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Abstract The amount of installed solar power in Finland is increasing as a result of decreasing photovoltaic (PV) system component prices. The growth is especially noticeable in residential systems, and ways to make PV electricity a more competitive choice for Finnish residents are studied. One of these ways is to decrease the solar PV electricity production costs by decreasing the investment costs by undersizing the inverter of the PV system. The objective of undersizing is to find the optimal array-to-inverter sizing ratio (AISR) where the ratio of the economic loss from the clipped energy to the economic gain from the decreased system investment achieved by an undersized inverter is lowest. In this paper, the economically most optimal AISRs are determined for different residential array sizes, orientations, and inclinations when operating in Finnish locations and conditions. Calculations for each inverter size are carried out by using recorded Finnish meteorological data and the current Finnish PV system cost distribution, and by analyzing existing 1-s resolution production measurement data of a Finnish PV system. It is concluded that it is necessary to use 1-s resolution data as the use of 1-h resolution production data would lead to more significant undersizing caused by the power clipping occurring within an hour. The optimal AISRs presented in this study are higher than the optimal ratios reported in previous studies for locations further south than Finland. This can be explained by the northern location of Finland, where the irradiance above Standard Test Conditions (STC) is lower than in central Europe, for example. This allows more significant undersizing as less energy is clipped even at higher ratios. In the case of south-oriented arrays in a 30° installation angle, the optimal AISRs for the 10 kW, 6 kW, and 3 kW inverters were 1.6, 1.8, and 2.08, respectively. Again, the AISRs for the southwest-southeast facade installations were 1.8, 1.9, and 2.17 for the inverters under study. They do not clip the produced energy as much as rooftop systems because their production is more evenly distributed throughout the day, yet they do not achieve as low production costs either. It is pointed out that if the PV self-consumption is optimized by using PV to heat water or batteries as a storage, limitation of the PV generation might not be the correct solution.

The effect of the combined application of nano-hydroxyapatite (NHAP) or nano-carbon black (NCB) on the phytoextraction of Pb by ryegrass was investigated as an enhanced remediation technique for soils by field-scale experiment. After the addition of 0.2% NHAP or NCB to the soil, temporal variation of the uptake of Pb in aboveground parts and roots were observed. Ryegrass shoot concentrations of Pb were lower with nano-materials application than without nano-materials for the first month. However, the shoot concentrations of Pb were significantly increased with nano-materials application, in particular NHAP groups. The ryegrass root concentrations of Pb were lower with nano-materials application for the first month. These results indicated that nano-materials had significant effects on stabilization of lead, especially at the beginning of the experiment. Along with the experimental proceeding, phytotoxicity was alleviated after the incorporation of nano-materials. The ryegrass biomass was significantly higher with nano-materials application. Consequently, the Pb phytoextraction potential of ryegrass significantly increased with nano-materials application compared to the gounps without nano-materials application. The total removal rates of soil Pb were higher after combined application of NHAP than NCB. NHAP is more suitable than NCB for in-situ remediation of Pb-contaminated soils. The ryegrass translocation factor exhibited a marked increase with time. It was thought that the major role of NHP and NBA might be to alleviate the Pb phytotoxicity and increase biomass of plants.

Abstract Egg yolk-derived P and N dual doped nano carbon capsules (PNCCs) have been synthesized and used as lithium ion battery anodes. The application of egg yolk as the carbon source is a new and environmental-friendly approach for biomass recycling. The reversible capacity of half cells made of PNCCs is as high as ~770 mA h g−1 at a current density of 0.5 A g−1 with considerable rate capacity and cycling stability. PNCCs show a capsule-like structure, which provide extra edges and active sites for lithium intercalation. The heteroatom doping also introduce defects and disorder, which increases the electrochemical activity and creates more active sites for lithium insertion.

This study aims to introduce, conceptualize, and design a novel biomass/gasification-driven hybrid energy configuration. The proposed hybrid configuration has four subsystems: reformer solid oxide fuel cell (RSOFC), biomass/gasification, homogeneous charge compression ignition engine (HCCIE) plus waste heat recovery system (WHRS). RSOFC and HCCIE systems are embedded to generate electric energy. The syngas required for these two subsystems is captured from the biomass/gasification subsystem. In addition to generating electrical energy, fuel cell is responsible for providing combustible fuel to the HCCIE subsystem. The embedded engine in the system can improve the proposed configuration efficiency by increasing the rate of electrical energy production. In addition, the dissipated heat of fuel cell and engine subsystems is recovered by WHRS. The proposed energy configuration is evaluated and discussed from energetically, exergetically and exergoeconomic and environmental aspects to obtain a comprehensive feasibility study of the plant. The offered hybrid design has new component's structure and relationships that have not been reported in the publications. The analysis indicated that the proposed hybrid configuration is capable of generating approximately 1100 kW and 366.3 W of electric and thermal power, respectively, with the overall energetic and exergetic efficiencies of 69.4% and 52.1%. Exergoeconomic analysis results revealed that the specific fuel cost of the total proposed configuration was approximately 1.96 USD per GJ. In addition, compared to a coal and petroleum oil-based power generation plants, the proposed hybrid configuration can have approximately 2.75-fold and 97.7% lower CO2 emissions, sequentially. Besides, the proposed system can rival other similar biomass-driven designs.

Ni3Mo3C was prepared by a modified organic colloid method and explored as anode catalyst for high-performance microbial fuel cell (MFC) based on Klebsiella pneumoniae (K. pneumoniae). The prepared sample was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET). The activity of the sample as anode catalyst for MFC based on K. pneumoniae was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and polarization curve measurement. The results show that the adding of nickel in Mo2C increases the BET surface area of Mo2C and improves the electrocatalytic activity of Mo2C towards the oxidation of microbial fermentation products. The power density of MFC with 3 mg cm(-2) Ni3Mo3C anode is far higher than that of the MFC with carbon felt as anode without any catalyst, which is 19 % higher than that of Mo2C anode and produced 62 % as much as that of Pt anode, indicating that Ni3Mo3C is comparative to noble metal platinum as anode electrocatalyst for MFCs by increasing the loading.

Abstract Solar energy and wind power supply are renewable, decentralised and intermittent electrical power supply methods that require energy storage. Integrating this renewable energy supply to the electrical power grid may reduce the demand for centralised production, making renewable energy systems more easily available to remote regions. Control systems optimise solar energy and wind power sources to supply renewable energy to the power grid. Vehicle to Grid (V2G) operations support intermittent production as battery storage. In V2G operations, electric power flows from the power grid to the battery storage and from the battery storage back to the power grid. The primary goal of this study is to improve the existing renewable energy supply to provide more reliable units in the power grid. We consider the V2G concept as an extension of the smart charging system allowing electric vehicles to be able to inject battery energy into the power grid, acting as distributed generators or energy storage systems. This review shows how parallel V2G storage and battery storage supports the power grid. Further, the review indicates that decentralised V2G battery storages will be included in future renewable energy systems.

In this study, the effect of recycling the non-condensable gases (NCG) in the catalytic pyrolysis of hybrid poplar using FCC catalyst was investigated. A 50mm bench scale fluidized bed reactor at 475°C with a weight hourly space velocity (WHSV) of 2h(-1) and a gas recycling capability was used for the studies. Model fluidizing gas mixtures of CO/N(2), CO(2)/N(2), CO/CO(2)/N(2) and H(2)/N(2) were used to determine their independent effects. Recycling of the NCG in the process was found to potentially increase the liquid yield and decrease char/coke yield. The model fluidizing gases increased the liquid yield and the CO(2)/N(2) fluidizing gas had the lowest char/coke yield. The (13)C-NMR analysis showed that recycling of NCG increases the aromatic fractions and decreases the methoxy, carboxylic and sugar fractions. Recycling of NCG increased the higher heating value and the pH of the bio-oil as well as decreased the viscosity and density.

Abstract Global irradiance spectra vary with location, different viewing angles and times of day, depending on the fraction of direct and diffuse irradiance. Owing to big differences in spectral responses, PV module technologies might therefore show a differing behaviour with varying orientation and tilt angles. The purpose of this work is to verify the thesis, that thin film modules are – due to their spectral response – more suitable for horizontal orientation than crystalline. Diffuse irradiation (except from circumsolar radiation) can be captured best by a horizontal surface and consists to a greater fraction of short wavelengths than direct irradiation. At the same time thin film modules primarily absorb photons of short wavelengths and could therefore be better suited for horizontal application. Based on the semi-empirical spectral model Sedes2 and quantum efficiency data, a model has been developed to analyse differences in optimum orientation of several PV module technologies. In a first step, hourly global irradiance spectra are generated from a 1 year dataset of hourly climate data derived from long-term averages by the Meteonorm database for two sites in different climes. Based on this, average photocurrent densities are computed for each technology and for a matrix of different orientation and tilt angles using quantum efficiency data. Normalised to their maximum, the photocurrent densities are compared between the technologies. The results we obtained show, that for each site the maximum relative photocurrent densities are located at about the same orientation for all technologies, i.e. the optimum orientation is the same. At horizontal orientation, thin film modules show a slightly higher value of normalised average photocurrent densities than monocrystalline modules. Yet, for a whole year this advantage lies below 1% for both sites.

Extreme events, both natural and anthropogenic, increasingly affect cities in terms of economic losses and impacts on health and well-being. Most people now live in cities, and Asian cities, in particular, are experiencing growth on unprecedented scales. Meanwhile, the economic and health consequences of climate-related events are worsening, a trend projected to continue. Urbanization, climate change and other geophysical and social forces interact with urban systems in ways that give rise to complex and in many cases synergistic relationships. Such effects may be mediated by location, scale, density, or connectivity, and also involve feedbacks and cascading outcomes. In this context, traditional, siloed, reductionist approaches to understanding and dealing with extreme events are unlikely to be adequate. Systems approaches to mitigation, management and response for extreme events offer a more effective way forward. Well-managed urban systems can decrease risk and increase resilience in the face of such events.