice method can consider the post-stall behaviors. • The most suitable location of control point is half chord for vortex lattice method. • The strong wake interaction and tip vortex breakdown occur at low wind speed. • The wake structure becomes stable and expansion angle reduces at high wind speed. [ABSTRACT FROM AUTHOR]

Abstract Energy poverty in developing regions is a major global concern, with the rural areas of South Asia, South-East Asia and Sub-Saharan Africa being the most affected. The major residential energy consumption in these regions is for cooking and lighting, which is basically covered with traditional biomass and fossil fuels. This situation acts as a development barrier, while implying stress on resources and the environment. Solar home systems (SHS) can play an important role in overcoming this problem. Recent technological advances and cost reductions in lithium-ion batteries favour their use in such application. Domestic electric devices with outstanding energy efficiency are becoming the standard around the globe. This paper focuses on exploiting these innovations to provide a solution for domestic energy poverty in developing regions. The layout of a SHS that integrates a lithium-ion battery-pack and is complemented with LED lamps and an energy efficient multicooker is presented. The paper assesses the SHS in contrast with existing practices under domestic energy poverty, with consideration of the learning curve. It is concluded that the cost of energy of the SHS is slightly cheaper than the business as usual case on the short term, and notably cheaper on the longer run. Furthermore, a financing scheme is proposed to overcome implementation barriers. Government support is considered, and quantified based on the SHS carbon abatement and saved fossil fuel subsidies. A substantial share of the initial investment can be covered under such scheme. This case study allows to draw general conclusions on the potential of SHS as a solution for domestic energy poverty in developing regions, on the financing gaps that hamper implementation and eventually on the required actions to overcome these. Highlights • The state of the art of domestic energy poverty in developing regions is summarized. • A solar home system with lithium-ion battery is proposed as a solution. • The solar home system is assessed in contrast with current practices under energy poverty. • The solar home system is more cost effective and has an incremental cost advantage over time. • A financing scheme is suggested to overcome implementation barriers. [ABSTRACT FROM AUTHOR]

Abstract The safety operation and economic benefits of wind farms are paid more attention by industry and society. Therefore, it's necessary to evaluate the wind power projects to find the deviation between actual situation, forecast target and first-class level. The commonly used methods of post-evaluation are AHP and fuzzy comprehensive evaluation which have three problems to be solved. The first is AHP method can't represent the correlation among the indexes. The second is the uncertainty of project data and experts' judgment. The third is the rectangle membership function can't realize data classification between adjacent levels. ANP can describe the relationship between indicators to eliminate deviation caused by independent calculation. The trapezoidal membership function is useful for rapid classification data between adjacent levels by maximum membership degree. And the interval can utilize imperfect information to solve the limitation of point estimation. So this paper proposes ANP model and fuzzy comprehensive evaluation model based on trapezoid membership which are all improved by interval numbers to evaluate projects. The paper makes a calculation of Pinglu wind farm, and the result shows new model is more stable with accuracy and applicability for post-evaluation which can solve the problems such as incomplete information, data fluctuation and subjective judgment. Highlights • The paper aims at the post evaluation of wind power projects. • A new evaluation model is set up which is improved ANP and Fuzzy comprehensive evaluation model improved by interval number. • Improved ANP model by interval number is used to determine the weight of the index. • Improved fuzzy comprehensive evaluation model is based on trapezoid membership which is impoved by interval numbers. [ABSTRACT FROM AUTHOR]

Abstract This paper presents an investigation on the efficiency performance of the leading-edge undulated tidal turbine blades under the effect of waves. This biomimetic blade application is inspired by humpback whale flippers which provide these mammals with an exceptional manoeuvring ability that is mainly accredited to the beneficial of their leading-edge tubercles. The paper first presents the design, optimisation and experimental validation of these turbine models. With the aim of further validating the efficiency performance in a different testing environment as well as exploring the combined effect of the tidal current and wave interaction, a test campaign in a towing tank facility was conducted. Both regular and irregular wave conditions were considered combining with varying towing speeds to simulate the tidal current effect. The test results revealed that the leading-edge undulated turbine has a stable hydrodynamic performance over a combined range of current speeds and waves indicating that the overall performance was not affected considerably by the combined effects as opposed to the performance solely due to steady tidal current. Highlights • Biomimetic concept of applying leading-edge tubercles on a tidal turbine blade has been performed. • Leading-edge tubercles have significant impacts on the improvement of the hydrodynamic performance. • First practice of testing bioinspired tidal turbine blade in a towing tank facility under the wave and current. • Power generation performance under waves were evaluated and proved the effectiveness of leading-edge tubercles under wave conditions. [ABSTRACT FROM AUTHOR]

This paper proposes a new model for determining optimal investment time for residential photovoltaic (PV) power systems. The model explicitly incorporates the cost uncertainty of the PV system and a resident's option to defer investment, using a real option model. The paper provides theoretical analysis as well as case studies. Using the real option model, we show that the optimal investment threshold decreases in case of volatility increase, mean-drift decrease and benefit decrease. A sensitivity analysis using different PV sizes illustrates that the optimal waiting time for substantial PV diffusion to smaller PV systems is longer than that of larger systems. The paper also investigates the expected investment times in the United States, Germany, Japan, and Korea and shows that all countries except Germany need to wait to invest. Moreover, a comparison study to the net present value (NPV) method demonstrates that PV system investment can be additionally delayed by 5.76–11.01 years. [ABSTRACT FROM AUTHOR]

The European Union targets for 27% renewable energy share by 2030. At the same time, all new buildings should be nearly zero energy buildings from 2020 onwards. A major obstacle to these objectives is a combination of current economic stagnation and limited investors' confidence, which leads to low investment proportion. Despite many renewable energy technologies are already at a competitive level, the implementation rate in buildings is still low. In this paper, we focus on advances in efficient mechanisms to overcome non-technical barriers to the increase of renewable energy applications in buildings, such as Energy Performance Contracting (EPC). Tertiary sector holds a huge untapped potential for such applications, especially in Southern Europe. The Trust-EPC-South European initiative, implemented in six southern EU countries with a mix of beginner and intermediate energy service markets, aims at encouraging the financing of sustainable energy solutions in the tertiary sector, by creating a framework for standardization, assessment and benchmarking, thus improving trust and confidence in the financing parties. This paper presents three case studies in Greece, a Mediterranean family resort hotel, a resort and spa hotel and an office building. The installation of renewable energy measures, including photovoltaic systems, solar thermal systems and heat pumps, was examined and their EPC potential was rated, by using the described standardization and benchmarking methodology. Their economic savings range from 3 to 23% on yearly energy costs, at a discounted payback of 3–6 years, depending on the measure. A sensitivity analysis shows the impact of the variation of technical and economic parameters on the EPC projects feasibility. The standardization practice applied is expected to support the project actors in securing appropriate financing and eventually proceed with the renewable energy installations through the EPC. [ABSTRACT FROM AUTHOR]

The increasing greenhouse gas (GHG) emission and environmental degradation (ED) is a serious concern for the various economies, and a similar issue is observed in Asia. This paper investigated the role of clean energy from renewable sources, urbanization, and economic growth in determining the level of GHG emissions from 1995 to 2018 for ten Asian States through a cross-sectional autoregressive distributed lagged (CS-ARDL) model. Meanwhile, the current research also examined the cross-sectional dependence, unit root properties, and co-integration between the study variables. The study findings confirmed that clean energy and GDP2 played their constructive role in reducing GHG emissions in the natural environment or targeted economies. In contrast, urbanization and economic growth caused more GHG emissions both in the long and short run. Furthermore, the robust check through augmented mean group (AMG) and common correlated effect means group (CCEMG) also confirmed that clean energy and GDP2 have a good sign for lowering ED compared to GDP and urbanization. The study findings could support policymakers, specifically in the field of energy economics and environmental sustainability. Therefore, it is highly recommended that some strong policy implications are needed to reduce environmental issues through controlling the negative impact of economic growth and urbanization. This study contributes in the literature of GHG emission with respect to economic growth, urbanization and clean energy and guided the regulators while formulating policies related to control the GHG emission. • The increasing GHG emission is a serious concern for the various economies. • We examined the clean energy, urbanization and economic growth impact on GHG emissions. • We examined cross-sectional dependence, unit root and cointegration among variables. • Clean energy plays constructive role in reducing GHG emissions in natural environment. • Urbanization and economic growth caused more GHG emissions in long and short run. [ABSTRACT FROM AUTHOR]

Energy is one of the essential components for the social and economic growth of urban and rural communities worldwide. However, the lack of energy supply is one of the most significant challenges facing remote or local communities in Nigeria. Distributed generation systems based on renewable energy, conventional sources, or hybrid resources are possible energy production solutions for these communities. This paper, therefore, focused on providing an energy generation system based on photovoltaics (PV) and diesel generators (DG) for stand-alone applications. A comparative analysis was carried out to assess the impact of control strategies, namely load following (LF), cycle charging (CC), and combined dispatch (CD). The designed energy systems: 60 kW PV, 78.69 kW PV, PV-DG-LF, PV-DG-CC, and PV-DG-CD were simulated using HOMER Pro while technical, economic, and environmental indices were used as performance metrics. Simulation results showed that 60 kW PV generated 84,927 and 75,859 kWh, without and with temperature effect, respectively, with the corresponding unmet electric load (UEL) of 13.8 and 14.2%. The result further demonstrated that PV-DG-LF is the optimal design with the highest renewable penetration of 80.7% and the least annual total fuel consumption (TFC) of 6,594 l. The economic results further confirm the suitability of PV-DG-LF with the lowest fuel cost (FC) and moderate cost of energy (COE) of $219,934 and 0.302 $/kWh, respectively. The PV-DG-LF is found to be more environmentally friendly, with the least annual CO 2 emission of 16,629.652 kg. The study considers veritable strategies to achieve affordable, clean, and reliable energy in line with research efforts on realizing the sustainable development goal (SDG) 7. [ABSTRACT FROM AUTHOR]

In this paper, the performances of a floating wind energy converter (the National Renewable Energy Laboratory 5 MW wind turbine installed on the ITI energy barge) in a realistic, multi-directional random sea are rigorously investigated. The wind loads acting on the floating wind energy converter are also fully considered in the numerical simulation process. Meanwhile, in order to improve the simulation efficiency, a new state space model (the FDI-SS model) is utilized to approximate the convolution integral term when solving the motion equation of the floating wind energy converter. For comparison purpose, the simulation results when the convolution integral term in the motion equation is approximated by a commonly used state space model based on the time domain (TD) realization theory are also included. The simulation results in this paper are systematically analyzed and compared, and the accuracy and efficiency of the new FDI-SS model are verified. Moreover, the simulation results in this article demonstrate the great necessity of using a realistic, multi-directional random sea state when calculating the generated electrical power and the dynamic responses of a floating wind energy converter. [ABSTRACT FROM AUTHOR]

The objective of this paper is to investigate the reliability of the mathematical model used for estimating the U-Oscillating Water Column (U-OWC) response in the time domain. This device is a wave energy harvester belonging to the family of Oscillating Water Columns. It comprises a water column, an air chamber with a self-rectifying turbine and a vertical U-shaped duct connecting the water column to the open wave field. The model used for describing the water column oscillations is based on the application of the unsteady Bernoulli equation for a real fluid and involves the determination of energy losses occurring over the entire duct length. The reliability of this mathematical model is assessed against experimental data. For this purpose, a U-OWC experimental model is installed in a benign natural basin, the Natural Ocean Engineering Laboratory NOEL. The experimental model is exposed to waves stochastically characterized. Thus, its response is described by relevant statistics. The paper shows that the current mathematical model may yield relevant overestimations of the system response. This relates to the approximate representation of the head losses, which are based on the Darcy-Weisbach formula traditionally employed in the analyses of steady flows. For overcoming these limitations, the paper proposes the utilization of the instantaneous acceleration-based model, which includes unsteady head losses proportional to the water column inertia. In this context, the model shows a general good agreement with the experimental measurements and demonstrate a superior capability of predicting the U-OWC response in all the processed records. [ABSTRACT FROM AUTHOR]

Accurate estimation of extreme wave conditions is critical for offshore renewable energy activities and applications. Wave power is the transport of energy by wind waves, and the capture of that energy to do useful work. Wave energy converter (WEC) devices are designed to sustain the wave-induced loads that they experience during both operational and survival sea states. The extreme values of these forces are often a key cost driver for WEC designs. These extreme loads often occur during severe storms; therefore careful examination of harsh wave conditions during the device design process is needed. Consequently the development of a specific extreme condition modeling method is essential. This paper presents a novel method for estimating extreme wave statistics, based on the hourly measured wave height maxima at the location of interest. Wave measurements, analyzed in this paper, were collected at SEM-REV offshore sea station located near the coast of France, during years 2001–2010. Note that applied statistical methodology is general and can be well applied to a measured WEC response, and its technology risk assessment. Accurate estimation of extreme wave conditions is critical for offshore renewable energy activities and applications. SEM-REV is known French wave energy test site. The method, referred to as ACER method, is presented in brief detail. ACER method provides an accurate extreme value prediction, utilizing available data efficiently. In this study the estimated return level values, obtained by ACER method, are compared to the corresponding return level values obtained by Gumbel method. Based on the overall performance of the proposed method, it is concluded that the ACER method can provide a robust and accurate prediction of extreme wave height at a given location. [ABSTRACT FROM AUTHOR]

In grid–connected photovoltaic (GCPV) systems, applying a solar tracker results in a higher energy production level. However, this does not necessarily mean a greater profit due to the excess of generation selling, since the capital and maintenance costs increase as well. In this paper, a comprehensive economic analysis method for selecting the PV array structure type has been proposed. To this end, a precise method to compute the yearly generated electrical energy (solar converted energy) has been presented by applying the global radiation relation between different structures, i.e. fixed, single axis (vertical and horizontal) and dual axis trackers. Also, the simple and yet accurate efficiency model and power relation are used for solar inverter and panel, respectively. The analysis is accomplished by determining the economic parameters, including net present value (NPV), internal rate of return (IRR), and payback period time (PBT) for all PV structures with the same electrical energy generation or profit. Due to the results simplicity and robustness in different economic conditions, the same energy production scenario is chosen in this paper. In accordance with this assumption, PV panel, inverter and tracker sizes and net present costs (NPC) are determined. Since the net present benefit (NPB) for all structures is equal, the lowest NPC is considered the most economic choice. The performance of the suggested algorithm is evaluated through a commercial dual axis GCPV system simulation. Moreover, in order to determine the best suited economic parameters, a sensitivity analysis has also been carried out in the process. [ABSTRACT FROM AUTHOR]

In the field of renewable energy, reliability analysis techniques combining the operating time of the system with the observation of operational and environmental conditions, are gaining importance over time. In this paper, reliability models are adapted to incorporate monitoring data on operating assets, as well as information on their environmental conditions, in their calculations. To that end, a logical decision tool based on two artificial neural networks models is presented. This tool allows updating assets reliability analysis according to changes in operational and/or environmental conditions. The proposed tool could easily be automated within a supervisory control and data acquisition system, where reference values and corresponding warnings and alarms could be now dynamically generated using the tool. Thanks to this capability, on-line diagnosis and/or potential asset degradation prediction can be certainly improved. Reliability models in the tool presented are developed according to the available amount of failure data and are used for early detection of degradation in energy production due to power inverter and solar trackers functional failures. Another capability of the tool presented in the paper is to assess the economic risk associated with the system under existing conditions and for a certain period of time. This information can then also be used to trigger preventive maintenance activities. [ABSTRACT FROM AUTHOR]

Tidal current energy is a promising renewable energy, and it has become a research hotspot all over the world. Tidal current turbines (TCTs) are the devices that capture tidal current energy and convert it into electricity. Power train is one of the key technologies, and a gearbox is traditionally used. Because of the disadvantages of the gearbox, several soft power transmission methods have been studied, such as hydraulic power train and direct-drive train. Aiming for maximum power point tracking (MPPT) and constant frequency simultaneously, this paper introduces the hydraulic-mechanical hybrid transmission for TCT. Different from the traditional mechanical transmission, the hydraulic-mechanical hybrid transmission uses a two-degree-of-freedom planetary gear (TDPG) as the power split device. In this transmission, the rotor speed can be regulated by hydraulic pump displacement control to realize the MPPT, and the power can be stabilized through the hydraulic system. In this paper, the hydraulic-mechanical hybrid transmission is introduced, and the characteristics of the TDPG are analyzed first. Then, the control strategy of TCT is proposed. Finally, the system is modeled and constructed, and the simulation results confirm the validity of the hydraulic-mechanical hybrid transmission of TCT. [ABSTRACT FROM AUTHOR]

Harnessing biomass-derived energy can improve environmental and economic sustainability of a Combined Heat and Power production. The paper presents a new decision making policy and its application in meeting the energy up-grading needs of the Bari airport (300 kWe), based on an economic-environmental analysis related to the use of different bioenergy from short chain (<70 km). The main aim of this paper is to demonstrate how a “Zero Kilometer Energy” design model in a CHP plant represents a more sustainable alternative to the conventional approach, in terms of impacts on the local socio-economic system. The study has been carried out in order to promote a synergistic and sustainable relationship between a territory and the infrastructures that service it, in terms of energy supply chain. For this purpose, three different bioenergy production systems (biomass from wood waste, vegetable oil/biodiesel and biogas from food waste) harnessing local agro-energy resources in Apulian region (Italy) were analyzed. The analysis has been integrated by a DCF (Discounted Cash Flow) Method, identifying the economic feasibility to make an informed choice. Finally the theoretical paybacks under different governmental incentive schemes, from 2012 to 2015, have been calculated along with estimated carbon savings to highlight the energy market trends for the different biomass resources. [ABSTRACT FROM AUTHOR]

This paper presents the energy performance evaluation of a marketable net-zero-energy house (NZEH): Solark I at Solar Decathlon China 2013. The assessment methodologies are based on EnergyPlus simulations and measured data. The paper also discusses the reasons for the differences between the results of the simulations and the measurements, analyzes the investment cost, summarizes the lessons learned from the competition, and presents the potential for replicability and transposition from Solark I to implementation in a practical NZEH. The conclusions are that Solark I's investment cost is reasonable, its systems for building-integrated photovoltaics, hot water and heating, and ventilation and air conditioning demonstrated excellent performance based on the results of the energy performance evaluations using EnergyPlus simulations and measured data. Thus, Solark I is a marketable NZEH. [ABSTRACT FROM AUTHOR]

Generating companies (GENCOs) with wind farms always suffer from the variations of wind power and energy prices. The coordination of wind power with hydro units is an effective way for GENCOs to enhance the ability of wind power dispatch, increase profit, and reduce risk. However, GENCOs still need to prepare a certain amount of economic capital to cover the possible losses and keep them operating even in a worst-case scenario. In this paper, bidding strategies' value at risk is adopted to determine the economic capital requirement, and the risk adjusted return on capital (RAROC) which represents the return of economic capital is introduced. Then, this paper proposes a coordination bidding strategy for wind farms and hydro stations in a GENCO based on RAROC optimization. RAROC can measure the performance of risk management and estimate the tradeoff between profit and risk. Compared to the risk-neutral strategies, the proposed method prevents the GENCO from huge losses by risk management. Compared to the traditional risk-averse strategies, the proposed method does not need to quantify the GENCO's risk aversion and it is helpful for economic capital determination. Numerical example illustrates the proposed bidding strategy, as well as the comparison analysis and sensitivity analysis. [ABSTRACT FROM AUTHOR]

In this paper, technical and economical studies conducted on the SEAREV Wave Energy Converter (WEC) are presented. This technology was first proposed in 2002 with the aim of addressing critical challenges in wave energy conversion. It consists of a closed floating hull in which a heavy pendulum oscillates. The controlled relative motion of the pendulum is used to produce electricity. The SEAREV WEC was developed over twelve years. Through the development process, three main generations of the technology were defined and studied in detail. They are presented in the paper, showing how each new generation brought significant improvements over the previous generation with respect to production and costs. In 2013, an economical model for wave energy farms was developed to assess the viability and competitiveness of the SEAREV technology. Although results show that the SEAREV technology is a sound technical solution, the cost of energy projection is still too high to allow direct access to mass electricity market in European countries in the short term. Finally, in light of the lessons learned from the SEAREV WEC development, the need for innovative technologies with higher technology performance level (TPL) or alternative markets is discussed in the context of wave energy. [ABSTRACT FROM AUTHOR]

Wind energy is a key portion of most clean and green energy strategy. However, wind energy is intermittent and uncertain. This uncertainty poses a techno-economic challenge of sourcing the least costing load balancing service (reserve). This paper looks to develop solutions for this challenge. Currently the system unbalance caused by the wind power is handled by the real time balancing market, which is operated by the system operators for maintaining reliable operation of power systems. This method cannot always work reliably when the amount of wind penetration increases in the future. A future electricity market, with no subsidies, is assumed in this paper where wind generators have to compete with other generators to sell energy. It is assumed that wind generators are competitively scheduled a day-ahead and would suffer penalties for under production while receiving a poor compensation for over production. To overcome the uncertainty in wind production, an options based network constrained intra-day secondary reserve market is proposed in this research with a mathematical formulation that considers purchasing energy from several reserve providers. Reserves may be purchased by procuring options ahead of transactions by paying premiums and paying strike prices while transacting. The market equilibrium amongst participants will be reached with proposed optimization and the lambda (LaGrange) multiplier associated with power balance equation at each bus determines optimal values of both premiums and strike prices. The amount of required reserve is calculated by using a Cauchy-Lorentz distribution model. The reserves are positive for under production and negative for over production. Transmission network MVA limits are considered to ensure feasibility of options contracts. A 5-bus test system and a real Ontario (Canada) wind farm data with IEEE 118-bus system illustrate the merits of this research. [ABSTRACT FROM AUTHOR]

Agricultural wastes vary widely in composition. Presently, these are either of no use or remain under-utilized in absence of available technology. Many of these have useful calorific values and can be used more efficiently with the development of suitable technology. Availability of these also varies widely in places and over the year. Polygeneration is the delivery of multiple utility outputs efficiently from a single unit through proper system integration. Combining suitable utility outputs with local agricultural wastes as inputs to polygeneration can be efficient future sustainable solution for rural people. Preliminary feasibility and performance estimation using thermodynamic model in Aspen Plus ® for such polygeneration with electricity, refrigeration, utility heat and ethanol as outputs is reported in this paper. Also economic feasibility of the polygeneration plant is reported in this paper. Rice straw, sugarcane bagasse and coconut fiber dust are three typical different agricultural wastes and are considered as inputs. Results show that such polygeneration is highly promising as decentralized efficient option, specifically for rural people. [ABSTRACT FROM AUTHOR]

The promotion and adoption of biofuels in Nigeria must be predicated on sufficient capacity for absorbing biofuels produced from the increasing investments in biofuels plantations, plants and processing facilities. This paper assesses the socioeconomic and related premises for biofuels development in Nigeria by conducting an econometric estimation of the petroleum products consumption. The paper first estimates aggregated petroleum product consumption, and then assess the response to specific petroleum products in terms of consumption, market (population), electricity generation, installed electricity generation capacity, and GDP. The result shows that all the petroleum products contribute significantly and about equally to aggregate petroleum consumption. The high proportion of petrol (about 44 percent) as a percentage of the aggregate petroleum product consumption validates the push for implementing the E10 petrol-ethanol blending for Nigeria. The consumption of diesel is also significant. Diesel is another petroleum product for which D20 biofuel blending policy has been proposed. The increase in population and GDP, coupled with the poor electricity situation, will keep driving the consumption of petroleum products. As the population increases, and the country continues to struggle to match electricity generation with population growth, the petrol-ethanol and diesel-biodiesel blending policy must be pursued tenaciously to ensure a reduction in carbon emission in Nigeria. [ABSTRACT FROM AUTHOR]

The increasing penetration of renewable energy sources in Europe requires market mechanisms which allow an efficient balancing of these sources. This paper analyzes the participation of renewable generators in the Spanish intraday market. First, the organization of the intraday market and the short-term market mechanisms influencing intraday trading are described. After that, day-ahead and intraday market prices, as well as intraday trading volumes, are used to study the behavior of market agents in the Spanish intraday market. Regarding renewable generators, the influence of support schemes on the behavior of these agents in the intraday market is also analyzed. This paper shows that the Spanish intraday market has effectively contributed to renewable generation balancing. Despite this, market distortions have incentivized some renewable generators to arbitrate between the day-ahead and intraday markets, giving rise to higher system costs. Based on the presented analysis, it is argued that these distortions need to be removed from short-term markets to incentivize market parties, especially intermittent generators, to reduce forecast errors over time, improving economic efficiency and avoiding the use of costly balancing actions performed by the System Operator. [ABSTRACT FROM AUTHOR]

This paper develops the temporal-spatial distribution of wave energy at the Beibu Gulf at a monthly, seasonal, and annual base using the Simulated WAves Nearshore (SWAN) model, which is called third generation wave prediction model. The model is forced with the ECMWF ERA Interim wind field data covering 34 years at a time interval of 6 h. Wave parameters, including significant wave height ( Hs ), peak wave period ( Tp ), and wave direction (θ) are simulated by SWAN model. Simulated data are validated against the altimeter data using Bias, MSE, and R, and the validation results show that the simulated data can effectively be used to calculate the wave energy in Beibu Gulf. This paper highlights the temporal-spatial distributions of monthly, seasonal, and annual of wave energy. The results reveal that (1) the wave energy propagations in inner waters are dominantly along northeast and west-northwest; (2) the high-energy areas are located at the middle and the southern Beibu Gulf; (3) the biggest monthly wave energy is from January through March with approximately 2.5 kW/m, and the biggest seasonal wave energy is from winter through spring with approximately 1.7 kW/m, and the biggest annual wave energy is about 1.5 kW/m. Additionally, the quantitative analysis, in which the total storage of wave energy vs. the percentage of wave energy greater than 2 kW/m is mapped at a 0.5° × 0.5° grid, identifies those grids used for wave energy convertor deployment. Finally some suggestions are drawn up for decision-makers of the local government. [ABSTRACT FROM AUTHOR]

The twenty-first century must see a decarbonisation of electricity production to mitigate the flow of greenhouse gas emissions into the atmosphere. This paper presents an econometric analysis of the factors that motivate the use of renewable energy in electricity production using panel data from European Union Member States during the period 2000–2015. The research extends the literature in this area in several ways. Firstly, the econometric analysis is focused on the electricity sector rather than on the overall primary energy supply, which also includes the diverse heating and transport sectors. In addition, an alternative public policy variable is proposed using the tax and levy component of electricity bills. Furthermore, an alternative econometric approach is employed using a hybrid mixed effects estimator. The results of this analysis are found to be broadly as expected. Electricity grid interconnection and higher levels of greenhouse gas emissions both motivate the development of renewable electricity, with point elasticities of 0.55 and 0.87 respectively. Policy implications are that policy support for fossil fuels should be ceased; electricity grid interconnections should be developed between countries; and furthermore, levies on retail electricity prices to fund RE support schemes are effective at promoting renewable electricity. • Improved econometric approach using hybrid mixed effects estimator. • Alternative measure proposed for a continuous public policy support variable. • Grid interconnection positively associated with use of renewable electricity. • Higher carbon emissions found to motivate shift towards renewable electricity. • FDI not found to have significant effect on use of renewable electricity. [ABSTRACT FROM AUTHOR]

There is a growing interest on how climate change may affect the energy sector, including changes in wind energy generation. This paper builds on existing research adding an economic component that considers how climate change can affect operating margins and investment values in specific wind farms in Spain. A projection of wind speed was carried out using an ensemble of three climate models, two scenarios (RCP 4.5 and 8.5) and two time periods (2018–2041 and 2042–2065) per plant. Using historical power curves, the changes in wind speed were converted to production output. The results show variations in production of up to 8% and changes in operating margins up to 10%. Seasonal generation may fluctuate as well, with an increase in summer and decrease in winter. An investment analysis was also conducted to consider how climate change may influence future developments in the sector. • Climate change will affect wind speed and therefore wind energy production. • In four wind farms in Spain we project variations in wind speed of up to ± 5%. • This will imply changes in production (±8%) and in operative margins (±10%). • The regulatory framework is more relevant in comparison. [ABSTRACT FROM AUTHOR]

Abstract: An important issue in various domains of renewable energy is the use of technological improvement trends to project future capabilities of energy technologies. This paper analyzes two pairs of renewable energy technologies and finds that the annual improvement rate of cost/investment is quite different for the four technological domains: namely, solar photovoltaics (PV) (9.0% per year), wind turbines (2.9%), batteries (3.1%) and capacitors (21.1%). While these trends have been reasonably consistent over long time frames, projecting these trends into the future without a better understanding of the underlying causes of the improvements is not at all reliable. This paper establishes theoretical fundamentals for explaining the differences in such rates and a framework for empirically probing such explanations using patent data. Employing this framework, this study collects and analyzes a set of highly representative patents for each of the four domains, allowing measurement of: patenting rates, reliance on scientific literature and other characteristics of the different fields. Our study of the inventions, while not establishing an indisputable causal relationship for the differing rates, establishes a broader theoretical basis for why such rates differ so greatly and why they might be stable over time. Among many possible effects, this study indicates that the age of knowledge utilized in the patents and the percentage of very important inventions in the field are the most likely significant contributors to higher rates of advance. [Copyright &y& Elsevier]

Abstract: This paper categorises different concentrating solar power (CSP) hybrid options into light, medium and strong hybrids and discusses the combination of CSP with coal, natural gas, biomass and waste materials, geothermal, and wind. The degree of hybridisation depends on the interconnection of the plant components. Light hybrids create only limited synergies, such as the joint use of a substation, and their cost reduction potential is therefore limited, while strong hybrids share major plant components, such as steam turbine and condenser, and can better match their energy output with electricity pricing. The hybridisation options for CSP with different energy sources are plentiful ranging from feedwater heating, reheat steam, live steam to steam superheating with some options better suited for a specific energy source combination than others. The synergies created in hybrid plants can lead to cost reductions of 50%, better energy dispatchability as well as revenue maximisation. Several CSP hybrid studies exist for coal, natural gas and biomass but these are often investigating a specific hybrid concept. This paper considers several options at a higher level and also includes geothermal and wind which is novel. While the paper focuses on Australia the approach taken and concepts discussed are transferable to other countries. [Copyright &y& Elsevier]

Abstract: Green Building has been a large focus for the construction industry, with Green Star certified commercial buildings becoming the new standard for commercial office buildings. However there has been little focus on the improvement of existing buildings, and many of Australia's capital cities have ageing building stock that is not operating efficiently and contributing to the nation's growing greenhouse gas emissions. Retrofitting existing buildings for energy efficiency is receiving more attention across Australia, with grants and funding to incentivise owners to find energy efficient solutions for buildings. However it is important that optimising performance of these buildings considers the impact on occupants. Australians spend the majority of their day indoors and the quality of the indoor environment can have a major impact on the health and productivity of workers. This paper covers the development of a tool for a project sponsored by the Sustainable Built Environment National Research Centre to assist building stakeholders identify key energy performance issues with their buildings. The tool explores 5 key areas in buildings that influence energy performance: design elements, building management, occupant experience, agreements and culture and indoor environment quality. The paper explains the development of the tool and some surprising results from the first trial on the tenancy for a 28 year old commercial building in the Perth CBD that underwent a Green Star interiors fit-out. [Copyright &y& Elsevier]

Abstract: In 2012 there was approximately 2400 electric vehicle DC Fast Charging stations sold globally. According to Pike Research (Jerram and Gartner, 2012), it is anticipated that by 2020 there will be approximately 460,000 of them installed worldwide. A typical public DC fast charger delivers a maximum power output of 50 kW which allows a typical passenger vehicle to be 80% charged in 10–15 min, compared with 6–8 h for a 6.6 kW AC level 2 charging unit. While DC fast chargers offer users the convenience of being able to rapidly charge their vehicle, the unit's high power demand has the potential to put sudden strain on the electricity network, and incur significant demand charges. Depending on the utility rate structure, a DC fast charger can experience annual demand charges of several thousand dollars. Therefore in these cases there is an opportunity to mitigate or even avoid the demand charges incurred by coupling the unit with an appropriately sized energy storage system and coordinating the way in which it integrates. This paper explores the technical and economical suitability of coupling a ground energy storage system with a DC fast charge unit for mitigation or avoidance of demand charges and lessening the impact on the local electricity network. This paper also discusses the concept of having the system participate in demand response programs in order to provide grid support and to further improve the economic suitability of an energy storage system. [Copyright &y& Elsevier]

Abstract: In a world constantly shaped by climate change, the search for decarbonising pathways will deliver many innovative technological solutions as well as trigger changes in the way people behave. This however will take time and will require negotiations and new business models. There is increasing evidence that arresting climate change at 2°C is unlikely to be attained in a world where carbon is essential for development. Achieving agreement and commitments between developed and developing countries have proven difficult but is there something that those most responsible for the current levels of CO2e emissions in the atmosphere can do? The paper examines food consumption and argues that there is a lot of potential for decarbonisation if people reduce their meat consumption. The highest levels of meat consumption are observed in the developed world and the livestock sector has been shown to be the largest single contributor for greenhouse gas emissions globally. Estimates indicate that a low-meat diet can reduce the cost of abating climate change. The paper presents an argument as to how flexitarianism – reduced meat consumption to the recommended healthy levels, can help in arresting climate change. Flexitarianism offers an easy way to achieve fast decarbonisation and has the added benefits of contributing towards improving not only the biophysical health of the planet but also that of its human habitants. [Copyright &y& Elsevier]

Abstract: Many countries are searching for ways to reduce the energy and carbon impact of housing. The terms net zero-energy home and net zero-carbon home have entered the policy lexicon, without clear definitions and without widespread understanding of the likely policy impact. Is the concept limited to bespoke architect driven buildings for specific green clients, or does it have relevance in the mainstream house building sector and for typical households? When we consider volume house building and contemporary lifestyles, what is the energy end-use reality of so called zero-energy homes? Can government policy instruments deliver housing estates that are thermally comfortable, energy efficient and powered by renewable energy? The Lochiel Park Green Village in South Australia represents a genuine attempt through government policy processes to create a suburb of (nearly) zero-energy homes in a near zero-carbon estate. The development includes 103 highly energy efficient homes of various sizes, all utilising solar thermal and solar photovoltaic sources, and built to stringent environmental urban design guidelines. The energy used and generated at each house is being monitored and analysed to extend our understanding of what happens when families bring their energy habits to near zero-energy homes. Appliance and equipment audits are conducted to extend our knowledge of the energy services utilised in contemporary digital-age lifestyles. This paper provides an insight into the quanta of energy using appliances and equipment that fill our homes and satisfy our ever-growing needs. The paper presents key results from the first two years of monitoring for the initial tranche of houses, demonstrating that although significant reductions in operating energy use have been achieved, few households have reached a net zero energy standard. The research highlights the extent to which our choice of energy systems and our individual behaviour affect the total annual energy use. The energy end-use and energy generation results are examined to identify the contribution of near zero-energy homes to the twin policy challenges of anthropogenic climate change and peak power demand. Using empirical evidence from extensive monitoring, this paper throws new light on the energy use of actual families in contemporary near zero-energy homes. [Copyright &y& Elsevier]

Abstract: Today, world's city populations are growing at an unprecedented rate. Old centralised, city infrastructure networks are under pressure to support the production, distribution and consumption of city resources. New distributed, low and zero carbon infrastructure options are required to reduce global carbon emissions and pollution, and improve the efficient distribution of energy, water and waste products and services. Similarly, new strategies to manage these infrastructure systems are required. Outdated political, economic, and social barriers need to be reviewed to allow city precincts to succeed in reducing their carbon footprint, improve people's lifestyles, and live more harmoniously within the means of the Planet. This paper seeks to uncover some of the barriers, as well as the opportunities that exist for the process of decarbonising cities to succeed. The paper through a series of interviews with professionals from all different sectors of society, aims to shed some light on some of the key issues surrounding the topic of governance and decarbonised, urban development. The work also highlights some emerging business models that demonstrate the type of governance structures that can support decarbonised development within cities and regions. [Copyright &y& Elsevier]

Abstract: Situated at equator level, Central Africa is a wetted area, sunny and not that windy. The region owns important renewable energy potential, namely solar, hydro and biomass. For a number of reasons, this important potential is still suffering from poor development. The main cause of the poor use of renewable energy is the poor commitment and dedication of governments who have not taken the necessary measures to boost enough decentralized and renewable energy. Thermal plants are hence unfortunately heavily used where other alternatives are possible. The purpose of this paper is among other things aiming at showing how solar and hydro energy sources of Central Africa are currently developed and addressing the problems faced. The work also addresses the issue of filling the gap between the abundant solar and hydro resources and its poor development compare to the rest of the world. Based on some case studies in Cameroon, actions to sustain ongoing initiatives and promote their development are suggested. This paper also addresses the problems actually faced and recommends actions for mitigation for a significant improvement of energy infrastructure in remote areas. In such areas, the promotion of renewable energy and energy efficiency are very important for poverty alleviation. From lessons learned, suggestions will be made to help the countries of the region develop a vision aiming at developing adequate clean energy policy to increase the status of solar and microhydro energy sources and, thus, better contribute to fight against climate change. [Copyright &y& Elsevier]

Abstract: Prince Edward Island (PEI) is the smallest province in Canada measuring about 5700 km2 in area with a population of around 130,000 people. Small family farm operation is part of the Island's way of life. However, the dairy industry in North America is undergoing significant structural change. Statistics show a significant decline in the small dairy farms industry, while the number of large operations has been increasing. Advantages for large operations include purchasing energy in large quantities with better price margins and the inherent economy of scale created by such breaks. One strategy for small-scale farms to become competitive is to reduce their energy-related operational costs and greenhouse gas emissions. This can be achieved through taking energy efficiency steps, reducing overall energy consumption and generating energy through renewable energy resources and technologies. This paper uses a case study of a small dairy farm in Oyster Bed Bridge, PEI to gain insight into the direct use of energy within small dairy farms. An energy audit methodology is used to determine the energy intensity of the farm as well as energy efficiency opportunities. The paper also assesses the feasibility of meeting part of the energy demand of the farm with renewable energy generation. Energy efficiency recommendations for the case study farm include lighting retrofitting and regular maintenance of refrigeration condenser units. Renewable energy generation findings include the potential use of an anaerobic digester or a 25 kW wind turbine to generate the majority of the operation's energy. [Copyright &y& Elsevier]

Abstract: Renewable energy-based off-grid or decentralised electricity supply has traditionally considered a single technology-based limited level of supply to meet the basic needs, without considering reliable energy provision to rural consumers. The purpose of this paper is to propose the best hybrid technology combination for electricity generation from a mix of renewable energy resources to satisfy the electrical needs in a reliable manner of an off-grid remote village, Palari in the state of Chhattisgarh, India. Four renewable resources, namely, small-scale hydropower, solar photovoltaic systems, wind turbines and bio-diesel generators are considered. The paper estimates the residential, institutional, commercial, agricultural and small-scale industrial demand in the pre-HOMER analysis. Using HOMER, the paper identifies the optimal off-grid option and compares this with conventional grid extension. The solution obtained shows that a hybrid combination of renewable energy generators at an off-grid location can be a cost-effective alternative to grid extension and it is sustainable, techno-economically viable and environmentally sound. The paper also presents a post-HOMER analysis and discusses issues that are likely to affect/influence the realisation of the optimal solution. [Copyright &y& Elsevier]

Abstract: This paper briefly considers the recent dramatic reductions in the underlying costs and market prices of solar photovoltaic (PV) systems, and their implications for decision-makers. In many cases, current PV costs and the associated market and technological shifts witnessed in the industry have not been fully noted by decision-makers. The perception persists that PV is prohibitively expensive, and still has not reached ‘competitiveness’. The authors find that the commonly used analytical comparators for PV vis a vis other power generation options may add further confusion. In order to help dispel existing misconceptions, some level of transparency is provided on the assumptions, inputs and parameters in calculations relating to the economics of PV. The paper is aimed at informing policy makers, utility decision-makers, investors and advisory services, in particular in high-growth developing countries, as they weigh the suite of power generation options available to them. [Copyright &y& Elsevier]

Abstract: Electricity generation from renewable sources of energy will be a key part in the development of future strategies for many countries globally. This renewable electricity generation will be hugely important for Ireland, due to its lack of fossil fuel resources. The extremely good wind resource available provides Ireland with the opportunity of generating vast amount of electricity from wind energy. Large-scale wind electricity generation reached 1264 MW installed capacity by January 2010 in Ireland. However, micro scale wind electricity generation has not been very popular in Ireland to-date. The unclear economics of micro wind turbines, under Irish conditions, is considered the biggest obstacle for expanding micro wind turbine installation in Ireland. This paper presents a methodology to accurately evaluate the economic viability of a micro wind turbine on a case-by-case basis. The methodology utilises the software programmes HOMER and Microsoft Excel 2007 for the energy and economic analyses. This paper also presents a realistic economic analysis of a number of micro wind turbines available in Ireland. [Copyright &y& Elsevier]

Abstract This paper presents and evaluates a novel demand response method for households, designed for mitigating intermittency in smart grids with a high share of renewables. The method, named Dynamic-Active Demand Response (DADR), is based on an innovative paradigm of offering multiple electricity service levels and a dynamic-active demand response scheme. It provides the grid operator with the ability to influence consumption patterns in real time, so that responding to renewables intermittency is more effective in terms of reliability, predictability and response time. DADR's performance is evaluated using a Monte Carlo simulation model, which assesses the method's intermittency mitigation potential and estimates the expected economic value of implementing it in the Israeli residential sector. Major components of the model are based on a survey, conducted among Israeli households. The survey results indicate that, given a sufficiently attractive economic incentive, participation rates can reach as high as 85–90%. The Monte Carlo simulation results reveal that DADR can make a significant contribution to mitigating renewables intermittency, with energy savings of hundreds to thousands of MWh a day and a positive net economic benefit. Highlights • A residential DR method for smart grids with a high share of renewables is proposed. • Based on an innovative paradigm of electricity services and a dynamic-active DR. • Monte Carlo simulation is used to evaluate the method's performance. • Simulation results reveal a significant contribution to mitigating intermittency. • Cost benefit analysis shows a positive net benefit. [ABSTRACT FROM AUTHOR]

Abstract Optimal distribution system reconfiguration (DSR) and distribution generation (DG) allocation are viable solutions for improvement of technical and economic aspects of distribution systems. This paper proposes a stochastic multi-objective DSR (SMO-DSR) model, aims to maximize the DG owner's profit and minimizes the distribution company's (DisCo's) costs. The uncertainties of wind power generation, electricity price, and demand are handled via scenario based approach. The proposed SMO-DSR model is solved via ε -constraint method and the best compromise solution is selected by fuzzy satisfying criterion. The model is a mixed integer non-linear programing (MINLP) problem which is implemented on IEEE 33-bus distribution system in General Algebraic Modeling System (GAMS) environment. To show the effectiveness of the proposed SMO-DSR approach, it is studied in different cases. A sensitivity analysis is also performed to show the effect of contract price of wind energy on the objectives of DisCo and DG owner. The obtained results substantiate the interaction between the DSR and DG allocation problems. Also, it is shown that the contract price of wind energy considerably influences both DG owner and DisCo schedules. Besides, when a compromise is made between the DG owner's profit and DisCo's cost, the power losses of the network is reduced. Highlights • A multi-objective stochastic model is proposed for network reconfiguration and DG allocation. • The DG allocation and network reconfiguration problems are studied from economic viewpoint. • Scenario-based modeling approach is utilized to handle the uncertainties. • The uncertainties of wind power, demand and energy price are considered. • The interaction between DG allocation and network reconfiguration problems is studied. [ABSTRACT FROM AUTHOR]

Abstract Despite generally having significant renewable energy potential, islands tend to depend on imported fossil fuels with volatile prices. This paper aims to provide technical inputs for reorganizing the energy planning for Ometepe Island. The result of the wind and solar resource assessments indicates wind power densities of 147 W/m2 and 178 W/m2 at elevations of 80 m and 120 m, respectively, and an irradiation level of 5.3 kWh/m2/day. The estimated wind LCOEs are significantly lower than current diesel plant operating prices. Photovoltaic systems will probably become cost-effective 15 years from now for all non-subsidized end customers. However, it would be necessary to store energy to phase out diesel generation, and analyses were conducted to determine the possibility of a pumped-storage hydro plant. The annual biogas potential was estimated as ∼550,000 Nm3, and in conjunction with electric stoves, it could be used to replace other fuels for cooking. Electric buses are an option for replacing the current diesel-run public buses, but advantageous financial conditions and reorganization of the bus schedules would be required. Also, a street lighting program was found to be cost-effective. The renewable energy transformation of the island might act as a role model for energy transition in Nicaragua. Highlights • A low-medium wind potential and a high-medium solar potential are found. • The possibility of a hydro-pumped storage plant in the island is shown. • The energy and economics aspects of a public electric mobility are analyzed. • LPG-wood/electric stoves-biogas for cooking are considered. • A street lighting retrofit is cost-effective and helps to integrate renewable sources. [ABSTRACT FROM AUTHOR]

Abstract Commercial operation and maintenance of wind farms always involves trying to find the most cost-effective solution from various possible options. In this paper, a maintenance action within a Spanish wind farm was studied, whereby a blade replacement was required to prevent catastrophic failure. The conducted replacement was accompanied by an underperformance resolved in a later blade re-pitching. We analyse the decision taken in terms of the power performance and net present value from the cash flow resulting from the energy sales. The impact of the timing of the maintenance is discussed in various what-if scenarios. The sensitivity to environmental causes of underperformance is compared by varying the duration of blade icing and comparing the performance in different wind directions. Country dynamics and subsidy impacts are hypothetically evaluated for the prevailing electricity market conditions as if the turbine were operating in either Spain, Netherlands or the UK. The findings highlight the uncertainty in power performance and the importance of maintenance accuracy. It is shown that the decision-making of operators should not only consider the seasonality of the wind resource, but also the seasonality in electricity markets. Highlights • The financial impact of underperformance due to suboptimal maintenance is revealed. • Electricity market seasonality is an important driver in maintenance optimisation. • The effect of environmental conditions on power performance needs to be considered. [ABSTRACT FROM AUTHOR]

Abstract Policy makers are increasingly supporting the development of renewable electricity power generation projects not only for environmental concerns but also for economic reasons. Several studies have indeed documented that renewable electricity can be a viable economic alternative to electricity power generation based on non-renewable sources. Yet, most of the existing studies are based on microeconomic cost-benefit analyses which disregard the existence of large macroeconomic effects. This paper develops a novel method to evaluate the macroeconomic impact of renewable electricity power generation projects. Economic theory is used to identify the potential effects of these projects on the vector of macroeconomic variables affected by their implementation. A structural vector autoregression model is thus estimated using a novel dataset of quarterly macroeconomic and energy data for Portugal. The estimated impulse-response functions suggest that renewable electricity power generation projects have positive effects on real economic growth in the medium run, through both the investment and the operations phases. Import substitution is the key driver of the overall positive impact. Highlights • A new method to evaluate the macroeconomic impact of REPG projects is proposed. • Economic theory is used to identify the vector of variables affected by REPG projects. • A structural vector autoregression is estimated using a novel dataset for Portugal. • REPG projects are found to have positive effects on real economic activity. • Import substitution is the key driver of the positive impact of REPG projects. [ABSTRACT FROM AUTHOR]

Abstract Power-to-Gas (P2G) is a technology that converts electricity to gas and is termed gaseous fuel from non-biological origin. It has been mooted as a means of utilising low-cost or otherwise curtailed electricity to produce an advanced transport fuel, whilst facilitating intermittent renewable electricity through grid balancing measures and decentralised storage of electricity. This paper investigates the interaction of a 10MW e P2G facility with an island electricity grid with limited interconnection, through modelling electricity purchase. Three models are tested; 2016 at 25% renewable electricity penetration and 2030 at both 40% and 60% penetration levels. The relationships between electricity bid price, average cost of electricity and run hours were established whilst the levelised cost of energy (LCOE) was evaluated for the gaseous fuel produced. Bidding for electricity above the average marginal cost of generation in the system (€35–50/MW e h) was found to minimise the LCOE in all three scenarios. The frequency of low-cost and high-costs hours, analogous to balancing issues, increased with increasing shares of variable renewable electricity generation. However, basing P2G systems on low-cost (less than €10/MW e h) hours alone (999 h in 2030 at 60% renewable penetration) is not the path to financial optimisation; it is preferential to increase the run hours to a level that amortises the capital expenditure. Highlights • The viability of P2G depends on the electricity market in which it operates. • Low bid prices allow for lower run hours producing less gas at a higher LCOE. • Increased capacity factor due to higher bid price leads to a more economical system. • Bidding above the average marginal cost of generation minimises the LCOE. • Solely consuming cheap or otherwise curtailed energy is not economically viable. [ABSTRACT FROM AUTHOR]

Abstract Thermoelectric coolers have been abundantly investigated from the viewpoint of the first law of thermodynamic. However, extremely few exergy analysis have been probed for thermoelectric air-coolers. Because of the importance of exergy consideration in each thermodynamic process, this paper experimentally focuses on the effect of various parameters on exergy destruction and the second law performance through a thermoelectric air cooler. The effects of flow and thermodynamic parameters including air flow rate, incoming air temperature, water flow rate, incoming water temperature, DC voltage/ampere etc. on exergetic characteristics are clarified in this study. Interesting meaningful curve behavior was observed for exergetic performance of thermoelectric cooler. Indeed, curve behavior of exergetic performance is descending-ascending and therefore a critical value of DC voltage was found in which the amount of second law performance has a minimum/maximum value. Increment of air flow rate improved the exergetic performance of Peltier-air cooler. Besides, higher air inlet temperature reduced exergy destruction of thermoelectric module (TEM) which means that Peltier air cooler is appropriate for regions with warmer weather in comparison with moderate climates. Highlights • A prototype Peltier air cooler was designed and fabricated. • The effects of air and water parameters on exergetic characteristics are studied. • The effect of DC voltage/current on exergy destruction and exergy performance are analyzed. • Notable curves behavior were observed for exergy characteristics of Peltier cooler. [ABSTRACT FROM AUTHOR]

Abstract Traditional support policies for green energy have greatly contributed to the rise in prosumer numbers. However, it is believed that they will soon start to exert negative impact on stakeholders and on the grid. Policy makers advise to phase out two of the most widely applied policies – net metering and feed-in tariff, in favor of support policies that scale better with rising renewable generation. This work quantifies the impact of these traditional policies in future "what-if" scenarios and confirms the need for their replacement. Based on simulations with real data, we compare net metering and feed-in tariff to four state-of-the-art market-based mechanisms, which involve auction, negotiation and bitcoin-like currency. The paper examines the extent to which each of these mechanisms motivates not only green energy production but also its consumption. The properties and characteristics of the above mechanisms are evaluated from the perspective of key stakeholders in the low voltage grid – prosumers, consumers and energy providers. The outcome of this study sheds light on current and future issues that are relevant for policy makers in the evolving landscape of the smart grid. Highlights • Six support policies are evaluated in scenarios with various numbers of prosumers. • "What-if" scenarios are studied through multi-agent simulations with real data. • Net metering and feed-in tariff will cause issues in the immediate future. • Market-based support policies are a better fit when prosumer numbers rise. • Each policy offers different trade-offs between profits and costs for stakeholders. [ABSTRACT FROM AUTHOR]

Abstract Intensive condition monitoring of wind generation plant through analysis of routinely collected SCADA data is seen as a viable means of forestalling costly plant failure and optimising maintenance through identification of failure at the earliest possible stage. The challenge to operators is in identifying the signatures of failure within data streams and disambiguating these from other operational factors. The well understood power curve representation of turbine performance offers an intuitive and quantitative means of identifying abnormal operation, but only if noise and artefacts of operating regime change can be excluded. In this paper, a methodology for wind turbine performance monitoring based on the use of high-frequency SCADA data is employed featuring state-of-the-art multivariate non-parametric methods for power curve modelling. The model selection considerations for these are examined together with their sensitivity to several factors, including site specific conditions, seasonality effects, input relevance and data sampling rate. The results, based on operational data from four wind farms, are discussed in a practical context with the use of high frequency data demonstrated to be beneficial for performance monitoring purposes whereas further attention is required in the area of expressing model uncertainty. Highlights • The effectiveness of SCADA-based condition monitoring is negatively influenced by the low resolution of the 10-minute data. • A novel framework for wind turbine performance monitoring is presented, based on the use of high-frequency SCADA data. • The potential of high-frequency data for monitoring purposes is thoroughly investigated. • Wind turbine power curve is modelled using state-of-the-art multivariate nonparametric methods. • Sensitivity of power curve models to site specific conditions, seasonality, input relevance and sampling rate is studied. • The results demonstrate that using high-frequency data is beneficial for performance monitoring purposes. [ABSTRACT FROM AUTHOR]

Abstract Most of the wind turbines analysis studies have been conducted under steady and uniform wind conditions. The unsteady flow past rotating rotor blades is, however, one of the most challenging applications for a numerical simulation. This is attributed to the existing aerodynamic complexities under such conditions. In this paper, a numerical approach to investigate the global dynamic behaviour of a Darrieus turbine under unsteady and non-uniform flow conditions is proposed. The dynamic response of Darrieus wind turbine geared system operating in fluctuating inflow present a more significant challenge for this approach. In this work, unsteady Computational Fluid Dynamic simulation is used to investigate the aerodynamic performance. Using the validated numerical model, unsteady wind inflow performance that affects the aerodynamic performance and the bevel gear dynamic response is conducted. The present results show that the dynamic behaviour of the Darrieus turbine geared system is strongly affected by the fluctuating inlet velocity. As such, a change in the inlet velocity results in the entire response changing in both the aerodynamic performance and the dynamic vibration of the studied wind turbine. The study results will hopefully be of importance to wind industries that require designs of VAWTs operating in unsteady winds condition. Highlights • A numerical method is presented to investigate the influence of unsteady flow on the dynamic response of Darrieus wind turbine geared transmission system. • Unsteady CFD simulation is used to assess Darrieus wind turbine complex flow physics and aerodynamic performance under unsteady wind conditions. • A correlation between complex aerodynamic phenomena and mechanical gearing system vibration under unsteady flow is established. • A detailed understanding on both aerodynamic performance and dynamic behaviour of Darrieus turbine with unsteady wind are discussed. • Dynamic behaviour of the Darrieus turbine geared system is strongly affected by the fluctuating inlet velocity. [ABSTRACT FROM AUTHOR]

Abstract Wind turbines are among the most popular sources of renewable energy. The energy available from wind varies widely because wind energy is highly dependent on continually fluctuating weather related parameters such as wind speed and wind direction. Wind farms have difficulties with system scheduling and energy dispatching because the availability of wind power is not known in advance. Therefore, the growth of wind power penetration in the emerging power system has made a precise wind forecasting method indispensable for system operators to include wind power generation in unit commitment and economic scheduling. This paper proposes two methods for wind speed and direction forecasting based on the nonlinear relations between the internal states of echo state networks. The methods decrease the number of internal states, and reduce the computational load compared to classical ESNs with fixed sizes and topologies by reducing the orders of the weight matrices. The design is simple with high learning capability and prediction accuracy, and does not require extensive training, parameter tuning, or complex optimization. The methods are tested with wind speed and direction data provided by the Nevada department of transportation (NDOT) roadway weather stations in the Reno, NV area. To demonstrate the efficiency of the proposed methods, they are compared with classical echo state networks (ESN) and with adaptive neuro-fuzzy inference system (ANFIS). The results of the new methods compare favorably with both ESN and ANFIS. Highlights • A reservoir including linear internal states and readout containing units using nonlinear functions of the internal states. • High learning capability and forecasting accuracy without significant deterioration with time. • Fewer internal states and lower order weight matrices relative to ESN, which reduces the computational load considerably. • A simple design, far less computation, and do not require extensive training, parameter tuning, or complex optimization. • Significantly lower error values than those of ANFIS and ESN for different wind profiles. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a new configuration of distributed energy system (DES), which integrates a district cooling system, is proposed as a new energy-efficient technology to be used in cooling dominated districts. An optimal design approach is developed for DES design and operation scheduling by using the real site measurements of energy demands. A case study on the DES in a high density district, i.e., a university campus in Hong Kong, is performed. The energy and economic performance of the DES, the matching performance of on-site generations and the efficiency of electric chillers are analyzed and compared with that of the centralized energy system (CES). It can be found that the proposed DES is a cost-effective and energy-efficient technology for the regions concerned. The DES contributes to substantial primary energy saving of 9.6% and a significant reduction in the operating cost of 44%. The distributed generations in the DES can match electricity demand very well around the year while the absorption chillers can match cooling demand well in transition months. Compared with the CES, the DES allows electric chillers of larger capacities to be used and to operate at higher part load ratios, resulting in higher energy efficiency in operation. Highlights • A new configuration of DES integrating a district cooling system is proposed. • The DES performance is assessed by comparison with CES based on the real-site measurements. • DES reduces substantial primary energy consumption (9.6%) and operating cost (44%). • Distributed generation can match the electricity demand very well all year round. • The cooling efficiency is improved significantly by using DCS in a high demand density district. [ABSTRACT FROM AUTHOR]