Nuno Quaresma

Bio: Nuno Quaresma is an academic researcher from University of Coimbra. The author has contributed to research in topics: Efficient energy use & Environmental economics. The author has an hindex of 1, co-authored 1 publications receiving 7 citations.

Energy-efficient off-grid systems—review

Abstract: Globally, around 1.1 billion people do not have access to electricity and 84% of the population who do not have modern energy access are living in rural and remote areas of developing countries. Since the loads are far from the grid and providing the connection by extending from the main grid requires a high investment associated with long and costly transmission and distribution lines, addressing the problem requires innovative solutions. Therefore, off-grid microgrid systems, using solar photovoltaic and storage systems, integrated with very high-efficiency lighting appliances, are a promising solution to supply energy for rural and remote location in areas which lack access to the electric grid. This paper presents an overview on the existing solar photovoltaic technologies for off-grid systems including the most recent plug and play solutions. A characterization of the most common strategies used for control, communication and metering of microgrids is presented, as well as the recent evolution of the associated component technologies. The security and protection systems used to protect the system against theft or robbery of the systems itself or energy theft in remote areas are also addressed. Additionally, a resumed characterization of the sociologic profile and motivation of people to damage off-grid systems is presented. An overview on the main off-grid appliance market evolution and efficiency trends, in terms of energy efficiency, is also addressed in this paper. Finally, a set of recommendations to promote cost-effective systems is made, considering the market evolution path and the large growth potential of off-grid systems. There is an urgent need to reduce the total system costs, namely the soft costs of new microgrid systems in order to further accelerate the market growth, as well as widely accepted open standards to regulate and develop the market.

Promoting environmentally sustainable consumption behavior: an empirical evaluation of purchase intention of energy-efficient appliances

Abstract: The energy sector is one of the most prominent sectors in the development of nations. The scarcity of energy in developing nations urged the government and private sector to consider the efficient resources of energy. Energy-efficient appliances help to reduce the consumption of energy and fulfill consumers’ utilitarian needs. The purpose of this study is to empirically evaluate consumers’ purchase intention of energy-efficient appliances. The study employed convenience and quota based on the age sampling technique to select the participants of the study in one of the developing countries (Pakistan). Covariance-based structural equation modeling (CB-SEM) has been applied to test the hypothesized relationships among the constructs. In findings, knowledge of eco-labels, environmental concern, attitude, and perceived consumer effectiveness were found important antecedents of consumers’ purchase intention. Further, the findings provide environmental strategist with meaningful insight into the critical role that knowledge of eco-labels and environmental concern play in achieving energy-efficiency through the use of energy-efficient appliances.

Golden Cut-Oriented Q-Rung Orthopair Fuzzy Decision-Making Approach to Evaluation of Renewable Energy Alternatives for Microgeneration System Investments

Abstract: This study aims to find an appropriate system for microgeneration energy investments and identify optimal renewable energy alternatives for the effectiveness of these projects. In this context, a model is constructed by multi stepwise weight assessment ratio analysis (M-SWARA) and technique for order preference by similarity to ideal solution (TOPSIS) with q-rung orthopair fuzzy sets (q-ROFSs) and golden cut. At the first stage, five different systems are weighted for the effectiveness of the microgeneration energy investments. Secondly, four different renewable energy alternatives are ranked regarding the performance of these projects. In addition, a comparative analysis is also implemented with intuitionistic fuzzy sets (IFSs) and Pythagorean fuzzy sets (PFSs). The findings are the same in all different fuzzy sets that demonstrates the reliability of the findings. It is determined that grid-connected with battery backup is the most important system choice. On the other hand, solar energy is the most appropriate alternative for microgeneration system investments. Grid-connected system should be implemented for the performance of the microgeneration projects. Hence, providing a sustainable access to the electricity can be possible. Sufficient amount of electricity may not be obtained from wind and solar energy because of the climate changes. In this process, grid-connected system can handle this problem effectively.

Design and Modeling of a Standalone DC-Microgrid for Off-Grid Schools in Rural Areas of Developing Countries

Abstract: Energy access is critical for health, education and social welfare improvements. In countries like Ethiopia, with a low electrification rate and with the majority of the population located in rural areas, about 76% of primary schools do not have access to electricity. This limits the hours of classes and does not allow the use of basic or modern teaching resources. Off-grid solutions have emerged as potential cost-effective alternatives to electrify rural areas and schools, but the availability of off-grid appliances and the size of the system can lead to different solutions. Therefore, this study proposes a DC microgrid system to supply the electricity demand of a rural school located in Ethiopia, considering load estimation scenarios with standard and high-efficiency appliances. The simulation results show that the designed DC microgrid is a valid option to electrify the rural school under each load and generation scenarios. The system costs were also evaluated, and the high-efficiency appliances option has a 51% lower cost. The study also applies to other sub-Saharan countries in the region with very low energy access rates and abundant solar energy, thus giving a large contribution to achieve the United Nations Sustainable Development Education Goal 4 (SDG 4).

A Comprehensive Review on Off-Grid and Hybrid Charging Systems for Electric Vehicles

Abstract: In recent years, the research interest in off-grid (standalone mode) and hybrid (capable of both standalone and grid-connected modes) charging systems for electric vehicles (EVs) has increased. The main reason is to provide a seamless charging infrastructure in urban and rural areas where the electrical grid is unreliable or unavailable so that EV adoption can be increased worldwide. In this regard, this article reviews the state-of-the-art architectures of the off-grid and hybrid charging systems and investigates their various subsystems, such as single or multiple energy sources, power electronics converters, energy storage systems, and energy management strategies. These subsystems should be optimally integrated and operated to achieve low-cost and efficient EV charging. Moreover, each subsystem is explored in detail to find the current status and technology trends. Furthermore, EV charging connectors, their power level, and standards for all kinds of EVs (ranging from one-wheeler to four-wheelers) are reviewed, and suggestions are discussed related to the non-standardization of charging plugs. Finally, conclusions show the continuous efforts of the researchers in improving the systems in various aspects, such as cost reduction, performance improvement, longevity, negative environmental effect, system size minimization, and efficient operation, and highlight challenges for both charging systems.

Optimal sizing of Solar Home Systems: Charge controller technology and its influence on system design

Abstract: Solar Home Systems are a promising solution to enable access to affordable, reliable, sustainable, and modern energy for non-electrified areas, especially in the Global South. In this study, the influence of the charge controller technologies Maximum Point Tracker (MPPT) and Pulse Width Modulation (PWM) on the optimal system design and system performance is analyzed. Therefore, a multi-objective optimization that minimizes the number of days with Power-Cut-Offs and the Levelized Cost of Electricity for three Solar Home System sizes and three sub-saharan locations is conducted. Cost savings of the MPPT controller are in the range of 4.0% to 8.6% compared to the PWM controller. This is achieved by a reduction of the optimal installed photovoltaic peak power by 31.2% to 38.6% and the battery capacity by 2.8% to 8.8%. A sensitivity analysis shows the high robustness of cost savings regarding a variation in solar irradiance, load profile, and charge controller investment costs. Therefore, MPPT charge controllers are a promising solution even for the smallest Solar Home System sizes to reduce system costs compared to PWM controllers. The applied numerical simulation tool is open-source to enhance openness and transparency in modeling studies.