Jawaharlal Nehru Technological University Hyderabad B.Tech III ENERGY STORAGE SYSTEMS Previous Question Paper (May - 2019 - R16)

Flexible supply refers to the ability of an electricity generation system to rapidly adjust its output to match fluctuating demand. This is crucial for maintaining grid stability and reliability, especially with the increasing integration of intermittent renewable energy sources like solar and wind. A flexible supply can ramp up or down quickly, respond to sudden changes in load, and provide ancillary services such as frequency regulation. Key characteristics include fast response times, high ramp rates, and the ability to operate efficiently across a wide range of output levels. Traditional thermal power plants have limitations in flexibility, leading to the exploration of advanced technologies and energy storage solutions to enhance grid flexibility.

Generation cost is high during peak demand periods primarily due to the operational characteristics of power plants and the economics of electricity supply. During peak hours (e.g., early evening when residential and commercial loads are high), the demand for electricity exceeds the baseload capacity provided by the most efficient and cheapest power plants (like nuclear or large coal plants). To meet this surge in demand, utilities must bring online additional, less efficient, and more expensive power plants, often referred to as 'peaker plants'. These peaker plants, typically natural gas turbines or older, less efficient fossil fuel units, have higher variable costs (fuel, maintenance) and lower capital costs, making them suitable for short-duration, high-demand periods but uneconomical for continuous operation. Furthermore, the rapid start-up and shut-down cycles required for these plants can also increase operational and maintenance costs. The need to maintain a reserve margin to ensure grid stability during these critical times also contributes to overall costs.