Batteries at telecommunications facilities are typically used to back up critical infrastructure equipment during an outage, often during the transition when the power source shifts from the grid to a diesel generator or another energy source. Since many sites do not have a generator or an alternative grid connection, backup batteries will provide power for longer periods of time than simply during this transition, including up to when power from the electrical grid is restored.
Today, batteries are also playing a role in the integration of sustainable energy sources that are becoming more commonplace in telecommunications facilities.
In addition to greater environmental sustainability through a reduced carbon footprint, telecommunications facilities can benefit from cost savings with the use of sustainable resources such as renewable energy, microgrids, and the Smart Grid.
Toward this end, telecom facilities face the challenge of integrating sustainable energy sources with the existing infrastructure, often while trying to fit additional equipment into limited space. The use of existing resources, however, can ease the adoption of sustainable energy. One of the resources already available to these facilities is the backup battery system, which also can be used for energy storage as part of a more sustainable power system. This is changing the battery’s role to the dual purpose of backup and storage.
Batteries, Renewable Energy, and Sustainability
The traditional electrical grid has been powering telecommunications facilities since their beginning, but the recent pursuit of sustainability has led to increasing employment of microgrids, the Smart Grid, and renewable energy sources.
However, there are shortcomings to renewable energy sources. They include increased cycling requirements of backup diesel generators, and reductions of generator capacity and efficiency that shorten service life with thermal and mechanical fatigue (Malhotra, p. 18).
One solution is energy storage, which optimizes efficiency and reduces run times of diesel generators, especially smaller systems. Usually, the generator will run at peak efficiency until the energy storage system is charged to full capacity, when it assumes the powering of the load.
In hybrid systems, stored energy can also power partial loads, instead of the peak generator powering them. In addition to improving the efficiency of the diesel generator, the use of energy storage reduces operations and maintenance costs, extends power life, and facilitates integration with renewable energy sources (Malhotra, p. 18).
In telecommunications facilities that use less renewable energy, the energy storage system can alleviate demands on the diesel generator by powering residual loads. In facilities with greater renewable energy use, the energy storage system may be used to regulate frequency and spinning reserves (Malhotra, p. 18). Spinning reserves are defined as the unused power capacity that is synchronized to the grid and can be activated on demand (Central Electricity Regulatory Commission New Delhi, p. 5). The intermittent nature of renewable energy also poses challenges, especially when integrating a higher share in powering the unit site (Malhotra, p. 2).
The dual purpose of backup power and energy management enables batteries to reduce costs by storing energy for use during peak times, while enhancing power quality by regulating frequency and supporting voltage at the grid level. Batteries also offer the advantages of quick response to grid outages, scalability to the facility’s particular needs and modularity that offers flexibility to adjust to changes in the facility’s energy demands (Malhotra, p. 2).
Additionally, hybrid systems are effective in managing energy needs. Surplus power, created when the renewable energy sources generate more power than what is needed for the load, may be stored in the system’s batteries. This stored energy may then be used to meet a shortfall when there is inadequate power generated to meet the needs of the load (California Energy Commission, p. 16).
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Remote Telecommunications Facilities
Off-grid telecommunications base stations are becoming more common, especially in remote areas and in the developing world, as they can provide coverage of wide geographic areas. As traditional diesel generators are emission intensive, renewable energy is becoming more common in response to the demand for sustainability
(Aris, abstract, p. 10904).
Wireless tower facilities, particularly ones in remote locations that are not secured to the electrical grid, offer characteristic challenges. Often powered from stand-alone sources (Malhotra, p. 18), remote telecommunications facilities may be especially vulnerable to outages. The extended travel required for maintenance and fueling also creates additional costs for backup generators in remote locations. Additionally, unreliable access to the power grid, or no access at all, necessitates the use of oversized diesel generators to accommodate the high starting current for the tower site’s air conditioning, which reduces efficiency and therefore increases fuel consumption (Malhotra, p. 18).
The reduction of the facility’s carbon footprint with the use of renewable energy may make the facility vulnerable to the intermittent nature of solar and wind power (Malhotra, p. 2). Energy storage, through the use of batteries, often compensates for the inconsistencies of renewable energy sources, especially when located at sites that are too remote for a secure connection to the electrical grid (Malhotra, p. 18). When batteries are used with solar or wind power sources to form a hybrid system, the results are frequently a more reliable power supply and improved systems efficiency (Sharma, p. 2). As telecommunications facilities adopt more sustainable energy options, they also reduce transportation expenses accrued to maintain the backup power system and to deliver generator fuel (Ojo, p. 8).
Selection of the appropriate battery for telecommunications applications must include considerations related to the design of the system, dimensions of available space, needed response time, service life, round-trip efficiency, capital expenditure and operational expenditure. Other considerations include voltage requirements, charge and discharge cycle frequencies, operational temperature, and weight restrictions (Aris, p. 10914).
Lead acid batteries represent the most mature battery technology, but newer chemistries, such as lithium ion, offer lighter weight, smaller footprints, high energy density, and efficient energy storage. However, they typically cost more (Aris, p. 10914).
Thin Plate Pure Lead (TPPL) batteries are manufactured in a highly controlled grid fabrication process that ensures maximum consistency in the composition of battery components, especially the plates. The use of high-purity lead and acid also delivers more efficient energy consumption and greater conductivity by reducing the rate of grid corrosion and associated growth.
Due to end users’ insatiable demand for high-speed bandwidth, the amount of equipment has increased at these telecommunications facilities. An increased volume of equipment can elevate the interior temperature of central offices and occupy additional interior space that necessitates moving battery backup and storage systems to outdoor enclosures or shelters. TPPL batteries offer a solution to extreme temperatures, limited space, and higher cycling capability.
The greater tolerance to extreme temperatures, especially extreme heat, also enables TPPL batteries to require less maintenance, which further reduces operating costs at telecommunications facilities.
The adoption of renewable energy sources is in response to the generation of greenhouse gases from fossil fuel consumption and the ongoing depletion of fossil fuel sources. By implementing a more sustainable battery backup and energy storage system, telecommunications facilities also can reduce operational and maintenance expenses.
Aris, Asma Mohamad & Bahman Shabani, (2015) "Sustainable Power Supply Solutions for Off-Grid Base Stations," Energies, September 29, 2015. https://www.researchgate.net/publication/282367344_Sustainable_Power_Supply_Solutions_for_Off-Grid_Base_Stations
California Energy Commission, "Tracking Progress," July 2018. https://www.energy.ca.gov/renewables/tracking_progress/documents/renewable.pdf
Central Electricity Regulatory Commission New Delhi, "Report of the Committee on Spinning Reserve," September 17, 2015. http://www.cercind.gov.in/2015/orders/Annexure-%20SpinningReseves.pdf
Malhorta, Abishek, et al., "Use cases for stationary battery technologies: A review of the literature and existing projects," Renewable and Sustainable Energy Reviews, 56, 2016. https://www.researchgate.net/publication/287505510_Use_cases_for_stationary_battery_technologies_A_review_of_the_literature_and_existing_projects
Ojo, Olumide Olajide, Satya Shah and Alec Coutroubis, "Study of Energy Savings and Sustainable Practices Adoption in Telecommunication Services," University of Greenwich, U.K., 2017. http://gala.gre.ac.uk/17740/7/17740%20SHAH_Study_of_Energy_Savings_2017.pdf
Sharma, Virendra and Lata Gidwani, "A Comprehensive Review: Energy Storage System for Hybrid System Including Wind Energy Generation System and Solar Energy Generation System for Utility Grid," Current Journal of Applied Science and Technology, June 2017. https://www.researchgate.net/publication/317933665_A_Comprehensive_Review_Energy_Storage_System_for_Hybrid_System_Including_Wind_Energy_Generation_System_and_Solar_Energy_Generation_System_for_Utility_Grid