Replace DG Sets with BESS to Enhance Indian Pwr Grid’s Flexibilty: Study

“Replacement of DG sets distributed across the country with BESS is the fastest and cheapest route to build flexibility for the Indian grid. The reduction in emissions from DG sets will help meet the NDC targets as well,” states a new study published by India Smart Grid Forum (ISGF).

Delivering reliable 24×7 services is the primary objective of every large building for which uninterrupted power supply is essential. Diesel generating (DG) sets are commonly used for power backup for all critical infrastructure. Owing to increasing pollution levels, most cities are banning the use of DG sets. ISGF’s latest white paper, entitled “DG Replacement with Lithium-Ion Batteries in Commercial Buildings,” examines the business models for the replacement of a DG sets with lithium-ion battery energy storage systems in large buildings and campuses.

Cities are concentrations of economic, social, and technical assets, which are fundamental to addressing the climate challenges. With the unplanned growth of urban areas in most developing countries, electric utilities often struggle to provide reliable and uninterrupted power supply to all their customers.

This situation necessitates the provision of large sized DG sets for power backup in commercial buildings, government and private office buildings, industrial areas, IT parks, shopping malls, hotels, hospitals, educational campuses and residential complexes. In most cases, the DG sets automatically start once grid power is unavailable.

Mega-watt (MW) scale DG sets are deployed in large buildings in India. By some estimates there are over 70,000 MW of large DG sets in India. DG sets emit heat, particulate matters, carbon dioxide, carbon monoxide, nitrogen oxides and hydrocarbons besides causing the noise pollution.

In 2018, the National Green Tribunal (NGT) banned the usage of DG sets between October and March in the National Capital Region (NCR) in India. Many other Indian cities where the pollution levels are dangerously high are also likely yo ban the usage of DG sets soon. Commercial buildings, hotels, hospitals, data centres etc, cannot afford to run without power for more than few seconds, hence the replacement has to be highly efficient, cost-effective, pollution-free, and instantaneous sources of backup power.

There are many alternatives to DG sets such as gas turbines and hydrogen fuel cells but due to technological maturity, reliability, safety, and efficiency the best option presently is lithium-ion batteries (LiB) as described in ISGF’s paper.

A battery backup system can be charged either from the grid or from solar rooftop photovoltaic (RTPV) systems. While a typical DG set operates during the power outgaes which is few hours in a month, the battery energy storage system (BESS) connected to the grid can support the grid 24×7 by providing frequency and voltage support and can be a great resource for renewable energy (RE) and electric vehicle (EV) integration with the electricity distribution grid.

In its latest study, ISGF surveyed a few large hotels in different cities and analysed the data regarding the DG set usage and diesel consumption. The cost-benefit analysis indicates that the cost of generation of power with a DG set is presently INR 29.07 per kWh whereas it is INR 15.17 with LiB. On comparative analysis the LiB not only saves costs but also eliminates emission of carbon and other pollutants.

The paper also describes three business models through which BESS can replace DG sets:

•  owned by the electric utilities
• owned by the buiding and leased to the electric utility for grid support
• owned by third parties or Independent Power Producers (IPP)

According to the latest IEA projections, Indian power system is set to grow from the present capacity of 395 GW to 823 GW by 2030 and 1584 GW by 2040. Out of 1584 GW, 869 GW is expected to be renewable energy (RE) resources. Considering the larger share of RE in the generation portfolio, IEA estimates ±85% flexibility for the Indian power system by 2040 which will be a huge challenge to manage.

“Therefore, building flexibility in the power system assumes top priority and BESS is one of the most reliable resource to increase the flexibility of the grid, according to ISGF. During periods of surplus generation, electricity can be stored in the batteries, which can be later discharged during peak-hours,” concludes the paper. The full paper can be accessed here.

India Smart Grid Forum (ISGF) is a public private partnership initiative of the Government of India with the mandate to assist government, utilities and regulators on electric grid modernization and electric mobility.