Electricity and Control February 2023

ENERGY MANAGEMENT + THE INDUSTRIAL ENVIRONMENT : PROJECTS, PRODUCTS + SERVICES

Bridging loadshedding for telecoms operators

During one of the country’s worst stretches of loadshedding, MTN’s Corporate Affairs executive Jacqui O’ Sullivan was quoted as saying that although mobile operators have battery backup systems at network towers, loadshedding at higher stages meant the batteries did not have enough time to recharge, so there needed to be a backup for the backup in the form of generators. (The same concern has been noted in other sectors too, such as water and wastewater management, and more.) This is sobering and unfortunate, and the economic implications are huge. However, founders of REVOV, which manufactures lithium iron phosphate batteries, say there is a solution – for telecoms companies and others. Lance Dickerson, MD, and Felix von Bormann, CTO, see batteries as the environmentally preferable option for power backup. They say if the correct types of batteries in the correct configuration are used at the tower sites, they will have sufficient time to recharge, even during stage 6 loadshedding. This can fundamentally change the risk and costs currently being endured. O’Sullivan said for MTN, their batteries provide six to 12 hours of capacity, depending on the site, and need 12 to 18 hours between bouts of loadshedding to recharge. At the same time, Vodacom announced it was piloting a pro ject where it will source all its electricity from independent power producers in a bid to secure power supply. It is important to note here that wheeling, or transferring power between sites, will need to be managed by Eskom, as it is the utility’s transmission infrastructure that will be used – and like its generation plants, the transmission grid will also need a comprehensive overhaul and upgrade over the next decade. It is the localised transmission infrastructure that is especially important in ensuring sufficient battery backups can be maintained. REVOV was established in 2016, and the two founders spent more than a decade prior to that in the international telecoms industry in designing, planning, implementing, and testing various ways to keep the towers running in various regions of Africa. The challenges were many, but the basic question remained: how do we keep towers running when generators are not an option and there is no electricity? Hence they developed their foundational understanding of the power of batteries and their application in telecoms specifically, and power backup generally. Batteries work through chemistry and the traditional lead-acid technology has its limitations. For REVOV, lithium batteries are undoubtedly better batteries. The volatile nickel manganese cobalt (NMC) type of battery used in some smartphones and laptops has been known to ignite at higher temperatures. A newer battery chemistry – lithium iron phosphate – has emerged as the safest, most stable and longest lasting of storage battery chemistries. Beyond this, lithium iron phosphate

2nd LiFe batteries, which are built from the repurposed but fully functional cells of electric vehicle (EV) batteries, have the added benefit of inherent engineering for harsh operating conditions. Think of the heat and charge discharge ratio in the use of an EV. LiFe, in the name 2nd LiFe, is derived from the symbols for lithium (Li) and iron (Fe) in the periodic table. Dickerson and von Bormann consider 2nd LiFe bat teries prime candidates for backup storage, either for renewable energy installations or uninterrupted power supply systems – and for telecom tower battery back up. China Telecoms, the largest telecoms operator in the world, uses 2nd LiFe batteries exclusively at all its new sites and is reportedly swapping out old sites to 2nd LiFe when required. A recharge time equal to the discharge time In a properly set up and configured 2nd LiFe lithium iron phosphate battery backup system, the time to recharge is identical to the time of discharge. This means if the battery has been used for four hours, it needs four hours to recharge to full, if it has been used for six hours, it needs six hours to recharge to full. Beyond this, the dis charge curve is stable and, unlike that in lead acid bat teries, does not plummet after a critical point. This makes 2nd LiFe batteries fundamentally different from lead-acid batteries, in performance, reliability and lifespan. It also means they offer a solution as batteries that can be rapidly recharged in the hours between loadshedding in the higher stages. However, the transmission infrastructure also needs to deliver enough capacity, consistently, and obviously technical faults which can extend outages need to be minimised. Another key factor is the protective ac breaker size used at each site, which will determine the performance of the system during recharge periods. In simple terms, assuming the sites already have remote generators of 10 kVA, for example, the following solution could be implemented. Noting that a generator cannot be run under capacity for extended periods of time, as much as it cannot be overworked for extended periods, both of which compromise the life of the machine, running a 10 kVA generator could split 7 kVA to charge batteries while 3 kVA powers the tower. As a stop gap measure this prepares the site for the next power outage, as lithium iron phosphate performance enables a 1:1 discharge to charge ratio. As we all face the energy crisis that threatens our economy, working together, bringing expertise from various sectors, South Africans can devise workable solutions. An understanding of different battery technologies should inform the best backup options for various applications.

Lance Dickerson, MD, REVOV.

For more information contact REVOV. Visit: https://revov.co.za/

18 Electricity + Control FEBRUARY 2023