Renewable Energy

Learning Outcomes:

1. Understand the environmental impact of non-renewable energy sources.
2. Grasp the concept and significance of renewable energy sources.
3. Recognize various types of renewable energy sources and their potential.
4. Comprehend challenges and strategies in harnessing renewable energy.

The excessive use of non-renewable energy sources like fossil fuels has caused substantial environmental damage. The emission of harmful gases from burning these fuels has led to significant environmental and health issues. Consequently, renewable energy—which derives from naturally replenished resources like sunlight, wind, and water—has become increasingly important. Renewable energy is not exhaustible, provides clean energy, and greatly minimizes pollution. Despite this, some renewable sources like biomass can contribute to indoor pollution.

Renewable Energy Sources:

1. Solar Energy: Harvested from sunlight, either through photovoltaic cells or solar-thermal methods.
2. Hydel Energy: Generated by converting the kinetic energy of water into electrical power.
3. Biomass: Produced from the burning of firewood, animal dung, biodegradable waste, and crop residues.
4. Geothermal Energy: Extracted from the heat stored in the Earth’s interior.
5. Ocean Energy: Obtained from tidal waves and ocean thermal energy.
6. Co-generation: Producing two forms of energy (e.g., electricity and heat) from a single fuel source.
7. Fuel Cells: Use hydrogen or hydrogen-rich compounds to generate electricity efficiently.

Electricity is the most widely used energy form globally. It can be sourced from renewable (e.g., solar, wind) or non-renewable sources (e.g., coal, oil). India aims to achieve a renewable energy capacity of 175 GW by 2022, focusing on solar, wind, bio-power, and small hydro-power.

Solar Energy in India

India has long sunshine hours, making it ideal for solar energy production through photovoltaic cells and solar-thermal collectors.

Photovoltaic Electricity:

1. Solar panels consist of PV cells made up of two semiconductor layers with positive and negative charges.
2. Sunlight absorption releases electrons, generating a voltage differential that produces Direct Current (DC), which is converted to Alternate Current (AC) via inverters.

Concentrated Solar Power (CSP):

1. CSP technology uses focused sunlight to generate high-temperature heat, converting it into electrical power.
2. Utilizes parabolic troughs that concentrate solar radiation onto a fluid-filled glass tube, heating the fluid to produce steam that powers turbines.

Potential of Solar Energy:

1. India receives solar energy of about 5,000 trillion kWh annually, with most regions receiving 4-7 kWh/m²/day.
2. Key regions with high solar radiation: Rajasthan, northern Gujarat, Ladakh, Andhra Pradesh, Maharashtra, Madhya Pradesh.

Installed Capacity in India:

1. Solar power capacity surpassed 10,000 MW in 2017.
2. The National Solar Mission aims to achieve 100 GW solar generation capacity by 2022.

Wind Energy

Wind Energy is derived from the kinetic energy of moving air, transformed into electrical energy using wind turbines.

Wind Farms:

1. Onshore Wind Farms: Located on land; cost-effective, easier to operate and maintain.
2. Offshore Wind Farms: Located in large water bodies; more expensive but can capture stronger and steadier winds.

Working of Wind Turbines:

1. Horizontal-axis turbines have blades spinning upwind; optimal for electricity generation at elevated locations.
2. Vertical-axis turbines rotate on an axis perpendicular to the ground; useful for grinding grain or pumping water but less efficient for electricity generation.

Wind Energy Potential:

1. 302 GW potential at 100m above ground level, with Gujarat leading in capacity.
2. Wind energy targets: 60 GW by 2022, 200 GW by 2030.

Installed Capacity:

1. Major players: Tamil Nadu (7,200 MW), Maharashtra (4,000 MW), Karnataka (2,700 MW), Rajasthan (2,700 MW).

Important Note: The National Offshore Wind Energy Policy, 2015 allows the development of offshore wind energy up to 200 nautical miles from the country’s baseline.

Hydropower

Hydropower utilizes the kinetic energy of flowing water to turn turbines and generate electricity.

Types of Hydropower Stations:

1. Impoundment: Uses a dam to store water in a reservoir; released water spins a turbine to produce electricity.
2. Diversion: Channels a portion of river water to flow through turbines; may not require a dam.
3. Pumped Storage: Stores excess electricity by pumping water to an upper reservoir, generating power during peak demand when water is released.

Small Hydro Power (SHP):

1. Defined as hydro projects with installed capacity below 25 MW; usually run-of-river installations with minimal environmental impact.
2. India has identified 5,415 SHP sites with a potential of around 19,750 MW.

Installed Capacity: The cumulative capacity of SHP amounts to 3,726 MW.

Ocean Energy

The vast oceans store enormous solar energy, harnessed through Ocean Thermal Energy Conversion (OTEC).

1. Wave Energy: Converts kinetic energy from sea waves into electricity.
2. Tidal Energy: Uses the movement of tidal waters through turbines to generate power.

Biomass Energy

Biomass energy is derived from organic materials like agricultural crops, woody plants, and waste. When burned, it releases carbon dioxide, which is balanced by the carbon absorbed during the growth of the biomass.

Processing Methods:

1. Anaerobic Digestion/Biomethanation: Decomposition of biodegradable matter to produce methane-rich biogas.
2. Combustion/Incineration: Direct burning of organic matter at high temperatures.
3. Pyrolysis/Gasification: Chemical decomposition in the absence of air, producing syngas.

Potential in India:

1. Biomass constitutes 32% of India’s total primary energy use.
2. Annual biomass availability: 450-500 million tonnes, translating to around 18,000 MW potential.

Installed Capacity: Approximately 3,700 MW from biomass power and cogeneration projects.

Geothermal Energy

Geothermal energy taps into the Earth’s internal heat stored in hot springs, magma, and geothermal reservoirs.

Potential in India:

1. Estimated potential: 10,600 MW.
2. Key geothermal sites: Puga Valley (J&K), Tattapani (Chhattisgarh), Godavari Basin.

Important Note: Challenges in geothermal energy include high generation costs, drilling expenses, and transmission barriers due to the proximity requirement to geothermal sites.

Fuel Cells

Fuel cells convert chemical energy of hydrogen into electricity efficiently, with only water and CO₂ as by-products.

Applications:

1. Automobiles: Fuel-cell-powered vehicles have high energy conversion efficiency and near-zero emissions.
2. Power Generation: Ideal for small-scale decentralized power generation, serving commercial buildings and remote locations.

Important Note: High initial costs hinder the widespread commercialization of fuel cells.

Comparative Table of Renewable Energy Sources

Source	Key Feature	Potential in India	Installed Capacity
Solar Energy	Uses sunlight for electricity	100 GW by 2022	10,000 MW (2017)
Wind Energy	Kinetic energy of air	302 GW (100m AGL)	28,700 MW (2016)
Hydropower	Energy from water flow	19,750 MW (SHP)	3,726 MW (SHP)
Biomass	Organic matter burning	18,000 MW	3,700 MW
Geothermal	Heat from Earth’s interior	10,600 MW	None

Major Renewable Energy Organizations

1. International Solar Alliance (ISA): Platform for 121 solar-rich nations to collaborate and drive solar energy initiatives.
2. International Renewable Energy Agency (IRENA): Supports countries in their transition to sustainable energy.
3. REN21: Multi-stakeholder network promoting renewable energy policies.

Important Concept: Co-generation refers to producing two forms of energy (heat and electricity) from a single fuel source, achieving efficiency levels up to 90%.

Note: Efficient use of renewable energy decreases dependency on non-renewable sources, fostering energy self-sufficiency and environmental sustainability.

Multiple Choice Question: What is the main benefit of using fuel cells for power generation?

1. Low initial costs.
2. Near-zero emissions and high efficiency.
3. Requires minimal maintenance.
4. Can be installed in any location.
   Correct Answer: 2