Khalid Loudiyi

Sizing and economic analysis of gravity storage

Energy storage plays a key role in providing more flexibility and balancing to the electric grid. With the increasing penetration of renewable energy technologies, there is a need to instantaneously match demand with supply. Energy storage has the potential to provide a back-up to intermittent renewable energy by storing electricity for use during more valuable periods. At this time, there are limited storage options, because several technologies are at very early stage of development. Pumped hydro energy storage is currently the most widely installed technology. This form of storage has some drawbacks which include the technology siting, as it cannot be implemented everywhere. This paper presents a concept that is similar to the existing pumped hydro storage technology. This concept is known as gravity storage, as it stores electricity in the form of gravitational potential energy. This storage option provides better operating characteristics and economically sounds solution over conventional pumped hydr...

Modeling the variation of optimum tilt angles for flat-plate solar collectors in Ifrane, Morocco

The conventional flat-plate solar collectors that are used in domestic solar water heating systems are often mounted at a fixed position from the horizontal, which makes them less efficient as they do not always face the sun. Adjusting the tilt angle seasonally ensures high energy collection efficiency through different seasons, especially winter, when the sun radiation is limited. The purpose of this study is to determine the variations in tilt angles for domestic solar collectors in order to maximize the amount of solar radiation captured. As an example of this for the Moroccan environment, the monthly optimum tilt angles in Ifrane were determined from the monthly average direct and diffuse radiations on horizontal surfaces, which were estimated based on the Liu and Jordan model [1, 2]. The results showed high tilt angles during winter (71° average tilt) and autumn (47° average tilt) and very low tilt angles during summer season (5° average tilt). Moreover, a significant increase was noticed in the estimated solar radiation on tilted surfaces as we change the tilt angle monthly, seasonally and bi-annually instead of leaving it mounted at a fixed position throughout the entire year. The study indicates that changing the tilt angle monthly would result in an increase of total radiation on the inclined surface by 14.5% during winter season and a yearly average increase of 10% compared to a fixed position. On the other hand, adjusting the tilt angle bi-annually would result in an increase of 12.5% during winter season and a yearly average increase of 7% in total radiation.

Optimal Modeling of Energy Storage System

The variability of solar and wind energy generation presents significant grid integration challenges especially in the operation of power systems. The optimal use of energy storage system may be a viable solution to control and match the power generation to the load profile. This paper proposes a method to identify the optimum daily operational strategy of a storage system. An hourly optimization problem was formulated for this purpose to maximize the economic gain of a wind farm considering the market price and the main operational restrictions of the hybrid energy system. This method is also suitable for other energy resources and energy storage technologies. Another prominent issue facing renewable energy farms is the proper sizing of the energy storage system. A method to optimize the size of the storage system with respect to the net present cost (NPC), while meeting the service requirement is also proposed. Case studies are presented to verify the effectiveness of these models.

Wind powered water desalination

Renewable energy, and more specifically, wind energy powered desalination, has been going through an upwards trend, especially during the last decade. Still, there is a domain that has not been much researched [1]; hence, this paper tries to address wind powered independent desalination systems. With its lower energy consumption and portability, Reverse Osmosis (RO) method has been chosen as the desalination technology that will be integrated with wind energy. In this work a MATLAB simulation is used to find out the effects of fluctuating wind energy on a system that is designed to operate under steady conditions. The results show that varying electrical power leads to extreme fluctuation in feed water pressure, beyond the operational range of the RO membranes. Still, this does not draw a cross on the wind and desalination combo; in fact, several methods exist to diminish the pressure variation, including wind turbine de-rating, or use of pressure stabilizers.

Operation optimization and economic assessment of energy storage

The increasing penetration of renewable energy in the utility grid presents significant challenges caused by the fluctuating nature of this generation source. Energy storage is portrayed as a viable option to overcome these challenges and to ensure the integration of this source of energy. This paper proposes a strategy to optimally operate energy storage in a residential application. The optimal scheduling methodology is based on real-time electricity price and is aimed to maximize the profit of a hybrid energy system. This paper develops a Nonlinear programming optimization that would be suitable for other grid applications. Simulation results illustrate, that the presented optimal operation method is an effective measure to achieve maximum profits. Furthermore, the cost of storage has prevented its high penetration on electrical systems. Therefore, it is important to perform a cost analysis study to determine the cost of storing each kWh of electricity.

CPV plants data analysis. ISFOC and NACIR projects results

Now it is the moment for CPV to become a reliable solution for large scale electricity generation, because it is one of the technologies with higher efficiency, and moreover, it has still margin for improvement. In order to continue with this development, it is important to introduce, in the design of the installations, all the lessons learned during the operation of pilot plants. This paper presents the operation results obtained at the ISFOC pilot plants, during the first three and a half years of operation, and the NACIR project. The CPV technology is not demonstrating signs of degradation which could reduce its high capability of transforming light into electricity. From the operation issues, valuable information is obtained in order to improve the design, turning CPV prototypes into an industrialized product ready to compete with other technologies, making a great effort in the reduction of the installation costs.

Integration of renewable energy and the benefit of storage from a grid and market perspective - results from Morocco and Egypt case studies

This paper presents results from case studies of the future power systems in Morocco and Egypt, with a high increase in renewable generation capacity. Datasets representing 2030 scenarios have been generated and studied with a simplified grid-market model that takes into account variable renewable generation, energy storage and electricity grid constraints. Simulation results for Morocco and Egypt are studied and compared, with emphasis on the benefit of energy storage.

Computer Simulation for Design Configuration and Optimization Performance of Flat Plate Collectors Case Study for Ifrane, Morocco

Feasibility study and efficiency assessments are mandatory prior to installing flat plate collectors. It is very useful to evaluate the performance of flat plate collectors depending on the location and environment they are set in. A model that predicts the performance of flat plate collectors, calculates the exact size of collectors needed to heat an amount of water to a specific temperature, and also gives the optimal tilt angle for the collector, has been developed and implemented in the scope of this project and presented in this paper. An analysis of both the configuration of the collector and intensity of solar radiation in the concerned area is used in the calculations for maximum efficiency and minimum costs. The computer program allows the user to investigate the different design parameters and configurations for optimal performance. It also enables the user to calculate the optimal tilt angle for the collector and the optimal size for collectors needed to heat a specific amount of water. According to the results obtained from this study, flat plate collector tilted at an optimum angle can increase the intensity of the global solar radiation received by 12.62 % in the same location with no extra cost. The program simulation is practical and can forecast the performance of flat plate collectors at a high degree of accuracy. To test the validity of the simulation a study of flat plate collectors installed at Al Akhawayn University in Ifrane, Morocco, has been performed. The 60 installed collectors tilted at 45° were found not achieving maximum solar energy collection. The optimal tilt angle for the location, as established by the computer simulation as well as using manual calculations for the daily, monthly and seasonally average optimal tilt angle, corresponds to plate collectors inclined at 32°. Moreover, only 48 collectors would be needed to heat the same amount of water to the same outlet temperature instead of the 60 used currently. These results illustrate the usefulness of the computer simulation analysis before choosing a design, configuration and installation for the flat plate collectors system.

Comparative study of internal and external thermal insulations based on PET waste bottles

We present a comparative study of internal and external thermal insulations in two pilot rural houses in the mountainous cold region of the middle atlas in the Dayet Aoua region, province of Ifrane, Morocco. In both studies we used plastic waste bottles (PET bottles) in cavity walls and roofs. The idea is to increase insulation by reducing convection fluxes in wall cavities using cheap insulating materials. We recorded temperatures in different rooms of each house before and after insulation as well as the ambient temperature outside the houses for a long period of time. Our study shows a significant increase in room temperatures translated in an important reduction of wood burning and better household comfort especially during the cold season.

First CPV Installation in Morocco: Made By Isofoton

Isofoton has built and launched the first CPV installation of Morocco. It is a 30 kW nominal power and a grid connected power plant that is located in the University of Al Akhawayn at Ifrane (Meknes County). In this paper is shown an outline of the CPV technology, the description of the installation and the first results that has been collected.