Green Technology (RGT6A003)

Photosynthesis is the biological process by which green plants, algae, and some bacteria convert sunlight, water (H2O), and carbon dioxide (CO2) into glucose (C6H12O6) and oxygen (O2).

• Occurs in chloroplasts containing chlorophyll
• Plants act as natural carbon sinks, absorbing atmospheric CO2
• Essential for carbon mitigation and maintaining Earth's oxygen supply

Carbon-neutral items are products or processes whose net carbon emissions are zero. This is achieved by balancing emissions with carbon offsets or by using renewable energy throughout the production cycle.

Examples:

• Electric vehicles running on renewable energy
• Products with carbon offset certificates
• Bamboo products (bamboo absorbs more CO2 than trees)
• Goods produced using 100% solar/wind energy

MRV stands for Measurement, Reporting, and Verification. It is a system to ensure transparency and accountability in emission reduction reporting under international climate agreements.

Components:

• Measurement: GHG inventory, monitoring systems, data collection
• Reporting: National communications, biennial reports to UNFCCC
• Verification: Independent review, compliance assessment, third-party audits

MRV helps track progress toward Paris Agreement goals and ensures credibility of climate commitments.

GRIHA (Green Rating for Integrated Habitat Assessment) is India's national green building rating system developed by TERI and supported by Ministry of New and Renewable Energy (MNRE).

Role of GRIHA:

• Evaluates environmental performance of buildings throughout their lifecycle
• Assesses energy efficiency, water management, waste handling, and indoor air quality
• Promotes sustainable construction practices in India
• Reduces resource consumption and ecological impact
• Provides certification for commercial, residential, and institutional buildings

Renewable energy sources are naturally replenishing energy resources that are virtually inexhaustible.

Two main renewable energy sources:

• Solar Energy: Harnessed through photovoltaic (PV) panels or concentrating solar power (CSP) systems. India has vast solar potential with National Solar Mission targeting 100 GW capacity.
• Wind Energy: Generated using wind turbines that convert kinetic energy of wind into electricity. Major sites in Tamil Nadu, Gujarat, Karnataka, and Rajasthan.

Other examples: Hydropower, Biomass, Geothermal, Tidal energy

Net accumulation refers to the buildup of greenhouse gases (especially CO2) in the atmosphere when emissions exceed natural absorption by carbon sinks.

Key Points:

• Earth's carbon sinks (forests, oceans, soil) absorb only ~50% of emissions
• The remaining ~50% accumulates in the atmosphere
• Causes: Rapid industrial emissions, deforestation reducing sinks, ocean saturation
• Results in enhanced greenhouse effect and global warming

Current atmospheric CO2 level: ~420 ppm (pre-industrial: 280 ppm)

Net-Zero refers to achieving a balance between greenhouse gases emitted into the atmosphere and those removed from it.

Key Aspects:

• Cutting emissions as much as possible through clean energy transition
• Offsetting remaining emissions through carbon removal methods (afforestation, CCS, BECCS)
• Paris Agreement target: Global Net-Zero by 2050
• India's target: Net-Zero by 2070 (announced at COP26)

Net-Zero is different from "zero emissions" - it allows some emissions as long as they are fully offset.

Eco-friendly building materials minimize environmental impact during production, use, and disposal.

Two important eco-friendly materials:

• Fly Ash Bricks: Made from industrial waste (fly ash from thermal power plants). Reduces cement use by 20-30%, lower embodied energy, better thermal insulation, and utilizes industrial waste.
• Recycled Steel: Reduces need for virgin iron ore mining, saves up to 75% energy compared to new steel production, fully recyclable without quality loss.

Other examples: Bamboo, low-VOC paints, reclaimed wood, aerated concrete blocks (AAC), compressed earth blocks, recycled glass.

Solar PV (Photovoltaic) systems convert sunlight directly into electricity using semiconductor cells.

Working Principle:

• Photovoltaic Effect: When sunlight (photons) strikes the PV cell made of semiconductor material (usually silicon), it knocks electrons loose from atoms
• Electric Current: The freed electrons flow through the material, creating an electric current (DC power)
• Inverter: DC power is converted to AC power by an inverter for household/grid use
• Grid Connection: Excess power can be fed back to the grid (net metering)

Components: Solar panels, inverter, mounting structure, battery (optional), charge controller

India has significant wind energy potential concentrated in coastal and hilly regions. Total wind potential: 302 GW at 100m height.

Major Windy Sites in India:

State	Key Locations	Potential (GW)
Gujarat	Kutch, Jamnagar, Porbandar	84.4
Karnataka	Chitradurga, Davangere, Bellary	55.9
Maharashtra	Ahmednagar, Satara, Sangli	45.4
Tamil Nadu	Muppandal, Kayathar, Coimbatore	33.8
Rajasthan	Jaisalmer, Jodhpur	18.8
Andhra Pradesh	Anantapur, Kurnool	44.2

Greenhouse gases (GHGs) trap heat in the atmosphere, causing the greenhouse effect.

Three Major Greenhouse Gases:

• Carbon Dioxide (CO2): Primary GHG from fossil fuel combustion, deforestation. Contributes ~76% of global warming. GWP = 1
• Methane (CH4): From agriculture, livestock, landfills, natural gas leaks. 28-36 times more potent than CO2 (GWP = 28-36)
• Nitrous Oxide (N2O): From fertilizers, industrial processes, combustion. GWP = 265-298

Other GHGs: Water vapor, Ozone (O3), Fluorinated gases (HFCs, PFCs, SF6)

Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy, water, and carbon dioxide into glucose and oxygen.

• Takes place in chloroplasts using chlorophyll pigment
• Two stages: Light-dependent reactions and Calvin cycle (light-independent)
• Critical for carbon sequestration - plants absorb atmospheric CO2
• Produces oxygen essential for life on Earth

Both are green building rating systems that assess sustainability and environmental performance of buildings.

Parameter	LEED	GRIHA
Full Form	Leadership in Energy and Environmental Design	Green Rating for Integrated Habitat Assessment
Origin	USA (USGBC)	India (TERI + MNRE)
Scope	International	National (India-specific)
Certification Levels	Certified, Silver, Gold, Platinum	1 to 5 Stars

Both assess: Energy efficiency, water conservation, materials, indoor environment quality, site planning.

Long half-life refers to the exceptionally long atmospheric lifetime of CO2, meaning it persists in the atmosphere for hundreds to thousands of years.

CO2 Removal Timeline:

• ~40% removed within 30 years
• ~30% removed in a few centuries
• ~20-30% persists for several millennia

Implications:

• Carbon emitted today affects many future generations (intergenerational impact)
• Makes emission reduction urgent - effects are long-lasting
• Justifies strong climate action now

Green Technology (also called clean technology or environmental technology) refers to environmentally friendly technologies designed to mitigate or reverse the negative effects of human activity on the environment.

Key Areas of Green Technology:

• Renewable Energy: Solar, wind, hydro, biomass, geothermal
• Energy Efficiency: LED lighting, efficient appliances, smart grids
• Green Buildings: ECBC compliance, sustainable materials, passive design
• Clean Transport: EVs, hydrogen fuel cells, biofuels
• Waste Management: Recycling, waste-to-energy, composting
• Water Conservation: Rainwater harvesting, wastewater treatment

Goal: Reduce carbon emissions, conserve resources, protect ecosystems.

Tidal Energy is renewable energy harnessed from the rise and fall of ocean tides caused by gravitational forces of the moon and sun.

Technologies:

• Tidal Barrages: Dams across estuaries that capture water during high tides and release through turbines during low tides
• Tidal Stream Generators: Underwater turbines placed in fast-flowing tidal currents (like underwater wind turbines)
• Tidal Lagoons: Artificial enclosures that capture tidal water

India's Potential Sites:

• Gulf of Khambhat (Gujarat) - 7000 MW potential
• Gulf of Kutch (Gujarat) - 1200 MW potential
• Sundarbans (West Bengal)

Advantages: Predictable, reliable, no fuel cost, long lifespan

Renewable energy sources are naturally replenishing and virtually inexhaustible on a human timescale.

Examples:

• Solar Energy: Photovoltaic panels, Concentrating Solar Power (CSP)
• Wind Energy: Onshore and offshore wind turbines
• Hydropower: Large dams, run-of-river, small hydro plants
• Biomass Energy: Agricultural waste, wood, biogas, biofuels
• Geothermal Energy: Heat from Earth's interior
• Tidal/Ocean Energy: Tidal barrages, wave energy converters

India's RE Capacity (2024): ~180 GW installed (Solar: 80+ GW, Wind: 45+ GW)

Heating Potential (Global Warming Potential - GWP) is a measure that compares the heat-trapping ability of a greenhouse gas relative to CO2 over a specified time period (usually 100 years).

GWP Values:

Gas	GWP (100 years)	Source
Carbon Dioxide (CO2)	1 (reference)	Fossil fuels
Methane (CH4)	28-36	Agriculture, landfills
Nitrous Oxide (N2O)	265-298	Fertilizers, industry
Sulfur Hexafluoride (SF6)	>23,000	Electrical equipment

Usage: GWP helps calculate CO2-equivalent emissions for climate inventories and policies.

China was the highest emitter of CO2 by 2010, surpassing the United States.

Top CO2 Emitters (2010):

Rank	Country	Emissions (Gt CO2)
1	China	~8.3
2	United States	~5.4
3	European Union	~3.6
4	India	~1.7
5	Russia	~1.6

Note: India ranks 4th in total emissions but has low per-capita emissions (~1.9 tCO2/capita vs USA's ~15 tCO2/capita).

Carbon neutral means achieving net-zero carbon emissions by balancing emissions with carbon offsets or removal.

Examples of Carbon Neutral Entities:

• Bhutan: World's first and only carbon-negative country (absorbs more CO2 than it emits due to 70%+ forest cover)
• Costa Rica: Achieved nearly carbon-neutral status through massive reforestation (forest cover increased from 21% to 52%)
• Iceland: Uses geothermal and hydropower for 100% renewable electricity

Carbon Neutral Companies:

• Microsoft (carbon negative since 2020)
• Google (carbon neutral operations)
• Apple (carbon neutral by 2030 goal)

Greenhouse gases (GHGs) are atmospheric gases that trap infrared radiation, causing the greenhouse effect and global warming.

Major Greenhouse Gases:

• Carbon Dioxide (CO2): From fossil fuel combustion, deforestation. ~76% of warming effect. Atmospheric lifetime: centuries to millennia
• Methane (CH4): From livestock, rice paddies, landfills, natural gas. GWP = 28-36
• Nitrous Oxide (N2O): From fertilizers, industrial processes. GWP = 265-298
• Water Vapor (H2O): Most abundant GHG but acts as feedback, not driver
• Ozone (O3): Tropospheric ozone is a GHG
• Fluorinated Gases: HFCs, PFCs, SF6 - synthetic, very high GWP

Biofuel is renewable fuel derived from organic biomass like plants, algae, or animal waste. It serves as a cleaner alternative to fossil fuels.

Types of Biofuels:

• Bioethanol: Alcohol from fermentation of sugarcane, corn, wheat. Used in petrol blending (E10 = 10% ethanol)
• Biodiesel: From vegetable oils, animal fats through transesterification. Used in diesel blending (B20 = 20% biodiesel)
• Biogas: Methane-rich gas from anaerobic digestion of organic waste
• Bio-CNG: Purified biogas (95% methane) - vehicle fuel

India's Biofuel Policy: Target of 20% ethanol blending in petrol by 2025-26 (achieved E12 in 2024)

Zero Energy Building (ZEB) is a building that produces as much renewable energy on-site as it consumes annually, resulting in net-zero energy consumption.

Key Features:

• Energy Efficiency: High insulation, efficient HVAC, LED lighting, passive solar design
• Renewable Energy: Rooftop solar PV, small wind turbines, solar water heaters
• Smart Systems: Building automation, smart meters, energy management
• Net Metering: Excess energy fed back to grid, drawn when needed

ZEB Hierarchy:

• ZEB Ready - highly efficient but no on-site RE
• Nearly ZEB - produces most of its energy
• Net ZEB - produces 100% of annual consumption
• Plus Energy Building - produces more than consumed

Renewable sources of energy are derived from natural processes that are constantly replenished and cannot be depleted.

Examples with Applications:

Source	Technology	Application
Solar	PV panels, CSP	Electricity, water heating
Wind	Turbines	Grid electricity
Hydro	Dams, turbines	Large-scale power
Biomass	Gasification, biogas	Heat, electricity, fuel
Geothermal	Heat pumps	Heating, electricity
Tidal	Barrages, turbines	Coastal electricity

Photosynthesis is the process by which plants, algae, and cyanobacteria convert light energy into chemical energy, storing it in glucose molecules. Process:

• Light Reactions: Occur in thylakoids; water splits, O2 released, ATP and NADPH produced
• Calvin Cycle: Occurs in stroma; CO2 fixed into glucose using ATP and NADPH

Environmental Significance:

• Removes CO2 from atmosphere (carbon sequestration)
• Produces oxygen for respiration
• Basis of food chain and biomass energy

Net accumulation of GHGs is the net increase in atmospheric concentration of greenhouse gases when global emissions exceed absorption by natural sinks.

Carbon Balance:

• Global Emissions: ~40 Gt CO2/year (fossil fuels + land use)
• Natural Absorption: ~20 Gt CO2/year (oceans + forests)
• Net Accumulation: ~20 Gt CO2/year remains in atmosphere

Consequences:

• CO2 levels risen from 280 ppm (pre-industrial) to ~420 ppm (2024)
• Enhanced greenhouse effect causing global warming
• Ocean acidification as oceans absorb excess CO2

Solution: Reduce emissions + enhance carbon sinks (afforestation, CCS)

The MRV Debate concerns disagreements between developed and developing nations on how to measure, report, and verify emission reductions under climate agreements.

Key Issues in the Debate:

• Differentiation: Developed nations want uniform, strict verification for all countries
• Flexibility: Developing nations (like India) seek flexibility based on their circumstances and capacities
• CBDR Principle: Common But Differentiated Responsibilities - historical emitters should bear more burden
• Capacity Building: Developing nations need financial and technical support for MRV systems
• Sovereignty: Concerns about international scrutiny of domestic actions

India's Position: Supports transparency but demands consideration of development needs, technology transfer, and climate finance.

Carbon Tax is a fee imposed on the burning of carbon-based fuels (coal, oil, gas) to reduce greenhouse gas emissions by making polluters pay for emitting CO2.

How it Works:

• Government sets a price per tonne of CO2 emitted
• Industries/consumers pay tax based on carbon content of fuels
• Creates economic incentive to reduce emissions and switch to clean energy

Advantages:

• Simple to implement and administer
• Provides price certainty for businesses
• Generates revenue for green investments

India's Approach:

• Coal Cess (now GST Compensation Cess)
• PAT Scheme (Perform, Achieve, Trade) for industries

Global Examples: Sweden ($130/tonne), Canada ($50/tonne), EU ETS

Ozone-depleting substances (ODS) are chemicals that destroy the protective ozone layer in the stratosphere.

Major Ozone-Depleting Gases:

• Chlorofluorocarbons (CFCs): Used in refrigerators, air conditioners, aerosol sprays. Most damaging ODS
• Halons: Used in fire extinguishers. Contain bromine which is more destructive than chlorine
• Carbon Tetrachloride (CCl4): Industrial solvent
• Methyl Bromide: Agricultural pesticide/fumigant
• HCFCs: Transitional substitutes for CFCs, less damaging but still harmful

Regulation:

• Montreal Protocol (1987): International treaty phasing out ODS
• Kigali Amendment (2016): Phasing down HFCs (potent GHGs)

Global Warming Potential (GWP) is a measure of how much heat a greenhouse gas traps in the atmosphere over a specific time period, compared to carbon dioxide (CO2).

Definition: CO2 is the reference gas with GWP = 1. Other gases are compared to it. GWP Values (100-year horizon):

Gas	GWP	Atmospheric Lifetime
CO2	1	Centuries to millennia
CH4	28-36	12 years
N2O	265-298	121 years
SF6	23,500	3,200 years

Use: Calculating CO2-equivalent (CO2e) emissions for inventories and climate policies.