Comparisons and critical assessment of global and diffuse solar irradiation estimation methodologies

Defining better methodologies of accurate predictions of the amount of monthly mean daily global and diffuse solar irradiation exposed is of utmost importance in order to determine the potential for utilizing the solar energy. This study compares and discusses the main methodologies, databases, and software that are used in estimating the solar irradiation to be used for the short- and long-term performances and feasibilities of solar energy systems, especially photovoltaic power plants in Turkey, and addresses the best one to be used to make the most accurate estimations. The comparisons are carried out between the recent methodologies developed by the authors, some models taken from the related literature that are concluded to be better, a widely used database, namely Meteonorm, and a widely used software, namely EU PVGIS. The reference data to develop the methodologies and to make comparison are provided from the State Meteorological Service of Turkey, which is the responsible body in Turkey to make measurements of solar irradiation. The comparisons are based on monthly mean daily values of global and diffuse solar irradiation and are carried out by statistical errors: mean bias error and root mean square error. The results showed that the methodology developed by the authors has shown better performances in estimating the monthly mean daily global and diffuse solar irradiation amount for Turkey.     

Comparative study on performances of a heat-pipe PV/T system and a heat-pipe solar water heating system

The heat-pipe solar water heating (HP-SWH) system and the heat-pipe photovoltaic/thermal (HP-PV/T) system are two practical solar systems, both of which use heat pipes to transfer heat. By selecting appropriate working fluid of the heat-pipes, these systems can be used in the cold region without being frozen. However, performances of these two solar systems are different because the HP-PV/T system can simultaneously provide electricity and heat, whereas the HP-SWH system provides heat only. In order to understand these two systems, this work presents a mathematical model for each system to study their one-day and annual performances. One-day simulation results showed that the HP-SWH system obtained more thermal energy and total energy than the HP-PV/T system while the HP-PV/T system achieved higher exergy efficiency than the HP-SWH system. Annual simulation results indicated that the HP-SWH system can heat the water to the available temperature (45°C) solely by solar energy for more than 121 days per year in typical climate regions of China, Hong Kong, Lhasa, and Beijing, while the HP-PV/T system can only work for not more than 102 days. The HP-PV/T system, however, can provide an additional electricity output of 73.019 kWh/m², 129.472 kWh/m², and 90.309 kWh/m² per unit collector area in the three regions, respectively.     

A preliminary process design and economic assessment of a catalyst rejuvenation process for waste disposal of refinery spent catalysts

Spent hydroprocessing catalysts from refineries have been classified as hazardous solid waste by the United States Environmental Protection Agency (USEPA), refiners must find a viable but economical solution to solve this serious environmental issue. Catalyst rejuvenation is an attractive option for minimizing the environmental problems associated with spent catalysts. In this study, a preliminary design for such a process and the corresponding economic analysis are performed to assess the proposed catalyst rejuvenation process for metal-fouled spent catalysts generated in residue hydroprocessing units. The scenarios used in the economic assessment are based on three options of process synthesis and two operator modes. It is found that the option of rejuvenating medium and lightly fouled spent catalyst produced by the refinery will be the best solution for refiners, both environmentally and economically.     

The global solar radiation estimation and analysis of solar energy: Case study for Osmaniye,Turkey

This paper investigates the prediction of solar radiation model and actual solar energy in Osmaniye, Turkey. Four models were used to estimate using the parameters of sunshine duration and average temperature. In order to obtain the statistical performance analysis of models, the coefficient of determination (R²), mean absolute percentage error (MAPE), mean absolute bias error (MABE), and root mean square error (RMSE) were used. Results obtained from the linear regression using the parameters of sunshine duration and average temperature showed a good prediction of the monthly average daily global solar radiation on a horizontal surface. In order to obtain solar energy, daily and monthly average solar radiation values were calculated from the five minute average recorded values by using meteorological measuring device. As a result of this measurement, the highest monthly and yearly mean solar radiation values were 698 (April in 2013) and 549 (2014 year) W/m² respectively. On an annual scale the maximum global solar radiation changes from 26.38 MJ/m²/day by June to 19.19 MJ/m²/day by September in 2013. Minimum global solar radiation changes from 14.05 MJ/m²/day by October to 7.20 MJ/m²/day by January in 2013. Yearly average energy potential during the measurement period was 16.53 MJ/m²/day (in 2013). The results show that Osmaniye has a considerable solar energy potential to produce electricity.     

Comparative study of photovoltaic technologies based on performance,cost and space requirement: Strategy for selection and application

The module performance is an important consideration for selecting PV technologies for electricity production, as well as the economic aspect. Also, PV energy yield under varying environmental conditions is largely dependent on the type of technology used. Therefore, this article presents a comparative analysis of different PV modules, of the same power, namely, monocrystalline, polycrystalline, amorphous silicon and hybrid, based on performance, cost and space requirement. The performance is evaluated in terms of module power output, yield, capture losses, fill factor and efficiency, according to the IEC 61724 standards, using Gwako, Nigeria as a case study. A novel technique called Fundamental PV Module Performance Analysis is used to analyze and compare the performance of the PV modules. The performance of a single module is then employed to calculate the overall performance of a PV array designed for a small off-grid house, and a suitable module is determined amongst the modules under study. Results provide insights into the behaviors of the different technologies with the environmental factors of the location, which have an impact on their power and kWh/kW outputs and the efficiency. This knowledge, coupled with the understanding of the constraints of cost and the module space requirements would be useful to researchers, engineers, installers etc. in Nigeria, for planning and developing photovoltaic electric systems for off-grid applications.     

Comparative performance assessment of mono crystalline,multi crystalline,and amorphous silicon grid-connected photovoltaic systems under actual climatic conditions of Agadir,Morocco

This paper analyses actual performance of three grid-connected photovoltaic systems based on different silicon technologies, installed at the faculty of sciences of Agadir. The outdoor facilities consist of 2.04 kW_p of mono crystalline (m-Si), 1.86 kW_p of amorphous (μcSi/a-Si:H), and 2.04 kW_p of multi crystalline (mc-Si) silicon PV systems. Datasets were collected during one entire year under real measured irradiation and ambient temperature conditions. The performance of these roof mounted PV systems was conducted on daily and monthly bases. Parameters like annual specific yield, system efficiency, and performance ratio were evaluated and found to be 1827 kWh/kW_p.year, 20.9% and 80.2% for amorphous, 1863 kWh/kW_p.year, 21.3% and 80.7%, for mono crystalline and 1895 kWh/kW_p.year, 21.7% and 82.2% for multi crystalline.     

Influence of DC electric and magnetic fields on silicon solar cells/modules

ABSTRACT

In this study, the impact of DC electric and magnetic fields on the output power, open-circuit voltage, and photocurrent density of a silicon photovoltaic (PV) cell/module is assessed. In this regard, the influence of DC electric and magnetic fields is first evaluated in theory by formulating and discussing related basis and concepts. Then, experimental measurements and data obtained from two different sets of experiments are given that verify theoretical results. In theory and practice, it is shown that depending on the direction of a DC electric field applied to a silicon PV cell/module, it causes an increase or reduction in the output power and open-circuit voltage of the PV cell/module. In detail, when the DC electric field points in the direction of the junction electric field of the PV cell(s), the output power and open-circuit voltage of the silicon PV cell/module increase, otherwise the output power and open-circuit voltage decrease. Regarding the magnetic field, it is proved that depending on the direction of a DC magnetic field applied to a silicon PV cell/module, different effects are observed. In detail, when the DC magnetic field points along the junction electric field of the PV cell(s), it has no effect on the output power and open-circuit voltage of the silicon PV cell/module. But, the output power and open-circuit voltage of the silicon PV cell/module decrease when the DC magnetic field points in the other directions. Moreover, the reduction in the output power and open-circuit voltage reaches its peak when the DC magnetic field is applied in the direction perpendicular to the junction electric field.     

Performance investigation of a new solar desalination unit based on sequential flat plate and parabolic dish collector

A new system composed of a sequential flat plate and parabolic dish solar collector was applied to enhance the solar desalination productivity. Heated saline water was desalinated using the evaporation/condensation principle and an effort was made to achieve higher distillate production compared to previous studies. Desalination efficiency values were calculated between 23% and 57%. Maximum desalinated water productions were obtained as 1,038 mL/m².h in autumn and 1,402 mL/m².h in summer. The cost of solar desalination system was found as economically feasible with 3 years’ payback period and the produced water cost of 0.014 $/L. Physicochemical analyses revealed that as a result of the desalination process, salinity level decreased from 35.6‰ to 0.0–0.1‰, chloride concentration decreased from 21,407 mg/L to 10 mg/L, and electrical conductivity decreased from 53.1 mS/cm to 0.11 mS/cm.     

Sizing and performance analysis of standalone hybrid photovoltaic/battery/hydrogen storage technology power generation systems based on the energy hub concept

In this study, the optimal sizing and performance analysis of a standalone integrated solar power system equipped with different storage scenarios to supply the power demand of a household is presented. One of the main purposes when applying solar energy resource is to face the increasing environmental pollutions resulting from fossil fuel based electricity sector. To this end, and to compare and examine two energy storage technologies (battery and hydrogen storage technology), three storage scenarios including battery only, hydrogen storage technology only and hybrid storage options are evaluated. An optimization framework based on Energy Hub concept is used to determine the optimum sizes of equipment for the lowest net present cost (NPC) while maintaining the system reliability. It was determined that the most cost effective and reliable case is the system with hybrid storage technology. Also, the effects of solar radiation intensity, the abatement potential of CO₂ emissions and converting excess power to hydrogen on the system’s performance and economics, were investigated and a few noticeable findings were obtained.     

Modelling future copper ore grade decline based on a detailed assessment of copper resources and mining

The concept of “peak oil” has been explored and debated extensively within the literature. However there has been comparatively little research examining the concept of “peak minerals”, particularly in-depth analyses for individual metals. This paper presents scenarios for mined copper production based upon a detailed assessment of global copper resources and historic mine production. Scenarios for production from major copper deposit types and from individual countries or regions were developed using the Geologic Resources Supply-Demand Model (GeRS-DeMo). These scenarios were extended using cumulative grade-tonnage data, derived from our resource database, to produce estimates of potential rates of copper ore grade decline.The scenarios indicate that there are sufficient identified copper resources to grow mined copper production for at least the next twenty years. The future rate of ore grade decline may be less than has historically been the case, as mined grades are approaching the average resource grade and there is still significant copper endowment in high grade ore bodies. Despite increasing demand for copper as the developing world experiences economic growth, the economic and environmental impacts associated with increased production rates and declining ore grades (particularly those relating to energy consumption, water consumption and greenhouse gas emissions) will present barriers to the continued expansion of the industry. For these reasons peak mined copper production may well be realised during this century.     

Toward sustainable use of natural resources: Nexus between resource rents,affluence, energy intensity and carbon emissions in developing and transition economies

Sustainable use of natural resources would entail ensuring that derived economic benefits today do not undermine the welfare of generations to come. On this basis, this study examines the nexus between natural resource rents and carbon dioxide (CO₂) emissions disaggregated into production and consumption-based (i.e., trade-adjusted) CO₂ emissions for a selected panel of 45 developing and transition economies over the period 1995–2017. The empirical model also incorporates the impacts of population, affluence, and energy intensity. The results show that affluence increases production-based CO₂ emissions by 1.407%, with the EKC's predicted inverted U-shaped curve only explaining consumption-based CO₂ emissions. Economic reliance on natural resource rents and energy intensification contribute 0.022% and 0.766%, respectively, to CO₂ emissions embedded in territorial production inventories and 0.035% and 0.583%, respectively, to CO₂ emissions embedded in consumption inventories. The bootstrap non-causality test shows that historical data on each variable has significant predictive power for future CO₂ emissions from both sources. The historical information about natural resource rents has significant predictive power over the future levels of affluence and energy intensity. Clearly, the results show that the environmental impact of natural resource rents is stronger when CO₂ emissions are adjusted for trade and varies among the countries, with Bangladesh, Guinea, India, Malaysia, Mexico, Nigeria, Pakistan, Saudi Arabia, Vietnam, and Zimbabwe among the most affected countries. Overall, this study provides motivation for policies to keep the use of natural resources within sustainable limits.     

浙江省废纸再生产业的经验、问题及对策

文章分析了浙江省在废纸再生方面的3个典型模式的经验，指出了存在的问题并提出了建议对策。     

An energetic life cycle assessment of C&D waste and container glass recycling in Cape Town,South Africa

This study presents the results of a comparative life cycle assessment (LCA) on the energy requirements and greenhouse gas (GHG) emission implications of recycling construction and demolition (C&D) rubble and container glass in Cape Town, South Africa. Cape Town is a medium sized city in a developing country with a growing population and a rising middle class, two factors that are resulting in increased generation of solid waste. The City is constrained in terms of landfill space and competing demands for municipal resources.The LCA assessment was based on locally gathered data, supplemented with ecoinvent life cycle inventory data modified to the local context. The results indicated that recycling container glass instead of landfilling can achieve an energy savings of 27% and a GHG emissions savings of 37%, with a net savings still being achieved even if collection practices are varied. The C&D waste results, however, showed net savings only for certain recycling strategies. Recycling C&D waste can avoid up to 90% of the energy and GHG emissions of landfilling when processed and reused onsite but, due to great dependence on haulage distances, a net reduction of energy use and GHG emissions could not be confidently discerned for offsite recycling. It was also found that recycling glass achieves significantly greater savings of energy and emissions than recycling an equivalent mass of C&D waste.The study demonstrated that LCA provides an important tool to inform decisions on supporting recycling activities where resources are limited. It also confirmed other researchers’ observations that strict adherence to the waste management hierarchy will not always result in the best environmental outcome, and that more nuanced analysis is required. The study found that the desirability of recycling from an energy and climate perspective cannot be predicted on the basis of whether such recycling conserves a non-renewable material. However, recycling that replaces a virgin product from an energy-intensive production process appears to be more robustly beneficial than recycling that replaces a product with little embodied energy. Particular caution is needed when applying the waste management hierarchy to the latter situations.     

An economic evaluation on the purification and storage of waste hydrogen for the use of fuel cell scooters

Safe and reliable metal hydride canisters (MHCs) for the use of hydrogen storage at low pressure can be applied to supply small fuel cell vehicles or scooters with hydrogen fuel. However, greater cost-effectiveness of hydrogen gas is obviously necessary to the successful promotion of hydrogen fuel cell scooters in the market. In this study, we use the net present value (NPV) method to evaluate the feasibility of an investment project on the supply of purified hydrogen in a pulp company at Hualien, Taiwan. The purified hydrogen can be separated from waste hydrogen by using pressure swing adsorption (PSA) technology and then be stored in MHCs. Under some assumptions of improved parameters about hydrogen production cost and hydrogen gas price, the discounted payback period of hydrogen purification and storage project in our study can be less than 10 years and the unit cost of hydrogen gas can be close to the price of gasoline. Moreover, the unit cost of hydrogen gas in our study can be lower than the cost from other sources of hydrogen.     

A review on the potential of citrus waste for D-Limonene,pectin, and bioethanol production

Citrus peel waste is a valuable lignocellulosic feedstock for bioethanol production due to its richness in fermentable sugars and low lignin content. Citrus peel contains two major value-added products: d-limonene and pectin. d-Limonene is widely used in food, cosmetics, and pharmaceutical industries. However, it acts as a microbial growth inhibitor for yeast during the fermentation process and hence it has to be removed prior to fermentation. Pectin is used as thickening agent, gelling agent, and stabilizer in the food industry. Since pectin increases the viscosity of the fermentation medium and makes fermentation troublesome, it has to be either extracted or degraded into galacturonic acid using pectinase enzyme. Thus, the removal and recovery of both D-limonene and pectin from citrus peel are essential for better fermentation. For bioethanol production, pretreatment plays a crucial role in the utilization of citrus peels since the reduction of d-limonene concentration to less than 0.05% is necessary. This review solely describes the potential of citrus waste for value added products such as d-limonene and pectin and the production of bioethanol from citrus peel waste is discussed in detail.     

Impact of utilizing reflector,single-axis and two-axis sun trackers on the performance of an evacuated tube solar collector

ABSTRACT

In this paper, a novel evacuated tube solar collector (ETSC) is first designed and built. Then, the impact of adding reflector, reflector plus single-axis sun tracker and reflector plus two-axis sun tracker to the built ETSC on the thermal efficiency of the ETSC is evaluated both theoretically and experimentally. In this regard, four identical versions of the proposed ETSC have been built and utilized in four collectors built and presented in this research work. The first collector is the same proposed built ETSC, the second collector is a parabolic trough solar collector comprising one built ETSC and a reflector (ETSC+R), the third collector is composed of one built ETSC, a reflector and a single-axis sun tracker all built in this study (ETSC+R+ ST), and the fourth collector consists of one built ETSC, a reflector and a two-axis sun tracker all built in this study (ETSC+R+ DT). Theoretical basis and concepts of the four collectors are formulated and analyzed in separate subsections. Theoretical results are outlined and highlighted at the end of each subsection. Experimental measurements and data obtained from the operation of the four collectors in the four seasons are presented that point by point verify theoretical results obtained in this study. To provide a comprehensive view, a techno-economic numerical comparison is performed between the four collectors. The following points, which are also the novelty and contributions of this work, are deduced from theoretical concepts, experimental data, and comparison provided in this study:

?There is no technical and economic justification for adding a reflector to an ETSC that results in forming a parabolic trough solar collector (ETSC+R) without any sun tracker.

?There is no economic justification for adding a single-axis sun tracker to a parabolic trough solar collector (ETSC+R).

?There is no economic justification for adding a two-axis sun tracker to a parabolic trough solar collector (ETSC+R).

?Comparing between a two-axis sun tracker and a single-axis sun tracker, adding the single-axis type to a parabolic trough solar collector (ETSC+R) is more advantageous.     

川渝地区页岩气钻井固废分类资源化处置利用略论

本文在简要分析川渝地区主要页岩气区域长宁、威远和涪陵页岩气钻井作业主要特点基础上,重点论述了页岩气钻井不同井段及不同钻井液体系钻井固废性质特点,针对页岩气钻井水基固废和油基钻屑两大类固废的资源化处置利用情况及存在的主要问题进行了论述,提出了川渝地区页岩气钻井应分井段或分不同钻井液体系固废进行收集并分类采用不同处置利用技术进行资源化处置利用,可达到更经济安全环保的利用效果。水基钻井固废就地生物处理资源化土壤利用是最优先择,第二选择是就地作为井场公路及井场场地路基建设利用,其次才是制成水泥块或免烧砖,最后才是转运制砖利用;油基钻屑的处置利用最关键的问题是争取脱油能按一般固废对待的国家或地方政策或规定争取,脱油后的油基钻屑最好的资源利用方式应是协同水泥窑焚烧处置,其次制成水泥块或作井场路基材料利用。同时针对性提出了页岩气钻井固废分类处理利用等方面的建议措施,对油气勘探钻井环保决策管理者和工作者具有一定参考价值和指导意义。