Renewal Type Research Articles

Renewal type bootstrap for increasing degree U-process of a Markov chain

In this paper, we investigate the uniform limit theory for a U-statistic of increasing degree, also called an infinite-degree U-statistic. Infinite-degree U-statistics (IDUS) (or infinite-order U-statistics (IOUS)) are useful tool for constructing simultaneous prediction intervals that quantify the uncertainty of several methods such as subbagging and random forests. The stochastic process based on collections of U-statistics is referred to as a U-process, and if the U-statistic is of infinite-degree, we have an infinite-degree U-process. Heilig and Nolan (2001) provided conditions for the pointwise asymptotic theory for the infinite-degree U-processes. The main purpose here is to extend their findings to the Markovian setting. The second aim is to provide the uniform limit theory for the renewal bootstrap for the infinite-degree U-process, which is of its own interest. The main ingredients are the decoupling technique combined with symmetrization techniques of Heilig and Nolan (2001) to obtain uniform weak law of large numbers and functional central limit theorem for the infinite-degree U-process. The results obtained in this paper are, to our knowledge, the first known results on the infinite-degree U-process in the Markovian setting.

전수조사를 통한 초·중·고 학교시설의 신재생에너지 적용 현황 및 에너지소비구조 분석

The purpose of this study is to analyze energy consumption structures in elementary, middle, and high schools where energy consumption occurs on a quantitative scale. Another purpose of this study is to derive application of a renewable energy system by regional group and system type. By analyzing the installation ratio of renewable energy system by remodeling educational facilities, whether an appropriate and effective system was applied and operated in old schools was investigated. The analysis of the application of renewable energy system was carried out as a complete enumeration survey targeting a total of 11,819 schools nationwide. The ratio of installed schools in 17 regions and installation items by renewable energy system type (n = 5) were analyzed. The difference in the ratio of renewable energy installation between public schools and private schools was about 20%, which could further lead to an imbalance in educational conditions. In the case of energy independence of educational facilities, it is meaningful to increase the installation rate of new and renewable energy. It is also necessary to develop and operate an energy saving program that combines educational elements that students can voluntarily participate in.

Economic policy uncertainty and renewable energy innovation: International evidence

This research investigates the impact of economic policy uncertainty on renewable energy innovation, based on a panel of 22 countries during the period 1985–2019. The results indicate that economic policy uncertainty exerts a positive effect on renewable energy innovation that lasts for at least 3 years. Subsample analysis shows that OECD members and right-wing countries experience higher growth in renewable energy innovation compared to non-OECD members and left-wing countries. In addition, economic policy uncertainty improves renewable energy innovation only for high institutional quality countries, while the effect becomes insignificant for low institutional quality countries. After separating different renewable energy types, this paper presents that wind energy witnesses a largest incline in renewable energy innovation compared to other renewable energy types. This research provides international evidence for the relationship between economic policy uncertainty and renewable energy innovation.

Physiochemical Properties of Poly-vinyl alcohol-modified Fly- Bottom Ash Mixture for Engineering Utilization

Despite the current advancements in, and increasing use of renewable types of energy, approximately 40% of the world’s electricity is still produced by coal fired power stations. This trend is significantly higher in some continents, for example approximately 70% in India and up to 90% in South Africa. In this study the fly-bottom ash (FBA) mixture with different component percentages of BA (bottom ash)100, FA (fly ash) 25-BA75, FA50-BA50, FA75-BA25 and FA100 were modified with 2% of poly-vinyl alcohol (PVA), and tested in terms of particle size distribution, specific gravity, pH, surface morphology, mineralogical-compound content, and engineering properties. The physiochemical modified FBA were examined via scanning electron microscope (SEM), X-ray fluorescence, and Fourier transform infrared spectroscopy (FTIR) analysis. Polymeric-modified FBA for all compositions exhibited high pH values within the range of 10.11–10.70. SEM image exhibited agglomerated and strongly bonded PVA-modified FBA with FA50-BA50 composition because of the effect of polymer that reacted with the fine ashes. The unsubstantial shift in peak position of Si/Al-O stretches showed electrostatic interaction between PVA and FBA based on FTIR analysis. The PVA-modified FBA at composition of FA50-BA50 increased the gradient of stress–strain curves, which significantly improved the strength behavior of PVA-modified FBA sample. It is thus imperative that other sustainable methods of managing coal combustion-by products be expanded .

Sustainable Renewal of Historical Urban Areas: A Demand–Potential–Constraint Model for Identifying the Renewal Type of Residential Buildings

The assessment of buildings facilitates the exploration of the viability of progressive and organic renewal, prevents the aimless and unorganized demolition of residential buildings in previous urban renewal projects, and facilitates the balancing of the preservation and sustainable development of historical urban areas. Studies have rarely examined the effect of regional factors on building renewal or differentiated the effects of historic preservation and development conditions. The fundamental function of historical urban areas in China is to provide residence. Therefore, this study developed a framework to identify the renewal type of residential buildings. The developed framework was used to construct a demand–potential–constraint model with assessment indicators related to three dimensions, namely renewal demand, development potential, and preservation constraint. Moreover, discriminant matrices were employed to divide the renewal of residential buildings into four modes and subdivide it into six types. The historical urban area of Suzhou was selected as the study site. According to the results of renewal type identification, renewal schedules and models with high referential value can be developed by urban renewal planners, which facilitates the optimization of resource allocation. The developed framework provides novel theoretical and practical insights regarding building renewal assessment in historical urban areas.

Towards just transition of coal regions - Cultivation of short rotation copies and dedicated energy crops for biomass co-firing vs photo voltaic power plants

• Abandoned coal mine areas to continue sustainable use now in the green energy business. • Options proposed include forming biomass plantations vs construction of solar power plants. • Sustainability criteria such as economic, environmental and social aspect need to be considered. • Decision can be made using both aggregated economic analysis and multi criteria sustainability assessment. In developing countries, which dominantly produce electricity by burning coal, energy transition represents a significant challenge. Short rotation coppice and dedicated energy crops could be a promising raw material for production of biofuel and its further usage for electricity and heat generation. This work assesses possibilities and elaborates on the sustainability of cultivation of short rotation coppice type willow and dedicated energy crop Miscanthus on former areas of coalmines belonging to the largest power utility in Bosnia and Herzegovina, namely JP Elektroprivreda BiH d.d. – Sarajevo. Abandoned coal mine areas were mapped and, by settled criteria, dedicated either to future photovoltaic power plants integration or the cultivation of energy crops and their further use in the considered generation portfolio mix. In order to assess the contribution of both photovoltaic power plants and biomass in the upcoming energy transition process, an adequate method has been developed in this article and specific sustainability indicator groups determined to further calculate the sustainability ratio. The paper focuses on economic, environmental and social indicator groups, which were used to perform the aggregated economic analysis and the multi criteria analysis. Performed aggregated economic analysis lightly favours the construction of photovoltaic power plants over the use of willow as fuel. In this analysis, Mischantus is lagging far behind due to its lower yield compared to willow. The multi criteria analysis on the other hand, valorises the social indicator adequately and the sustainability ratio results are much closer for both considered renewable sources types. This shows the importance of a comprehensive approach and definition of appropriate methods to enable decision-makers to draw appropriate conclusions.

Stochastic Modeling of Renewable Energy Sources for Capacity Credit Evaluation

In power system planning, the growth of renewable energy generation leads to several challenges including system reliability due to its intermittency and uncertainty. To quantify the relatively reliable capacity of this generation, capacity credit is usually adopted for long-term power system planning. This paper proposes an evaluation of the capacity credit of renewable energy generation using stochastic models for resource availability. Six renewable energy generation types including wind, solar PV, small hydro, biomass, biogas, and waste were considered. The proposed models are based on the stochastic process using the Wiener process and other probability distribution functions to explain the randomness of the intermittency. Moreover, for solar PV—the generation of which depends on two key random variables, namely irradiance and temperature—a copula function is used to model their joint probabilistic behavior. These proposed models are used to simulate power outputs of renewable energy generations and then determine the capacity credit which is defined as the capacity of conventional generation that can maintain a similar level of system reliability. The proposed method is tested with Thailand’s power system and the results show that the capacity credit depends on the time of day and the size of installed capacity of the considered renewable energy generation.

The effect of aluminum fins and air blowing on the electrical efficiency of photovoltaic panels; environmental evaluation

For a long time, electricity is supplied by means of firing the fossil fuels in thermal power plants. Now, it is well-known that the activity has many environmental and health issues, which are sharply menace the future of earth and humanity. Photovoltaic (PV) system is one of the popular renewable types of energy generation, which is available in most parts of the earth. Unfortunately, temperature rise in a PV module, leads to a significant reduction in its electrical efficiency. In this paper, two methods of wind blowing and mounting fins are considered separately and simultaneously, to overcome the mentioned weak-point. The wind velocity is set to 2 km/h. So, four cases are assessed, experimentally. As results, it was revealed that wind blowing of 2 km/h is more effective than fins in cooling PV module, so that, it can create more than 15 °C lower temperature than mounting fins. The mentioned temperature reduction leads to enhance the electrical efficiency and output power by 2.4% and 21.7%, respectively. In order to show the accuracy of results, all experimental outcomes in electrical efficiency were compared with the analytical formula. Moreover, the environmental evaluation of commissioning a 10 kW PV power plant with the proposed cases are reported, too.

Preventive Renewal Model with Diverse Maintenance Activities

Abstract The paper presents a developed computational model based on decision- random models, which allows us to develop a strategy for preventive renewal of complex technical objects whose maintenance activities cover various actions. Depending on the renewal type, diversification of the cost and maintenance time may influence the interval at which preventive renewal should be performed. The developed algorithm takes into account the predicted time of proper operation based on the probability distribution of operating time to failure, as well as the cost of each preventive action and potential failure. The defined strategy is a set of activities that must be performed every specified time interval in a manner that is economically justified and minimizes the risk of failure. The technical object on which the model is discussed is the wheel tyre of a rail vehicle.

Distribution of Non-Uniform Complex of Resources in Production Systems

The problem of planning a job complex with the use of resources of various types - renewable (performers who can differ with the productivity) and several types of non-renewable is considered. We allow interruptions, and switching from one performer to another and performing one work simultaneously by several performers. The available number of performers at different times is not constant, and their productivity may vary. A developed algorithm finds the optimal allocation of resources and builds the optimal schedule of jobs. The algorithm based on building a flow network model and modifying the packing procedure.

A New Integrated Approach for Determination of Turkey’s Solar Energy Production Strategies: The Fuzzy Expanded SWOT

Because of Turkey's high solar energy potential due to its geographical location and certain advantages of the solar energy, the solar energy is one of the most important among renewable energy types which are invested in the country. Therefore, it aimed to determine of the strategies related to Turkey's solar energy production in this study. For this, a new integrated method called the Fuzzy Expanded SWOT, consisting of the Fuzzy AHP and the Expanded SWOT methods, has been proposed. The proposed method eliminates many disadvantages of the traditional SWOT analysis. First of all, factors and sub-factors related to the solar energy were determined by the Expanded SWOT analysis. Subsequently, the local weights of the factors and sub-factors were determined by the Fuzzy AHP method. The sub-factors which are insignificant according to the weights found, were eliminated and the global weights of the remaining sub-factors were found. Finally, sub-factors were prioritized according to their global weights and strategies were determined based on the Expanded SWOT matrix, taking these priorities into consideration. As a result of the analyzes, it was observed that the strategies which should be dwelled on related to solar energy production in the Turkey, are ones which concentrate on R&D studies in public institutions, private sector and universities.

The Effects of Photovoltaic Panel’s Temperature towards Photovoltaic Electrical Power Output

Photovoltaic (PV) system is recognized as one of the most current renewable energy types in producing electrical power. The theories that science explain related to the function of the sun is in accordance with what is also described in the Qur'an. There is one ayah Quran related to the Greatness of Allah and The Mercy which is “And from among His Signs are the night and the day, and the sun and the moon. Prostrate yourselves to Allah Who created them, if you (really) worship Him [Fussilat:37]. However, one of the main issues of PV system is that the performance of the system is highly dependent to environmental conditions such as weather and solar irradiance. Increases in temperature reduce the band gap of a semiconductor. The decrease in the band gap of a semiconductor with increasing temperature can be viewed as increasing the energy of the electrons in the material. The parameter most affected by an increase in temperature is the open circuit voltage. Temperature coefficient indicates how much will be the decrement in power output if PV module. Hence, it is important to predict the actual generating output power of PV systems. This study investigates the relationship between the temperatures of the PV panel with the PV power output. The PV systems installed at the rooftop of Mega label SDN. BHD. with type of poly-crystalline 405.72KWP has been chosen as the reference system in this study. The results have shown that the rise of PV panel’s temperature will make the value of the PV electrical power output decreases.

Limit theorems for prices of options written on semi-Markov processes

We consider plain vanilla European options written on an underlying asset that follows a continuous time semi-Markov multiplicative process. We derive a formula and a renewal type equation for the martingale option price. In the case in which intertrade times follow the Mittag-Leffler distribution, under appropriate scaling, we prove that these option prices converge to the price of an option written on geometric Brownian motion time-changed with the inverse stable subordinator. For geometric Brownian motion time changed with an inverse subordinator, in the more general case when the subordinator’s Laplace exponent is a special Bernstein function, we derive a time-fractional generalization of the equation of Black and Scholes.

Hosting Capacity Assessment in Distribution Networks Considering Wind–Photovoltaic–Load Temporal Characteristics

Under the background of clean and low-carbon energy transformation, renewable distributed generation is connected to the distribution system on a large scale. This study proposes a probabilistic assessment method of hosting capacity considering wind–photovoltaic–load temporal characteristics in distribution networks. First, based on time series of wind, photovoltaic, and load demands, a discretization–aggregation technique is introduced to generate and filter extreme combinations. The method can effectively reduce the scenarios that need to be evaluated. Then a holomorphic embedding method considering generation and load scaling directions is proposed. The holomorphic function of voltage about an embedding variable is established, and it is analytically expanded in the form of series. The hosting capacity restrained by the voltage violation problem is calculated quickly and accurately. Finally, the proposed stochastic framework is implemented to evaluate hosting capacity involving renewable energy types, penetration levels, and locations. The hosting capacity of single energy and hybrid wind–solar renewable energy systems is evaluated from the perspective of probability analysis. The results verify the outstanding performance of the hybrid wind–solar energy system in improving the hosting capacity.

Energy transition and willingness to pay for renewable energy: The case of environmental students

Examining willingness-to-pay (WTP) for renewable energy sources (RES) as well as views on energy topics can enable policymakers to design effective measures for facilitating the transition from fossil fuels to a renewable-based energy system. The aim of this study was to investigate environmental students’ willingness-to-pay for renewables and their views on various energy topics. Results showed that respondents preferred renewable-based electricity production to conventional energy production while solar energy emerged as the most preferred renewable type. In addition, most respondents were willing to pay for renewable energy but would pay relatively low sums of money per month. Moreover, respondents were divided over whether new lignite plants should be constructed in Greece. Finally, social media and special websites were the most favored media of daily information.

Role of banking sector performance in renewable energy consumption

To secure future universal access to modern energy, large investments in renewable energy technology are required. This paper estimates the impact of five banking sector performance indicators (return on asset, market capitalisation, asset quality, managerial efficiency and financial stability) on renewable energy consumption for a global panel consisting of 124 countries. The study used two-step system-GMM panel model to handle potential endogeneity and serial correlation. The paper considers three homogenous subpanels which are constructed based on the income group classification (high-, middle-, and low-income countries). Generally, our results show that improved banking sector performance enhances renewable energy consumption, with heterogenous effect across income group classification. For high -income (HI) countries, an increase in bank size together with improved asset quality and managerial efficiency have positive effects on renewable energy consumption. For middle-income (MI) and low-income (LI) countries, a high return on asset, an increase in bank size and financial stability are positive determinants of renewable energy consumption. We also find heterogenous effect of banking performance indicators across various renewable energy consumption types. The results highlight the importance of a well-functioning bank sector to achieve the investment in renewable energy needed to meet future energy demand and simultaneous decrease CO2 emissions.

Prediction of the Energy Self-Sufficiency Rate of Major New Renewable Energy Types Based on Zero-Energy Building Certification Cases in South Korea

There is an increasing interest in new renewable energy sources for achieving net zero emissions. Consequently, the construction industry has mandated zero-energy building certification (ZEB), through the usage of new renewable energy. However, because of the variations in the energy self-sufficiency rate (ESR) among the new renewable energy types, incorrect ESR prediction at the design stage may lead to problems. Hence, in this study, the ESR and construction cost are analyzed for each new renewable energy capacity to predict the ESR of photovoltaic (PV), building integrated photovoltaic (BIPV), geothermal, and fuel cell systems. Passive and active technology elements of the ZEB cases in Korea are analyzed, and by establishing a standard model with the average value of each case, the ESR is calculated for each new renewable energy capacity, and the calculation formulas are derived. The results indicate that for the PV and BIPV systems, the rate of ESR increases with the capacity (kWp) and is constant at 0.54% and 0.34%, respectively. However, for the geothermal system and fuel cells, the average ESR is 0.016% and 1.46%, respectively, but as the rate of ESR increase with the capacity (kW) gradually decreases, the calculation formulas are derived with a log graph.

GIS-based site suitability analysis and ecosystem services approach for supporting renewable energy development in south-central Chile

Renewable energy systems have a relevant land footprint, and their development can lead to land-use conflicts and trade-offs between energy supply and ecosystem services. Accordingly, this work identified the more suitable renewable energy development areas and discussed the potential trade-offs between energy supply and priority ecosystem services, combining the Geographic Information System-based suitability analysis and ecosystem service approach. The expert consultations were carried out to assess and identify the supply capacities of priority ecosystem services in South-Central Chile. The suitability maps for four renewable energy types were generated and spatially overlapped with priority ecosystem service maps to assess the trade-offs resulting from energy development. The results showed that suitable sites for solar, wind and biomass energy showed limited capacities to supply relevant provisioning and regulatory services and medium-to-low capacity to deliver cultural services. More than half of potential hydropower stations can be located on zones with a medium capacity to supply provisioning services and a high capacity for regulation and maintenance and cultural services. In most cases, sitting energy plants on areas of cultural relevance and other adverse impacts may cause social rejection toward their installation. This work provides valuable spatial information to support land-renewable energy planning, minimizing the environmental and social conflicts on ecosystem services.

Potential of Renewable Energy in Africa: Review of Various Sources of Renewable Energy and Promising Enterprises Working in this Sector

This paper breaks down the renewable energy space in Africa. It researches the types of different renewables, providing a balanced evaluation of every single one. Specifically, it looks at certain companies with potential for massive growth in their respective sectors and regions. Not only this, but it also investigates challenges those companies have faced while converting Africa into a sustainable place. All in all, the use of PEST analysis and quantitative information frames discussions in a simple manner.

Experimental Analysis of Bi-Directional Heat Trading Operation Integrated with Heat Prosumers in Thermal Networks

District cooling and heating methods that can utilize highly efficient heat pumps and various unused new and renewable types of energy are required to achieve low carbon emissions and zero energy usage in buildings and community units. The technical requirements for the implementation of decentralized thermal networks and heat trading are increasing, both for thermal networks in new buildings and for those remodeled based on existing centralized thermal networks. In this study, a conventional centralized thermal network was implemented as a decentralized thermal network and the possibility of heat prosumers feeding thermal networks was demonstrated experimentally. A real-scale plant was constructed by employing unused thermal energy facilities as prosumers in a school and childcare center based on the existing small-scale block heating and cooling thermal network. The decentralized thermal network and heat prosumer concepts were proven through operation experiments performed on the constructed system in summer and winter. An economic benefit can be achieved by increasing the peak power cost. The experimental results also showed that the proposed bi-directional heat trading reduced carbon emissions by 12.7% compared with conventional centralized thermal systems.