Energy Generation Technologies Research Articles

Thermodynamic modelling of hydrogen production in sorbent‐enhanced biochar‐direct chemical looping process

AbstractHydrogen (H2) has been widely considered the clean energy carrier of choice for emerging renewable energy generation technologies. However, H2 is a secondary fuel mainly derived from natural gas. Over the past decades, research on developing H2 production technology that reduces carbon emissions has gained momentum due to increasing atmospheric levels of carbon dioxide (CO2). This study proposed a new sorption‐enhanced (SE) and biochar‐direct (BD) integrated chemical looping system for hydrogen production from biomass gasification, using iron oxide as an oxygen carrier, calcium oxide (CaO) as a CO2 adsorbent, and biochar as a reducing agent. In this study, a thermodynamic model with the proposed sorbent‐enhanced biochar‐direct (SE‐BD) chemical looping hydrogen production (CLHP) process has been developed using an Aspen Plus simulator. The effect of important process parameters, including the reactor temperature, the syngas composition, and the molar feeding ratios of iron oxide/syngas, biochar/syngas, and CaO/syngas on the performance in terms of product gas composition, iron oxide conversion, H2 yield, H2 purity, and reactor heat demand has been evaluated. The simulation results show that the addition of biochar significantly enhances the overall hydrogen yield compared to the conventional CLHP process; whereas the addition of CaO‐sorbent was found to significantly improve the H2 purity. Moreover, the exothermic lime carbonation further reduced the thermal requirements of the process. In addition, this thermodynamic simulation demonstrates that the sorbent‐enhanced biochar‐direct chemical looping hydrogen production (SE‐BD‐CLHP) process can achieve a wide operating window for complete iron oxide (Fe3O4) reduction by adjusting the CaO and biochar feeding ratio.

Techno economic viability of hydroelectric energy storage systems for high-rise buildings

Intermittent sustainable energy generation in the electrical grid from sources such as solar, hydro, and wind has increased significantly in recent years which for stability purposes has required the concurrent implementation of a wide array of large-scale energy storage solutions like chemical battery and pumped hydro plants. The current study assesses the potential techno-economic viability of two alternative hydroelectric energy storage systems - a building-based pumped hydro system, and a building-based gravity module system. The levelized electricity cost and variable storage cost are used as performance metrics in the study. A numerical model of the proposed systems is developed in Matlab® and analyzed over a number of scenarios in which system capacity and building height are varied. Further comparisons are made with the two following conventional rapidly deployable grid-scale energy generation and/or storage technologies - natural gas peaker plants, and lithium-ion battery plants. This research is unique as no such comparative study has been conducted to date. Results show that the building-based gravity module system is more financially viable and has a greater energy storage capacity than the building-based pumped hydro system in all scenarios considered. The building-based gravity module system can provide energy storage capacities as high as 1358 kWh in buildings that are 300 m tall. Moreover, this system has a lower levelized electricity cost than equivalent lithium-ion battery systems (≤$1.02/kWh) in all buildings that are taller than 156 m. The current study demonstrates that the levelized electricity cost is better suited than the variable storage cost as a metric for gauging the economic viability of grid energy storage systems since system lifetime costs and the time value of money are considered.

Pathway to a land-neutral expansion of Brazilian renewable fuel production

Biofuels are currently the only available bulk renewable fuel. They have, however, limited expansion potential due to high land requirements and associated risks for biodiversity, food security, and land conflicts. We therefore propose to increase output from ethanol refineries in a land-neutral methanol pathway: surplus CO2-streams from fermentation are combined with H2 from renewably powered electrolysis to synthesize methanol. We illustrate this pathway with the Brazilian sugarcane ethanol industry using a spatio-temporal model. The fuel output of existing ethanol generation facilities can be increased by 43%–49% or ~100 TWh without using additional land. This amount is sufficient to cover projected growth in Brazilian biofuel demand in 2030. We identify a trade-off between renewable energy generation technologies: wind power requires the least amount of land whereas a mix of wind and solar costs the least. In the cheapest scenario, green methanol is competitive to fossil methanol at an average carbon price of 95€ tCO2−1.

A solar energy desalination analysis tool, sedat, with data and models for selecting technologies and regions

There is interest for desalination technologies powered by solar energy as arid areas are typically bestowed with good solar potential. In response to a US DOE call for solar desalination analysis tools, we developed an open-source solar energy desalination analysis tool, sedat, for techno-economical evaluation of desalination technologies and selection of regions with the highest potential for using solar energy to power desalination plants. It is expected that this software will simplify the planning, design, and valuation of solar desalination systems in the U.S. and worldwide. Sedat uses Dash for integrating various layers of large volumes of GIS data with Python-based models of solar energy generation and desalination technologies. It derives time-series of energy generation and water production, with details of plant performance and suggestions for improving the solar-desalination coupling. This paper summarizes the various phases of the tool’s development, presents example results showing the potential, under multiple objectives, of solar desalination in parts of the U.S. southwest, and discusses method details that would be useful for future model development.

Comparative life cycle environmental impact assessment of renewable electricity generation systems: A practical approach towards Europe, North America and Oceania

The choice of a power plant in different nations depends on the required resources availability, abundance, and reliability. It is evident that renewable energy generation resources provide a more sustainable solution than the fossil fuels. However, as a complete system, renewable energy generation systems also have some overall environmental impacts on humankind and ecosystems. The main objective of this paper is to addresses the environmental effects caused by different types of renewable energy generation systems through process-based life-cycle impact analysis. A comparative study is carried out among different renewable energy generation technologies which include wind, photovoltaic, biomass, and hydro power. Life-cycle impact analysis has been carried out by Institute of Environmental Sciences (CML), Eco-indicator 99, Cumulative Energy Demand (CED) and Ecopoints 97 approaches. The superiority of this work is creating a comprehensive life-cycle inventory following a reliable global database, assessing the impacts for about 10 midpoint impact categories and three endpoint indicators, and taking account of the fossil-fuel-based energy consumption rate of each plant. The key findings reveal that photovoltaic power plants have the highest environmental impacts in the types of ozone layer depletion, fresh water aquatic ecotoxicity and marine aquatic ecotoxicity, while biomass plants impact on the categories of abiotic depletion, global warming, photochemical oxidation, acidification, and eutrophication. Moreover, the wind power plants have the more significant environmental effect on human toxicity and terrestrial ecotoxicity types. Overall, hydropower plants are found to be much more environment-friendly than other renewable electricity generation systems.

Optimal heat and power management of a reversible solid oxide cell based microgrid for effective technoeconomic hydrogen consumption and storage

This paper proposes and examines a highly integrated microgrid based on a reversible solid oxide cell, aimed at satisfying electrical and thermal loads of a 20-unit residential complex as well as the demands of electric and fuel cell vehicles. Such a system has been conceived as a profitable ready-made solution to be embedded into existing plants already equipped with renewable energy sources (i.e., wind farm and photovoltaic panels) by means of a reversible solid oxide cell and energy storage technologies. A dynamic programming-based routine has been suitably implemented as an algorithm for both the electrical and thermal sides of the plant for managing the power split indices. In addition, an external routine has been deployed to consider economic aspects; in particular, attention has been paid to the levelized cost of energy, allowing for comparisons with current reliable energy generation technologies. The analyses involve parametric assessments of multiple reversible solid oxide cell sizes and economic discount rates while fixing the lifetime of the plant at 30 years. In accordance with the results of the optimal microgrid design, by exploiting 100% of the rSOC working time (shared by mode as 40% fuel cell and 60% electrolyzer) a simple payback period of 5.97 years is achieved along with a levelized cost of energy index value in the 0.1 €/kWh-0.2 €/kWh range.

Estimation of wind turbine output power using soft computing models

ABSTRACT Among renewable energy generation technologies, wind energy has become one of the most outstanding issues, especially in the last decade. Wind speed is the most critical parameter influencing the power obtained from a wind turbine. The unstable structure of the wind causes an impossibility to receive a direct theoretical relation between wind power and speed. Accordingly, obtaining a simulation of the generated turbine power concerning the approaching wind speed has become vitally essential, nowadays. In the current study, generated wind turbine power (P) has been predicted using three forecasting methods. The computer was trained using wind speed (V) and the turbine rotor rotational speed (ṅ) as the inputs of the forecasting methods. The methods used for this purpose were to include adaptive neuro-fuzzy inference system (ANFIS), Elmanneural network (ENN), and feed-forward neural network (FNN) approaches. In the training of the programs, among the cumulative of 43,800 wind speed, turbine rotor rotational speed, and wind power data, 80% and 20% of the total data were used for training and testing stages of the algorithms, respectively. The statistical results of the computations demonstrated that among three methods, ANFIS gave better outcomes when compared to ENN and FNN, in both the training and testing stages of the algorithms. The proposed models of the current study have revealed low and acceptable mean absolute error (MAE) and root mean square error (RMSE) statistical error results of ANFIS tool; corresponding to 52.448 kW and 87.204 kW error, respectively, were obtained at the training stage, whereas 48.675 kW and 78.453 kW error, respectively, were obtained at the testing stage. For the estimation of wind power, while the coefficient of determination (R 2) was detected as R2 = 0.9948 and 0.9961 in training and testing stages, respectively, with ANFIS model, it was found out as R2 = 0.9942 and 0.9957 with ENN model and R2 = 0.9943 and 0.9956 with FNN model. Namely, it has been reported that ANFIS tool can be successfully applied in wind output power estimations, as long as wind speed and turbine rotor rotational speed values are provided without the need for numerous experimental measurements, which induces additional time, labor, and measurement expenses.

Synthesis of α-Fe2O3 Nanoparticles By Photolysis Method For Novel Dye-sensitized Solar Cell

The dye-sensitized solar cell (DSSC) is a cost-effective and simple-to-implement technology for future energy generation. It has a comparable power conversion efficiency (PCE) to traditional silicon solar cells while having lower material and production costs. α-Fe2O3 nanoparticles were synthesized by photo irradiation method using complexes solution of iron. The synthesized nanoparticles are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Uv.visable spectroscopy. Results show that nanoparticles have a uniform rhombohedral shape with an 11 to 29 nm average size. The hematite nanoparticles were applied to fabricate a novel Dye solar cell, with an energy conversion efficiency of about 2.5 % by (ITO/ α-Fe2O3 Nps/ Dye (Rhodamine 6 G) /iodine / Ag film / ITO).

Of Fe2O3Nanoparticles By Photolysis Method For Novel Dye-sensitized Solar Cell

The dye-sensitized solar cell (DSSC) is a cost-effective and simple-to-implement technology for future energy generation. It has a comparable power conversion efficiency (PCE) to traditional silicon solar cells while having lower material and production costs. Fe2O3 nanoparticles were synthesized by photo irradiation method using complexes solution of iron. The synthesized nanoparticles are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Uv.visable spectroscopy. Results show that nanoparticles have a uniform rhombohedral shape with an 11 to 29 nm average size. The hematite nanoparticles were applied to fabricate a novel Dye solar cell, with an energy conversion efficiency of about 2.5 % by (ITO/ ?-Fe2O3 Nps/ Dye (Rhodamine 6 G) /iodine / Ag film / ITO).

An Experimental Investigation of a Small-scale Solar Updraft Tower in the Sultanate of Oman

Solar updraft towers (SUT) continue to attract investigations as to their viability as a technology for energy generation. In this study, the experimental method is used to investigate the behavior of airflow in a small-scale solar updraft tower structure in the Sultanate of Oman. A prototype solar updraft tower with a collector diameter of 1.7 m and a chimney height of 2.14 m has been built. The chimney is a 0.023 m PVC pipe with a collector inlet height of 0.07 m. The temperature distribution in the SUT and the velocity of air at the chimney base are investigated. The impact of collector inlet opening on temperature and velocity was also explored. Results indicate that heating generally occurs as air flows through the collector and cooling happens as air exits the chimney. Also, a reduced collector inlet results in improved temperature difference and consequently an increase in air velocity.

Local leader's impact on adoption of renewable energy generation technology by rural communities in the Himalayan region

Sustained energy access to remote hilly regions is a challenge. Governments have made efforts to implement renewable energy solutions in these areas, but the acceptance of such technologies by local communities has not been easy. An action research was conducted to introduce a renewable energy technology for energy generation through pine needles to rural communities of Himalayan region. Based on the theoretical underpinning of the Unified Theory of Acceptance and Use of Technology this empirical study explored the determinants of behavioural intentions to adopt the specifically designed briquetting machine. Results show that in addition to effort expectancy and performance expectancy, local leader's influence also affects the community's intention to use the technology. However, perceived effort expectancy and performance expectancy mediate the relationship between the leader's influence and behavioural intention. Age was also found to be a moderating variable. This modified model of technology adoption has significance in policy making and implementation of similar renewable energy based development projects for mountainous community.

Anion Exchange Membranes for Fuel Cell Application: A Review.

The fuel cell industry is the most promising industry in terms of the advancement of clean and safe technologies for sustainable energy generation. The polymer electrolyte membrane fuel cell is divided into two parts: anion exchange membrane fuel cells (AEMFCs) and proton exchange membrane fuel cells (PEMFCs). In the case of PEMFCs, high-power density was secured and research and development for commercialization have made significant progress. However, there are technical limitations and high-cost issues for the use of precious metal catalysts including Pt, the durability of catalysts, bipolar plates, and membranes, and the use of hydrogen to ensure system stability. On the contrary, AEMFCs have been used as low-platinum or non-platinum catalysts and have a low activation energy of oxygen reduction reaction, so many studies have been conducted to find alternatives to overcome the problems of PEMFCs in the last decade. At the core of ensuring the power density of AEMFCs is the anion exchange membrane (AEM) which is less durable and less conductive than the cation exchange membrane. AEMFCs are a promising technology that can solve the high-cost problem of PEMFCs that have reached technological saturation and overcome technical limitations. This review focuses on the various aspects of AEMs for AEMFCs application.

Transforming wastewater ammonia to carbon free energy: Integrating fuel cell technology with ammonia stripping for direct power production

The transformation of ammonia from pollutant to energy rich carbon free fuel presents an opportunity for the transition of wastewater services to net zero. However, there is only limited knowledge of how the product quality of ammonia recovered from real wastewater might impact on its downstream exploitation in fuel cells. This study therefore exploited vacuum stripping to produce an aqueous ammonia concentrate from real wastewater that was then evaluated within a direct ammonia fuel cell, as a reference technology for energy generation. A 17 g L−1 aqueous ammonia product was created by vacuum stripping centrate from a full-scale anaerobic digester (2 gN L−1). The pH of the product was lower than expected due to the mild-acidification of solution by the co-transport of low MW volatile organic compounds. This reduced power density in the fuel cell, due to the incomplete deprotonation of ammonia (lowering oxidation potential at the fuel cell anode) and a decrease in [OH–] which is required for complete electrochemical conversion. We propose that improved vacuum stripping design can increase the distillate ammonia concentration and produce a more alkaline product, yielding markedly higher fuel cell power density by enhancing ammonia oxidation at the anode (through concentration and deprotonation) and reducing [OH–] mass transfer limitations. As the separation energy for ammonia is dominated by the latent heat demand of water vapour, a synergy exists between creation of a concentrated ammonia product (that improves power density) and reducing the energy demand for separation. The energy balance from this research evidences that despite the high latent heat demand for separation, the low cost of heat coupled with the power produced from ammonia yield a favourable economic return when compared to conventional biological treatment. This study also identifies that revaluing ammonia as a carbon free fuel can help reposition wastewater treatment for a zero-carbon future.

Grid-Forming Wind: Getting ready for prime time, with or without inverters

Variable wind power is one of the fastest-growing energy-generation technologies, harnessing the energy of wind, both on land and at sea. During the past decade, the global share of wind power has grown tremendously, and wind power is evolving into a major contributor to electricity supplies in many countries. In this journey, wind is also becoming a source of reliability services to the grid, which has required grid-supporting functions originally provided by synchronous generators, enabling very high levels of instantaneous penetration (ranging from 60 to 70% in some power systems). To get beyond this, a fundamental shift is required to address challenges associated with the transition to a grid with only a few remaining (or even without any) conventional synchronous generators while achieving a minimum acceptable level of stability.

Energy and economic evaluation of MSW incineration and gasification in Brazil

Ever-increasing waste generation from the world population, along with the demand for renewable energy sources, are two topics gaining prominence in global conversations. Energy recovery of municipal solid wastes stands out as a possible solution for both problems. Thus, the present study aims to analyze the use of gasifiers and incinerators as technology for municipal solid waste treatment and energy generation from economic and energetic perspectives. The study was carried out in three municipalities in different regions of Brazil with distinct characteristics: Itajubá, Campinas and Campo Grande. The calculations were performed considering each city's waste production values and gravimetric composition. For each, two different waste flow scenarios were considered: the first adopted constant power and waste treatment values, while the second used values that varied year to year. The results obtained showed that the second scenario had greater energy potential than the first; however, its generation costs are higher, due to the greater flow of waste. Regarding the types of technology, gasification resulted in lower generation costs in Itajubá, while incineration was more attractive for Campinas and Campo Grande. This distinction can be explained by the different levels of organic matter in the cities involved. The use of both types of technology did not prove to be economically viable for any of the cities and conditions analyzed, thus demonstrating the need for government incentives for their viability.

Hybridizing Triboelectric and Thermomagnetic Effects: A Novel Low‐Grade Thermal Energy Harvesting Technology

AbstractDeveloping new energy generation technologies able to effectively convert low‐grade thermal energy into electricity is an urgent necessity to tackle the continuous surge in energy demand and mitigate climate change. Here, a hybrid device that couples triboelectric and thermomagnetic effects to generate electrical power in the presence of small temperature gradients near room temperature is demonstrated. The thermomagnetic effect allows to induce the periodic and sustained motion of a second‐order ferromagnetic material in temperature gradients below 30 °C. This mechanical motion is then converted into electrical energy using a low‐cost triboelectric nanogenerator (TENG). The applicability of this concept is demonstrated in a broad range of operating temperatures in both the cold (15 to 37 °C) and hot (60 to 90 °C) sides. It is further shown that the electrical power generated by the hybrid TENG is more than 35× higher than that obtained by a conventional thermomagnetic generator driven by magnetic induction. The obtained results show that this implementation is a feasible thermal energy conversion technology, further expanding the applicability of triboelectricity into the realm of room temperature thermal harvesting.

Impact of innovation in marine energy generation, distribution, or transmission-related technologies on carbon dioxide emissions in the United States

This study contributes to the energy economics literature by inspecting the association between innovation in marine energy generation, distribution, or transmission-related technologies and carbon dioxide emissions, with the gross domestic product per capita, expansionary monetary policy, trade openness, international collaboration in green technology development, and renewable energy consumption in the United States from 1990Q1 to 2018Q4. First, results from the canonical co-integration regression estimator, dynamic ordinary least squares estimator, and fully modified ordinary least squares estimator indicated that innovation in marine energy generation, distribution, or transmission-related technologies helps reduce carbon dioxide emissions. Second, the findings indicated that renewable energy consumption and international collaboration in green technology development were negatively associated with carbon dioxide emissions. Third, trade openness, expansionary monetary policy, and gross domestic product per capita were positively associated with carbon dioxide emissions. Fourth, the Granger causality test confirmed two-way causality between international collaboration in green technology development and carbon dioxide emissions. Fifth, the findings also showed that there exists a one-way causality between innovation in marine energy generation, distribution, or transmission-related technologies and carbon dioxide emissions, gross domestic product per capita and carbon dioxide emissions, expansionary monetary policy and carbon dioxide emissions, and trade openness and carbon dioxide emissions.

Experimental, economic and life cycle assessments of recycling end-of-life monocrystalline silicon photovoltaic modules

The utilization of solar technology for clean energy generation has seen a dramatic increase over the past decade. Eyeing the ever-growing solar capacity and the subsequent inevitable deluge of solar panel wastes, the ideal approach to handle End-of-Life (EoL) solar photovoltaic (PV) panels is to recycle their materials for reuse. This present study explores an optimal recycling process with a high resource recovery efficiency on a laboratory scale, which comprises of three main steps: module delamination, acid etching and sequential electrodeposition. High recoveries of 86, 95 and 97% were achieved for silver, lead and aluminum, respectively. The acquired results are further applied in a life cycle assessment. The process was scaled up to simulate an industrial process and its human and environmental impacts were compared to those of the landfilling disposal method, with six main impact categories analyzed and described: global warming potential, human toxicity potential, freshwater ecotoxicity potential, acidification potential, eutrophication potential and ozone depletion potential. Mitigation strategies are also proposed. Lastly, economic analysis demonstrated that at a treatment capacity of 892.5 kg/h, the process is feasible with an internal revenue rate of 28.2% and a payback time of less than a year, provided the waste collection is subsidized.

On the impact of load profile data on the optimization results of off-grid energy systems

Access to electricity via large scale power grids is seen as one of the solutions for a fully renewable power system. However, it remains a huge technical, economical, and geopolitical challenge. In the meantime, millions of people across the world have none or limited access to electricity and quite often to rely on autonomous solutions such as diesel generators. With the decreasing cost of renewable energy generation technologies in recent years, one could observe a simultaneous increase in studies dedicated to optimal sizing of renewable off-grid systems. Many of these studies rely on the usage of typical daily load profiles to model the electricity demand, sometimes enhanced with seasonal or random components. Such approaches tend to overlook the existing potential case-specific correlation between availability of renewable energy and energy demand and in particular the natural variability of the load in terms of its extreme values or ramp rates. The objective of this study is to investigate the impact of different types of load input data (for instance real load, monthly adjusted typical load, and typical daily load) on the cost of energy provided by off-grid PV-battery systems supplying various loads with different reliability levels. For this purpose, we determine the optimal capacity of PV-battery systems based on commonly used energy management strategies and optimization algorithms. The analysis of the obtained results indicates that, on average, using daily load profiles tends to underestimate the cost by 1.2% points (pp) for a system with 100% reliability and by over 5 pp for a system characterized by 95% reliability. Using monthly adjusted typical daily load profiles leads to slight differences compared to the results obtained by using real load as input. Although the obtained average values indicate a tendency of underestimating the energy cost, some outliers have been also observed reaching values of up to 15% of overestimating the cost of energy.

Enhancement of visible light-driven hydrogen production over zinc cadmium sulfide nanoparticles anchored on BiVO4 nanorods

Photocatalytic water splitting to produce H 2 is a promising technology for clean energy generation. However, the use of expensive noble metals, toxicity, low charge separation efficiency and wide band gap of semiconductors hampering the widespread commercialization. Herein, we showed the potential of combining BiVO 4 nanorods with ZnCdS forming a hetero-structure which extend the spectral responsive range, separate the charge carriers effectively and enhances photocatalytic activity compared to single-component materials. The two components of hetero-structure forms an interface contact which also mitigate the problems of lower conduction band position of BiVO 4 and fast recombination of charge carriers of ZnCdS. The BiVO 4 –ZnCdS hetero-structure was studied through surface morphology, crystallization properties, elemental analysis and optical properties. Under visible light irradiation, the BiVO 4 –ZnCdS heterostructure produced 152.5 μmol g −1 h −1 hydrogen from water splitting, which was much higher than that of the individual components and stability of the hydrogen production was observed in three consecutive cycles. The as-obtained heterostructure showed improved visible light harvesting ability, prolong life of charges carriers and charge separation efficiency and Z-scheme mechanism features which results in enhanced photocatalytic activity for water splitting. • A novel BiVO 4 –ZnCdS heterostructure is introduced as photocatalyst. • The developed catalyst was used for visible light driven hydrogen production. • Interface among BiVO 4 and ZnCdS improved photocatalytic profile of catalyst. • BiVO 4 –ZnCdS heterostructure produced up to 152.5 μmol g −1 h −1 hydrogen. • Z-scheme mechanism enhanced the performance herein as noble-metal-free catalyst.