A mixture of canola oil (Co), n-hexane (Hex), and ethyl alcohol (Et) was proposed as a new energy material for powering diesel engines. For this purpose, surface tension, density, and viscosity measurements, as well as engine tests, were performed for 88%Co10%Hex2%Et and 83%Co15%Hex2%Et mixtures at 20 °C. The adsorption and volumetric properties of these mixtures were compared to those of individual mixture components, as well as diesel fuel (Df) and oleic, linoleic, α-linolenic, palmitic, and stearic acids. It was revealed that the values of surface tension, viscosity, and density of Co were higher than those of the Co components. The addition of 10% Hex and 2% Et to Co caused a more than twofold decrease in its viscosity, while the addition of 15% Hex and 2% Et caused a more than fourfold reduction of Co viscosity. In addition, a mixture of Co with 2% Et and 10% Hex had a density similar to that of Df. In turn, theoretical calculations showed that the addition of n-hexane and ethanol... [more]

With sustainable energy being the key to reaching climate neutrality, the utilization of non-wooden biomass is a necessity. This article compares the emissions and efficiency of combusting a number of types of agrobiomass and wood pellets. A comparison was made on a moving grate pellet burner mounted in a boiler, where flue gas had a vertical flow via two pass heat exchangers with turbulization elements. Tests were conducted on wood pellets (ENPlus), miscanthus straw pellets, sunflower husk pellets, and corn stover pellets. During combustion, both wood and miscanthus pellets met the PN-EN 303-5:2012 emission and efficiency requirements. Corn stover pellets met the requirement on the nominal capacity. Sunflower husk pellets are characterized by excessive CO and particulate matter emissions. Sunflower husk pellets were the most problematic fuel from the point of view of the results of this research. During combustion of the miscanthus straw pellets there was a need to decrease the nomina... [more]

It remains unclear whether the decision to cook with both polluting and cleaner-burning fuels (‘fuel stacking’) serves as a transition phase towards the full adoption of clean-cooking practices, or whether stacking allows households to enhance fuel security and choose from a variety of cooking technologies and processes. This paper offers a unique contribution to the debate by positioning fuel stacking as the central research question in the exploration of existing household survey data. This research analyses the World Bank’s Multi-Tier Framework survey data concerning energy access and cooking practices in Cambodia, Myanmar, and Zambia. Its novel approach uses fuel expenditure data to group urban households according to the intensity of biomass consumption (wood, charcoal) relative to modern fuel consumption (electricity, gas). The research explores how different fuel-stacking contexts are associated with factors related to household finances, composition, experiences of electricity,... [more]

Solar energy has been extensively used in industry and everyday life. A more suitable solar collector orientation can increase its utilization. Many studies have explored the best orientation of the solar collector installation from the perspective of data analysis and local-area cases. Investigating the optimal tilt angle of a collector from the perspective of data analysis, or guiding the angle of solar collector installation, requires an a priori theoretical tilt angle as a support. However, none of the current theoretical studies have taken the real motion of the Sun into account. Furthermore, a complete set of theoretical optimal tilt angles for solar energy is necessary for worldwide locations. Therefore, from the view of astronomical mechanics, considering the true orbit of the Sun, a mathematical model that is universal across the globe is proposed: the Kepler motion model is constructed from the solar orbit and transformed into the local Earth coordinate system. After that, th... [more]

With global climate change and resource scarcity becoming increasingly serious issues, the green energy economy is transforming on a global scale. There are an increasing number of large-scale green energy development projects. However, these are often beset with risks; thus, this study conducted an analysis of the renewable energy risks in Taiwan using the analytical hierarchy process technique. Accordingly, a comprehensive study focusing into the current energy situation and potential development is needed. Renewable energy status and the availability by its main types, including, wind, solar, thermal, and biomass energies, were critically reviewed and discussed in this study. The findings of this study include the top 10 key operating risks recognized by specific green energy companies, as well as an assessment of which risks have been addressed and which have caused losses.

With a growing demand for safe, clean, and affordable energy, countries across the world are now seeking to create and rapidly develop renewable energy (RE) businesses. The success of these businesses often hinges on their ability to translate RE into sustainable value for energy consumers and the multiple stakeholders in the energy industry. Such value includes low production costs due to an abundance of natural resources (e.g., wind, water, sunlight), and public health benefits from reduced environmental pollution. Despite the potential for value creation, many RE businesses have struggled to create affordable energy as abundant as that which is produced by traditional fossil fuels. The rationale being that traditional RE sources emanating from natural resources tend to rely on unpredictable weather conditions. Therefore, to help RE businesses deliver sustainable value, we should leverage disruptive innovation that is less dependent on natural resources. This paper is one of the firs... [more]

Knowing the process of generating exhaust emissions and the determination of influential parameters are important factors in improving two-stroke slow-speed marine engines, particularly for further reductions in fuel consumption and stringent regulations on the limitation of nitrogen oxide emissions. In this article, a model of a marine low-speed two-stroke diesel engine has been developed. Experimental and numerical analyses of the nitrogen monoxide formations were carried out. When measuring the concentration of nitrogen oxides in the exhaust emissions, the amount of nitrogen dioxide (NO2) is usually measured, because nitrogen monoxide is very unstable, and due to the large amount of oxygen in the exhaust gases, it is rapidly converted into nitrogen dioxide and its amount is included in the total emission of nitrogen oxides. In this paper, the most significant parameters for the formation of nitrogen monoxide have been determined. Model validation was performed based on measured comb... [more]

Infrastructure systems, such as wind farms, are prone to various human-induced and natural disruptions such as extreme weather conditions. There is growing concern among decision makers about the ability of wind farms to withstand and regain their performance when facing disruptions, in terms of resilience-enhanced strategies. This paper proposes a probabilistic model to calculate the resilience of wind farms facing disruptive weather conditions. In this study, the resilience of wind farms is considered to be a function of their reliability, maintainability, supportability, and organizational resilience. The relationships between these resilience variables can be structured using Bayesian network models. The use of Bayesian networks allows for analyzing different resilience scenarios. Moreover, Bayesian networks can be used to quantify resilience, which is demonstrated in this paper with a case study of a wind farm in Arctic Norway. The results of the case study show that the wind farm... [more]

A synergetic sliding mode (SSM) approach is designed to address the drawbacks of the direct field-oriented control (DFOC) of the induction generators (IGs) integrated into variable speed dual-rotor wind power (DRWP) systems with the maximum power point tracking (MPPT) technique. Using SSM controllers in the DFOC strategy, the active power, electromagnetic torque, and reactive power ripples are reduced compared to traditional DFOC using proportional-integral (PI) controllers. This proposed strategy, associated with SSM controllers, produces efficient state estimation. The effectiveness of the designed DFOC strategy has been evaluated on variable speed DRWP systems with the MPPT technique.

The significant offshore wind energy potential of Oregon faces several challenges, including a power grid which was not developed for the purpose of transmitting energy from the ocean. The grid impacts of the energy resource are considered through the lenses of (i) resource complementarity with Variable Renewable Energy resources; (ii) correlations with load profiles from the four balancing authorities with territory in Oregon; and (iii) spatial value to regional and coastal grids as represented through a production cost model of the Western Interconnection. The capacity implications of the interactions between offshore wind and the historical east-to-west power flows of the region are discussed. The existing system is shown to accommodate more than two gigawatts of offshore wind interconnections with minimal curtailment. Through three gigawatts of interconnection, transmission flows indicate a reduction of coastal and statewide energy imports as well as minimal statewide energy export... [more]

Proton-exchange membrane fuel cells (PEMFCs) are the heart of promising hydrogen-fueled electric vehicles, and should lower their price and further improve durability. Therefore, it is necessary to enhance the performances of the proton-exchange membrane (PEM), which is a key component of a PEMFC. In this study, novel pore-filled proton-exchange membranes (PFPEMs) were developed, in which a partially fluorinated ionomer with high cross-linking density is combined with a porous polytetrafluoroethylene (PTFE) substrate. By using a thin and tough porous PTFE substrate film, it was possible to easily fabricate a composite membrane possessing sufficient physical strength and low mass transfer resistance. Therefore, it was expected that the manufacturing method would be simple and suitable for a continuous process, thereby significantly reducing the membrane price. In addition, by using a tri-functional cross-linker, the cross-linking density was increased. The oxidation stability was greatl... [more]

Sustaining economic growth while reducing dependence on fossil fuels remains a challenge for our world to fight against climate change and therefore finding a way to promote economic growth and increase renewable energy use is needed. This paper uses a 22-year panel dataset (1994−2015) of 9 countries in the Association of Southeast Asian Nations provided by the World Bank World Development Indicators to examine the impact of medium- and high-tech export on renewable energy use. We employ a fixed-effects regression model with the Driscoll−Kraay nonparametric covariance matrix estimator to account for sectoral and temporal dependence. We also control for inflation, employment, population growth, and gross domestic product per capita in our estimations. Our results demonstrate a U-shaped association between medium- and high-tech export and renewable energy consumption of these economies. The results propose that enhancing medium- and high-tech export could be a feasible solution for promo... [more]

This paper is a comparative study of the multiple RC, Oustaloup and Grünwald−Letnikov approaches for time domain implementations of fractional-order battery models. The comparisons are made in terms of accuracy, computational burden and suitability for the identification of impedance parameters from time-domain measurements. The study was performed in a simulation framework and focused on a set of ZARC elements, representing the middle frequency range of Li-ion batteries’ impedance. It was found that the multiple RC approach offers the best accuracy−complexity compromise, making it the most interesting approach for real-time battery simulation applications. As for applications requiring the identification of impedance parameters, the Oustaloup approach offers the best compromise between the goodness of the obtained frequency response and the accuracy−complexity requirements.

Electrolyte stability can be improved by incorporating complexing agents that bind key decomposition intermediates and slow down decomposition. We show that hexamethyl-phosphoramide (HMPA) extends both the thermal stability threshold of sodium hexafluorophosphate (NaPF6) in dimethoxyethane (DME) electrolyte and the cycle life of double-layer capacitors. HMPA forms a stable complex with PF5, an intermediate in PF6 anion thermal degradation. Unbound, this intermediate leads to autocatalytic degradation of the electrolyte solution. The results of electrochemical impedance spectroscopy (EIS) and galvanostatic cycling measurements show large changes in the cell without the presence of HMPA at higher temperatures (≥60 °C). Fourier transform infrared spectroscopy (FTIR) on the liquid and gas phase of the electrolyte shows without HMPA the formation of measurable amounts of PF5 and HF. The complimentary results of these measurements proved the usefulness of using Lewis bases such as HMPA to in... [more]

With the rapid development of integrated circuit technology, the heat flux of electronic chips has been sharply improved. Therefore, heat dissipation becomes the key technology for the safety and reliability of the electronic equipment. In addition, the electronic chips are distributed discretely and used periodically in most applications. Based these problems, the characteristics of the heat transfer performance of flow boiling in parallel channels with discrete heat source distribution are investigated by a VOF model. Meanwhile, the two-phase flow instability in parallel channels with discrete heat source distribution is analyzed based on a one-dimensional homogeneous model. The results indicate that the two-phase flow pattern in discrete heat source distribution is more complicated than that in continuous heat source distribution. It is necessary to optimize the relative position of the discrete heat sources, which will affect the heat transfer performance. In addition, compared wit... [more]

The urgent energy transition needs a better penetration of renewable energy in the world’s energy mix. The intermittency of renewables requires the use of longer-term storage. The present system uses water displacement, in a lined rock cavern or in an aerial pressurised vessel, as the virtual piston of compressor and expander functions in a carbon dioxide heat pump cycle (HPC) and in an organic transcritical cycle (OTC). Within an impermeable membrane, carbon dioxide is compressed and expanded by filling and emptying pumped-hydro water. Carbon dioxide exchanges heat with two atmospheric thermal storage pits. The hot fluid and ice pits are charged by the HPC when renewable energy becomes available and discharged by the OTC when electricity is needed. A numerical model was built to replicate the system’s losses and to calculate its round-trip efficiency (RTE). A subsequent parametric study highlights key parameters for sizing and optimisation. With an expected RTE of around 70%, this CO2... [more]

The health and safety of lithium-ion batteries are closely related to internal parameters. The rapid development of electric vehicles has boosted the demand for online battery diagnosis. As the most potential automotive battery diagnostic technology, AC impedance spectroscopy needs to face the problems of complex test environment and high system cost. Here, we propose a DC impedance spectroscopy (DCIS) method to achieve low-cost and high-precision diagnosis of automotive power batteries. According to the resistance−capacitance structure time constant, this method can detect the battery electrolyte resistance, the solid electrolyte interphase resistance and the charge transfer resistance by controlling the pulse time of the DC resistance measurement. Unlike AC impedance spectroscopy, DCIS does not rely on frequency domain impedance to obtain battery parameters. It is a time-domain impedance spectroscopy method that measures internal resistance through a time function. Through theoretica... [more]

High-performance optical power converters (OPCs) enable isolated electrical power and power beaming applications at new wavelengths and higher output powers. Broadcom’s vertical epitaxial heterostructure architecture (VEHSA) multi-junction OPCs permit optical-to-electrical conversion at high efficiency and at manageable external loads. This study provides details of how the power outputs have been extended from 20 W. The work also provides details of how the spectral range options have been extended from 800−830 nm to other key laser diode wavelengths such as 960−990 nm and 1500−1600 nm.

Due to the growing demand for electrical energy generation worldwide [...]

A membrane-based enthalpy exchanger is a device used for heat and humidity recovery in ventilated buildings. The energy-saving potential of such a device is dependent on the parameters responsible for heat and moisture recovery. The trend is toward composite membranes, which are custom produced, and their parameters can be adjusted for a given application; therefore, the diffusion and sorption characteristics of such membranes are unknown. In order to obtain the values of the water vapor diffusivity of three investigated handmade membranes, a serial resistance model using a Field and Laboratory Emission Cell (FLEC) is proposed. Experiments were conducted to identify the resistance in each step of the moisture transfer process to extract the moisture diffusivity in the membranes. The calculated moisture diffusivities in the membranes were 8.99 × 10−12 (m2/s) for the membranes from cellulose acetate, 1.9 × 10−10 (m2/s) for the microporous PE/PUR membranes, and 1.53 × 10−11 (m2/s) for the... [more]

Since the invention of the light bulb by T [...]

We investigated the effective use of cross-flow wind turbines for small-scale wind power generation to increase the output power by using a casing, which is a kind of wind-collecting device, composed of three flow deflector plates having the shape of a circular-arc airfoil. Drag-type vertical-axis wind turbines have an undesirable part of about half of the swept area where the inflow of wind results in low output performance. To solve this problem, we devised a casing consisting of three flow deflector plates, two of which were to block the unwanted inflow of wind and the remaining flow deflector plate having an angle of attack with respect to the wind direction to increase the flow toward the rotor. In this study, output performance experiments using a wind tunnel and numerical fluid analysis were conducted on a cross-flow wind turbine with three flow deflector plates to evaluate the effectiveness of the casing on output performance improvement. As a result, it was confirmed that the... [more]

In recent years, one of the key postulates in the European Union’s policy has become the development of renewable energy sources. In order to achieve the desired synergy effect, the idea of combining two selected sources of energy appeared. This article presents a technical and economic analysis of a hybrid connection of a ground source heat pump with a photovoltaic installation. Taking into account the heat demand of the building, a ground heat pump with a catalog nominal heating power of 25 kW was selected. This article presents the problem of the economic profitability of using a hybrid combination of a heat pump and photovoltaic panels in domestic hot water and central heating systems. The justification for the use of such heat sources in these installations is due to global trends and the gradual departure from conventional energy sources such as oil or gas boilers. This paper presents the economic and ecological results of using the pump heat connected together with photovoltaic... [more]

Hydrogen (H2) is the most abundant element in the universe and it is also a neutral energy carrier, meaning the environmental effects of using it are strictly related to the effects of creating the means of producing of that amount of Hydrogen. So far, the H2 generation by water electrolysis research field did not manage to break the efficiency barrier in order to consider H2 production as a technology that sustains financially its self-development. However, given the complexity of this technology and the overall environmental impacts, an up-to-date research and development status review is critical. Thus, this study aims to identify the main trends, achievements and research directions of the H2 generation using pure and alkaline water electrolysis, providing a review of the state of the art in the specific literature. Methods: In order to deliver this, a Systematic Literature Review was carried out, using PRISMA methodology, highlighting the research trends and results in peer review... [more]

The increase in the dissemination of renewable energies constitutes a new energy model that can be used to face the global challenges derived from the reduction in fossil fuels to limit the effects of global warming [...]