Power networks are undergoing a fundamental transition, with traditionally passive consumers becoming ‘prosumers’ — proactive consumers with distributed energy resources, actively managing their consumption, production and storage of energy. A key question that remains unresolved is: how can we incentivize coordination between vast numbers of distributed energy resources, each with different owners and characteristics? Virtual power plants and peer-to-peer (P2P) energy trading offer different sources of value to prosumers and the power network, and have been proposed as different potential structures for future prosumer electricity markets. In this Perspective, we argue they can be combined to capture the benefits of both. We thus propose the concept of the federated power plant, a virtual power plant formed through P2P transactions between self-organizing prosumers. This addresses social, institutional and economic issues faced by top-down strategies for coordinating virtual power plants, while unlocking additional value for P2P energy trading. The rise of prosumers has led to creation of virtual power plants and peer-to-peer trading to help manage a diverse and distributed array of energy sources. This Perspective proposes the federated power plant, which combines these concepts to meet some of their individual challenges and offer new value.

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Using peer-to-peer energy-trading platforms to incentivize prosumers to form federated power plants

The growing global demand for energy from fossil fuels plays a key role in the upward trend in greenhouse gas (GHG) emissions and air pollutants. Rapid population growth and increasing energy demand in the developing countries have brought many concerns such as poverty, pollution, health and environmental problems. While for these countries, particularly the poorest ones, modern energy is necessary to stimulate production, income generation and social development plus reduce the serious health issues that are caused by the use of fuelwood, charcoal, animal dung and agricultural waste. Solar energy is the best answer to energy poverty and it can provide excellent opportunities for reduction of GHG emissions and indoor air pollution through substituting kerosene for lighting and firewood for cooking. Solar photovoltaic (PV) can be an appropriate technology for a source of renewable electricity in developing nations especially in remote rural areas where grid extensions are financially or technically not viable. PV can also be used to reduce demand for fossil fuels and associated emissions, including carbon dioxide (CO2), nitrogen oxides (NOx) and sulfur dioxide (SO2). The use of PV systems can reduce 69–100 million tons of CO2, 126,000–184,000 t of SO2 and 68,000–99,000 t of NOx by 2030. In case countries use concentrating solar power (CSP) systems, each square meter of concentrator surface is enough to save about 200–300 kg (kg) of CO2 emissions annually. Although there are excellent renewable opportunities in many developing countries, several key barriers have prevented large-scale deployment of solar energy technologies in these countries. This study reviews the sources of energy-related emissions, risks of climate change, global solar energy potential, sustainability indicators of renewable energies, environmental impacts of fossil fuels and renewable energies, benefits of solar energy utilization. It also discusses barriers to widespread use of solar energy.

Potential of solar energy in developing countries for reducing energy-related emissions

Variability and intermittency are some of the main features that characterize renewable energy sources. Intermittency usually includes both predictable and unpredictable variations. The many drawbacks of intermittency of renewable sources can be overcome by considering some special design considerations. Integrating more than one renewable energy source and including backup sources and storage systems are among the few measures to overcome these drawbacks. These additional design considerations usually increase the overall cost of the renewable system. Furthermore, the presence of more than one energy supply/storage system requires the control of energy flow among the various sources. Therefore, optimizing the size of the components and adopting an energy management strategy (EMS) are essential to decreasing the cost of the system and limiting its negative effects. The energy management strategy is commonly integrated with optimization to ensure the continuity of load supply and to decrease the cost of energy production. Therefore, energy management is a term that collects all the systematic procedures to control and minimize the quantity and the cost of energy used to provide a certain application with its requirements. The energy management strategy usually depends on the type of energy system and its components. Various approaches and techniques have been used to develop a successful energy management strategy. In this paper, a comprehensive review of the approaches proposed and used by authors of many papers is conducted. These approaches include both the standalone hybrid renewable energy systems and the grid-connected hybrid renewable systems. More attention is focused on popularly used techniques to address the features of each system. The selected papers in this review cover the various configurations of the hybrid renewable energy systems for electric power generation only.

https://scholar.ptuk.edu.ps/bitstream/123456789/89/1/2.pdf

Energy management strategies in hybrid renewable energy systems: A review

The increasing need for thermal comfort has led to a rapid increase in the use of cooling systems and, consequently, electricity demand for air-conditioning systems in buildings. Heat-driven ejector refrigeration systems appear to be a promising alternative to the traditional compressor-based refrigeration technologies for energy consumption reduction. This paper presents a comprehensive literature review on ejector refrigeration systems and working fluids. It deeply analyzes ejector technology and behavior, refrigerant properties and their influence over ejector performance and all of the ejector refrigeration technologies, with a focus on past, present and future trends. The review is structured in four parts. In the first part, ejector technology is described. In the second part, a detailed description of the refrigerant properties and their influence over ejector performance is presented. In the third part, a review focused on the main jet refrigeration cycles is proposed, and the ejector refrigeration systems are reported and categorized. Finally, an overview over all ejector technologies, the relationship among the working fluids and the ejector performance, with a focus on past, present and future trends, is presented.

https://re.public.polimi.it/bitstream/11311/984261/1/2016_RSER_BesagniMereuInzoli.pdf

Ejector refrigeration: A comprehensive review

Interest in the advancement of energy storage methods have risen as energy production trends toward renewable energy sources. Vanadium redox flow batteries (VRFB) are one of the emerging energy storage techniques being developed with the purpose of effectively storing renewable energy. There are currently a limited number of papers published addressing the design considerations of the VRFB, the limitations of each component and what has been/is being done to address said limitations. This review briefly discusses the current need and state of renewable energy production, the fundamental principles behind the VRFB, how it works and the technology restraints. The working principles of each component are highlighted and what design aspects/cues are to be considered when building a VRFB. The limiting determinants of some components are investigated along with the past/current research to address these limitations. Finally, critical research areas are highlighted along with future development recommendations.

Vanadium redox flow batteries: A comprehensive review

Access to electric power supply has always had a significant role in promoting improvements in all the society sectors, nevertheless nowadays 1.3 billion of people still do not have electricity access. Moreover, most of them live in rural areas of developing countries which are often isolated, scattered populated and characterized by poor infrastructure and services. In this situation, the growing consideration towards the target of universal access to energy has emphasized the role of rural electrification, and off-grid small-scale generation represents one of the most appropriate options. As a consequence, the scientific literature has devoted attention to this topic with a large number of papers. In this frame, the present analysis focuses on off-grid systems for rural electrification and provides a general framework to this topic and an analytical review of the literature. The work is based on the review of more than 350 papers mainly published from 2000 to 2014 within selected journals, and it is organized in two sections. In the first one we describe the role of small-scale generation systems throughout the process of electrification, the main features of rural areas and their typical energy uses, and we propose a new comprehensive taxonomy for off-grid systems for rural electrification. In the second one we develop an extensive review of the selected literature according to the proposed classification and to five main research areas: Technology: layout and components; Models and methods for simulation and sizing; Techno-economic feasibility analyses and sustainability analyses; Case studies analyses; Policy analyses. The work results in a comprehensive review which organizes and capitalizes the main fundamentals of the addressed topic and provides elements to get acquainted with the literature.

Off-grid systems for rural electrification in developing countries: Definitions, classification and a comprehensive literature review

CFD study of Savonius wind turbine: 3D model validation and parametric analysis

Analysis of flow field design on vanadium redox flow battery performance: Development of 3D computational fluid dynamic model and experimental validation

Riccardo Mereu

Papers

Ejector refrigeration: A comprehensive review

Off-grid systems for rural electrification in developing countries: Definitions, classification and a comprehensive literature review

CFD study of Savonius wind turbine: 3D model validation and parametric analysis

Analysis of flow field design on vanadium redox flow battery performance: Development of 3D computational fluid dynamic model and experimental validation

An Integrated Lumped Parameter-CFD approach for off-design ejector performance evaluation