Modelling Of An Architecture For Local Energy Generation And Distribution With Peer-To-Peer Electricity Sharing In A South African Context

DissertationThe increasing share of variable renewable energy sources, strict targets set for the reduction of greenhouse gas emissions and the requirements on the improvement of system security and reliability, are calling for important changes in our energy systems. In South Africa, distributed renewable energy systems have emerged as effective ways in improving the quality of energy service. The integration of distributed renewable energy, such as solar photovoltaic systems (PV) and micro-grids, is significantly increasing the coupling and interactions between sources and between supply and end use, at various scales, from multinational, national, and community scale, down to building level. In a South African context, power produced from the renewable energy that is not consumed by the load, needs to be stored for later use, or discarded, as the power utility, as well as the municipalities do not generally allow the power to be sold, or shared through the national grid. In the case where various small generation units residing on the same land (estates or a block of townhouses), the power generated from the PV may be shared between the various consumers on the same land. Consumers on the same land having different load patterns as not everyone uses electricity simultaneously connecting them in a micro-grid may allow the power to flow between the different generation systems and consumers. This will decrease the size of the storage systems, as well as the amount of power dumped and lost when it is not in use. On the other hand, the reliance on the grid power will further decrease. With the increasing installation of distributed generation at the demand side, more and more consumers become prosumers, that may both generate and consume energy. The high penetration of sporadic renewable energy may cause severe problems to power systems. Therefore, in order to facilitate the self-consumption of local generation, the export price at which the prosumers sell electricity to the utility grid is usually designed to be significantly lower than the retail price at which electricity is being purchased. This is the major motivation for prosumers to share excess electrical energy amongst each other, rather than to feed it back to the utility grid at a significantly reduced cost. The decreasing tariff rate of the feed-in tariff in most countries, does make this incentive a significantly more attractive approach. The mathematical modelling of the operation of Peer-to-peer (P2P) energy sharing model between two dissimilar load profiles, will be discussed. These profiles are of typical commercial and residential nature. The P2P system consists of two prosumers: the residential prosumer that has a roof mounted PV system that is fixed at a 30° angle, with energy storage capabilities and commercial prosumer, with a solar tracking system. A description of the system is discussed in detail, with all the relevant components outlined. In order to evaluate the cost effectiveness of the hybrid system, in terms of money spent, a baseline system was established, consisting solely of energy supplied by the grid. The optimal operation of the proposed system was simulated and compared to the baseline system. A life cycle cost (LCC) analysis was conducted for a period of 20 years, for both the baseline and the optimally controlled P2P energy sharing scheme. In addition, two electrical energy storage technologies were evaluated for the proposed system. These technologies include lead acid and lithium ion energy storage configurations. Results from the analysis indicated that, if the system were to use lead acid batteries as a storage medium, the proposed system would break-even in 5.304 years, with an approximate saving of 57%, translating into savings of R 1,972,277.98. The proposed system with Li-ion battery storage, indicated a break-even point of 5.131 years, with an expected saving of 54%, translating into cost savings of approximately R 1,861,939.36 at the end of the evaluated life cycle period. Based on the results from the study, it was observed that the optimally controlled P2P energy sharing scheme has shown to be economically feasible, in the South African context

An optimal schedule model of multi-energy hubs network integrating solar energy

Recently, multi-energy systems based on energy hub are introduced because of significant benefits in reducing energy and emission cost. This paper proposed an optimal schedule model of multi-energy hubs networks consisting of energy hubs, renewable sources, and energy storage which are connected by electrical and natural gas distribution networks. In the proposed mixed-integer nonlinear programming model, the objective is to minimize the operation, energy, and emission costs of energy hubs with both renewable sources and storage and energy distribution networks. The proposed schedule framework allows simultaneously selections of optimal operation structure of EHs together with the optimal operation parameters of energy distribution networks and therefore this model can maximize the profit of the entire large-scale multi-energy hubs network. Besides, the operation parameters and energy loss of both electrical and natural gas distribution networks are considered in conjunction with optimal operation of energy hubs and thus guarantee the operation and optimization of the network in all operational scenarios. The IEEE 5-bus test system is utilized to demonstrate the applicability of the proposed model. The simulation results show the feasibility of the proposed model, and demonstrate that the energy hubs, renewable sources, and energy storage in the proposed structure significantly enhance the efficiency of the multi-energy hubs network by reducing not only energy and operation costs but also emission

Simulation-Based Evaluation and Optimization of Control Strategies in Buildings

Over the last several years, a great amount of research work has been focused on the development of model predictive control techniques for the indoor climate control of buildings, but, despite the promising results, this technology is still not adopted by the industry. One of the main reasons for this is the increased cost associated with the development and calibration (or identification) of mathematical models of special structure used for predicting future states of the building. We propose a methodology to overcome this obstacle by replacing these hand-engineered mathematical models with a thermal simulation model of the building developed using detailed thermal simulation engines such as EnergyPlus. As designing better controllers requires interacting with the simulation model, a central part of our methodology is the control improvement (or optimisation) module, facilitating two simulation-based control improvement methodologies: one based in multi-criteria decision analysis methods and the other based on state-space identification of dynamical systems using Gaussian process models and reinforcement learning. We evaluate the proposed methodology in a set of simulation-based experiments using the thermal simulation model of a real building located in Portugal. Our results indicate that the proposed methodology could be a viable alternative to model predictive control-based supervisory control in buildings.Research leading to these results has been partially supported by the Modelling Optimization of Energy Efficiency in Buildings for Urban Sustainability (MOEEBIUS) project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 680517. Georgios Giannakis and Dimitrios Rovas gratefully acknowledge financial support from the European Commission H2020-EeB5-2015 project “Optimised Energy Efficient Design Platform for Refurbishment at District Level” under Contract #680676 (OptEEmAL). Georgios Kontes and Christopher Mutschler gratefully acknowledge financial support from the Federal Ministry of Education and Research of Germany in the framework of Machine Learning Forum (grant number 01IS17071). Georgios Kontes, Natalia Panagiotidou, Simone Steiger and Gunnar Gruen gratefully acknowledge use of the services and facilities of the Energie Campus Nürnberg. The APC was funded by MOEEBIUS project. This paper reflects only the authors’ views and the Commission is not responsible for any use that may be made of the information contained therein

Smart grid systems infrastructures and distributed solar power generation in urban slums–A case study and energy policy in <i>Rio de Janeiro</i>

This article discusses the relationship between urban slums and the management of the urban infrastructure network (electrification). An extensive survey of the scientific literature on the subject points out the main challenges and possible solutions for fixing precarious electrical infrastructure in urban slums through the promotion of public policies and the establishment of new arrangements based on distributed generation technologies and smart grid. A dialogue was also developed involving topics such as sustainable development and electrification of slums; relationship between communities and modernization of electrification; and emerging and sustainable technologies in the context of urban slums. Thus, a design was constructed that triggered a discussion of the relationship between this work and several other works found in the literature. This research indicates the need to strengthen local governance and the participation of urban slums for the technological modernization of the local electrical network, mainly with the implementation of smart grid and photovoltaic generation systems

Tecniche integrate di Remote Sensing e GIS a supporto della stima del potenziale fotovoltaico su tetti in aree urbane

Le ultime linee guida approvate dal Governo Italiano per sostenere finanziariamente il fotovoltaico (PV) e lo sviluppo della produzione di energia solare (Quarto e Quinto Conto Energia, Gennaio 2012 e succ.), al fine di evitare il consumo di suolo in aree agricole o naturali, comprendono indicazioni specifiche che rendono più vantaggiosa l’installazione d’impianti su tetti o superfici di copertura di edifici. In questo contesto diventa importante, per una adeguata attività di pianificazione e monitoraggio del PV, la mappatura estensiva delle superfici a disposizione, coincidenti con i tetti e l’accurata valutazione del loro potenziale fotovoltaico. Dal momento che tali coperture si trovano soprattutto nelle aree urbane o industriali, in cui fattori come eterogeneità tridimensionale, albedo, torbidità atmosferica ed ombreggiamenti reciproci influenzano in modo significativo l’irraggiamento solare locale, è necessario tenere conto adeguatamente di questi elementi mediante una mappatura GIS tridimensionale ed avanzati strumenti di modellazione, in modo da stimare efficacemente la radianza solare disponibile a livello dei tetti. La metodologia implementata, basata su tecniche di telerilevamento e GIS, ha permesso di valutare e mappare la radiazione solare globale su tutti i tetti presenti nel territorio del Comune di Avellino. Partendo da dati di tipo LIDAR, è stato ottenuto in primo luogo il DSM di tutta l’area di interesse (~ 42 Km2), quindi il modello tridimensionale di ogni edificio da cui sono stati derivati i parametri geometrici di tutte le coperture. Per tenere conto della trasparenza atmosferica e della percentuale di radiazione solare (diffusa/diretta) sulle superfici di interesse, sono stati utilizzati i dati e gli strumenti applicativi presenti sul sito web PVGIS, sviluppato dalla UE. L’elaborazione finale, basata sull’utilizzo di strumenti GIS anche di tipo open source, ha permesso di ottenere le mappe di radianza solare e di potenziale PV per tutti i tetti presenti nell’area di studio.The last guidelines approved by Italian government to financially support the solar Photovoltaic (PV) Energy production development (Fourth and Fifth feed-in-scheme, January 2012 and later), in order to avoid soil consumption in agricultural or naturals areas, include specific indications for more advantageously funding the installations exploiting roofs or covers surfaces. In this context it becomes important, for a suitable PV planning and monitoring, the extensive mapping of the available surfaces extent, usually corresponding to covers and properly assessing their quality in term of PV potential. Since the covers are mainly located in urban or industrial areas, whose 3D heterogeneity, albedo, atmospheric turbidity and casting shadows significantly influence the local solar irradiance, it is necessary to suitably account for these distributed factors by means of GIS mapping and advanced modeling tools in order to provide realistic estimates of solar available radiance at roofs level. The implemented methodology, based on remote sensing techniques, has allowed to estimate and map the global solar radiance over all the roofs within Avellino municipality. Starting from LIDAR data, DSM of the entire area of interest (~42 Km2) has been firstly obtained; then the 3D model of each building and related cover has been derived. To account for the atmospheric transparency and the related time-dependent diffuse/direct radiation percentage on the area, data and tools from EU PVGIS web application have been also used. The final processing to obtain the solar radiance maps has been carried out using specific software modules available within commercial and open-source GIS packages

Redevelopment Initiatives on Brownfield Sites: An Evaluation Model for the Definition of Sustainable Investments

With reference to brownfield sites redevelopment interventions, an innovative model for the definition of effective and financially sustainable initiatives is proposed and tested. The model borrows the operative logic of the break-even analysis (BEA). It neglects the basic assumption of BEA related to revenue linearity, by considering the real trend of the revenues. In fact, in specific contexts characterized by a real estate over supply—e.g., in small urban centers, or where a new plan includes a relevant increase in new buildings and/or the functional reconversion of existing disused complexes—the BEA hypothesis on revenue linearity could be inconsistent, as prices will tend to become depressed. In the mentioned situations, discount mechanisms on the unit prices could occur. These phenomena determine a reduction in the unit selling price in correspondence of the amount of gross floor area (GFA) increase. Taking into account the current and cogent needs of effective strategies for brownfields renovation, the innovative evaluation model is developed for supporting public and private investors’ decision processes. It could represent a valid reference in the preliminary phases of decision-making processes for public and private subjects, able to ensure the break-even point of the initiative balance sheet is reached

Design, modelling and optimisation of an isolated small hydropower plant using pumped storage hydropower and control techniques.

Ph. D. University of KwaZulu-Natal, Durban 2015.Pumped Storage Hydropower (PSH) has proved to be a reliable power generation technology, especially in cases of emergency peak power demand. It is best utilised in areas where the availability of water is a challenge because it allows water retention and reuse using the pump back mechanism instead of the water being discharged to continue its course. A pumped storage hydropower system consists of two reservoirs, one higher in elevation than the other lower, the turbine house (power station) and pumping plant between the two reservoirs. During off-peak periods, excess electricity which is cheap pumps water from the lower to the upper reservoir because power demand is low. The stored energy is released to run back into the lower reservoir through the turbines to generate electricity in peak demand period, converting the stored potential energy into electricity at a higher economic value. South Africa is among the highest emitters of carbon dioxide in the world, with more than 75% of primary energy requirement from fossil fuels. Specifically South Africa is ranked 12th in the world in terms of top emitters of carbon dioxide, exposing its citizens to risks associated with this emission [1]. Therefore there is an urgent need to protect lives by technically reducing release of the poisonous gases through reducing fossil fuel dependency. Renewable Energy (RE), which is abundant and sustainable, can be quickly implemented, offer many work opportunities and have a much lower impact on the environment. With over 8 000 potential small Hydropower sites identified in Eastern Cape and KwaZulu Natal (KZN) Provinces, generation can improve. The system proposed is the design, optimisation and integration of a control system to a standalone micro hydropower hybrid. The conventional hydropower plant, which is a primary electricity source, allocates power to pump from the lower reservoir to the upper at off-peak periods when consumption and price of electricity is low at regulated flow. Various calculations were derived to compute the primary design parameters (flow, head and system efficiencies) with the other inputs. Matlab Simulink was engaged to describe the interaction between these variables and to vary parameters for optimum output, especially in reducing pumping mode power input for maximum pumped storage hydropower plant generation. Different categories of small hydropower plant sizes can be determined and analysed using this model which will give suitable results. Though the value of generation output from the PSH is small compared to input pump power it is able to compensate for peak load demand. The control system is introduced using Flowcode software to automate every technical process to ensure optimum system performance. The automation considers, time of the day, the volume of the upper reservoir and the available pumping power to efficiently manage the hydropower plant model. With the introduction of this generation technique, the results have shown that generation of more electricity at peak time when the price of selling the electricity is very high can be easily accomplished. The control effectively minimises electricity losses, breakdown of equipment, and ensures availability of resource at the exact time of demand. With this design, existing hydro plants may be upgraded for optimum generation without posing any negative effect on the environment in the way that coal fired plants do. Other renewable energy sources may be exploited in pumping activities to reduce the effect of pumping to the upper reservoir on the conventional hydropower plant

100% Renewable Energy Transition: Pathways and Implementation

Energy markets are already undergoing considerable transitions to accommodate new (renewable) energy forms, new (decentral) energy players, and new system requirements, e.g. flexibility and resilience. Traditional energy markets for fossil fuels are therefore under pressure, while not-yet-mature (renewable) energy markets are emerging. As a consequence, investments in large-scale and capital intensive (traditional) energy production projects are surrounded by high uncertainty, and are difficult to hedge by private entities. Traditional energy production companies are transforming into energy service suppliers and companies aggregating numerous potential market players are emerging, while regulation and system management are playing an increasing role. To address these increasing uncertainties and complexities, economic analysis, forecasting, modeling and investment assessment require fresh approaches and views. Novel research is thus required to simulate multiple actor interplays and idiosyncratic behavior. The required approaches cannot deal only with energy supply, but need to include active demand and cover systemic aspects. Energy market transitions challenge policy-making. Market coordination failure, the removal of barriers hindering restructuring and the combination of market signals with command-and-control policy measures are some of the new aims of policies.The aim of this Special Issue is to collect research papers that address the above issues using novel methods from any adequate perspective, including economic analysis, modeling of systems, behavioral forecasting, and policy assessment.The issue will include, but is not be limited to: Local control schemes and algorithms for distributed generation systems; Centralized and decentralized sustainable energy management strategies; Communication architectures, protocols and properties of practical applications; Topologies of distributed generation systems improving flexibility, efficiency and power quality; Practical issues in the control design and implementation of distributed generation systems; Energy transition studies for optimized pathway options aiming for high levels of sustainabilit

Sizing and control of a Hybrid hydro-battery-flywheel storage system for frequency regulation services

Energy security and environmental challenges are some of the drivers for increasing the electricity generation from non-programmable Renewable Energy Source (RES), adding pressure to the grid, especially if located in weakly connected (or isolated) islands, like Sardinia. Variable-speed Pumped Storage Hydro Power (PSHP) can offer a high degree of flex ibility in providing ancillary services (namely primary and secondary regulations), but due to the hydromechanical nature of the equipment, sudden variations in the power output cause wear and tear. Other energy storage devices can not compete with PSHP in terms of energy and power availability. This work aims to assess the potential benefits derived from the hybridization of a PSHP with Battery Energy Storage System (BESS) and Flywheel Energy Storage System (FESS) in providing frequency regulation services to the grid of the Sardinia Island (Italy). The focus of the study tries to cross both the plant owner point of view, whose aim is to have a smooth PSHP operation and the economic incentive to hybridize the plant, and the Transmission System Operator’s, whose aim is to have a fast reacting plant that better stabilizes the grid frequency. This is done by simulations of a detailed dynamic model of the PSHP, whose hydraulic machine has been characterized from real experimental data, the BESS and the FESS. Moreover, two power management strategies are presented, based on different criteria, to effectively coordinate the devices making up the Hybrid Energy Storage System (HESS). First the simulations are performed open-loop, to assess the impact of various combinations of installed BESS and FESS powers over the wear and tear of the equipment. Later the model is used in an optimization procedure to find the combination of installed BESS and FESS powers and the respective controlparameters that would guarantee the maximum economic return at the end of the investment life. Last, the model is included into a Sardinian power system model and simulated in a future scenario with high RES penetration, assessing the plant capabilities to effectively contain and restore the frequency. Results show that there is not a catch-all solution in terms of hybridization and that a trade-off must be made between the plant owner’s urge to smoothly operate the plant in order to reduce the equipment degradation, and the TSO’s objective to have fast responsive plants providing high quality frequency regulation services. If on one hand open-loop simulations show that the hybridization reduce the main wear and tear indicators, on the other the optimal hybrid system limits the plant ability to contain the frequency excursions in closed-loop simulations, as the optimization problem was formulated over the plant owner’s interests. The results show that there much potential for frequency stabilization and wear and tear reduction, but more techno-economic data is required to fully investigate the benefits of this configuration.Energy security and environmental challenges are some of the drivers for increasing the electricity generation from non-programmable Renewable Energy Source (RES), adding pressure to the grid, especially if located in weakly connected (or isolated) islands, like Sardinia. Variable-speed Pumped Storage Hydro Power (PSHP) can offer a high degree of flex ibility in providing ancillary services (namely primary and secondary regulations), but due to the hydromechanical nature of the equipment, sudden variations in the power output cause wear and tear. Other energy storage devices can not compete with PSHP in terms of energy and power availability. This work aims to assess the potential benefits derived from the hybridization of a PSHP with Battery Energy Storage System (BESS) and Flywheel Energy Storage System (FESS) in providing frequency regulation services to the grid of the Sardinia Island (Italy). The focus of the study tries to cross both the plant owner point of view, whose aim is to have a smooth PSHP operation and the economic incentive to hybridize the plant, and the Transmission System Operator’s, whose aim is to have a fast reacting plant that better stabilizes the grid frequency. This is done by simulations of a detailed dynamic model of the PSHP, whose hydraulic machine has been characterized from real experimental data, the BESS and the FESS. Moreover, two power management strategies are presented, based on different criteria, to effectively coordinate the devices making up the Hybrid Energy Storage System (HESS). First the simulations are performed open-loop, to assess the impact of various combinations of installed BESS and FESS powers over the wear and tear of the equipment. Later the model is used in an optimization procedure to find the combination of installed BESS and FESS powers and the respective controlparameters that would guarantee the maximum economic return at the end of the investment life. Last, the model is included into a Sardinian power system model and simulated in a future scenario with high RES penetration, assessing the plant capabilities to effectively contain and restore the frequency. Results show that there is not a catch-all solution in terms of hybridization and that a trade-off must be made between the plant owner’s urge to smoothly operate the plant in order to reduce the equipment degradation, and the TSO’s objective to have fast responsive plants providing high quality frequency regulation services. If on one hand open-loop simulations show that the hybridization reduce the main wear and tear indicators, on the other the optimal hybrid system limits the plant ability to contain the frequency excursions in closed-loop simulations, as the optimization problem was formulated over the plant owner’s interests. The results show that there much potential for frequency stabilization and wear and tear reduction, but more techno-economic data is required to fully investigate the benefits of this configuration