Hybrid Renewable Energy Systems for Remote Telecommunication Stations

The progress in telecom networks has changed the way people live, work, and play. Since many people around the world are connected by telecom networks, the challenge is to provide reliable and cost-effective power solutions to these expanding networks using Renewable Energy Sources (RES). In remote areas, grid electricity is not available or is available in limited quantities. Diesel generators with the backup battery were used for powering these locations. These systems usually located in areas with difficult accessibilities require regular maintenance and are characterized by their high fuel consumption and high transportation cost. Also, due to the rapid depletion of fossil fuel reserves and increasing demand of clean energy technologies to reduce the greenhouse gas emission (CO₂, NO_X, and SO_X). Due to the development of new convergent broadband technologies that comprise voice, video, and data in a single platform system, the telecom operator has grown an interest in reliable power services to provide a guarantee of the quality of service for the remote BTS operation hours and traffic management. This chapter presents a brief introduction about some types of RES and proposal power system that depends on renewable energy system.

There are main two types of communication networks: cellular networks and wired networks. Each type contains different sector which discussed in this chapter, also corresponding energy consumption models are introduced. Over 90% of the wireless network power consumption is part of the operator’s operating Exchange (OPEX), which includes the Mobile Switching Centers (MSCs) and Radio Base Stations (RBSs). The key elements are the highly deployed radio base stations because the total number of base stations is exceptionally high. There are approximately more than 4 million installed Base Transceiver Station (BTS) cabinets in the world today with relatively high energy consumption, about 60 TWh per year. Furthermore, the corresponding CO₂ emissions are around 30 Mt. In general terms, access radio equipment is responsible for about 80% of energy consumed by a cellular network. Main components of BTS are presented. Sectors of wired networks and energy consumption rate of each sector are discussed.

Traditional telecom backup power solutions include batteries for short duration backup and diesel generators for more extended duration backup. Fuel cells are reliable and quiet, with fewer moving parts than a generator, and a more extensive operating temperature range, −40 to +50 °C, than a battery. Also, a fuel cell system has a lower lifetime cost than a generator. The lower prices for the fuel cell are the result of only one maintenance visit per year and significantly higher system efficiency. Finally, the fuel cell is a clean technology solution with minimal environmental impact. Fuel cell systems provide backup power to critical communication network infrastructures in wireless, fixed, and broadband telecom applications ranging from 250 W to 15 KW, and they offer many outstanding features. This chapter presents the principles of fuel cells, the idea of their functioning and their internal components—the benefits of fuel use in communications. Regenerative fuel cells (RFC) have been selected in this study. Hydrogen and oxygen output and their relationships to the energy consumed are explained. The rates of used hydrogen for electricity production were also explained. Calculations of the water and hydrogen tanks and ways of hydrogen storage are displayed. How to get RFC efficiency was explained.

The batteries cannot get an immediate response to the load requirement when sudden clouds or no wind occur. The batteries are often deep discharged, which damages the battery and shortens its useful life. It is not possible to ensure an optimum charge/discharge cycle. Undercharging of the battery leads to sulfating and stratification; both of which shorten the lifetime of the battery. Another cause of reduced battery life is gassing, which results from battery overcharging. For avoiding all previous problems, new storage devices should be used, one of these devices is ultracapacitor (UC). This chapter exposes ultracapacitors composition, theory, and characteristics. Also, advantages, the equivalent circuits, temperature effect, and voltage variation effect of ultracapacitors are displayed. This chapter also addressed the methods of ultracapacitors sizing. ANN technique is used to determine the optimum UC type for a certain load. Application and results of applied sizing methods and ANN techniques on different loads are displayed.

Photovoltaic power systems are introduced. The calculation of solar radiations incident on surfaces is provided, the required number of solar panels to feed a certain loads. Three locations in Egypt are selected and four types of modern solar panels, computer program is prepared to calculate the number of panels required to supply the load in cases the angle of incidence optimum monthly tilt angle as well as in the case of fixed solar panels at an angle of latitude for this site. Through what has been done, the best type of solar panels and the optimal number of each location have been identified. A study was also conducted on the connection of the photovoltaic power system to the UG. ANN technique is used to obtain MPPT. It is very important with photovoltaic generation to operate the system at high power efficiency by ensuring that the system is always working at the peak power point regardless of changes in load and weather conditions. The MPPT system is an electronic device inserted between the PV array and the load.

The wind energy power system contains wind turbines as main source and RFC as backup source and means of stored energy in the form of hydrogen. Equations have been provided for the calculation of generated wind energy. Eleven types of wind turbines with appropriate capacity rates for the loads were selected to choose the best of them according to wind speeds for each of the sites selected for the study also according to the value of the power coefficient of each site, where it is choosing the highest power coefficient because this means that it is the most appropriate for this site. A capacity balance program has also been developed to determine the optimal number of wind turbines required to feed loads, taking into account the efficiency of RFC. The value of hydrogen produced by energy conversion was determined during the surplus times. The value of hydrogen consumption during defect times. The connection of the wind energy system to the UG has also been studied.

The hybrid power generation concept is a system aimed at the production and utilization of electrical energy coming from more than one source within an integrated arrangement. The hybrid system studied in this book is one combining solar PV and wind turbines with power conditioning units such as inverters. Hybrid wind turbine and solar PV modules offer more excellent reliability than any one of them alone because local energy supply cannot depend entirely on any one of these sources. Powerful system of hybrid (solar panels, wind turbines, regenerative fuel cells, and ultracapacitor) is proposed. The economic study of the hybrid system is in two ways: analytical method and artificial intelligence method, it has appeared that the final results of the two methods are almost identical. The results showed that there are locations where solar panels are more economically used than air turbines and vice versa. But because loads of electrically small, the mixed system of solar panels and wind turbines is costly. Analytic method and particle swarm optimization (PSO) method are two methods that are used for determining the economics construction of hybrid power system. A comparison is done between results of analytic method and PSO method.

This book presents the optimum design and sizing of the renewable energy system to supply communication stations. Now, there are a lot of failures in the power supply system of communication stations especially in remote and distant locations, so this book determined the failure points and tried to treat the failure points.