Small-scale Generation Research Articles

Price-Guided Peer-To-Peer Trading Scheme and Its Effects on Transaction Costs and Network Losses

Distributed energy resources (DERs), such as small-scale renewable energy generators, storage systems, and controllable loads, have been attracting great attention. Accordingly, interest in peer-to-peer (P2P) energy trading between prosumers with DERs is growing. The prosumers may perform the P2P electricity trading within the loss-guided framework, where network losses are primarily considered during the peer matching process. However, the loss-guided framework has limitations in that prosumer welfare is neglected in favor of prioritizing the network losses caused by the P2P transactions. Thus, in this study, a price-based framework for P2P electricity trading is suggested, where the prosumer welfare is considered by including not only network loss costs but also energy costs in the matching procedure. The effects of the suggested price-based framework on network efficiency, prosumer welfare, and social welfare are examined by comparing simulation results with the loss-guided framework and the random transactions. Further, how those three properties are affected by the change in loss price is analyzed and a guideline for the suitable choice of the loss price is suggested.

Fusion-fission hybrid reactor with a plasma source of deuterium-tritium neutrons in a linear configuration

The current state of research in nuclear and thermonuclear energy enables the further development of modern energy using hybrid systems. In this work, the concept of a hybrid reactor with a plasma source of deuterium–tritium (D–T) neutrons (PSN) is proposed. The study is aimed at small-scale energy generation (∼10–100 MWt) which can be used in the medium term. The proposed facility consists of an axisymmetric assembly of high-temperature gas-cooled reactor (HTGR) fuel blocks and a PSN in a linear configuration. The synergy between HTGR and PSN technologies enables the transfer of the entire system to a hybrid, subcritical mode of operation, thereby dramatically increasing its nuclear safety level. The numerical studies conducted in this work may establish the basis for the design of a hybrid reactor with an extended pulsed PSN based on a magnetic trap.

Experimental study for thermal methane cracking reaction to generate very pure hydrogen in small or medium scales by using regenerative reactor

Non-catalytic thermal methane cracking (TMC) is an alternative for hydrogen manufacturing and traditional commercial processes in small-scale hydrogen generation. Supplying the high-level temperatures (850–1800°C) inside the reactors and reactor blockages are two fundamental challenges for developing this technology on an industrial scale (Mahdi Yousefi and Donne, 2021). A regenerative reactor could be a part of a solution to overcome these obstacles. This study conducted an experimental study in a regenerative reactor environment between 850 and 1,170°C to collect the conversion data and investigate the reactor efficiency for TMC processes. The results revealed that the storage medium was a bed for carbon deposition and successfully supplied the reaction’s heat, with more than 99.7% hydrogen yield (at more than 1,150°C). Results also indicated that the reaction rate at the beginning of the reactor is much higher, and the temperature dependence in the early stages of the reaction is considerably higher. However, after reaching a particular concentration of Hydrogen at each temperature, the influence of temperature on the reaction rate decreases and is almost constant. The type of produced carbon in the storage medium and its auto-catalytic effect on the reactions were also investigated. Results showed that carbon black had been mostly formed but in different sizes from 100 to 2000 nm. Increasing the reactor temperature decreased the size of the generated carbon. Pre-produced carbon in the reactor did not affect the production rate and is almost negligible at more than 850°C.

Small-Scale Energy Generation for Remote Rural Areas using Solar-Powered Compressed Air Storage System

Energy reach in the rural areas is still of major concern today especially in developing nations. Small-scale energy generation with stored compressed air is the focus of this work towards solving the energy deficit in remote rural environments through renewable sources. The method involves an experimental setup that harnessed energy from the sun through solar PV for isothermal compression and expansion of an air storage system to gain the advantages of low cost, longevity, and environmental friendliness of air storage in small scale electrical power generators. Results from a small, scalable, artificial air storage system of 360m3 show that one charge results in approximate temperature loss of 29oC for compression and 10oC for expansion (in a single cycle). A pressure charge of about 6bars from a compressor speed of 300rpm was also obtained and was able to maintain a constant alternator speed of 2500rpm on no load to produce electricity at 230Vac during expansion. When advanced and standardized, the air storage could provide a medium for cheap electrical energy storage for small scale renewable sources and a means for electrical energy availability in remote rural environments.

Effective grid connection approach for an overshot waterwheel

Interest in very small-scale hydropower generation has increased over the past few years. These pico-hydro systems range from a few watts to several kW. The exploitation of low head sites does not require expensive civil works and is environmentally sustainable. Pico-hydro systems are attractive not only for remote areas where the grid is not available, but also for grid connection. This is especially relevant in existing infrastructures, used for other activities but which can also be used for energy generation. Waterwheels are emerging with enormous potential in this context. Low speeds and variations in head and water flow are a constraint to their connection to the grid. This study shows that they can be effectively connected to the grid using competitive and widely available technology for other renewable sources, such as photovoltaics. This paper presents an innovative approach for an effective grid connection of a pico-hydro system based on an overshot waterwheel. For this purpose, a permanent magnet synchronous generator and a photovoltaic inverter are used. The compatibility between them is analysed in detail and the analysis is valid for other hydro turbines. The 2 m diameter waterwheel has been installed on an existing infrastructure of an aquaculture centre. With a flow rate of about 13 l/s, it injects an average power of 126 W into a microgrid with a global efficiency of 50%.

A survey on low speed low power axial flux generator design and optimization using simulation

Axial Flux Generator is a permanent magnet generator commonly used for low-speed power generation using wind power. This generator can generate useful amount of power even under very low revolutions per minute (rpm). Over the last three decades, many researchers and engineers have developed plethora of designs with varying success. Due to the commercial availability of rare-earth magnets such as NdFeB with very high magnetic flux density at very low prices, the propensity to develop new designs have sky rocketed. Yet, many designs even with the availability of many advanced analytical software tools have failed to produce useful amount of power under very low wind speeds. When the world is heading towards a more conscionable climate policy, wind power remains in the forefront of green energy. However, one major challenge in utilizing wind power is the inability of the small-scale generators to generate useful amount of power at very low wind speeds. This poses a formidable challenge to the scientific community to come up with the simplest, affordable and the most efficient design in harnessing wind power at very low wind speeds; that is the most common situation around the world.This research is the result of comprehensive and an exhaustive effort in bringing the best designs into the forefront of research by critiquing innovative designs for their strengths and weaknesses. Almost all the work in the literature has failed to realize the impact of the crucial parameters such as coil shape, coil distance and rare-earth magnet shape and their distances from each other on the eventual generator efficiency. This has resulted in most of the designs producing a very low output at very low revolutions. This article will present a comprehensive survey of best designs in axial flux generators followed by a mathematical analysis of coil shapes, magnet shapes and gaps between these coils and magnets. Then the article will present a very comprehensive electromagnetic simulations with multiple iterations in an effort to optimize the many parameters which have not been analysed in previous works. This new insight will open the research to a new height in achieving high efficiency in future designs.

A methodology for improved TSO-DSO coordination in grid operation planning

The pan-European electric grid evolves towards a network with a wide diversity of (micro-)energy systems spread throughout all voltage levels. At the transmission level, this poses new challenges for cross-border energy exchange. At the distribution level small-scale generation, storages, and controllable loads offer flexibility available for provision of ancillary services. Meeting the EU energy supply policy while optimally operating the network under these conditions needs advanced TSO-DSO collaboration schemes. Taking this into account, this paper proposes a methodology which combines application of local flexibility management and control with central grid operation planning in order to meet planning criteria for future network operation. We discuss motivation and methodology process and present results of a proof-of-concept where the methodology was applied to a synthetic benchmark grid model.

Mechanism for sequestering magnetic energy at large scales in shear-flow turbulence

Straining of magnetic fields by large-scale shear flow, which is generally assumed to lead to intensification and generation of small scales, is reexamined in light of the persistent observation of large-scale magnetic fields in astrophysics. It is shown that, in magnetohydrodynamic turbulence, unstable shear flows have the unexpected effect of sequestering magnetic energy at large scales due to counteracting straining motion of nonlinearly excited large-scale stable eigenmodes. This effect is quantified via dissipation rates, energy transfer rates, and visualizations of magnetic field evolution by artificially removing the stable modes. These analyses show that predictions based upon physics of the linear instability alone miss substantial dynamics, including those of magnetic fluctuations.

Design and Performance Evaluation of PM Vernier Generator Technology for a Small-Scale Uncontrolled Passive Wind Generator System

In this article it is proposed that permanent magnet Vernier generators be used for its new and unknown application in a small-scale uncontrolled passive wind generator system. Various aspects, such as the machine selection, conventional versus split-tooth topology, power matching, torque quality, and the overall feasibility of the proposal are investigated by evaluating optimized generator designs. It is found that the conventional permanent magnet Vernier generator with a magnetic gearing ratio of eight is the superior generator choice for this application. The performance of the optimum permanent magnet Vernier generator is validated through test results of a manufactured prototype. Other designs in the article are confirmed by comparing 2-D and 3-D finite element results.

Optimal design of a 5th generation district heating and cooling network based on seawater heat pumps

This work presents the design and the thermo-economic optimization of a novel layout of a 5th generation district heating and cooling network, for a residential district located in the Pantelleria island (South of Italy). The research focuses on a novel arrangement based on two bidirectional low-temperature neutral rings. For both rings, the fluid temperature is controlled by means of two groups of heat pumps cooled by seawater. The investigated layout also includes wind turbines and photovoltaic panels for power production. This layout will be used as a driver to promote the transition from the present centralized energy paradigm to a novel one, based on small-scale distributed generation integrated with renewables. The paper aims at evaluating the energy, economic and environmental savings achieved by this novel layout. A thermo-economic optimization is also implemented in order to determine the set of design/operating variables, maximizing system economic profitability. To this scope, a detailed approach is implemented, developing a dynamic simulation model of the system in TRNSYS 17. The developed simulation tool is able to mimic the real time operation of the system, for whatever weather condition, boundary and/or design variable. The results of the simulations show that the proposed layout achieves significantly positive results, with a primary energy saving and avoided greenhouse gases emissions equal to 133% and 134%, respectively. The economic profitability of the system is limited with the payback period close to 15 years, due to the high capital cost of the plant. The renewable electric production of the plant meets 57% of the district demand, although only 37% of this amount is self-consumed by the district. The study also includes a sensitivity analysis suggesting to limit the capacities of solar and wind fields to reduce the electricity in excess sold to the grid.

Statistical evaluation of wind speed forecast models for microgrid distributed control

With the increasing needs to decarbonise existing energy systems, there is an effort to integrate small-scale distributed generation sources, such as wind generators, with the electric demand in circuits known as microgrids. The operation of distributed variable renewable resources is subject to an optimum operating regime, ahead of real-time, which relies on output forecast. However, many wind speed forecast models are designed for centralised controllers, which are vulnerable to control failures. A suitable wind forecast model for a distributed control system is, therefore, required for optimal and reliable use of renewable generation. This paper presents a comparison of wind speed forecast models suited for distributed control, evaluating them in terms of the statistical significant difference in accuracy and computational resource requirements. This is essential since computational resources are limited in distributed control schemes. The data used in this paper is the historical wind speed of the Auchencorth Moss Atmospheric Observatory from 2016 to the end of 2019. Two forecast model types based on Auto-regression and Artificial Neural Network (ANN) are compared using the Diebold-Mariano test. Results show that ANN models with parallel hidden layers have the highest accuracy with statistical significant difference, while remaining suitable for microgrid distributed control.

An Operative Framework for the Optimal Selection of Centrifugal Pumps As Turbines (PATs) in Water Distribution Networks (WDNs)

The current significant increase in energy consumption has resulted in the need to develop and implement effective approaches for defining alternative and sustainable solutions to couple primary resources with supporting methods of energy generation. In the field of effective water distribution network (WDN) management, the suitability of combining pressure regulation with small-scale hydropower generation is attracting even more interest, given that it can possibly reduce water leakages, as well as produce attractive rates of renewable energy. Specifically, pumps as turbines (PATs) are widely considered a viable solution because they combine hydraulic benefits with affordable investment and management costs. Nevertheless, despite several approaches available in the literature for the optimal selection and management of PATs, choosing the most suitable device to be installed in the network is still a challenge, especially when electrical regulation is arranged to modulate the PAT rotational speed and optimize the produced energy. Several approaches in the literature provide interesting solutions for assessing the effectiveness of electrical regulation when a PAT is installed within a water network. However, most of them require specific knowledge of the PAT mechanical features or huge computational efforts and do not support swift PAT selection. To overcome this lack of tools, in this work, an operative framework for the preliminary assessment of the main features (the head drop and the produced power at the best efficiency point (BEP), the impeller diameter and the rotational speed) of a PAT is proposed, aimed at both maximizing the daily produced energy and performing challenging economic selection. Then, it is assessed by estimations of the corresponding payback period (PP) and the net present value (NPV).

AI Based Smart High Way with Green Energy Resources Using IoT Devices

Abstract: The Worldwide concern to mitigate the soaring energy crisis introduces us to the small-scale renewable energy generation as a preferred enabling source for highway lighting. Production of renewable energy from highways using solar tracking panel can be utilized in various applications. In this project we use solar panels to generate renewable energy which can be stored in lithium batteries. The IOT monitoring system in interfaced with Adafruit software which is used to check the pollution and stores the daily utilization in cloud. The SOS alarm is used along with the device to indicate the accident occurred in remote areas to the nearby toll gate. SOS message will send IFTTT to the domain mail ID toll gate. This prototype uses Node MCU for controlling application and database monitoring. In future the project can be extended by implementing other renewable resources like wind energy. Keywords: Sos alarm, Solar tracking panel, Adafruit, Mcu , Renewable enegry.

A Novel Model Predictive Control for Stability Improvement of Small Scaled Zero-inertia Multiple DGs Micro-grid

A zero-inertia micro-grid is a power system consisting of multiple renewable energy power sources and energy storage systems without the presence of conventional synchronous generators. In such a system, a large variation of the load or source sides during the islanded mode of operation extremely degrades the micro-grid's voltage and frequency stability. This study presents a virtual inertia-based predictive control strategy for a small-scale zero-inertia multiple distributed generators (DGs) micro-grid. In islanded mode, Voltage Model Predictive Control (VMPC) was implemented to control and maintain the voltage and frequency of the micro-grid. However, instabilities in frequency and voltage may rise at the Point of Common Coupling (PCC) due to large variations at both source and load sides. Therefore, the proposed virtual inertia loop calculates the amount of active power to be delivered or absorbed by each DG, and its effect is reflected in the estimated d current component of the VMPC, thus providing better frequency regulation. In grid-connected mode, Direct Power Model Predictive Control (DPMPC) was implemented to manage the power flow between each DG and the utility grid. The control approach also enables the DG plug and play characteristics. The performance of the control strategy was investigated and verified using the PSCAD/EMTDC software platform.

Design of a smart microgrid with small-scale hydro generation: a practical case study

Microgrids are local electric grids integrating distributed generation and consumption, energy storage and management and power control. They can be an alternative for the energy supply of a house, a building, a small village or a wider region. Small-scale hydropower, in the range of 5 kW, consists of distributed generation systems gaining increasing interest. These so-called pico-hydro systems are becoming popular since they can take advantage of the integration of low-power wind generators and photovoltaic (PV) inverters, which are widely available at competitive prices. Thus, pico-hydro systems are not only relevant for energy generation in off-grid systems in remote areas but also for new contexts where the utility grid is available. This paper presents the design of a smart microgrid with small-scale hydro generation. It is a practical case study with the integration of two grid-connected pico-hydro turbines: a low-head propeller turbine and a water wheel. The microgrid was designed and implemented in a small museum: Casa da Seda (House of Silk). The energy generation is based on the complementarity between hydro and PV. The microgrid can operate in both grid-connected and islanded modes and feeds the House of Silk loads. The connection of both pico-hydro turbines into the microgrid is based on the integration of wind generators and PV inverters.

Development of a Small-Scale Electricity Generation Plant Integrated on Biomass Carbonization: Thermodynamic and Thermal Operating Parameters Study

Biomass has been known as a source of energy with a thermochemical process that produces heat and can be converted further into electricity. However, thermal energy losses are a huge problem during combustion. To overcome this problem, a system based on organic Rankine cycle (ORCs) was developed to recover and utilize them to generate electricity. The proposed ORCs include an evaporator, a turbine, a condenser, and a pump coupled with a biomass carbonizing system to create a promising technology for small-scale electricity generation. In this work, a thermodynamic modelling equation based on energy and exergy balances was briefly expressed for each subcomponent of the system. A case study with R134a as the working fluid is being investigated to validate the system’s performance. In addition to the effects of R134a on temperature at the turbine exit, the suitable operating pressures has been specially adopted from several valid journals that focused on the effects of a wide range of possible operating pressure on the working fluid characteristics, which have a significant effect on the system performance. Finally, the theoretical analysis shows that the turbine work is profitable at an inlet pressure of 5 bar and an outlet pressure of 2 bar. This system is recommended to be integrated into the thermochemical biomass process. Recommendations have been made for the future development of small-scale biomass-fuelled power generation systems. This study shows that the thermal losses of the biomass thermochemical processes can be theoretically recovered in the form of electricity by using ORC efficiently.

Energy communities and key features emerged from business models review

Climate emergency has changed the way of supplying energy, replacing fossil fuels in favour of a transition to renewable sources crucial for the system decarbonization. This change has led to a review of the electricity consumption and distribution model. Recently end-users connected to distribution grids have taken an increasing active role in the electrical power system. Such a situation highlights how the combination between distributed generation-active user, through the concept of energy self-consumption that turns in energy sharing for a ‘collective’ form, allowed by virtual self-consumption, seems to be a good solution to achieve both climate targets and solve technical issues related to renewables penetration. Aggregation of end-users which produce and self-consume their energy within the same geographical perimeter express a new way to use renewable energy represented by the energy communities. The paper identifies the key elements that effect a business model for energy sharing by residential end-users equipped with small-scale renewable generation plants. In addition the simulation analysis investigate the feasibility from the aggregator point of view as well as the individual end-users evaluating also a minimum size for a viable renewable energy community.

Selection of O-negative induced pluripotent stem cell clones for high-density red blood cell production in a scalable perfusion bioreactor system.

ObjectivesLarge‐scale generation of universal red blood cells (RBCs) from O‐negative (O‐ve) human induced pluripotent stem cells (hiPSCs) holds the potential to alleviate worldwide shortages of blood and provide a safe and secure year‐round supply. Mature RBCs and reticulocytes, the immature counterparts of RBCs generated during erythropoiesis, could also find important applications in research, for example in malaria parasite infection studies. However, one major challenge is the lack of a high‐density culture platform for large‐scale generation of RBCs in vitro.Materials and MethodsWe generated 10 O‐ve hiPSC clones and evaluated their potential for mesoderm formation and erythroid differentiation. We then used a perfusion bioreactor system to perform studies with high‐density cultures of erythroblasts in vitro.ResultsBased on their tri‐lineage (and specifically mesoderm) differentiation potential, we isolated six hiPSC clones capable of producing functional erythroblasts. Using the best performing clone, we demonstrated the small‐scale generation of high‐density cultures of erythroblasts in a perfusion bioreactor system. After process optimization, we were able to achieve a peak cell density of 34.7 million cells/ml with 92.2% viability in the stirred bioreactor. The cells expressed high levels of erythroblast markers, showed oxygen carrying capacity, and were able to undergo enucleation.ConclusionsThis study demonstrated a scalable platform for the production of functional RBCs from hiPSCs. The perfusion culture platform we describe here could pave the way for large volume‐controlled bioreactor culture for the industrial generation of high cell density erythroblasts and RBCs.

A novel strategy to reduce carbon emissions of heavy oil thermal recovery: Condensation heat transfer performance of flue gas-assisted steam flooding

• Flue gas-assisted steam flooding was investigated to reduce carbon emissions. • Flue gas-assisted steam flooding improved the oil recovery factor by 20.02%. • Flue gas treatment and injection processes for steam injection wells were designed. • Site application showed that the underground CO 2 storage rate was 74.5%. • The novel strategy is suitable for a small-scale steam generator used in oilfields. In this paper, the flue gas-assisted steam flooding process from a novel perspective of condensation heat transfer performance was investigated to reduce carbon emissions of heavy oil thermal recovery. More specifically, steam condensation heat transfer coefficients with and without flue gas were tested, and heat transfer and oil recovery for steam flooding assisted by flue gas in a sandpack were studied. The experimental results indicate that the existence of the gas film on the condensation block increased the heat transfer resistance and decreased the condensation heat transfer coefficient. The gas channeling of flue gas provided a flow path for the steam and promoted heat transfer deep into the sandpack. Flue gas-assisted steam flooding improved the oil recovery factor by 20.02% compared with steam flooding, and 46.4% of the injected flue gas could be stored in the sandpack. The storage of flue gas could be divided into two parts: the flue gas dissolved in the residual heavy oil and the flue gas trapped in the porous media. Flue gas treatment and injection processes for steam injection wells were designed. Site application of flue gas-assisted steam injection showed that the oil production increased by 28.3%, and the underground CO 2 storage rate was 74.5%. The novel strategy of flue gas treatment and injection with steam greatly reduces the carbon emissions of heavy oil thermal recovery, which is very applicable for small-scale steam generator used in oilfields.

Performance enhancement of vertical axis hydrokinetic turbine using novel blade profile

Savonius hydrokinetic turbine is a promising technology for small-scale hydropower generation. The savonius turbine has a simple design and good starting characteristics but suffers from poor performance. In this study, a novel blade profile has been proposed to improve the performance of the conventional savonius turbine rotor. The new blade profile is based on a S1048 airfoil section. The geometry of S1048 airfoil section blades is composed of straight and curved segments. The long straight edge provides larger moment arm and gap flow while the curved segment decreases the effect of negative torque on the rotor. Unsteady RANS CFD simulations have been performed to evaluate and compare the performance of the proposed blade profile. It is shown that the maximum power coefficient of the conventional design can be improved by 14% at a tip speed ratio of 1, by using the new blade profile. The performance of the proposed design has also been evaluated by augmenting an upstream curtain arrangement with the turbine. As a result, an additional 13% increase in the power coefficient was realized when compared with the conventional augmented rotor.