Renewable sources of energy are the sustainable energy sources because these are not depleted with usage as they can be replenished either naturally or manually within the short time scale and hence can be used again and again.
Advantages/Benefits of Renewable sources of energy
ü Ensure energy Security
ü Reduction in greenhouse gas emissions,
ü Help to combat the changes in climatic conditions
Types of Renewable sources of energy
1. Solar Energy
Solar energy is one of the most abundant and widely used renewable sources of energy which can be used as follows:
i. Either directly as heat for solar heater for boiling water/preparing food etc.
ii. Or converted to electricity using Photovoltaic (PV) Solar Panels which is then used as energy source for diverse purposes.
Photovoltaic (PV) Solar Panels: These are the panels prepared using semiconductor materials (e.g., silicon) for direct conversion of sunlight into electricity. These Solar panels are available in various capacities and can be installed on rooftops, buildings, and farms for generating electricity depending upon the requirement.
Position of India in Harnessing Solar Energy
l 7th position in photovoltaics
l 9th in solar water heating systems
Advantages of Solar energy:
1. Abundant
2. No direct emissions
Drawbacks of Solar energy:
Ø Unavailability/low availability at different places in winter seasons
Ø Intermittent (not available at night and on cloudy days)
Ø Costly application due to requirement of accessories like photovoltaic panels for conversion to electricity, batteries as energy storage devices and their maintenance among various others.
Requirement/possible solution: More R & D in the designing of the accessories used for harnessing solar energy so that it can be made cost effective.
2. Wind Energy
Wind energy is the renewable source of energy in which the kinetic energy of wind is converting into electricity with the help of wind turbines. The various wind turbines that are installed in an area combinedly form wind farm or wind park. In India western states have a stable, steady and speedy wind flow which contributes to most of its wind energy production. The topmost wind energy user states in India are: Tamil Nadu, Gujarat, Maharashtra, Karnatka and Rajasthan.
Depending on their location these wind farms/parks are of two types:
Onshore: Wind turbines located on land
Offshore: Wind turbines located over water bodies
Muppandal wind farm located at Kanyakumari, Tamilnadu is the largest onshore wind farm in India with the capacity of 1500 MW.
Jaisalmer wind park located at Jaisalmer, Rajasthan has a capacity of 1064 MW.
Advantages of Wind Energy:
Ø cost-effective
Ø Clean and efficient
Challenges of Wind Energy:
l Noisy
l Effected by changes in wind conditions
l Impact on local wildlife, specially birds
Position of India in Harnessing Wind Energy
l 4th position in world
3. Hydropower
Hydropower is also known as Hydroelectric Energy as electricity is generated by harnessing the energy of flowing or falling water using turbines.
l The first Hydro electricity generating station in India was established in Darjeeling in 1897.
l Some examples of hydro projects in India include Hirakund dam on river Mahanadi, Bhakra Nangal dam on river Satluj, Nagarjuna Sagar dam on River Krishna among various others.
Types of hydro-power stations: Depending upon the method of hydro electric energy generation, these are of two types:
Dams and Reservoirs: These are the large hydro power plants in which huge reservoirs are made for water storage and water is released from these over turbines for generating electricity.
Dams: Dams are the barrier across flowing water that obstructs and then directs the flow of water
Run-of-the-River: These are the smaller hydro power plants which generate electricity by channelizing the natural flow of rivers without the need for large dams thereby minimizing the harm to the existing ecosystems.
Advantages of Hydropower:
l Clean and efficient energy source
l Efficient (provides continuous and stable electricity)
Challenges of Hydropower:
l Negative impacts on existing ecosystems (habitat destruction, and displacement of local communities).
l Low/No hydroelectricity generation during droughts
Position of India in Harnessing Hydro Power
l 5th position in world
4. Geothermal Energy
Ø Geothermal energy is the renewable source of energy in which heat energy from the Earth's core is utilized to generate electricity or for direct heating (industrial processes/ heating buildings/ various agricultural applications).
Ø The utilization of geothermal energy is most effective in areas depicting high geothermal activity(like at the boundaries of tectonic plates)
Ø Puga Valley (Ladakh) is the example of geothermal sites in India.
Process for utilizing geothermal energy for Generating electricity:
l For utilising geothermal energy, first the cold water is pumped down into rocks where it is converted into steam.
l This steam is then taken out via holes and and is allowed to run turbines for generating electricity.
Advantages of Geothermal energy:
l Provides clean energy
l Economic
Challenges of Geothermal energy:
l Availability of suitable sites for drilling as it is accompanied by evolution hazardous gases and minerals.
l Expensive Drilling for localizing suitable sites and plant construction.
Position of India in Harnessing Geothermal Energy
India is facing difficulty in utilizing the geothermal energy in appreciable amount and is only exploratory stages of its utilization.
5. Biomass Energy
Biomass energy is another renewable source of energy in which the energy from the organic matter derived from plants, animals, other microorganisms, their waste products and dead remains is used to generate heat, electricity and biofuels etc.
Different processes utilized in generating Biomass Energy: Combustion, gasification, fermentation, and anaerobic digestion are some of the processes used to generate biomass energy.
1. Combustion: It is the process of direct burning of biomass producing heat energy which can be used either directly or converted into electricity.
2. Gasification: It is the process of heating biomass in a low-oxygen environment to produce a mixture of gases called as syn-gas, which are further converted into other liquid fuels.
3. Fermentation: It is the process of treating sugars from various crop residues like corn or sugarcane with yeast or bacteria in the absence of oxygen and generates ethyl alcohol.
4. Anaerobic Digestion: It is the process of digestion of organic residues such as food scraps or manure or dead remains by various microbes in the absence of oxygen to produce biogas whose major component is methane.
5. Pyrolysis: It is the process of thermal degradation of biomass at high temperatures and in the absence of oxygen to generate a mixture of products such as bio-oil, syngas etc.
Some Most Commonly Used Biomass Energy Sources:
i. Wood and Wood Products
l Oldest and most common forms of biomass energy
l Can be burned directly for heat production
l Can be converted into bio-fuels like wood pellets.
l Can be used to produce electricity in power plants.
ii. Agricultural Residues
l Can be burned directly for heat production
l Can be converted into bio-ethanol via fermentation
l Can be used to produce biogas through anaerobic digestion
iii. Animal Manure, Food and Yard Waste, Municipal Solid Waste (MSW)
l Can be used to produce biogas through anaerobic digestion which further can be used to produce heat or electricity or fuel in transport vehicles.
iv. Algae
· fast-growing organism grown in water frequently used to produce biofuels
· Can be converted into biodiesel or bioethanol
· Can be used to produce biogas
v. Biofuels
· Bioethanol: Prepared from fermentation of sugars in presence of yeast and is commonly used as an additive to gasoline (Petrol).
· Biodiesel: Prepared from trans-esterification of vegetable and animal oils and can be blended with diesel.
· Biobutanol: owing to its higher energy content and similar octane number to gasoline, it can be used as a direct replacement for gasoline.
vi. Biogas
· Produced by the breakdown of organic materials in the absence of oxygen through a process called anaerobic digestion.
· Used for cooking, heating or electricity generation
· Also enriched as Biomethane for usage in transport vehicles
Biomethane: It is the enriched biogas from which hydrogen sulphide, carbon dioxide and water have been removed and its composition is almost similar to fossil natural gas.
Advantages of Biomass Energy:
· Sustainable and Renewable source of energy
· Carbon Neutral as it releases Carbon dioxide which is used by plants in photosynthesis.
· Reduces Waste accumulation by converting it into energy
Challenges of Biomass Energy:
· Competition for Land and Resource Use
· Air Pollution
· Need more optimization of production processes
6. Ocean Energy
Ocean energy is derived from the movement of ocean water, either from tides or waves. This is still a developing field, but it holds great potential.
i. Wave energy
The energy of the waves is also utilized at coastline where waves break for generating electricity with the help of floating turbine platform
Tidal energy:
l Energy is produced by using the tidal movement of seawater for about 10 hours/day when tide is actually moving in and out in India.
l In India, Gulf of Gulch, Gulf of Combat and Sundarban are identified as prospective sites of tidal energy.
Ocean thermal energy:
Ocean thermal energy is energy due to difference in temperature of water at the surface of ocean and at deeper level separated by a thermocline is called ocean thermal energy.
Ocean Thermal Energy Conversion (OTEC):
l The process of Ocean Thermal Energy Conversion is used to convert Ocean Thermal Energy into electricity.
l The difference in temperature of minimum 20°C or more is required for the efficient operation of ocean thermal energy conversion.
Operation of Ocean Thermal Energy Conversion Plant:
l In the ocean thermal energy conversion plant, pressurized ammonia is used as the mediator for heat exchange
l First ammonia is converting into its vapours by heat exchanged through warm water.
l The resulting vapors of ammonia are then used to move turbine for generating electricity.
l Then again these ammonia vapours are condensed using heat exchange with cold ocean water.
l In India OTEC sites are located near the islands of Lakshadweep and Andaman and Nicobar.
Advantages of Ocean energy:
l Predictable as tides and waves follow regular cycles.
l Huge potential for coastal regions.
l Clean energy source
Challenges of Ocean energy:
l Optimization of technology is required
l Negative impacts on marine ecosystems.
7. Hydrogen Energy
Hydrogen is a secondary energy source, but it itself is produced using other energy sources through a process called electrolysis, which splits water into hydrogen and oxygen using electricity from various other energy sources
It is of two types:
Green Hydrogen: produced using renewable energy sources
Grey Hydrogen: produced using energy from fossil fuels.
Advantages of Hydrogen Energy:
l Clean fuel
l High energy efficiency
Challenges of Hydrogen Energy:
l Expensive Synthesis
l Safety issues in storing and transporting hydrogen
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