Large-scale Electricity Production Research Articles

Uncertainty Evaluation of a Gas Turbine Model Based on a Nonlinear Autoregressive Exogenous Model and Monte Carlo Dropout.

Gas turbines are thermoelectric plants with various applications, such as large-scale electricity production, petrochemical industry, and steam generation. In order to optimize the operation of a gas turbine, it is necessary to develop system identification models that allow for the development of studies and analyses to increase the system's reliability. Current strategies for modeling complex and non-linear systems can be based on artificial intelligence techniques, using autoregressive neural networks of the NARX and LSTM type. In this context, this work aims to develop a model of a gas turbine capable of estimating the rotation speed of the turbine and simultaneously estimating the uncertainty associated with the estimation. These methodologies are based on artificial neural networks and the Monte Carlo dropout simulation method. The results were obtained from experimental data from a 215 MW gas turbine, getting the best model with a MAPE of 0.02% and an uncertainty associated with the turbine rotation speed of 2.2 RPM.

Transition Energétique - Remplacement d’une Microcentrale Diesel par un Système Renouvelable Hybride : Etude de cas.

This paper aims to study the replacement of a Diesel Generator based plant by a hybrid renewable system. To overcome both source and load fluctuations, a battery-based storage system is used. The renewable energy resources available in southern Algeria is considerable. Actually, this region has one of the largest wind capacity in the country with wind speeds up to 4 to 6 m/sec, the wind energy density is 280-Watt/m2/ day. Meanwhile, the solar potential is characterized by an average duration of sunshine above 11 hours/day and the energy they can provide for a large-scale industry can change the development of the region and of the whole country.Genetic algorithms under optimtool is used to size hybrid systems. The resulting levelized cost of electricity (LPSP) of $0.262/kWh, is competitive and economical if a large-scale electricity production is undertaken. The loss of power supply probability or customer dissatisfaction rate (LPSP) of 1.2545 %, which is within standard limits.

Inclusion of key social indices for a comparative assessment of the sustainability of the life cycle of current and future electricity generation in Spain: A proposed methodology

The purpose of this work is to offer a methodology for the introduction and consolidation of social indexes within a Life Cycle Sustainability Assessment for the evaluation of large-scale electricity production. This methodology is based on an interrelation of the UNEP subcategories with the global indicator framework for the Sustainable Development Goals, resulting in 9 categories of social impact quantified by 10 indexes. To evaluate the introduction of this methodology in an LCSA a study case is used. It is applied to obtain social indexes for the 2019, 2030 and 2050 Spanish electricity scenarios, which involve different electricity generation and storage technologies: involve coal, natural gas, nuclear, hydropower, wind, solar photovoltaic, concentrated solar, biomass and storage technologies. Within the study case, an environmental life cycle assessment is also conducted, while the impacts of the economic dimension are estimated by the levelized cost of energy. This study reveals that even before important qualitative information is brought to light, as should be done in any decision-making process, there are important gaps that can be filled in terms of quantitative information in an LCSA. To do so, it provides with a methodology to expand the number of social indexes normally used in this type of assessments with the purpose of contributing to decision processes with clarity and transparency. Labour rights, salary differences for the same position, diversity in executive positions, child labour, and R&D expenditure complement the previously used occupational injuries, fatalities due to large accidents, and direct employment. The proposed methodology is applied to a Spanish case study, demonstrating the benefits and disadvantages associated with the modification of the electricity mix. However, it also highlights significant information gaps in availability and transparency that need to be addressed in future research, as part of the path towards standardizing LCSA.

Inter- and intra-annual variability of wave energy in Northern mainland Portugal: Application to the HiWave-5 project

Ocean wave energy capacity has been pointed out as one of the unexplored renewable energy sources to help reach net zero carbon emissions by 2050, contributing to meeting the European Green Deal targets. However, despite the broad range of wave energy converter technologies already developed in a sustainable and economic model, there is still a lack of structured projects with high performance beyond the prototype stage. This paper investigates the potential for large-scale electricity production by the innovative HiWave-5 project in Aguçadoura (on the Northern coast of mainland Portugal). Wind–wave data (1950–2020) from the ERA5 reanalysis model are used to estimate inter- and intra-annual wave energy variability in Aguçadoura. ERA5 data is compared with field wind–wave data recorded between 2012–2019 near the study area. A mean wave power resource of 25.84 kW/m is obtained, for a possible device capture equal to 119.45 kW, despite a considerable intra-annual variability (ranging between 8.03 and 47.57 kW/m) and inter-annual variability (between 18.29 and 35.47 kW/m). Results show that local wave conditions do not substantially compromise the absolute performance of the device, given its survival limitations to adverse conditions. Considering a Levelized Cost of Energy of around €60/MWh, an annual investment of €62 885 is estimated, tending to meet targets for large sustainable electricity generation with the exponential growth expected until 2030, aided by the increase of devices in an energy farm concept. Wave power resources estimated using ERA5 data can underestimate about 7.20% values obtained with the wave buoy data.

Assessment of the Wind Energy Potential of Two Burundian Sites

1-year hourly wind speed data from two Burundian stations, namely Bujumbura and Muyinga, have been processed in this work to bring an efficient help for the planning and installation of wind energy conversion systems (WECS) at those localities. Mean seasonal and diurnal variations of wind direction and wind shear exponent have been derived. Two-parameter Weibull probability density functions (PDFs) fitting the observed monthly and annual wind speed relative frequency distributions have been implemented. As shown through three complementary statistical tests, the fitting technique was very satisfactory. A wind resource analysis at 10 m above ground level (AGL) has led to a mean power density at Bujumbura which is almost thirteen fold higher than at Muyinga. The use of the empirical power law to extrapolate wind characteristics at heights from 150 to 350 m AGL has shown that energy potential of hilltops around Muyinga was only suitable for small, individual scale wind energy applications. At the opposite, wind energy potential of ridge-tops and hilltops around Bujumbura has been found suitable for medium and large scale electricity production. For that locality and at those heights, energy outputs and capacity factors (CF or Cf) have been computed for ten selected wind turbines (WTs), together with costs of electricity (COE) using the present value of cost (PVC) method. Amongst those WTs, YDF-1500-87 and S95-2.1 MW have emerged as the best options for installation owing to their highest CF and lowest COE. Moreover, an analysis of those two quantities at monthly basis for YDF-1500-87 WT has led to its best performance in the dry season. Compared to the average present COE of household hydroelectricity consumption, results of this study have evidenced economical feasibility and benefit of WECS setting in selected Burundian sites in order to supplement traditional electricity sources.

Ultra-low lattice thermal conductivity and high thermoelectric efficiency in Cs2SnX6 (X=Br, I): A DFT study

High-performance thermoelectric materials provide an environmentally friendly route for future large-scale electricity production from waste heat recovery. In this work, we present an in-depth analysis of electronic, phononic, and thermoelectric properties of vacancy-ordered double perovskite Cs2SnX6 (X = Br, I) compounds based on generalized gradient approximations (GGA) and post-density functional theory treatments. We find that the optical phonon scattering mechanism plays a more critical role than the acoustical phonon and impurity scattering in both materials' transport properties. These materials also exhibit a relatively large Seebeck coefficient and ultra-low lattice thermal conductivity about 0.123/0.062 W/mK for Cs2SnBr6/Cs2SnI6 at room temperature calculated by single relaxation time model (SMRT). Such ultra-low lattice thermal conductivity arises from significant phonon-phonon scattering due to highly overlapped acoustic and optical phonon branches around ~1 THz. This occurrence introduces the Cs atom's rattling motion inside [SnX6]2- (X = Br, I) cages. The most considerable ZT values with the SMRT method at 300/500 K are about 0.32/0.82 for Cs2SnBr6 and 0.9/1.96 for Cs2SnI6. Our theoretical results suggest that both compounds have a great potential to be good candidates for thermoelectric materials and can be used to guide experimental investigation to obtain the optimal ZT performance.

Hydrogen production in the Swedish power sector: Considering operational volatilities and long-term uncertainties

With more renewables on the Swedish electricity market, while decommissioning nuclear power plants, electricity supply increasingly fluctuates and electricity prices are more volatile. There is, hence, a need for securing the electricity supply before energy storage solutions become widespread. Electricity price fluctuations, moreover, affect operating income of nuclear power plants due to their inherent operational inflexibility. Since the anticipated new applications of hydrogen in fuel cell vehicles and steel production, producing hydrogen has become a potential source of income, particularly when there is a surplus supply of electricity at low prices. The feasibility of investing in hydrogen production was investigated in a nuclear power plant, applying Swedish energy policy as background. The analysis applies a system dynamics approach incorporating the stochastic feature of electricity supply and prices. The study revealed that hydrogen production brings alternative opportunities for large-scale electricity production facilities in Sweden. Factors such as hydrogen price will be influential and require in-depth investigation. This study provides guidelines for power sector policymakers and managers who plan to engage in hydrogen production for industrial applications. Although this study was focused upon nuclear power sources, it can be extended to hydrogen production from renewable energy sources such as wind and solar.

Improving electricity from silk cocoons through feeding silkworms with silver nanoparticles

Silk Cocoon Membrane (SCM) a complex natural protein fibrous membrane is gaining significant attention in the textile industry, the biomedical industry and the research society due to its outstanding properties and ecological friendliness. In this work, we report improved electrical properties of SCM through in-vivo addition of silver nanoparticles (AgNPs) to the silkworm. After feeding silkworm larvae with different concentrations of nanoparticles, the survival rates, and the performance of the larva and cocoon weights were evaluated, it was found that AgNPs through increase cocoon weights, in high concentrations, had some lethal effects on silkworms as well as affecting normal body performance of the silkworm larva. An analysis of the electric properties of the SCM fed on AgNPs under different conditions of temperature and humidity revealed the in-vivo fed AgNPs to silkworm for the production of SCM embedded with AgNPs results in an increase in electricity obtained from the SCM. Therefore, the successful generation of silver nanoparticle cocoons by in-vivo feeding is expected to open up possibilities for the large-scale production of electricity from the silk cocoon membrane.

Methods of Improving the Efficiency of Thermal Power Plants

As one of the most important power sources in modern society, electricity takes up a large proportion of modern energy consumption. Among all those methods of power generation, fossil-fuel thermal power generation is one of the earliest ways of large-scale electricity production. Its popularity in the modern society comes from its stability and controllability. Given the wide applications of electricity around the world, improving the efficiency of thermal power plants would be an effective way to reduce the total energy consumption and protect the environment. The paper discusses the efficiency of energy transition and its determinant during each stage of power generations along with proposals to improve the efficiency of thermal power generation.

Tailoring large-scale electricity production from variable renewable energy sources to accommodate baseload generation in europe

Abstract This work investigates the possibility of combining large-scale penetration (around 50% of annual demand) of variable electricity production (wind and solar power) with baseload generation of electricity (e.g., via nuclear power or coal burning). A new methodology is developed that focuses on renewable resource and variation management in combination with transmission expansion and curtailment of excess electricity generation. Using the Conditional Value-at-Risk (CVaR) measure in the objective function, the optimization model targets the residual load and tailors it to fit the baseload generation. Using Europe as an example, the results show that it is possible to tailor the residual load to fit the baseload with only a small sacrifice (∼1%) of output of generation from variable renewable energy sources (VRES). Expansion of the electricity transmission system is an important factor in accommodating baseload generation in systems with a high penetration level of VRES, whereby, for example, 50 GW of transmission capacity opens the way for baseload generation to increase from 20% to 32% of annual demand. The results show that wind power is the main contributor to VRES production, even in the case of exceptionally low future costs for solar PV.

Arrays of Point-Absorbing Wave Energy Converters in Short-Crested Irregular Waves

For most wave energy technology concepts, large-scale electricity production and cost-efficiency require that the devices are installed together in parks. The hydrodynamical interactions between the devices will affect the total performance of the park, and the optimization of the park layout and other park design parameters is a topic of active research. Most studies have considered wave energy parks in long-crested, unidirectional waves. However, real ocean waves can be short-crested, with waves propagating simultaneously in several directions, and some studies have indicated that the wave energy park performance might change in short-crested waves. Here, theory for short-crested waves is integrated in an analytical multiple scattering method, and used to evaluate wave energy park performance in irregular, short-crested waves with different number of wave directions and directional spreading parameters. The results show that the energy absorption is comparable to the situation in long-crested waves, but that the power fluctuations are significantly lower.

Small-Scale Renewable Energy Converters for Battery Charging

This paper presents two wave energy concepts for small-scale electricity generation. In the presented case, these concepts are installed on the buoy of a heaving, point-absorbing wave energy converter (WEC) for large scale electricity production. In the studied WEC, developed by Uppsala University, small-scale electricity generation in the buoy is needed to power a tidal compensating system designed to increase the performance of the WEC in areas with high tides. The two considered and modeled concepts are an oscillating water column (OWC) and a heaving point absorber. The results indicate that the OWC is too small for the task and does not produce enough energy. On the other hand, the results show that a hybrid system composed of a small heaving point absorber combined with a solar energy system would be able to provide a requested minimum power of around 37.7 W on average year around. The WEC and solar panel complement each other, as the WEC produces enough energy by itself during wintertime (but not in the summer), while the solar panel produces enough energy in the summer (but not in the winter).

Optimization of a Heliostat Field Layout on Annual Basis Using a Hybrid Algorithm Combining Particle Swarm Optimization Algorithm and Genetic Algorithm

Of all the renewable power generation technologies, solar tower power system is expected to be the most promising technology that is capable of large-scale electricity production. However, the optimization of heliostat field layout is a complicated process, in which thousands of heliostats have to be considered for any heliostat field optimization process. Therefore, in this paper, in order to optimize the heliostat field to obtain the highest energy collected per unit cost (ECUC), a mathematical model of a heliostat field and a hybrid algorithm combining particle swarm optimization algorithm and genetic algorithm (PSO-GA) are coded in Matlab and the heliostat field in Lhasa is investigated as an example. The results show that, after optimization, the annual efficiency of the heliostat field increases by approximately six percentage points, and the ECUC increases from 12.50 MJ/USD to 12.97 MJ/USD, increased about 3.8%. Studies on the key parameters indicate that: for un-optimized filed, ECUC first peaks and then decline with the increase of the number of heliostats in the first row of the field (Nhel1). By contrast, for optimized field, ECUC increases with Nhel1. What is more, for both the un-optimized and optimized field, ECUC increases with tower height and decreases with the cost of heliostat mirror collector.

Study of Charge Transfer Dynamics in Spray Deposited Cu2ZnSnS4 (CZTS) Photoelectrodes for Performance Improvement

Thin film solar cell based on Cu2ZnSnS4 (CZTS) has the potential for large scale electricity production using solar radiation where the elements are earth abundant, inexpensive and environment friendly. The state of art CZTS solar cell has reached 12.6% efficiency while the commercial production will require at least 15% for economic feasibility. Here, we approach to understand the charge transfer dynamics in CZTS using ultrafast laser spectroscopy and focus on improving the efficiency of CZTS photovoltaics through the incorporation of a mesoscopic hole acceptor, nickel oxide. CZTS photo electrode is prepared using spray deposition of precursor solution, and characterized using SEM, TEM, XRD, XPS and Raman Spectroscopy. The performance of the material is tested in three electrode photo electrochemical cell.

Calling for Nexus Thinking in Africa's Energy Planning

The simultaneous achievement of the sustainable development goals (SDGs) is, to say the least, challenging. In a situation of increasing and multiple demands over limited resources, pursuing each goal separately could lead to increased competition. The situation in Africa is particularly problematic, as the continent lags behind all others in terms of quality and quantity of infrastructure and counts the highest shares of population living in poverty and without access to food, safe water, and energy. At the same time, natural resources are under increasing pressure from population growth, environmental degradation, and climate change. Given the entity of the challenge, finding synergies and strengthening coordination across sectors will be crucial and the energy sector has an important role to play. As recognized in the Agenda 2030, the energy sector holds the key to many aspects of development, however no energy solution (albeit green or synergetic) should be casually labelled as a nexus solution. This could be deceiving also because of the ambiguities that surround the concept of nexus. In order to give concrete insights to policy makers, this paper proposes a pragmatic approach to the nexus that allows on one hand to detect areas where cooperation needs to be strengthened, on the other to explore the nexus potential of energy solutions. This is in line with a view of the nexus as a way of thinking, which can apply both at the level of policy making and in the actual implementation of projects. We will give three concrete examples to improve energy access at different levels: multipurpose hydropower for large-scale electricity production, solar pumps for irrigation in farms, and efficient cookstoves in households. These can catalyse much needed action in other areas (notably water supply, agriculture, and forestry) but realizing their potential requires stronger cooperation and coordination across sectors. Moreover, their successful implementation requires an honest and thorough assessment of the local context in terms of constraints as well as opportunities.

Inter-fuel substitution possibilities in South Africa: A translog production function approach

This study applies the translog production function to investigate technical change and energy substitution possibilities among petroleum, coal and electricity over the period 1980–2012. Ridge regression technique is introduced to correct for multicollinearity in the data. The study documents several findings: first, electricity and coal are found to be the major drivers of South African output and also have a faster technological progress over petroleum. Second, all energy inputs were found to be substitutes; therefore removing all price ceilings and subsidies on petroleum will decrease the demand for petroleum in effect protecting South African economy from external petroleum price shocks while reducing CO2 emissions. This will also increase the demand for electricity from renewable sources; however the success of this substitution will depend on policies geared towards large scale electricity production to meet demand. Third and finally, this study points to evidence that, even though coal dominates as the main energy source of South Africa, enhancement in research and development of renewable energy technologies could present opportunities for electricity as a potential replacer of coal; and as such, accelerating the CO2 mitigation effort of the South African government.

A conceptual framework for hydropeaking mitigation

Hydropower plants are an important source of renewable energy. In the near future, high-head storage hydropower plants will gain further importance as a key element of large-scale electricity production systems. However, these power plants can cause hydropeaking which is characterized by intense unnatural discharge fluctuations in downstream river reaches. Consequences on environmental conditions in these sections are diverse and include changes to the hydrology, hydraulics and sediment regime on very short time scales. These altered conditions affect river ecosystems and biota, for instance due to drift and stranding of fishes and invertebrates. Several structural and operational measures exist to mitigate hydropeaking and the adverse effects on ecosystems, but estimating and predicting their ecological benefit remains challenging. We developed a conceptual framework to support the ecological evaluation of hydropeaking mitigation measures based on current mitigation projects in Switzerland and the scientific literature. We refined this framework with an international panel of hydropeaking experts. The framework is based on a set of indicators, which covers all hydrological phases of hydropeaking and the most important affected abiotic and biotic processes. Effects of mitigation measures on these indicators can be predicted quantitatively using prediction tools such as discharge scenarios and numerical habitat models. Our framework allows a comparison of hydropeaking effects among alternative mitigation measures, to the pre-mitigation situation, and to reference river sections. We further identified key issues that should be addressed to increase the efficiency of current and future projects. They include the spatial and temporal context of mitigation projects, the interactions of river morphology with hydropeaking effects, and the role of appropriate monitoring to evaluate the success of mitigation projects.

Dynamic modelling and validation of a commercial scale geothermal organic rankine cycle power plant

The organic rankine cycle (ORC) is a heat recovery technology used for renewable energy generation such as the large-scale production of electricity from geothermal resources. In this paper a dynamic model of a commercial-scale geothermal ORC is developed in process simulation software and validated against plant data. The difference in power output between the model and plant was found to be 0.24% with a standard deviation of 1.40% of the average power output. The results from model validation are used to suggest improvements to the model, which is intended to be used for further investigation of optimisation and process control.

ANALYSIS OF ECOLOGICAL ACTIVITY OF PODLASIE PROVINCE

The beginning of the period where the impact of human activity took dangerous size is considered to be 40 years of the nineteenth century. Then the large-scale production of electricity increased production of metallurgical industry and transport development. Significant changes contributed to rapid population growth and urbanization and in dustrialization processes. Man by intensive exploitation reduces or completely exhausted most natural resources. This has resulted in the availability criterion, which is distinguished by inexhaustible and exhaustible resources. Exhaustible resources may include solar, wind, energy, ocean currents and the energy of the Earth. Exhaustible resources, however, are the elements of nature that as a result of the operation can be completely depleted or destroyed. These resources include: water, soil, plant world, animal world natural resources. The greater the intensity of acquiring human resources, the faster will be the depleted. There is also a very important division of exhaustible resources: non-renewable resources, renewable and very difficult reproducible (living areas). Non-renewable resources are mainly minerals, such as iron ore, crude oil, coal, sulfur, natural gas, useful stones, limestone, salt, and many other minerals). After extraction resources are processed, and the bed from which they were extracted can no longer be used. It is different from renewable resources; they are characterized by the fact that over time they are reconstituted, although, for this to happen balance of the environment through the rational use must be maintained. These resources include, among others, soil, water, flora and fauna, as well as atmospheric air.

Decentralized Control of Solid Oxide Fuel Cells

Environmental concerns and limited availability of natural resources have made solid oxide fuel cells (SOFC) a promising alternative for large-scale electricity production. A control system is needed for SOFCs to meet operational objectives and ensure safe operation. Previous studies showed that the control of SOFC is challenging due to its slow response time, tight operating constraints and unavailability of some key measurements. In this work, simple yet reliable decentralized proportional-integral-derivative (PID) controllers are systematically designed based on a benchmark nonlinear dynamic model of SOFC . The design procedure involves selection of controlled variables (CVs), input-output pairing selection, and PID controller tuning. For CV selection, a novel method is proposed such that maintaining the CVs at constant setpoints facilitates constraint satisfaction for all key variables. Closed-loop simulations demonstrate that the proposed decentralized PI controllers are able to closely meet the control objectives of SOFC even in the presence of changing operating conditions.