Search

The design of solid oxide fuel cells (SOFC) using biogas for distributed power generation is a promising alternative to reduce greenhouse gas emissions in the energy and waste management sectors. Furthermore, the high efficiency of SOFCs in conjunction with the possibility to produce hydrogen may be a financially attractive option for biogas plants. However, the influence of design variables in the optimization of revenues and efficiency has seldom been studied for these novel cogeneration systems. Thus, in order to fulfill this knowledge gap, a multi-objective optimization problem using the NSGA-II algorithm is proposed to evaluate optimal solutions for systems producing hydrogen and electricity from biogas. Moreover, a mixed-integer linear optimization routine is used to ensure an efficient heat recovery system with minimal number of heat exchanger units. The results indicate that hydrogen production with a fuel cell downstream is able to achieve high exergy efficiencies (65–66%) and a drastic improvement in net present value (1346%) compared with sole power generation. Despite the additional equipment, the investment costs are estimated to be quite similar (12% increase) to conventional steam reforming systems and the levelized cost of hydrogen is very competitive (2.27 USD/kgH2).

Rüzgar enerjisinin değerlendirilmesi, herhangi bir yerde bulunan potansiyel rüzgar enerjisi hakkında uzmanları bilgilendiren entegre analizlerin bir biçimidir. Bu tür değerlendirmenin başlangıç noktası, belirli bir yerde yaygın olarak meydana gelen rüzgar modellerini anlamaktır. Bunu, rüzgar verileri toplama ve toplanan verileri analiz etme izler. Bu makale, birinci ve ikinci bölgelerin kapsamlı bir çalışmasıdır. Bu nedenle, ortalama rüzgar hızı, yön verisi, kısa vadeli varyasyonlar (veya rüzgarlar), yıllık, mevsimsel ve hatta günlük değişiklikler / varyasyonlar ve yüksekliğe bağlı varyasyonlar gibi birkaç parametre dikkate alınmalıdır. Bahsedilen tüm parametreler sahaya özgü olduğundan, uzun bir süre boyunca yerinde ölçümlerle doğru bir şekilde belirlenebilir. Bu çalışma, rüzgar değerlendirmesi ve potansiyel rüzgar enerjisi üzerine odaklandığından Gharyan şehri bir konum olarak seçildi ve alt konumları Gharyan 1, 2, 3 ve 4 olarak adlandırıldı. İlk olarak, rüzgar enerjisi kaynağı ile ilgili konumun yakınında bulunan meteoroloji istasyonlarından alınan veriler arka planda toplandı. Genellikle, her bir konum için 3 saatlik uzun vadeli rüzgar verileri kullanılır ve daha sonra, göbek yüksekliğindeki gerçek rüzgar hızını bulmak için rüzgar verilerinin yeniden hesaplanması yapılır. Önemli hesaplama parametreleri arasında, önerilen her bir saha için hesaplanması gereken Weibull dağılımı, ortalama rüzgar hızı, yıllık kapasite faktörü ve yıllık enerji faktörü yer alır. Yıllık kapasite ve enerji faktörlerinin hesaplanması, genellikle Vestas (V60, 850kW) olarak adlandırılan rüzgar türbinini seçmek için gereklidir. Bu makale, Libya'daki bazı tesislerin, özellikle yıllık enerji, kapasite faktörü ve kabul edilebilir enerji üretim kapasitesinin kaydedildiği Gharyan'da bulunan dört bölgede yeterli rüzgar enerjisine sahip olduğunu açıkça göstermektedir., Assessing the potential of wind energy involves an integrated analysis approach, the conclusions of which inform the experts of the field about the possibilities of harnessing wind energy on a certain location. This type of analysis is made of multiple steps, starting from observing and understanding commonly occurring wind patterns at the designated site, followed by collection of data and finally analysis. The current paper is an extended study on the first two steps where several parameters such as wind’s average speed and its direction, as well as various changes such as short-term ones (or gusts), yearly, seasonal, and even daily changes, and height-related variations were collected. Since the above-mentioned parameters are site-specific, they can be accurately determined through on-site measurements during extended time periods. The site for this study is the city of Gharyan in Libya which was divided into four sub-locations. Data were gathered from meteorological stations located in the vicinity of the designated area in three-hours periods, and they were then used to recalculate wind’s real speed and height at a specific hub. Among the important calculation parameters were Weibull's distribution, average wind speed, annual capacity factor, and the annual energy factor, all of them required for each proposed site. The calculations of the annual capacity and energy factors are necessary for choosing the appropriate wind turbine, generally named Vestas (V60, 850kW). The current study clearly shows that some sites, in particular four locations in Ghayran where feasible annual energy, capacity factor, and acceptable power generation capacity were recorded have wind energy for civilian purposes.

Microbial fuel cells (MFC) provide a breakthrough development for wastewater treatment combined with electricity production. Though, MFC applications are restricted in laboratory scale level. Present study an effort has been made to employ the electroplating industrial wastewater as feedstock in dual chambered anaerobic microbial fuel cell for organic content removal as well as energy production. The ultimate goal of this research is to analyze the effect of organic load (OL) on removal of organic matter and power production. The maximum removal efficiency of total, soluble oxygen demands (TCOD, SCOD) and total suspended solids (TSS) of about 87%, 79% and 72% respectively was obtained at the OL of 1.5 gCOD/L. The maximum power and current density of about 260 mW/m2 (6.2 W/m3) and 364 mA/m2 was also recorded at a same OL of 1.5 gCOD/L. From the above findings proposed that utilization of high strength organic wastewater in MFC could pave the way to handle the problem of electroplating industries as well as minimize a small portion of energy demand.

China’s energy system requires a thorough transformation to achieve carbon neutrality. Here, leveraging the highly acclaimed The Integrated MARKAL-EFOM System model of China (China TIMES) that takes energy, the environment, and the economy into consideration, four carbon-neutral scenarios are proposed and compared for different emission peak times and carbon emissions in 2050. The results show that China’s carbon emissions will peak at 10.3–10.4 Gt between 2025 and 2030. In 2050, renewables will account for 60% of total energy consumption (calorific value calculation) and 90% of total electricity generation, and the electrification rate will be close to 60%. The energy transition will bring sustained air quality improvement, with an 85% reduction in local air pollutants in 2050 compared with 2020 levels, and an early emission peak will yield more near-term benefits. Early peak attainment requires the extensive deployment of renewables over the next decade and an accelerated phasing out of coal after 2025. However, it will bring benefits such as obtaining better air quality sooner, reducing cumulative CO2 emissions, and buying more time for other sectors to transition. The pressure for more ambitious emission reductions in 2050 can be transmitted to the near future, affecting renewable energy development, energy service demand, and welfare losses.

The principal aim of the current research is the design and optimization of a multi-generation unit capable of generating electricity and potable water and hydrogen. The system comprises a gas turbine unit, a high-temperature solid-oxide fuel cell (SOFC), a combustion chamber, and a multi-effect desalination (MED) system. The pressurized steam and fuel enter the anode side of high-temperature SOFC and the air goes to the cathode side. Due to reactions inside the SOFC, a high amount of electricity produces, and excess H 2 enters the combustion chamber. Hot flue gases can run a gas turbine and a MED unit to generate more electrical power and desalinated water. The study illustrated the impact of current density on voltage losses and output power and output voltage of SOFC. A parametric examination is also conducted to demonstrate the influence of primary design variables on the system performance. Exergo-economic multi-criteria optimization is used to determine the optimized parameters to obtain the higher efficiency and lower cost of fuel and equipment. Calculations represented that the suggested arrangement is able to generate 53.46 kg/s desalinated water, and 54.8 MW electricity and 7.43 kg/h hydrogen energy. The system exergy efficiency under this condition is about 36.45% but the results of optimization showed that this value could rise up between 50.8% and 61.17% with the lowest system cost.

In this research paper, comprehensive thermodynamic modeling of an integrated energy system consisting of a multi-effect desalination system, geothermal energy system, and hydrogen production unit is considered and the system performance is investigated. The system's primary fuel is a geothermal two-phase flow. The system consists of a single flash steam-based power system, ORC, double effect water–lithium bromide absorption cooling system, PEM electrolyzer, and MED with six effects. The effect of numerous design parameters such as geothermal temperature and pressure on the net power of steam turbine and ORC cycle, the cooling capacity of an absorption chiller, the amount of produced hydrogen in PEM electrolyzer, the mass flow rate of distillate water from MED and the total cost rate of the system are studied. The simulation is carried out by both EES and Matlab software. The results indicate the key role of geothermal temperature and show that both total exergy efficiency and total cost rate of the system elevate with increasing geothermal temperature. Also, the impact of changing absorption chiller parameters like evaporator and absorber temperatures on the COP and GOR of the system is investigated. Since some of these parameters have various effects on cost and efficiency as objective functions, a multi-objective optimization is applied based on a Genetic algorithm for this system and a Pareto-Frontier diagram is presented. The results show that geothermal main temperature has a significant effect on both system exergy efficiency and cost of the system. An increase in this temperature from 260 C to 300 C can increase the exergy efficiency of the system for an average of 12% at various working pressure and also increase the cost of the system by 13%.

In recent decades, solar collector and heat pump combinations have been widely applied to supply heat and hot water, such as in heat supply and power generation for domestic and commercial buildings and relevant applications in the manufacturing and agricultural industries. However, the solar-assisted heat pumps already in extensive use may undergo system performance deterioration in a cold environment. To solve this problem, we designed a heat pump system assisted with hot water where a water medium was used to store energy to assist the operation of the heat pump at low temperatures. Three factors were comprehensively considered: the opening degree of the electronic expansion valve, the temperature of the low-temperature heat source, and the auxiliary hot water temperature. Crossover experiments were designed with three levels for each factor, and 36 groups of experiments were carried out. The results showed that as the auxiliary hot water temperature increased, the heating capacity and the coefficient of performance also increased. Thus, the overall working efficiency of the system improved. According to the orthogonal test, the most important influencing factor of system performance was the auxiliary hot water temperature, followed by the ambient temperature and opening degree of the electronic expansion valve. These results fully demonstrated that the addition of auxiliary hot water could dramatically improve system performance. In addition, optimization of the opening degree of the electronic expansion valve produced different results, indicating that the optimal value ranged from 50%−75%.

The utilization of biomass energy is important from both an energetic and environmental point of view. Saudi Arabia has a considerable amount of biomass waste that can be converted to renewable energy using different technologies. This study evaluated and analyzed the quantity and energy potential of biomass waste, Greenhouse gases (GHG) emissions, and cost estimation of power generation using different conversion techniques. The results showed that the annual biomass waste in Saudi Arabia could reach approximately 31.50 million tons, which can generate 15 TWh of electricity. Municipal solid waste (MSW) is the largest contribution to the total waste and total power generation potential, which is approximately 70% and 74% of the total, respectively. Although incineration of MSW has the highest cost requirements, it has the highest power generation potential compared with the other studied techniques. However, the anaerobic digestion of other biomass types has the advantages of low costs and GHG emissions and generates considerable energy. The findings of this study can support decision-makers in developing sustainability strategies using eco-friendly and economical technologies for efficient power generation from biomass wastes.

The increased usage of natural gas for power generation in Europe due to raising carbon prices and developments of intermittent renewable energy has led to a stronger intertie between gas and power grids. With this the resilience of the total energy system is quantified by the ability of each type of grid infrastructure to withstand disturbances in the other ones. The main goal of the paper is to study the resilience of the Baltic energy system in the case of a major disturbance in the natural gas transmission grid. A case study of a disturbance is performed, response of the power grid is studied and the resilience of the energy system is assessed. The results can be used in the planning activities of Baltic power grid operators.

Increasing surface temperature significantly affects the electrical performance of photovoltaic (PV) panels. A closed-loop forced circulation serpentine tube design of cooling water system is used to effectively manage the surface temperature of PV panels. A real-time experiment was first carried out with a PV panel with a cooling system at HTF flow rates of 60 kg h-1, 120 kg h-1, and 180 kg h-1. Based on the experimentation, a correlation for a nominal operating cell temperature (NOCT) and thermal efficiency for collector was developed for experimental validation of useful energy gained, cell temperature and electric power generation. The developed corrections are validated with electrical power and useful energy gained in photovoltaic serpentine thermal solar collector (PV/STSC) and fit into experimental results with a deviation of 1% and 2.5 % respectively. Further, with the help of developed correlations, a system was developed in the TRNSYS tool through which an optimization study was performed based on electric and hot water demand. The findings indicate that an optimal system with an 8 m2 PV/STSC area, a HTF flow rate of 60 kg h-1, and TES system having a volume and height of 280 l and 0.8 m could meet 91 % and 33 % of the hot water demand for Ac loads and 78 % or DC loads, respectively.

Medium-term forecasting of water inflow is of great importance for small hydroelectric power plants operating in remote power supply areas and having a small reservoir. Improving the forecasting accuracy is aimed at solving the problem of determining the water reserve for the future generation of electricity at hydroelectric power plants, taking into account the regulation in the medium term. Medium-term regulation is necessary to amplify the load in the peak and semi-peak portions of the load curve. The solution to such problems is aggravated by the lack of sufficiently reliable information on water inflow and prospective power consumption, which is of a stochastic nature. In addition, the mid-term planning of electricity generation should consider the seasonality of changes in water inflow, which directly affects the reserves and the possibility of regulation. The paper considers the problem of constructing a model for medium-term forecasting of water inflow for planning electricity generation, taking into account climatic changes in isolated power systems. Taking into account the regularly increasing effect of climate change, the current study proposes using an approach based on machine learning methods, which are distinguished by a high degree of autonomy and automation of learning, that is, the ability to self-adapt. The results showed that the error (RMSE) of the model based on the ensemble of regression decision trees due to constant self-adaptation decreased from 4.5 m3/s to 4.0 m3/s and turned out to be lower than the error of a more complex multilayer recurrent neural network (4.9 m3/s). The research results are intended to improve forecasting reliability in the planning, management, and operation of isolated operating power systems. © 2021 The Author(s). The reported study was funded by RFBR, Sirius University of Science and Technology, JSC Russian Railways and Educational Fund “Talent and success”, project number 20-38-51007.

Thermal power plants are generally constructed near to sea coast to meet their requirement of cooling water. The warm water discharge from the thermal power plant is one of the major environmental concerns in view of the thermal pollution in the sea water. The temperature limit for the warm water discharge from the thermal power plant has to be monitored and controlled. Coastal Gujarat Power Limited (CGPL) operates (24 × 7) at an “once-through system” based sea water circulation for power generation. The used sea water is then discharged into the sea through an outlet channel. As per environmental norms, the discharge water temperature needs to be maintained below the stipulated “delta” rise (+7 °C) with respect to ambient sea surface temperature at the inlet. We demonstrate the applicability of thermal remote sensing data in understanding the seasonal and temporal variations of the temperature difference between the discharge water and the ambient sea water. We used thermal band data from Landsat-8 satellite imagery to map water surface temperature and create temperature profiles along the intake and outflow channels (till the sea), to understand the variation of temperature and estimate the “ΔT” between intake point and various observation points along the outflow. This analysis was carried out for all 11 months (except June) of the year 2018 to correlate temperature variations with seasonal changes. Tidal conditions during the time of data acquisition were also considered to account for the effect of tides on ΔT. The result shows that the average temperature rise between intake and outflow are maintained at ∼3 °C across all the months of 2018, with minor variations in the months of July and August. Further, average temperature drop from outflow to cooling channel (before diaphragm) is seen to be ∼2 °C across all the months with similar seasonal fluctuations.

Due to financial and temporal limitations, the small wind community relies upon simplified wind speed models and energy production simulation tools to assess site suitability and produce energy generation expectations. While efficient and user-friendly, these models and tools are subject to errors that have been insufficiently quantified at small wind turbine heights. This study leverages observations from meteorological towers and sodars across the United States to validate wind speed estimates from the Wind Integration National Dataset (WIND) Toolkit, the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5), and the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), revealing average biases within ±0.5 m s−1 at small wind hub heights. Observations from small wind turbines across the United States provide references for validating energy production estimates from the System Advisor Model (SAM), Wind Report, MyWindTurbine.com, and Global Wind Atlas 3 (GWA3), which are seen to overestimate actual annual capacity factors by 2.5, 4.2, 11.5, and 7.3 percentage points, respectively. In addition to quantifying the error metrics, this paper identifies sources of model and tool discrepancies, noting that interannual fluctuation in the wind resource, wind speed class, and loss assumptions produces more variability in estimates than different horizontal and vertical interpolation techniques. The results of this study provide small wind installers and owners with information about these challenges to consider when making performance estimates and thus possible adjustments accordingly. Looking to the future, recognizing these error metrics and sources of discrepancies provides model and tool researchers and developers with opportunities for product improvement that could positively impact small wind customer confidence and the ability to finance small wind projects.

Electricity demand is increasing mainly due to population expansion and the continuous supply of electricity in the residential, industrial, and service sectors. This energy is a critical factor of economic growth, and clean energy resources must be utilized and substituted to reduce the effects of climate change and move toward sustainable development. Site selection and construction of renewable power plants help to diversify the country's energy basket. This study aims to locate and evaluate a photovoltaic solar power plant's potential in Khuzestan province, using Fuzzy-Boolean logic and Analytical Hierarchy Process (AHP) decision analysis based on GIS. The main criteria for selecting the optimal locations include climatic (annual horizontal solar irradiance, sunshine hours, air temperature, relative humidity, windspeed), economic (the proximity to roads, transmission lines, substations, urban areas, and villages), orography (slope, orientation, and altitude) and the environment. According to the results, 0.12% of the province's area has excellent suitability, 25.66% has suitable suitability, and 59.46% lacks any suitability for installing a photovoltaic system. The annual electric power generation potential using single-crystalline silicon panels and polycrystalline silicon panels is calculated as 3189.54 and 2453.49TWh, respectively. Izeh, Bandar-e-Mahshahr, and Bagh-eMalek cities are the most suitable areas for photovoltaic solar farms in province.

Offshore wind turbines are the key enabling technology to increase the green energy penetration in the electricity market. Increasing the power generation per tower and reducing the levelized cost of energy are the two significant problems faced by wind turbine manufacturers. Traditional turbine manufacturers use rare-earth permanent magnets (PMs) to increase the air-gap flux density and maximize the machine outer diameter to increase the torque output. Since the air-gap flux density achievable with available PM is limited, increasing the power output of a traditional generator invariably leads to a significant increase in the volume and mass on top of the turbine tower and associated manufacturing, transportation, and installation costs. Superconducting (SC) wind turbine generators offer 5 to 10 times the air-gap flux density of a PM generator, and a corresponding increase in specific power and power density. Previous MW scale SC wind turbines designs used heavy back iron in the design, iron saturation limits the achievable air-gap flux density in the designs and resulted in bulky generators and moderate efficiency. In this paper a hybrid design approach is proposed to reach an ultra high field (5 to 10 times of PM air-gap flux density) and high efficiency (>98turbine for offshore wind turbine. An additional stray field limitation is introduced for safety concerns and shielding techniques are explored. Electromagnetic, mechanical, and cooling designs are provided to support the feasibility of proposed SC wind turbines. A nacelle integration inside a commercially available 6-MW wind turbine is shown to demonstrate the size comparison of the proposed generator.

Refrigeration and power are the most desirable requirements in commercial places and offices. Goswami cycle is one of the solutions to generate power and refrigeration simultaneously with less pollution. In the Goswami cycle, the power and refrigeration streams are connected in series, the refrigeration output is limited in a series arrangement. In the present study, parallel streams are proposed to improve the performance of the cycle. In the Goswami cycle, the saturated vapour is enriched for power and refrigeration. In the present study, the saturated vapour is used for the power generation, the saturated liquid is flashed to the intermediate pressure, and the generated wet vapours are enriched for refrigeration processes. It is observed that power generation is increasing with an increase in dryness fraction and the fall in basic solution concentration, whereas the refrigeration effect is growing with the fall in dryness fraction and increase in basic solution concentration. The modified cycle is consistently generating higher output than the conventional cycle. The thermal efficiency of the Kalina flash cycle is 29.05% higher and the exergy efficiency is 5.61% lesser than the Goswami cycle.

The rapid development of photovoltaic plays an important role in achieving the carbon-neutral goal. How to improve the conversion efficiency and power generation of solar photovoltaic has always been a focus issue. However, more attention is paid to the impact of photovoltaic panel working temperature on the performance of photovoltaic power generation, and how air temperature affects photovoltaic power generation has been ignored. This paper compared and analyzed the impact of the difference in air temperature between lake and land on the revenue of photovoltaic power generation, and established the functional equation between photovoltaic power generation, air temperature and solar radiation, and revealed the relationship between air temperature, solar radiation and photovoltaic power generation.

Crop straw can not only be used as a raw material for bioenergy, but also can protect the soil after returning to the field. This research constructs a hybrid operation management model for combined power generation with multiple biomass fuels, with the purpose of exploring the impact of environmental protection on the operation and maintenance of biomass companies. First, the potential straw supply under different soil function protection scenarios was calculated. Based on this, a biomass power plant operation strategy was formulated under the mixed supply of multiple biomass. Lastly, taking Shandong Province as a sample case to verify the effectiveness of the model, we found that, (1) the theoretical amount of straw in Shandong Province in 2019 is about 78.57 million tons. Taking into account the agricultural, industrial and household use of crop straw, the total available straw in Shandong Province is 10.3–22.31 million tons. (2) owing to the heterogeneity of different straws, soil function protection will have great impacts on the inventory management of straw power plants. Reasonable straw allocation under different soil function protection scenarios can greatly improve the efficiency of different crop straws. In the case of high return to the field, the selection of maize decreased by 20%, and the amount of straw represented by potato increased by 40%. (3) Prioritizing soil function protection will reduce the total amount of straw that can be used for bio-energy production and reduce carbon dioxide emissions in the process of power generation. Therefore, when planning arbon capture and storage (CCS) technology based on straw power generation, the impact of soil function protection should also be fully considered.

This study aims to analyze many efficiency-enhancing and improvement activities such as manual and natural cleaning, a PV power plant type rainwater harvesting system, thermal monitoring, and snow load removal in a 600 kW grid-connected photovoltaic (PV) power plant. The study shows that up to 5.66% power reduction can occur for PV modules that have been dirty for close to one year. It was determined that the dust removal effect of the rain was up to 0.94%. This study showed that the potential for collecting rainwater from a small part of the PV plant is approximately 118 m(3)/year and that the harvesting system will reach 1646 m(3)/year when applied to the whole plant. A snow load of 0.117 kN per m(2) was removed. On the basis of three days, 50-75% higher energy production was achieved compared to the other power plant with snow load. Snow removal on PV arrays both prevented PV degradation and resulted in increased power generation, while panel cleaning improved energy efficiency. This study an innovative approach with rainwater harvesting from solar power plants with large surface area for the use in panel cleaning and agriculture of the obtained water, which is a novel idea in increasing the efficiency of the power plants, combating climate change and drought. (C) 2021 Elsevier Ltd. All rights reserved. WOS:000704082300009 2-s2.0-85115356498

Renewable energy-based hydrogen production plants can offer potential solutions to both ensuring sustainability in energy generation systems and designing environmentally friendly systems. In this combined work, a novel solar energy supported plant is proposed that can generate hydrogen, electricity, heating, cooling and hot water. With the suggested integrated plant, the potential of solar energy usage is increased for energy generation systems. The modeled integrated system generally consists of the solar power cycle, solid oxide fuel cell plant, gas turbine process, supercritical power plant, organic Rankine cycle, cooling cycle, hydrogen production and liquefaction plant, and hot water production sub-system. To conduct a comprehensive thermodynamic performance analysis of the suggested plant, the combined plant is modeled according to thermodynamic equilibrium equations. A performance assessment is also conducted to evaluate the impact of several plant indicators on performance characteristics of integrated system and its sub-parts. Hydrogen production rate in the suggested plant according to the performance analysis performed is realized as 0.0642 kg/s. While maximum exergy destruction rate is seen in the solar power plant with 8279 kW, the cooling plant has the lowest exergy destruction rate as 1098 kW. Also, the highest power generation is obtained from gas turbine cycle with 7053 kW. In addition, energetic and exergetic efficiencies of solar power based combined cycle are found as 56.48% and 54.06%, respectively.

The Generation Expansion Planning (GEP) process in Brazil involves computational models with a range of variables and constraints inherent in a mostly hydrothermal system. Such models generally use technical and economic parameters to represent the system, but with the growing concern about environmental and climatic issues, the need has arisen for environmental parameter analysis to promote a better representation of a more comprehensive optimum. In view of the recent Paris Agreement, through which the Brazilian government committed itself to significantly reduce its greenhouse gas emissions (GHG) by 2030, it has become essential that the GEP take into account the emission of gases. In this work, scenarios that penalize or limit the emission of greenhouse gases are created and compared inside the existent Investment Decision Model (MDI) used in Brazil. The main objective is to verify how the objective of reducing emissions would change the optimum expansion planning originally provided by the investment model. The results show that within the created scenarios, the largest reduction is achieved when considering a monetary penalty of US$ 25.00/tCO2eq in the burning of fossil fuels for power generation. In this case, to reduce the emissions, the investment model chooses a larger expansion of wind and biomass sources with a corresponding raise in the cost of approximately 5.3%, allowing a total reduction of about 39 MtCO2eq in relation to the reference scenario at the end of the planning horizon.

Historically, energy constraints have limited the spatial range, endurance and capabilities of ocean observation systems. Recently developed wave energy conversion technologies have the potential to help overcome these limitations by providing co-located and persistent power generation for ocean observations, enabling new opportunities for ocean research. In this paper, we develop the first techno-economic model for wave-powered ocean observation systems and use the model to study system characteristics and cost drivers. Our model utilizes time-domain simulation and optimization to identify cost-optimal system characteristics and to estimate capital and operational costs. Using our model, we evaluate the use of wave energy to power a 200 W ocean observation system deployed for five years at five unique geographic locations. We found that, depending on the geographic location, cost-optimal wave energy powered systems require an ≈ 0.5–3 kW wave energy converter and an ≈ 15-50 kWh battery. The corresponding range of power system costs over the deployment duration is between $110,800 and $673,200. We build on these results by performing a sensitivity analysis of key model parameters and identifying the potential economic impact of future technology advancements. Overall, our results indicate that characteristics of the geographic location, power system durability, and electrical power demand are key drivers of power system economics for ocean observing.

Global scenario of solar energy is increasing exponentially to mitigate environmental pollution and reduce the dependency on fossil fuels. In this sequence the research is continue to enhance the use of solar PV based panels for electricity generation. The companies across the globe are manufacturing several kinds of PV panels and these are utilized everywhere based on the generalized performance. Since these PV panels power drop with increase the temperature so it is now necessary to provide the choice for customers by emphasizing the temperature dependent local site performance. In this an analysis is conducted for a local site in Mathura where a 50kWp polycrystalline based project is installed. This analysis suggest that the PR for different technologies is 79.17%, 72.15%, 41.02%, 65.56%,56.45% and 97.27% respectively for mono crystalline, polycrystalline, amorphous silicon, Copper Indium Gallium Selenide, cadmium telluride and HIT. More over HIT -most suitable with fatigue life 6 years, mono crystalline -more suitable with fatigue life 5 years, poly crystalline – suitable with fatigue life 4 years, CIS – less suitable with fatigue life 3 years, CDTe-Lesser suitable with fatigue life 2 years and Amorphous- Least suitable with fatigue life 1 years.

In the light of increasing negative impacts on environment of fossil fuels, development of renewable energy utilization is a high priority. In this regard, hybridization of geothermal and solar energies (as two types of abundant renewable resources) has been proved to be a promising combination for renewable-based power generation systems. For power generation from low-grade renewable resources, the transcritical CO2 (TRCC) power cycle has been considered as an ambitious competitor against ORC and Kalina cycle. This paper aims at development and proposal of a novel efficient trigeneration system based on TRCC cycle for production of power, hydrogen, and freshwater driven by hybrid solar-geothermal energies. In proposed system, thermoelectric generators and HDH desalination unit are employed for waste heat utilization of TRCC cycle. Thermodynamic and thermoeconomic analyses and two-objective optimization are conducted and monthly performance of the system is estimated for real environmental data. Results showed that, the system yields highest values of power, hydrogen and freshwater in May, respectively as 1286 kW, 1.989 kg/h, and 13.38 m3/day. Under the optimized conditions, the system yields energy efficiency of 23.35% with a unit product cost of 17.07 $/GJ. Also, the results revealed efficiency improvement via increasing the solar energy share. In addition it is shown that, developed system in this work can yield higher efficiency compared to a similar trigeneration system based on the Kalina cycle.

Energy enhancement and utilization of renewable energy sources have become inevitable solutions for the concerns of fossil fuel depletion and global warming. Two different cogeneration systems are proposed for cooling and power generation. A gas turbine and an ejector refrigeration cycle are employed in the configurations, in which gas turbine cycle uses biogas as the required fuel. First, these two configurations are analyzed from energy and exergy perspectives. A comprehensive parametric study is also performed by decision variables for the optimization. Results reveal that both energy and exergy efficiencies of conventional combined gas turbine/ejector refrigeration cycle can be improved up to 44.6% and 33.54%, respectively. Besides, the outcomes of the parametric study point out that the combustion chamber has a significant effect on energy and exergy efficiencies and can increased them about 10%. Also, it is found that the vapor generator accounts for the highest exergy destruction among all components. Moreover, by using a genetic algorithm as an optimization method, the thermal and exergetic efficiencies of the base system improves. In the best operating condition, the thermal and exergetic efficiencies of the system reach 57.11% and 36.68%, respectively.

This paper proposes a comprehensive analysis method for levelized costs of energy (LCOE) in tidal current power generation farms (TCPGFs). The detailed investment and operation costs in the life cycles of TCPGF projects are all quantified and incorporated in the calculation of LCOE, including the emission reduction benefits brought by TCPGFs. An annual electricity production (AEP) evaluation technique is proposed, in which the impacts of wake effects, TCPGF reliability and tidal current velocity (TCV) characteristics in the planning sea area are considered. A detailed capital expenditures (CAPEX) model is developed to incorporate all related costs at different stages of TCPGF project. An evaluation model considering the variations of annual operation expenditures (OPEX) is presented. The accuracy of the proposed method is verified using the measured data, which are collected from MeyGen Phase 1A project in UK and two sites located in UK and America.

The need of world electricity production is growing at an increasing rate and because of its limited supply, it cannot completely be met by ordinary energy framework. The use of hybrid systems by renewable electricity sources for energy generation has also created considerations in general. There is no one source of renewables ready to continuously load electricity, and hybrid systems are thus a key solution. Renewable energy is produced by inexhaustible reserves, usually refilled on a human scale, such as sun, wind, hydro, mainstay, biomass, etc. In four core areas, renewable energy often provides energy: electricity, air and water heating/cooling, transport, and rural (stand-alone and network) energy services. In comparison with other sources, renewable power sources have reserves in large geographical regions amassed in a small number of countries. Rapid organization of renewable energy sources and energy conservation brings enormous energy stability, ecological change relief and financial benefits. Hybrid systems (PV-Biomass) are used in different regions to provide electricity to overcome discontinuity and transition in solar and wind power. This paper discusses the techno-economic feasibility analysis of solar biomass system in the Ludhiana district of Punjab.

Fluctuation in hydro-electricity production is primarily attributed to natural and human-induced flow variations. Reduced electricity generation because of unavailability of flow inflicts significant upward pressure on the sources and prices. Despite studies on the impact of externalities on river flow variation, there is a distinct research gap on the responsiveness of hydropower plants to change in flow. This study has introduced a novel concept of flow elasticity of power ( e ) to assess the resilience of hydropower projects to flow variation. The theoretical aspect has been established for run-of-river (ROR) and storage-type (ST) cases separately and validated at two projects, one of each type, located in the Budhigandaki Basin in central Nepal. Responsiveness of hydro-projects to the topographical parameters are also dealt with here. For ROR systems, wide-ranging values of e indicate varying levels of resilience to power generation and loss of resources. For ST projects, the response differs according to emptying, filling and ROR-equivalent phases. Furthermore, strong topographical implications on power production and its elasticity are evident. This concept of e sets out a significant research contribution in the hydropower sector and demonstrates its possibility of direct application in projects in ‘priori’ as well as ‘posteriori’ while planning/designing and updating stages, respectively. The e coefficient scientifically informs the planners and developers on the sensitivity of the powerplants to hydrological variations and topography ultimately benefitting the existing global challenge to minimize the loss of precious resources for sustainable hydropower development.

Hydrogen is currently receiving attention as a possible cross-sectoral energy carrier with the potential to enable emission reductions in several sectors, including hard-to-abate sectors. In this work, a techno-economic optimization model is used to evaluate the competitiveness of time-shifting of electricity generation using electrolyzers, hydrogen storage and gas turbines fueled with hydrogen as part of the transition from the current electricity system to future electricity systems in Years 2030, 2040 and 2050. The model incorporates an emissions cap to ensure a gradual decline in carbon dioxide (CO2) levels, targeting near-zero CO2 emissions by Year 2050, and this includes 15 European countries. The results show that hydrogen gas turbines have an important role to play in shifting electricity generation and providing capacity when carbon emissions are constrained to very low levels in Year 2050. The level of competitiveness is, however, considerably lower in energy systems that still allow significant levels of CO2 emissions, e.g., in Year 2030. For Years 2040 and 2050, the results indicate investments mainly in gas turbines that are partly fueled with hydrogen, with 30–77 vol.-% hydrogen in biogas, although some investments in exclusively hydrogen-fueled gas turbines are also envisioned. Both open cycle and combined cycle gas turbines (CCGT) receive investments, and the operational patterns show that also CCGTs have a frequent cyclical operation, whereby most of the start-stop cycles are less than 20 h in duration.

Direct steam generating parabolic trough power plant is an important technology to match future electric energy demand. One of the problems related to its emergence is energy storage. Solar-to-hydrogen is a promising technology for solar energy storage. Electrolysis is among the most processes of hydrogen production recently investigated. High temperature steam electrolysis is a clean process to efficiently produce hydrogen. In this paper, steam electrolysis process using solar energy is used to produce hydrogen. A heat recovery steam generator generates high temperature steam thanks to the molten carbonate fuel cell's waste heat. The analytical study investigates the energy efficiency of solar power plant, molten carbonate fuel cell and electrolyser. The impact of waste heat utilization on electricity and hydrogen generation is analysed. The results of calculations done with MATLAB software show that fuel cell produces 7.73 MWth of thermal energy at design conditions. 73.37 tonnes of hydrogen and 14.26 GWh of electricity are yearly produced. The annual energy efficiency of electrolyser is 70% while the annual mean electric efficiency of solar power plant is 18.30%. The proposed configuration based on the yearly electricity production and hydrogen generation has presented a good performance.

Electricity is predicted to be the energy vector that will undergo major changes in the future, and a transition would be observed in the resources such as waste and residual biomass that we use to satisfy the energy demand. Therefore, this study aims to highlight the main economic and environmental performances of different biowaste-to-energy technologies for small-scale electricity generation by comparing the direct combustion of refined vegetable oil obtained from waste cooking oils (thermal pathway), anaerobic digestion of biowaste (bio-chemical pathway), and gasification of wood residues (thermo-chemical pathway). The economic analysis is mainly based on personal experiences in the energy sector and shows an overview of the performance in investment of combined heat and power (CHP) systems, ranging from 100 to 500 kW for a period of 20 years. The environmental assessment is conducted considering the life-cycle thinking approach using support from the openLCA software, product environmental footprint (PEF) data-base, and previous studies that have reported environmental inventory data from real industrial cases.

Low-head hydropower bears tremendous potential as a renewable energy source, especially in the context of the progressing global warming. In locations with a low head, for economic and environmental reasons, a small hydropower plant with a waterwheel and an asynchronous generator may provide the best solution for sustainable electricity production. The purpose of this study is to demonstrate a new type of low-speed radial piston pump intended to be part of the hydrostatic transmission of such a small hydropower plant. The advantage of the transmission is the possibility of stepless, automatic change of the gear ratio during operation. First, we describe a mathematical model of the proposed pump and subsequently demonstrate a test stand equipped with its prototype with three suction-pressure units. The pump flow rate characteristics calculated using the theoretical model were compared with those obtained from experiments, resulting in the determination and characterization of the pump's efficiency. Supplementary experiments with a hydraulic accumulator installed as part of the investigated system, demonstrated the possibility of flow rate pulsation dampening. The experimental results showed the validity of the developed mathematical model. In conclusion, the correct operation of the pump was corroborated, and its potential application confirmed by the efficiency results.

Due to the fluctuation of LNG supply, the profile of power generation has a mismatch with that of power demand, which causes power shortage at the demand peak time and power overcapacity at the valley time. To address this issue, a combined system containing standalone power generation subsystem and liquid air energy storage subsystem is proposed. The energy storage subsystem stores the surplus cold energy of LNG at the valley time, and it is released as power supplement at the peak time. As a stable heat source, geothermal energy is utilized to enhance the work output. Considering the uncertainties of power supply and power demand, Gaussian distribution model is introduced. Finally, the energy storage subsystem obtains 138 kW net work output of unit mass flow of LNG, achieving at least 29% improvement compared with previous works in the literature. The stored power can reach 148 MW/day and can meet the power shortage in the boundary condition of Gaussian distribution, which is a unique work in contrast to previous studies. The combined system achieves the net present value of 326.7 million dollars at the end of span year, and 3.6 dynamic payback years.

A challenge in horizontal-axis wind turbines is power regulation and transient rejection during the transition between their three operational regions. In particular, the wind’s uncertain nature can lead to undesired electromechanical effects, which in turn decrease power generation efficiency and, in extreme cases, could also be the cause of irreparable damage to the system itself. This letter presents a robust controller that allows the fraction of captured wind energy to be kept while maintaining the transient loads in safe values and preserves electricity generation inside its nominal values in Region III. A linear plus a non-homogeneous quasi-continuous second-order sliding-mode control is proposed to supply energy into the system to maintain the desired power and reject the undesired electromechanical effects. The non-homogeneous controller improves the efficiency of the power generation by reducing the effects of chattering and allowing faster convergence.

The rise in electrical energy demand and environmental concern results in shifting the world’s focus towards sustainable energy sources. Over-reliance of conventional fossil fuel-based power generation can be combatted using new and potential technologies like Microbial Fuel cells (MFCs). Direct conversion of chemical energy to electrical energy by the application of the naturally found microorganisms, makes MFC more convenient source of energy generation. Despite having low power density, it has been able to grab the researcher’s attention due to the flexibility of usage of various organic substrates. This review discusses the various households and industrial waste substrate which has further potential to generate power. The various liquid and solid substrates have been analysed and summarized. The substrate used, power densities, reactor volumes and specific important features used by the researchers for the improved performance have been tabulated. In a higher number of researches, liquid substrates have been comparatively more used than that of the solid substrates. Ease of handling, storage and accessibility of the liquid waste could be one of the few reasons for it. Also, in this review, various components, and key factors for the experimental design of MFC has been discussed. Along with that losses associated with MFCs and its application is explored.

A precise and practical power generation forecasting method for outdoor photovoltaic (PV) arrays and its performance evaluation are essential for advancements in solar power generation. Specifically, accurate temperature measurements of each of the PV modules in an array, the entire outdoor PV array, and the power generation system are crucial regardless of climatic and irradiance conditions. However, outdoor PV temperatures are often affected by environmental factors, such as wind direction, wind speed, solar irradiance, and outdoor air temperature fluctuations. Hence, the temperature data vary greatly depending on the measurement point of the module, which is affected by the above environmental factors. The variations of and uncertainties in temperature often extend over long arrays of PV modules common to large-scale PV systems. Therefore, it is necessary to establish a straightforward and reproducible inspection method to determine a single and robust representative PV module temperature for an array. In this study, we have established one such inspection method for outdoor PV arrays. It was observed that the temperature at the center of the array was closest to the average temperature regardless of the measurement period and climatic conditions; thus, it can be considered as the unbiased and robust representative temperature for the PV array. Moreover, lower irradiance conditions are better for accurate and repeatable PV module temperature measurements. The mean temperature differences of the PV array from its average measured at the center of the array were 0.2 °C for low irradiance and 0.5 °C for high irradiance. The temperature difference observed will have 0.1% to 0.2% impact on the power estimation for monitoring purposes.

In the paper are presented and discussed the results of a more complex research of technology portfolio competitiveness in power systems with high penetration of i-RES. Possible technology portfolios compositions are analyzed. The portfolios comprise very high participation of i-RES, as well as a certain participation of energy storage technologies, but also and other energy technologies like nuclear and fossil fueled power plants. Within the research are developed new competitiveness indicators i.e., dispatchability indicator and the technology portfolio’s assured capacity. The latter is defined on the basis of recently published Ulrich’s and Schiffer’s paper. Obtained results point out that inclusion of pumped-hydro storage plants improves portfolio’s dispatchability. However, within the researched interval up to PHS installed capacities relative to i-RES capacities of 0,3; numerical values of the dispatchability indicators are still below their values for the portfolio without i-RES. Increased participation of nuclear power plants contribute to the improvement of numerical values of the dispatchability indicators. The sensitivity analysis for the case of two times smaller cost of pumped hydro storage capacities is also performed. Hypothetical change of power system’s technology structure in sense of substitution hard coal and lignite fired power plants with wind generators or with nuclear power plants is also analyzed. The analysis points out that the substitution with nuclear power plants enables much better results regarding power system’s ability to change the power on demand than substitution with wind generators, particularly in the countries with high participation of hard coal and/or lignite in electricity generation.

Punjab is a state with enormous biomass potential resource available as crop residue called agri-waste. In the wake of utilizing agricultural waste as local fuel, feeding and thatching, it is widely available. The burning of agricultural-waste in the atmosphere pollutes the environment and promotes global warming. Thereby it is essential to use this waste for human’s worthiness. This article presents the region-wise production from biomass build-ups and the surplus potential. Roughly 64 Mty-1 of the total build-up is created from diverse main and insignificant yields, out of which 60.22% is expended in diverse structures, bringing about 40.3% as a net surplus accessible for energy generation. Essential and net surplus product build-ups for energy potential were calculated in every province. Moga, Patiala, Gurdaspur, Ludhiana, and Jalandhar are the actual excess biomass potential areas. In contrast, Pathankot, Fatehgarh Sahib, Rupnagar Shaheed Bhagat Singh Nagar, Bathinda are the least biomass potential locale inside the state. About 1.263 GW and 1.199 GW of energy in the state can be produced using essential and net surplus biomass surplus individually. This paper also discussed the block-wise biomass potential in district Ludhiana. The proposed power plant location in this district, fuel cost, fuel availability and transportation cost are considered as constraints. It has been seen that maximum fuel is available at Sidhwanbet village. Still, by adding transportation cost and comparing results, it has been seen that the effective cost of fuel of plant located at the block–II Ludhiana is minimum.

In today’s world, use of renewable energy source is increased to decrease the usage of coal and water for generating electricity. One of the methods is, using solar energy for generating electricity. The efficient use of solar energy is an essential path which can deal with electricity crises. Even it has some problems, like aggregation of dirt and dust on the surface of the solar PV panel decreases the quantity of sunlight to penetrate and reach the solar cells, thereby shrinking the efficiency of PV panel. There are various techniques like manual cleaning, vacuum cleaning, electrostatic precipitator cleaning etc. With this cleaning mechanism, there can be an increase in the efficiency of the panel to about 15–20%. But each of the techniques has some disadvantages associated with it. Manual cleaning requires more manpower and there are some possibilities for damages to the Photovoltaic Panel on continuous usage of water or fluid. Vacuum cleaning mechanism results in scratches on the panel. So, we are using Automatic wiper cleaning using Arduino for cleaning the panel. In this paper we aim to reduce those disadvantages and enhance the efficiency and effectiveness of solar PV panel.

Conventional energy consumption in refrigeration is one of the important reasons in global warming. Solar cooling systems are becoming more compact, having lower costs, and are potential alternative technologies, especially in hot and sunny climates. The adsorption, absorption, and dissociative evaporative cooling (DEC) are the technologies used for sorption machines, which are discussed in this review paper. Various multi-criteria performance indicators appearing in the previous studies are discussed, followed by evaluating the benefits and drawbacks of distinguishing sorption solar thermal cooling systems. Market research is conducted to prove the capacity of these technologies. The review shows that compared to other technologies, the solar absorption system is more efficient, so it is very commonly used for cooling applications in various locations. An important topic was also presented using phase change materials and nanofluids in solar sorption systems, that need more research. It is noted from this that most solar cooling systems are hybrid in terms of source and there are multiple applications (cooling - heating and electricity generation). The software packages to study these systems are introduced. Further research is required on desiccant materials that can be regenerated under lower temperatures that would augment the extent of solar desiccant cooling application.

The role of Photovoltaic technologies integrated or attached to the building envelope is crucial in managing the building energy demand. In this paper, the performance of PV technologies with the mounting methods of Building integrated and Free-standing (Building attached) is discussed for six different climate zone of the country. A PVGIS program proposed with three PV cell technologies (Crystalline Silicon, Copper indium diselenide, Cadmium Telluride) is used to evaluate monthly energy generation potential and losses of the 2 kWp grid-connected PV system at the latitude and 90°. A 2 kWp PV system is chosen for Economic Weaker Section (EWS) housing schemes depending upon the roof area. From the evaluation, the performance parameter has been estimated. A new parameter Energy Deviation (ED), is proposed to choose the best PV technology in terms of performance. The results of ED agree with the parameters Performance Ratio (PR) and Capacity Factor (CF) defined under the IEC Standard 61724. The potential generation of PV technologies at 90° varies from 41% (Warm and Humid) to 64% (Cold and Sunny) when compared with the latitude. In case of Cold and Sunny and Cold and Cloudy at 90°, the generation performance of Copper indium diselenide is found better in Building integrated and Free-standing mounting methods, respectively. For the remaining zones, Cadmium Telluride technology shows better results. The Percentage loss in the system is found to be minimum in the case of Cold and Sunny, varies between 17% and 25%, and maximum is found for Warm and Humid and varies between 23.2% and 33.4% for the proposed PV technologies. The grid feed-in energy from these EWS houses for all the technologies and climatic zones is found above 45%. It is seen that the combined energy generation from the envelopes (Roof, walls, and facades) makes the houses energy plus in nature. The study has important implications for the government to promote the building integrated Photovoltaic policies in the country.

DC Microgrid (MG) with DC distribution system is an attractive technology over the last decade due to its inherent compatibility with renewable energy sources (RESs), DC loads, and storage devices. The worldwide growing concern on global warming and reduction of fossil fuel has raised the need for clean and eco-friendly RESs for electricity generation through the MG concept. DC MG can be linked to the main electrical grid or can act in isolation. Hence it is an effective system for isolated and rural areas, and it is accessible from small buildings up to huge plants. This paper reports an overview of the latest possible techniques and challenges in standardization, control approaches, protection issues associated with DC MG and DC distribution system. This paper also highlights the importance of DC MG for DC loads.

In this study, a thermodynamic and economic analysis of a synthetic fuel production facility by utilizing the hydrogenation of CO2 captured from biogas is carried out. It is aimed to produce methanol, a synthetic fuel by hydrogenation of carbon dioxide. A PEM electrolyzer driven by grid-tie solar PV modules is used to supply the hydrogen need of methanol. The CO2 is captured from biogas produced in an actual wastewater treatment plant by a water washing unit which is a method of biogas purification. The required power which is generated by PV panels, in order to produce methanol, is found to be 2923 kW. Herein, the electricity consumption of 2875 kW, which is the main part of the total electricity generation, belongs to the PEM system. As a result of the study, the daily methanol production is found to be as 1674 kg. The electricity, hydrogen and methanol production costs are found to be $ 0.043 kWh−1, $ 3.156 kg−1, and $ 0.693 kg−1, respectively. Solar availability, methanol yield from the reactor, and PEM overpotentials are significant factors effecting the product cost. The results of the study presents feasible methanol production costs with reasonable investment requirements. Moreover, the efficiency of the cogeneration plant could be increased via enriching the biogas while emissions are reduced.

A bottom hole temperature of 214 °C at 4700 m shows good potential for the development of an enhanced geothermal system (EGS) in the ZR2 well, Zhacang geothermal field, China. A reservoir stimulation plan has to be established to optimize the use of this target reservoir, with the objectives of increasing heat extraction and ensuring the service life. In this study, we used the lab parameters, ZR2 well logging data, and inverted in-situ stress data to conduct a numerical investigation to optimize reservoir stimulation and develop geothermal extraction strategies for the granodiorite reservoir at depths of 4100–4700 m. The results indicate that gel-proppant hydraulic fracturing and a two-horizontal-well system are feasible for this tight and unconfined reservoir. An installed capacity of 5.57– MW 6.80 MW and total power generation of 1695 GW · h are expected under the optimal combination of an injection temperature of 7.2 °C, an injection rate of 50 kg/s, and fracture spacing of 50 m during the 30-year operation period. The final production temperature will be maintained at approximately 171.3 °C, and the temperature drop is only 10.7%. The proposed geothermal engineering project will reduce greenhouse gas (GHG) emissions by 0.57–1.98 Mt compared to a fossil fuel plant. The levelized cost of electricity (LCOE) is estimated at 0.0413 $ / kW · h , which is much lower than the industrial electricity price of Qinghai province; thus, this project has significant development potential from an economic perspective.

One method of reducing atmospheric CO2 emissions in the transportationsector is the replacement of conventional fossil fuel-based vehicles withElectric Vehicles (EVs). However, fossil fuels are still the primary sourceof electricity production in many regions and the utilization of EVs in suchregions increases the electricity demand because of battery charging. Thisresults in increased burning of fossil fuels by thermal power plants andtherefore can offset savings in CO2 emissions resulting from the adoptionof EVs. In this paper, we consider a scenario where all fossil fuel-basedconventional vehicles are replaced by EVs and then estimate the net CO2emission savings resulting from the adoption of EVs in a region whereelectricity is primarily supplied by thermal plants. Only emissions generatedduring the operational phase of vehicle use are considered; emissions duringthe production phase are not considered. The region under consideration is Madeira, Portugal where thermal plants account for 80% of the total electric-ity produced. Our findings suggest that although EVs have huge potential tosave CO2 emissions, a substantial amount of the savings can be offset due tothe increased burning of fossil fuels by thermal plants to meet the electricaldemand of charging batteries.

Coal can be considered as the main fuel for electricity generation in Afghanistan. However, there is a quite limited data available about the overall quality, distribution, and character of coals in Afghanistan. Specific gravity (S.G) of coal as a key factor can be used for the estimation of potential tonnage production and be a fundamental parameter for the selection of coal washery process method. However, there is no investigation which comprehensively explores relationships between S.G and coal properties. In this investigation, the potential of S.G prediction based on conventional properties for Afghan coal samples was explored by stepwise regression and random forest. Pearson correlation (r) and variable importance measurement (VIM) of random forest (RF) were applied to select the most effective variables among conventional parameters for the S.G prediction. Results of VIM indicated that ash and carbon content of coal samples had the highest importance for the S.G prediction. Stepwise regression and RF models were developed based on these two coal variables. Testing the generated models indicated that S.G of Afghan coals can quite accurately predict by these models (R2 > 0.90). Modeling outcomes showed that the highest S.G (S.G > 2) for Afghan coal occurred when ash was higher than 40% and carbon was lower than 30%. Validerad;2023;Nivå 2;2023-06-30 (joosat);Licens fulltext: CC BY-NC-ND License

Industrial boilers by using biomass for electricity generation have received significant attention recent years. However, during the process, a significant fraction of thermal energy is often lost to the environment as flue gas. The exhaust flue gas heat loss which ranges from 150-180°C (423.15-453.15K) has led to discovery of importance of recovering the waste heat of the flue gas to overcome the reliance on fossil fuel. Stirling engine as an external combustion engine with high efficiencies and able to use any types of heat source is the best candidate to recover waste heat of the exhausted gas by converting it into power. Thus, in this study Stirling engine was introduced in order to evaluate the possibility of recovering waste heat from industrial boilers to produce power. For this reason, Computational Fluid Dynamic (CFD) simulation test was performed to design an initial computational model of Stirling engine for low temperature heat waste recovery. The CFD model was validated with the experiment model and shows 4.3% of deviation. The validated model then connected to a lower temperature. It shows that when the heat source is 400K, the work done by the engine is 8.4J compared to when heat source 773K the work done is 17.0 J. The computational model can be used to evaluate the performance of Stirling engine as waste heat recovery of biomass-based industrial boilers for low-grade temperature heat source.

This paper continues discussion on financial viability and design optimisation of biomass-fired Organic Rankine Cycle (ORC) Combined Heat and Power (CHP) systems. It examines influence of such decision variables as ORC system rated electric power output, architecture and working fluid. The considered ORC system structures are simple, regenerative and regenerative cycle with split heat exchanger. Eight working fluids are considered, namely: MM, MDM, MD2M, D4, D5, toluene, ethylbenzene, and cyclohexane. The system was modelled and simulated using Ebsilon® Professional software. Sample project is assessed in terms of power generation efficiency, Primary Energy Savings (PES), and financial indicators, such as Net Present Value (NPV) and Internal Rate of Return (IRR). Results revealed considerable differences in optimal power output. The optimal value of the ORC generator power output in terms of NPV is within the range from 1000 to 2600 kW depending on the system configuration and the working fluid. In terms of IRR the optimal rated power is between 750 and 1400 kW. The highest values of nominal rated power output have been obtained for ethylbenzene. What is more, the economic indicators get higher values for hydrocarbons than for silicone oils, which are nowadays widely used in biomass fired ORC systems.