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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 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]

Abstract Based on the autoregressive distributed lag (ARDL) bounds testing approach and vector error correction model (VECM) Granger causality approach, this paper explores the relationships among per capita carbon dioxide (CO 2) emissions, gross domestic product (GDP), renewable, non-renewable energy production and foreign trade for China covering the period 1980–2014. One finding is that there is a long-run relationship among those variables. Another important finding is that China does not have the Environmental Kuznets Curve (EKC) of CO 2 emissions under the influence of economic growth, non-renewable energy production and foreign trade. However, after the addition of renewable energy production variable, it is found that the inverted U-shaped EKC hypothesis is supported in the long-run. Our long-run estimates show that increasing non-renewable energy and GDP increases CO 2 emission, whereas renewable energy and foreign trade have a negatively impact on CO 2 emissions. The short-run Granger causality tests show that there are bidirectional causalities running from foreign trade, CO 2 emission and non-renewable energy to renewable energy. Furthermore, the finding indicates that renewable energy consumption is a key solution in reducing CO 2 emissions over time. Finally on the basis of this study, we put forward the corresponding countermeasures and suggestions on China's carbon emission reduction strategy. Highlights • Examine the relationships among CO 2 emissions, renewable energy and trade. • It is found that the inverted U-shaped EKC hypothesis is supported. • Renewable energy and trade have a negative impact on CO 2 emissions in the long-run. • There is bidirectional causality running from CO 2 emission to renewable energy. [ABSTRACT FROM AUTHOR]

Abstract This paper investigates different criteria for the design of multi-unit renewable energy (RES) auctions in small markets. The multi-technology RES auctions which are to be implemented in Denmark in 2018 serve as an exemplary case for the assessment. Focus of the analysis is how setting the auction schedule and the auctioned volume per round impacts the auction outcomes, accounting for the particular challenges of small markets. Agent-based modelling of the Danish auctions scheme demonstrates that the Danish RES market provides sufficient competition to auction higher volumes and follow more ambitious expansion goals. Furthermore, with a fixed budget, it is more effective in terms of deployment achieved, to hold fewer auctions with a larger volume. A flexibility mechanism that allows up to 50% of the auction volume to be shifted between auction rounds to accommodate potential large-scale marginal bidders, proves to be a useful tool to increase deployment rates, without negatively affecting bid prices. Furthermore it was shown that at current cost levels, only onshore bidders would be awarded in the envisaged multi-technology scheme. Also, large-scale and multi-project bidders are likely to be most cost competitive - indicating that further measures to maintain diversity could be useful. Highlights • Volume and frequency have to be carefully balanced for RES auctions in small markets. • A too small volume per round can deter especially large scale bidders and lower deployment. • A flexible auction volume is suitable to maximise deployment rates. • Further measures to avoid concentration in the long run are advised in Denmark. • Currently, onshore wind and solar PV are not cost competitive in joint auctions in Denmark. [ABSTRACT FROM AUTHOR]

Abstract Two-part, in-situ reactive thermoplastic resin systems for composite wind turbine blades have the potential to lower the blade cost by decreasing cycle times, capital costs of both tooling and equipment, and energy consumption during manufacturing, and enabling recycling at the end of the blade life. This paper describes a techno-economic model used to estimate the cost of a thermoplastic wind turbine blade relative to a baseline thermoset epoxy blade. It was shown that a 61.5-m thermoplastic blade costs 4.7% less than an equivalent epoxy blade. Even though the thermoplastic resin is currently more expensive than epoxy, this cost reduction is primarily driven by the decreased capital costs, faster cycle times, and reduced energy requirements and labor costs. Although thermoplastic technology for resin infusion of wind turbine blades is relatively new, these results suggest that it is economically and technically feasible and warrants further research. Highlights • A thermoplastic wind turbine blade could reduce the manufactured blade cost by 4.7% compared to a thermoset epoxy blade. • An assumed 50% reduction in blade tooling cost for the thermoplastic blade had a significant effect on the cost. • The thermoplastic resin cost would have to increase by over 25% for the thermoplastic blade to be the same price as the epoxy blade. [ABSTRACT FROM AUTHOR]

The dearth of power generation from energy resources, environmental concerns and ever-increasing demand for electrical energy necessitate optimal economic dispatch with minimum costs and emissions. Due to the confined optimum convergence and non-convexity of realistic scenarios, classical optimization methods are not proficient to handle such problems. Instead, evolutionary optimization methods have gained more attention in recent years. Application of a new proposed double weighted particle swarm optimization (DWPSO) technique in solving non-convex combined emission economic dispatch (CEED) problems with wind power penetration and also solving non-convex multiple fuel option economic dispatch problem has been technologically proposed in this paper. The results on several case study systems are compared with other published methods in literature and confirm the effectiveness of DWPSO against other existing methods. DWPSO successfully reduces the production costs as well as hazardous emissions considering wind power penetration, selects the best fuel types of the generators and adjusts the feasible and optimum settings to allocate load demand to the online generation units in power system. The results demonstrate that using the proposed method can minimize the total generation costs and optimally satisfy the power demands in the grid while the computation performance remains satisfactory even in case of changes in the scale of the network. [ABSTRACT FROM AUTHOR]

One of the prime challenges in offshore wind is to manage and coordinate with the various stakeholders involved in the operation and maintenance (O&M) phase. Therefore the aims of this paper are: i) to map the stakeholder groups involved in O&M of Offshore Wind Farm (OWF), ii) to assess the identified stakeholder group's interest and power to influence O&M, iii) to evaluate the relationship between different stakeholder groups and iv) to highlight potential strategies to manage the stakeholder groups. In this article, the stakeholder analysis approach is used. The results reveal that eleven key stakeholder groups are directly involved in the O&M phase. Among those, the stakeholder groups named Investor/owner, Turbine supplier, Operator's own technicians, Port facility and Vessel supplier are the most powerful stakeholders. In contrast, Onshore service providers and Component suppliers are considered less influential stakeholders. A friendly relationship exists between the governmental agency and the owner of OWFs. The operators consider themselves as competitors. The operator-subcontractor relationship is top-down. The relationship among the sub-contractors is complex because of the perception of losing business if they cooperate with their competitors. From the sustainability point of angel, achieving cooperative advantage is always preferable than competitive advantage. [ABSTRACT FROM AUTHOR]

Determining the optimum penetration of renewable energy systems and their associated aggregated technical and economic benefits is a growing concern for both researchers and policy makers. The purpose of this paper is to evaluate the cost-optimal pathways for a university campus in Illinois, USA to install solar PV systems by performing parametric analyses. Here we suggest cost-optimal solutions to deploy solar photovoltaic systems under two different finance scenarios: the Single Party economic model and the Two Party economic model. In addition, critical economic factors are highlighted by incorporating them into an energy performance model. This case study can be a replicable model for other academic institutions to actively implement renewable technologies and greatly support their decision-making processes. [ABSTRACT FROM AUTHOR]

The paper analyses the effect of renewable and non-renewable energy consumption as well as the regime type on economic growth in 30 Sub-Saharan African (SSA) countries over the period 1980–2012. Using heterogeneous panel cointegration and panel-based error correction tests, we find long-run relationship between the variables. However, short-run results are not robust, which suggest that energy sector investments are long-term in nature. Specifically, the results show that while both renewable and non-renewable energy have significant positive effect on economic growth, non-renewable energy has a greater growth enhancing effect than renewable energy. A 10% increase in renewable energy consumption is associated with an increase in economic growth by 0.27%, while a 10% increase in non-renewable energy consumption leads to an increase in growth by 2.11% ceteris paribus. Further, the findings of the study show that democratic states experience higher growth rates than autocratic states. [ABSTRACT FROM AUTHOR]

Economical design of Ground Heat Exchangers (GHEs) relies significantly on accurate estimations of ground thermal properties, including undisturbed ground temperature, ground thermal conductivity, and GHE thermal resistance. Typically these are measured in situ by a Thermal Response Test (TRT), where the parameters are back-calculated by fitting a heat transfer model to the temperature response. The accuracy of most models relies on an assumption of constant ground temperature with depth, but in reality there are several mechanisms by which this may be invalid, one being seasonal variation in ground temperature. In this paper a study of Infinite Line Source Model performance under different seasonal conditions using a Finite Element model is presented. The study aims to determine the robustness of interpretation of TRTs conducted at different times of the year and the sensitivity of the effect's key influencing variables. Results suggest that there is little variability in effective thermal conductivity but some variation in GHE thermal resistance. A dimensionless parameter was derived and found to be strongly linearly related to the difference in GHE thermal resistance, leading to generalized estimates of the potential impact on design length that were greater than 10% under relatively extreme conditions and for short GHEs. [ABSTRACT FROM AUTHOR]

In order to offer cost-effective options to supersede fossil fuel resources, we developed a research methodology based on techno-economic feasibility analysis. The purpose of this paper is to find off-grid renewable energy solutions, including solar panel, wind turbine and batteries as possible options for zero-emission stand-alone power generation in KhshU Site, a renewable energy laboratory in Iran. The HOMER software, which determines the most cost effective system for a given load by considering incident solar radiation, wind speed, electrical demand profile, and equipment characteristics, was employed. The results revealed that the most economical configuration among different renewable energy systems (RES's) was the PV-battery, which has a total net present cost (NPC) of 8173 US$ and a cost of energy (COE) of 0.546 $/kWh, followed by the hybrid PV/wind/battery. Sensitivity analysis demonstrated that raising discount rates could increase the cost of energy while net present cost of the entire system would be reduced in any inflation rate. The analysis also showed that the wind speed variation between 3 and 6 m/s didn't have a considerable effect on NPC and COE. [ABSTRACT FROM AUTHOR]

Researchers have shown growing interest in the development of traditional Savonius turbine due to their numerous benefits such as structural simplicity, self-start ability, relatively low operating speed, bi-directional rotational ability and lower environmental impact. However, Savonius turbines exhibits lower efficiency as compared to other similar marine current turbines. This paper proposes a novel design concept for the Savonius turbine. In addition, this work investigates flow and pressure distribution around the buckets of novel rotor with a two-dimensional unsteady numerical model. The proposed marine current turbine with novel design is named as Reza Turbine. Numerical model employed the Dynamic Mesh Method (DMM) for modelling mesh movement around the blades of rotor for different position with respect to computational domain. Developed numerical model solves the unsteady Reynolds averaged Navier-Stokes equations by using SIMPLE algorithm. In addition, we conducted an experiment in a low speed wind tunnel to obtain important performance parameters namely torque, power and performance for the proposed turbine. A set of flow speed were used as inlet boundary condition for both numerical and experimental model. A comparison between numerical and experimental results shows that the SST k-ω turbulence model gives satisfactory results for the developed novel turbine. The developed ReT is showed 52% improvement in efficiency as compared conventional Savonious turbine. Since the peak of power coefficient obtained was 0.321 for ReT, while 0.21 was reported for conventional Savonius turbine. [ABSTRACT FROM AUTHOR]

This paper is aimed at analysing the levelised cost of energy (LCOE) of onshore wind turbine generators (WTGs) that are in operation beyond their design lifetime. In order to do so, the LCOE approach is introduced and input parameters are discussed for a UK deployment. In addition, a methodology is presented to support economic lifetime extension and investment decision making at the end of an asset's design lifetime. As part of a case study, a wind farm consisting of six 900 kW WTGs is subjected to different combinations of i) lifetime extension (5–15 years), ii) input assumptions (pessimistic, central, optimistic), and iii) reinvestment types (retrofits). Results indicate that in the central lifetime extension scenario, LCOE estimates of 22.40 £/MWh are achievable. [ABSTRACT FROM AUTHOR]