JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III WIND AND SOLAR ENERGY SYSTEMS Previous Question Paper (August/September - 2021 - R18)

Wind energy has emerged as a critical pillar of the global transition toward renewable energy. The current scenario is characterized by rapid capacity additions driven by technological advancements, policy support, and the need for decarbonization.

Global Scenario: Globally, wind power has seen exponential growth, becoming one of the most cost-competitive sources of electricity. China leads the world in total installed capacity, followed by the United States, Germany, India, and Spain. The global trend is shifting from onshore wind farms to large-scale offshore projects, particularly in Europe and East Asia, due to higher capacity factors and the availability of vast maritime areas. Technological improvements, such as larger turbine rotors, taller towers, and advanced materials, have significantly increased the efficiency and capacity utilization factor (CUF) of modern wind farms.

Indian Scenario: India has established itself as a major player in the global wind energy market, ranking fourth in terms of installed capacity. The sector is primarily concentrated in the southern and western states, including Tamil Nadu, Gujarat, Maharashtra, Karnataka, and Rajasthan, which possess high wind power density. The Indian wind energy sector is supported by the Ministry of New and Renewable Energy (MNRE) through various policies, including competitive bidding processes and the development of wind-solar hybrid projects.

Key Statistics and Trends:

• Capacity Growth: India has achieved a significant milestone in cumulative installed wind power capacity, exceeding 40 GW. The government has set ambitious targets to reach 140 GW of wind capacity by 2030 as part of its net-zero emissions commitment.
• Repowering Policy: A major focus in India is the repowering of older, smaller, and less efficient wind turbines with modern, high-capacity machines to maximize energy yield from existing high-wind sites.
• Offshore Potential: While India's wind sector is currently dominated by onshore installations, the government is actively exploring the vast potential of offshore wind along the coastlines of Gujarat and Tamil Nadu, supported by international collaborations.
• Supply Chain: India possesses a robust domestic manufacturing ecosystem, with most components, including blades, towers, and nacelles, being produced locally, which reduces project costs and enhances energy security.

In summary, while global growth is increasingly focused on offshore expansion and grid integration, India is balancing massive capacity expansion with strategic repowering and the development of hybrid renewable energy systems to ensure grid stability and meet growing energy demands.

The power available in the wind is derived from the kinetic energy of the moving air mass. Consider a stream of air with density ρ (kg/m³) moving with a velocity v (m/s) through a cross-sectional area A (m²).

The mass flow rate m of the air passing through the area A per unit time is given by:

The kinetic energy E of this mass of air moving at velocity v is defined as:

Substituting the expression for mass flow rate into the kinetic energy equation, we obtain the power P, which is the rate of change of kinetic energy:

From this fundamental equation, it is evident that the power of the wind is directly proportional to the following parameters:

• Air density (ρ): The power is directly proportional to the density of the air, meaning higher air density results in higher power output.
• Cross-sectional area (A): The power is directly proportional to the area swept by the rotor blades, indicating that larger turbines capture more wind energy.
• Wind speed (v): The power is directly proportional to the cube of the wind speed (v³). This cubic relationship signifies that even small increases in wind velocity lead to significant increases in the available power.