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General Studies 3 >> Enivornment & Ecology

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1. Context
Heat is animus. It was there at the birth of the universe, and its death will be the universe’s death. It is impossible to overstate its importance, both throughout human history and across modern technologies. The innovation of steam-powered pumps and engines in the 17th and 18th centuries, reaching the first of many summits in James Watt’s setup in 1764, precipitated the first Industrial Revolution. Today, global warming is forcing us to deliberate on the roles heat plays in our lives.
2. What is Heat?
  • In the context of microscopy, the temperature of an object reflects the average kinetic energy of its particles.
  • When two objects at different temperatures come into contact, the cooler one will heat up while the warmer one cools down. Here, heat refers to the thermal energy exchanged between the objects to cause this change in temperature.
  • On a larger scale, heat is treated as a type of energy with distinct properties, analyzed through thermodynamics, statistical mechanics, and related disciplines.
  • A substance can take in heat at one location and release it at another, a principle that underlies many contemporary technologies such as thermal and nuclear power plants and air conditioning systems.
  • Engineers have devised methods to transform heat into mechanical energy, enabling the creation of machines like the internal combustion engine
3. How is Heat Used?
  • One of the best ways to grasp the concept of heat is by looking at its applications, such as internal combustion engines (ICEs) and thermal power plants.
  • An ICE transforms heat into mechanical work, effectively applying the theoretical Carnot cycle, which defines the highest efficiency an engine can achieve in converting heat to work.
  • The engine consists of four main components: a hot reservoir (with more heat), a cold reservoir (with less heat), an ideal gas between the reservoirs (transferring heat), and a piston next to the gas. Each cycle includes four stages.
  • In the first stage, isothermal expansion, the ideal gas is insulated from the cold reservoir and exposed to the hot reservoir.
  • Heat from the hot reservoir, produced for example by burning petrol, transfers to the gas, causing it to expand and push the piston. The second stage, isentropic expansion, continues the gas expansion while insulated from both reservoirs.
  • The gas cools slightly as it does work on the piston without a temperature change due to insulation. These two steps involve the piston doing work on its surroundings.
  • The third stage, isothermal compression, exposes the gas to the cold reservoir, where it releases its remaining heat.
  • The piston moves downward in this stage. In the fourth stage, isentropic compression, the gas is again insulated from the reservoirs while the piston continues downward, compressing and warming the gas, readying it for the next cycle. In these last two steps, the surroundings work on the piston.
  • Similarly, a thermal power plant consists of a boiler, turbine, generator, condenser, and pumps, with water as the working fluid. The ideal version of this system is the Rankine cycle, also comprising four stages.
  • In the first stage, isentropic compression, a pump compresses the water to high pressure. During the second stage, heat addition, the water is pumped to the boiler and heated by an energy source, such as burning coal or nuclear fission, transforming it into saturated vapor under high pressure.
  • The third stage, isentropic expansion, involves the pressurized vapor expanding in the turbine, releasing heat and reducing pressure. This expansion drives the turbine blades, generating power through the generator.
  • In the final stage, heat removal, the cooled vapor enters the condenser, where it is condensed back to a saturated liquid at a fixed pressure. The condenser acts as a heat exchanger, using a coolant, such as cold water, to absorb the vapor's heat
4. How is heat related to work?
  • Heat and work share the same physical dimensions, but not all heat can be converted into work. For instance, if a system performs work while losing thermal equilibrium, it will lose some energy.
  • This can occur in an internal combustion engine (ICE) if, for example, it isn't well-lubricated, causing friction as the piston moves against the combustion chamber walls. This loss of 'useful heat' is tied to the concept of entropy, which indicates disorder in a system and prevents the associated heat from being converted into work.
  • Additionally, when a system performs work without losing or gaining heat—such as during the isentropic expansion and compression steps of the Carnot cycle—the process is considered adiabatic. Fully adiabatic processes are reversible.
  • Components of ICEs and thermal power plants are designed to alternate a medium that transports heat through different states, in steps that aim to maximize work output and minimize entropy changes and other energy losses
5.Applications of Heat
  • Understanding the microscopic and macroscopic properties of heat has been vital in fields such as metallurgy and materials science, mining, refineries, various chemical reactions, semiconductor electronics, meteorology, and transportation.
  • Heat plays a significant role in Heating, Ventilation, and Air-Conditioning (HVAC) systems. In many cold regions, heat is generated and transported from centralized facilities to homes and offices.
  • Individual homes often use electric heaters, which convert electrical energy to heat by passing a current through a resistor, to stay warm. Recently, experts have advocated for a 'right to air-conditioning' for people in low- and middle-income countries facing extreme heat.
  • Heat engines like internal combustion engines (ICEs) and steam engines operate on the Carnot cycle. Heat pumps, which are essentially air conditioners that heat rather than cool, use the reverse Carnot cycle.
  • Air conditioners for cooling large spaces, such as halls and car interiors, utilize the reverse Rankine cycle.
  • Other cycles, depending on the heat-transporting medium and desired operating conditions, include the Brayton, gas-generator, regenerative, Siemens, and Stirling cycles
6. Heat and Climate Change
  • The global response to climate change is focused on two main strategies: mitigation and adaptation. For climate mitigation, researchers worldwide are developing new methods to generate heat energy without burning fossil fuels and finding ways to reduce emissions from existing technologies. Meanwhile, policymakers are working on new incentives to encourage the adoption of these solutions.
  • In terms of climate adaptation, heat waves are a significant concern, especially in India. During a heat wave, the impact on health depends on the body's pre-existing health conditions and its ability to prevent heat accumulation.
  • Long-term health is influenced by living conditions, access to clean environments, and healthcare. Short-term heat management depends on immediate measures to reduce heat buildup. When the wet-bulb temperature exceeds about 32 degrees Celsius, even brief periods of light outdoor activity can cause severe harm.
  • Global warming itself is essentially a heat issue. Solar energy reaches the Earth, with some being reflected, some absorbed by the atmosphere, and some warming the ground. At night, the Earth emits this absorbed energy as infrared radiation.
  • Greenhouse gases like carbon dioxide, methane, and water vapour absorb this radiation, convert it to kinetic energy, and heat the atmosphere, which reduces the Earth's ability to cool down efficiently
7. Way Forward
Addressing the role of heat in climate change requires a dual approach: mitigating the causes by reducing greenhouse gas emissions and adapting to the effects by improving our resilience to heat-related impacts. Both scientific innovation and policy action are essential to effectively manage heat in the context of climate change
For Prelims: COP28, Organisation for Economic Cooperation and Development, Climate Finance, Climate Change, United Nations Framework Convention on Climate Change,  Nationally Determined Contributions, COP27, Copenhagen Accord, Paris Agreement 
For Mains: 
1. Discuss the impact of climate change on developing economies. How can climate finance be effectively utilized to promote sustainable development in these economies? (250 Words)

Previous Year Questions
1. With reference to the Agreement at the UNFCCC Meeting in Paris in 2015, which of the following statements is/are correct? (UPSC 2016)
1. The Agreement was signed by all the member countries of the UN and it will go into effect in 2017.
2. The Agreement aims to limit greenhouse gas emissions so that the rise in average global temperature by the end of this century does not exceed 2°C or even 1.5°C above pre-industrial levels.
3. Developed countries acknowledged their historical responsibility for global warming and committed to donate $1000 billion a year from 2020 to help developing countries cope with climate change.
Select the correct answer using the code given below
A. 1 and 3 only
B.  2 only
C.  2 and 3 only
D.  1, 2 and 3
Answer: B
2. The term ‘Intended Nationally Determined Contributions’ is sometimes seen in the news in the context of ( UPSC 2016)
A. pledges made by the European countries to rehabilitate refugees from the war-affected Middle East
B. plan of action outlined by the countries of the world to combat climate change
C. capital contributed by the member countries in the establishment of the Asian Infrastructure Investment Bank
D. plan of action outlined by the countries of the world regarding Sustainable Development Goals

Answer: B

3. The UN Framework Convention on Climate Change (UNFCCC) has announced which country to host the 28th Conference of the Parties (COP28) in 2023? (SSC CGL  2023) 

A. UAE         B. US          C. UK         D. Russia

Answer: A


4. Consider the following statements with reference to Organisation for Economic Co-operation and Development (OECD): (RBI Grade B 2022)
1. OECD is an official Permanent observer to the United Nations and is referred to as a think-tank or as a monitoring group.
2. India is not a member of OECD.
3. OECD is funded by its member countries.
Which of the statement given above is/ are correct? 

A. 1 only       B. 1 and 2 only      C. 2 and 3 only        D. 1, 2 and 3          E. 2 only

Answer: D

5. Which of the following statements regarding 'Green Climate Fund' is/are correct? (UPSC 2015)
1. It is intended to assist the developing countries in adaptation and mitigation practices to counter climate change.
2. It is founded under the aegis of UNEP, OECS, Asian Development Bank and World Bank.
Select the correct answer using the code given below.

A. 1 only       B. 2 only         C. Both 1 and 2         D. Neither 1 nor 2

Answer: A

6. The 27th annual UN meeting on climate, COP27 (Conference of Parties) took place from 6th to 18th November, in which of the following country?  (SSC GD Constable 2023)

A. France       B. Brazil        C. Indonesia       D. Egypt

Answer: D

7. According to the Copenhagen Accord, what percentage of India has promised to reduce carbon emissions by the year 2020 as compared to 2005? (UP Police SI 2017) 

A. 20-25 percent  B. 10-15 percent         C. 30-35 percent       D. 5-10 percent

Answers: 1-B, 2-B, 3-A, 4-D, 5-A, 6-D, 7-A


1. Describe the major outcomes of the 26th session of the Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC). What are the commitments made by India in this conference? (upsc 2021)

Source: The Hindu

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