9.1. SOLAR TECHNOLOGY

Why in news?

• Recently, world’s largest solar park of 2,000 MW, named as ‘Shakti Sthala’ set up at Pavagada in Tumakuru district, Karnataka.

Solar Park scheme

• Launched by Ministry of New and renewable Energy (MNRE) and implemented by Solar Energy Corporation (SECI).
• Objective: To create at least 50 solar parts with a capacity of 500 MW and above by 2019-20.
•  Solar Park: It’s a concentrated zone of development of solar power generation projects and provides developers an area that is well constructed, with proper infrastructure, access to amenities and by minimizing paper works for project implementation.
  

  Solar Energy Corporation of India ltd” (SECI)

•  It’s a CPSU under the administrative control of the MNRE,
• Objective: It’s responsible for implementation of a number of schemes of MNRE, major ones being the VGF schemes for large-scale grid-connected projects under JNNSM, solar park scheme and grid-connected solar rooftop scheme etc
•  It is the only CPSU dedicated to the solar energy sector.

Sunrush: It’s a 25-year period (1992-2017) in which solar power has grown exponentially, transforming the technology from rarefied oddity to the world’s fastest-Solar technology growing energy source.

• Solar energy is the cleanest, most abundant renewable energy source available.
• Three primary technologies by which solar energy is commonly harnessed by:
•  Photovoltaics (PV): It directly convert sunlight to electricity.
•  Concentrating Solar Power (CSP): It uses heat from the sun (thermal energy) to drive utility-scale, electric turbines.

About Solar Cells/Photovoltaic (PV) Cells: PV gets its name from the process of converting light (photons) to electricity (voltage), which is called the PV effect.

•  How it works: When sunlight strikes the PV module, made of a semiconductor material, electrons are stripped from their atomic bonds. This flow of electrons produces an electric current. Types of solar cell
  First Generation solar cells are made from silicon, are usually flat-plate.
•  Second-generation solar cells are called thin-film solar cells because they are made from amorphous silicon or nonsilicon materials such as cadmium telluride.
•  Third-generation solar cells: They are made from a variety of new materials besides silicon, including solar inks using conventional printing press technologies, solar dyes, and conductive plastics.

Perovskite Solar Cells

• What is Perovskite: A perovskite is a material that has the same crystal structure as the mineral calcium titanium oxide (also known as Perovskite).
• Perovskite Solar Cell is one that includes a perovskite-structured compound, most commonly a hybrid organic-inorganic lead or tin halide-based material, as the light-harvesting active layer.
• Perovskite captures energy from a different part of sunlight’s wavelength than silicon.
• Perovskite solar cells in last few years have outpaced all other third-generation solar technologies in terms of efficiency and cost.

9.2. INDIA’S THREE-STAGE NUCLEAR POWER PROGRAMME

It was formulated by Dr. Homi Bhabha in the 1950s to secure the country’s long term energy independence, through the use of uranium and thorium reserves found in the monazite sands of coastal regions of South India.

Objective: To utilize the known resources of thorium reserve found in India (India has 25% of world thorium reserves but only 1-2% global uranium reserve), to provide safe and reliable electric power for the country’s social and economic progress and to be self-reliant in all aspects of nuclear technology.

STAGE 1: PRESSURISED HEAVY WATER REACTOR

•  In this natural uranium (0.7 % fissile U-235 and the rest is U-238) fuelled pressurised heavy water reactors (PHWR) which produce electricity while generating plutonium-239 as by-product.

STAGE II – FAST BREEDER REACTOR

• In the second stage, fast breeder reactors (FBRs) would use a mixed oxide (MOX) fuel made from plutonium-239, recovered by reprocessing spent fuel from the first stage, and natural uranium.
• In FBRs, plutonium-239 undergoes fission to produce energy, while the uranium-238 present in the mixed oxide fuel transmutes to additional plutonium-239.
• Thus, the Stage II FBRs are designed to “breed” more fuel than they consume.

STAGE III – THORIUM BASED REACTORS

• A Stage III reactor or an advanced nuclear power system involves a self-sustaining series of thorium-232- uranium-233 fuelled reactors.
• This would be a thermal breeder reactor, which in principle can be refueled after its initial fuel charge using only naturally occurring thorium.
• According to the three-stage programme, Indian nuclear energy could grow to about 10 GW through PHWRs fueled by domestic uranium, and the growth above that would have to come from FBRs till about 50GW.

About Atomic Energy Regulatory Board (AERB)

•  Atomic Energy Regulatory Board is a statutory body created by the President under Atomic Energy Act, 1962 to carry out the regulatory and safety functions under the Act.
•  It derives its regulatory powers from the rules and notifications promulgated under the Atomic Energy Act, 1962 and the Environmental (Protection) Act, 1986.

	BWR	PWR	PHWR	FBR
Purpose	Electricity	Electricity,nuclear powered ships	Electricity,plutonium,production	Electricity,plutonium,production
Coolant	Water	water	Heavy water (D2O)	Molten,liquid sodium
Moderator	Water	Water	Heavy Water (D2O)	Not required
Fuel	Uranium dioxide	Uranium dioxide (UO2)	UO2 or metal	Plutonium dioxide and UO2 in different combinations
Enrichment level	Low-enriched	Low-enriched	Not-enriched	Various mixtures of P-239 and U-235

BWR – boiling water reactor // PWR – pressurized water reactor.

9.3. COLD FUSION

Cold Fusion

• Cold fusion describes a form of energy generated when hydrogen interacts with various metals like nickel and palladium. Excess heat is generated by the interaction that can be used to turn the turbine.
• Cold fusion seeks to produce nuclear energy without harmful radiation, complex equipment and the application of very high temperatures and pressures.
• The major challenge is to control the reaction.

 

9.4. GRAPHENE BASED BATTERY

Why in news

• Recently, Scientists have developed a new graphene-based battery material with charging speed five times faster than lithium-ion batteries.

About Graphene

• Graphene form of carbon consists of planar sheets (2D structure) which are one atom thick, with  the  atoms  arranged   in  a hexagonal  lattice   (honeycomb-shaped lattice).
• Very good conductor of electricity and heat
• About 200 times stronger than steel and nearly transparent.
• Impermeable to gases
• Applications: It can be used as/in Paints and coatings, lubricants, oils and functional fluids, capacitors and batteries, thermal management applications, display materials and packaging, solar cells, inks and 3D-printers’ materials and films etc.

Types of Batteries

Alkaline batteries

• They are non-rechargeable, high energy density, batteries that have a long life span.
• Electrolyte used in it is alkaline (non-acidic).
• Generally, it has zinc as anode and a carbon rod/manganese dioxide as cathode with potassium hydroxide as the electrolyte. This is similar to dry cell where only electrolyte is different, i.e., ammonium chloride.
• Non-alkaline batteries: They are similar to alkaline batteries except the electrolyte used is acidic in nature, generally a mixture of ammonium chloride and zinc chloride.
• In lead acid battery, the reaction of lead and lead oxide with the sulfuric acid electrolyte produces a voltage

Fuel cell

• A fuel cell uses the chemical energy of hydrogen or another fuel to cleanly and efficiently produce electricity. If hydrogen is the fuel, electricity, water, and heat are the only products.
• Fuel cells work like batteries, but they do not run down or need recharging. They produce electricity and heat as long as fuel is supplied.
• Fuel-cell vehicles use a completely different propulsion system from conventional vehicles that can be two or three times more efficient
• Hydrogen as a pure gas is not easily available. Thus, making it very costly source of energy.

 

9.5. LITHIUM-ION BATTERY

Why in news?

• Recently, ISRO has approved commercial use of lithium-ion battery technology.

Advantages of lithium-ion batteries over lead acid batteries

• Weight: Lithium-ion batteries are one-third the weight of lead acid batteries.
• Efficiency: Lithium-ion batteries are nearly 100% efficient in both charge and discharge while the lead batteries have the 70% efficiency.
• Discharge: Lithium-ion batteries are discharged 100% versus less than 80% for lead acid.
• Cycle Life: Rechargeable lithium-ion batteries cycle 5000 times or more compared to just 400-500 cycles in lead acid.
• Voltage: Lithium-ion batteries maintain their voltage throughout the entire discharge cycle. Lead acid voltage drops consistently throughout the discharge cycle.
• Cost: Despite the higher upfront cost of lithium-ion batteries, the true cost of ownership is far less than lead acid when considering life span and performance.
• Environmental Impact: Lithium-ion batteries are a much cleaner technology and are safer for the environment.
• Common usage of Li-ion battery: Pacemakers, digital cameras, Smartphones, Solar Power Storage, battery backup systems, Rocket launcher etc.

9.6. ARTIFICIAL LEAF

Why in news?

• Scientists at CSIR have developed an artificial leaf that absorbs sunlight to generate hydrogen fuel from water.

CSIR

Council of Scientific and Industrial Research is India’s premier national R&D organisation established in 1942.

• It operates as an autonomous body under Societies Registration Act 1860 and comes broadly under purview of Ministry of Science and Technology.
• Prime Minister of India is the chairman of CSIR. Bionic Leaf uses solar energy to split water molecules into oxygen and hydrogen, and hydrogen-eating bacteria to produce liquid fuels from CO2.

Mechanism

• Artificial leaf is an ultra-thin wireless device that consists of semi-conductors stacked in such a manner as to simulate the natural leaf system.
• When visible light strikes the semi-conductors electrons move in single direction thus producing electric current which almost instantaneously splits water into hydrogen.
• A palm size artificial leaf can produce six litres of hydrogen fuel per hour thus making it extremely environment friendly.

<H3>9.7 SUPERCRITICAL CO2-BRAYTON CYCLE</H3>

Why in news?

• Indian scientists have developed a super critical carbon dioxide Brayton test loop facility that would help generate clean energy from future power plants.
• Brayton cycle – A thermodynamic cycle using constant pressure, heat addition and rejection to spin the blades of a turbine, which can be used to generate electricity.

Key facts

• This is India’s first test-bed for next generation, efficient, compact, waterless super critical carbon dioxide Brayton cycle test loop for power generation.
• The term “supercritical” describes the state of carbon dioxide above its critical temperature of 31°C and critical pressure of 73 atmospheres making it twice as dense as steam.
• Today’s thermal power plants use steam to carry heat away from the source and turn a turbine to generate power. However, it could generate more power if, instead of steam, supercritical CO2 (SCO2) is used.