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Power of Storage: New energy backup technologies offer higher efficiencies

November 18, 2014
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The telecom industry boasts of over 400,000 towers across the country but the majority of these are in areas with inconsistent power supply. Managing energy costs is a key focus area for telecom tower operators.

According to estimates, more than 70 per cent of towers have outages of more than eight hours a day. States with a higher tower density – Uttar Pradesh and Bihar – have an average grid power of less than 10 hours per day.

As a result, 100 per cent of the telecom tower sites in the country have energy storage systems installed. These are estimated to provide over 15 per cent of the required power at telecom sites. The majority (99 per cent) of these are lead acid-based systems with average (available) storage capacities of 15 kWh.

There has been limited deployment of new energy storage technologies, with most of them in the study phase. Recently, Rel-iance Jio Infocomm Limited has reportedly deployed new energy storage technologies.

Most manufacturers offering energy storage solutions provide their own data, which is mostly not certified. We are, therefore, forced to conduct trials and experiments for about a year before deciding to adopt these solutions.

Operational experience and challenges

The currently installed systems, which are largely lead acid based, are temperature sensitive. System performance claimed by manufacturers is at 25 degrees Celsius. However, actual conditions differ from site to site, with temperatures varying from 25 to 40 degrees Celsius in general. In fact, they are mostly at the higher end. At these temperature levels, battery life is adversely affected (estimates suggest that it reduces by 28 to 30 per cent).

Other technology limitations associated with energy storage systems are related to the space needed per unit of power storage; the time taken to charge systems; the round-trip inefficiency (25 to 30 per cent) of these units; and the need for manual intervention in maintaining these systems. The growing rental charges for tower sites also pose constraints as far as lead acid batteries are concerned as they occupy a significant amount of space and lead to higher rents.

Tower operators prefer charging battery systems with the cheapest available source of energy which, in most cases, is grid power. However, lead acid batteries take time to charge and this becomes a major problem in areas with low grid power availability.

All these constraints highlight the areas where battery manufacturers need to improve their systems. Given the circumstances, telecom operators need batteries which charge fast, require less space per kW, and have higher round-trip efficiency. In order to address the maintenance issue, many tower operators are in the process of integrating storage systems with intelligent energy systems, especially at remote sites.

New energy storage technologies are believed to have addressed most of these issues. They are adaptable to site infrastructure capabilities and mostly come embedded with integrated information systems.

However, the biggest problem with new technologies is the high replacement cost. Unless it is priced in the same range as lead acid batteries, it will be difficult to adopt the new solutions. This is especially true given that tower operators are yet to establish the performance of new systems in the long run. Moreover, there are issues related to the suitability and compatibility of new technologies with the existing site infrastructures, and limited field support. Take, for instance, the case of lithium-ion solutions. There are three aspects to these systems – cells and their bundling; sensors for each cell; and the battery management system. Each of these elements needs regular maintenance but none of them are standardised. Every supplier has different designs, which makes the support system questionable.

Viom has been running trials and experiments on various technologies. These include rechargeable batteries (lithium-ion and lead acid), flow batteries, thermal energy storage, and protection circuit module batteries to meet the growing demand for air conditioning during peak hours, fuel cells and compressed air storage.

Outlook

The opportunity for energy storage technologies is limitless. Going forward, the energy storage industry needs to work on improving round-trip efficiencies, developing segmented solutions according to the local environment, and devising a field support structure that engages the existing field management organisations. Moreover, the industry needs to design a business model that requires a minimum capex commitment from infrastructure providers.

One-third of the towers need battery replacement every year. Battery manufacturers should therefore focus on “end-of-life” replacement of existing energy storage systems.

Based on a presentation by

Ambikesh Pratap Singh, Additional Vice-President and Head, Energy, Viom Networks, at the Energy Storage in India conference

 
 
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