Battery Energy Storage Systems as An Alternative to Diesel Generators – A Comparative Cost Analysis for Tamil Nadu.

Power demand across the country is growing, and meeting peak demand is becoming more challenging. In Tamil Nadu, frequent power outages are observed, especially during summer months. To reduce economic impacts of unreliable power supply, commercial and industrial (C&I) entities, undertake investments in power backup systems. The most commonly used systems are diesel generator sets (DG sets) and battery energy storage systems (BESS), also known as an uninterrupted power supply (UPS).

DG sets have been a convenient power backup option due to an established market, their reliability, affordability, and modularity. But they have a high environmental footprint, cause noise pollution and negatively impact human health. On the other hand, BESSs could operate on zero emissions, if charged from renewable energy sources, and with minimal noise pollution. And with no exhaust emissions, they are particularly helpful in urban areas.

The cost of batteries, especially those of lithium-ion (Li-ion) battery packs, have been observing a dramatic drop – of 89% over the years 2010-2020. And, apart from performing their primary function as a power backup, BESSs can also provide grid services such as load shifting, load following, peak load management, voltage, and frequency support and facilitate higher levels of renewable energy integration. Thus, BESSs contest DG sets economically and technically as an alternative type of back-up system.

This report compares the economic and environmental performance of a Li-ion-based BESS with a conventional DG set, as power backup solutions. The analysis indicated that the levelized cost of battery storage (LCOS) is dictated by the battery pack costs in the market, while the levelized cost of energy (LCOE) of the DG is sensitive to diesel prices. The cost analysis was carried over a range of hours of back-up required, and the results favour the Li-ion BESS as a back-up option, in terms of economic and environmental performance, especially when charged at solar tariff solar tariff.

We hope that this report will assist C&I entities in Tamil Nadu to make the most economic and environmentally sound investment in their power backup systems.

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