2. The Air Quality Index (AQI)

The AQI is a colour-coded index launched under the Swachh Bharat campaign to simplify the understanding of pollution levels. It helps convey the condition of the air and guides appropriate measures based on the severity of pollution. The AQI consists of six categories, each with a corresponding colour code: 'Good' (0-50), 'Satisfactory' (51-100), 'Moderately Polluted' (101-200), 'Poor' (201-300), 'Very Poor' (301-400) and 'Severe' (401-500).

3. Calculation of AQI

• To calculate the AQI, a technical study was conducted by an expert group, including medical professionals, air quality experts, and academics.
• Various pollutants, such as PM10, PM2.5, Nitrogen Dioxide, Ozone, Carbon, and others, are measured.
• Each pollutant is assigned a weight based on its impact on human health.
• The composite air quality index is determined by combining these weights, simplifying multiple data points into a single number and colour to represent overall air quality.
• Monitoring stations across the country assess these pollutant levels.

4. Impact of Pollutants on Health

• Among the most harmful pollutants are fine particulate matter, such as PM2.5, which has a diameter smaller than 2.5 micrometres.
• PM2.5 particles can easily enter the circulatory system, bypassing the nose and throat.
• They are associated with respiratory problems and reduced visibility, posing health risks such as asthma, heart attacks, bronchitis, and other respiratory issues.

5. Influence on Government Policy

• Governments, especially in areas like Delhi, use the AQI to announce measures to combat air pollution.
• When the AQI in the National Capital Region (NCR) reaches the 'severe' category, Stage 4 of the Graded Response Action Plan (GRAP) is implemented.
• GRAP is designed for emergency measures to prevent further deterioration of air quality.
• Specific actions may include prohibiting the use of non-BS-VI-compliant diesel four-wheelers and restricting the entry of trucks into the city while allowing petrol cars to continue operating as usual.

6. Conclusion

The Air Quality Index is an essential tool that simplifies the understanding of air pollution, assesses its health impacts, and influences government policies and actions to combat deteriorating air quality. As Mumbai braces for worsening air quality, the AQI will continue to be a critical resource for both the government and the public.

 Source: The Indian Express

RENEWABLE ENERGY

1. Context

2. Why use Renewable energy

• Today we primarily use fossil fuels to heat and power our homes and fuel our cars. 
• It’s convenient to use coal, oil, and natural gas for meeting our energy needs, but we have a limited supply of these fuels on Earth. 
• We’re using them much more rapidly than they are being created. Eventually, they will run out. 
• And because of safety concerns and waste disposal problems, the United States will retire much of its nuclear capacity by 2020. 
• In the meantime, the nation’s energy needs are expected to grow by 33 per cent during the next 20 years. 
• Renewable energy can help fill the gap
• Even if we had an unlimited supply of fossil fuels, using renewable energy is better for the environment. 
• We often call renewable energy technologies “clean” or “green” because they produce few if any pollutants. 
• Burning fossil fuels, however, sends greenhouse gases into the atmosphere, trapping the sun’s heat and contributing to global warming. 
• Climate scientists generally agree that the Earth’s average temperature has risen in the past century. 
• If this trend continues, sea levels will rise, and scientists predict that floods, heat waves, droughts, and other extreme weather conditions could occur more often. 
• Other pollutants are released into the air, soil, and water when fossil fuels are burned. 
• These pollutants take a dramatic toll on the environment—and humans. 
• Air pollution contributes to diseases like asthma. 
• Acid rain from sulfur dioxide and nitrogen oxides harms plants and fish. Nitrogen oxides also contribute to smog.
• Renewable energy will also help us develop energy independence and security. 
• Replacing some of our petroleum with fuels made from plant matter, for example, could save money and strengthen our energy security. 
• Renewable energy is plentiful, and the technologies are improving all the time. 
• There are many ways to use renewable energy. 
• Most of us already use renewable energy in our daily lives.

2.1.Hydropower 

• Hydropower is our most mature and largest source of renewable power, producing about 10 per cent of the nation’s electricity. 
• Existing hydropower capacity is about 77,000 megawatts (MW). Hydropower plants convert the energy in flowing water into electricity. 
• The most common form of hydropower uses a dam on a river to retain a large reservoir of water. Water is released through turbines to generate power.
•  “Run of the river” systems, however, divert water from the river and direct it through a pipeline to a turbine. 
• Hydropower plants produce no air emissions but can affect water quality and wildlife habitats. 

2.2.Bioenergy 

• Bioenergy is the energy derived from biomass (organic matter), such as plants. If you’ve ever burned wood in a fireplace or campfire, you’ve used bioenergy. 
• But we don’t get all of our biomass resources directly from trees or other plants. 
• Many industries, such as those involved in construction or the processing of agricultural products, can create large quantities of unused or residual biomass, which can serve as a bioenergy source. 

2.3.Geothermal Energy 

• The Earth’s core, 4,000 miles below the surface, can reach temperatures of 9000° F. 
• This heat—geothermal energy—flows outward from the core, heating the surrounding area, which can form underground reservoirs of hot water and steam. 
• These reservoirs can be tapped for a variety of uses, such as to generate electricity or heat buildings. 
• By using geothermal heat pumps (GHPs), we can even take advantage of the shallow ground’s stable temperature for heating and cooling buildings. 

2.4.Solar Energy 

• Solar technologies tap directly into the infinite power of the sun and use that energy to produce heat, light, and power.

2.5. Wind Energy 

• For hundreds of years, people have used windmills to harness the wind’s energy. 
• Today’s wind turbines, which operate differently from windmills, are a much more efficient technology. 
• Wind turbine technology may look simple: the wind spins turbine blades around a central hub; the hub is connected to a shaft, which powers a generator to make electricity. 
• However, turbines are highly sophisticated power systems that capture the wind’s energy using new blade designs or airfoils. 
• Modern, mechanical drive systems, combined with advanced generators, convert that energy into electricity. 
• Wind turbines that provide electricity to the utility grid range in size from 50 kW to 6 
• Wind energy has been the fastest growing source of energy since 1990.

2.6.Ocean Energy 

• The ocean can produce two types of energy: thermal energy from the sun’s heat, and mechanical energy from the tides and waves. 
• Ocean thermal energy can be used for many applications, including electricity generation. 
• Electricity conversion systems use either the warm surface water or boil the seawater to turn a turbine, which activates a generator. 
• The electricity conversion of both tidal and wave energy usually involves mechanical devices. 
• A dam is typically used to convert tidal energy into electricity by forcing the water through turbines and activating a generator. 
• Meanwhile, wave energy uses mechanical power to directly activate a generator or to transfer to a working fluid, water, or air, which then drives a turbine/generator.

2.7.Hydrogen 

• Hydrogen is high in energy, yet its use as a fuel produces water as the only emission. 
• Hydrogen is the universe’s most abundant element and also its simplest. 
• A hydrogen atom consists of only one proton and one electron. 
• Despite its abundance and simplicity, it doesn’t occur naturally as a gas on the Earth. 
• Today, industry produces more than 4 trillion cubic feet of hydrogen annually. 
• Most of this hydrogen is produced through a process called reforming, which involves the application of heat to separate hydrogen from carbon. Researchers are developing highly efficient, advanced reformers to produce hydrogen from natural gas for what’s called Proton Exchange Membrane fuel cells.

3. Steps were taken by the government to promote Renewable energy

The Indian renewable energy sector is the fourth most attractive renewable energy market in the world. India was ranked fourth in wind power, fifth in solar power and fourth in renewable power installed capacity, as of 2020.

3.1.Distribution of prominent renewable energy Hubs

• Rajasthan
• Gujarat
• Andhra Pradesh
• Karnataka
• Telangana
• Tamil Nadu

3.2.Steps taken

• Permitting Foreign Direct Investment (FDI) up to 100 per cent under the automatic route,
• Waiver of Inter-State Transmission System (ISTS) charges for inter-state sale of solar and wind power for projects to be commissioned by 30th June 2025,
• Declaration of trajectory for Renewable Purchase Obligation (RPO) up to the year 2022,
• Setting up of Ultra Mega Renewable Energy Parks to provide land and transmission to RE developers on a plug-and-play basis,
• Schemes such as Pradhan Mantri Kisan Urja Suraksha evam Utthaan Mahabhiyan (PM-KUSUM), Solar Rooftop Phase II, 12000 MW CPSU Scheme Phase II, etc,
• Laying of new transmission lines and creating new sub-station capacity under the Green Energy Corridor Scheme for evacuation of renewable power,
• Setting up of Project Development Cell for attracting and facilitating investments,
• Standard Bidding Guidelines for tariff-based competitive bidding process for procurement of Power from Grid Connected Solar PV and Wind Projects.