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Subject: Renewable Energy Technology

  • Geothermal Energy

    Why in News

    A PIB Backgrounder on geothermal energy set out the resource, its potential in India, and its place in the clean energy transition.

    Core facts

    1. Definition: Geothermal energy is heat stored within the earth. It is drawn from hot rocks and hot water reservoirs below the surface and used for power generation and direct heating.
    2. Nature of the resource: Geothermal energy is a renewable and baseload source. It supplies power around the clock, unlike solar and wind, which vary with weather and time of day.

    Static Context

    1. India’s potential: The Geological Survey of India (GSI) has identified about 340 geothermal hot spring sites. The estimated geothermal power potential is placed around 10,600 megawatts (MW).
    2. Key geothermal provinces: Major sites include Puga and Chhumathang in Ladakh, Tattapani in Chhattisgarh, Manikaran in Himachal Pradesh, and the Godavari and Cambay basins.
    3. How it works: A geothermal plant taps steam or hot water from a well. The steam drives a turbine. The turbine drives a generator to produce electricity.
    4. Uses beyond power: Direct use includes space heating, greenhouse warming, aquaculture and cold storage. Ladakh has seen pilot efforts for geothermal power and heating.
    5. Nodal ministry: The Ministry of New and Renewable Energy (MNRE) is the nodal ministry for renewable energy sources, including geothermal.
    6. Global comparison: Countries with high geothermal output include the United States, Indonesia, the Philippines, Iceland and Kenya. India’s geothermal capacity remains at an early stage.

    Prelims angle

    1. The location of Puga, Tattapani, Manikaran and other geothermal sites, and the role of the Geological Survey of India in resource mapping.
    2. The classification of geothermal as a renewable and baseload source, and the nodal ministry. Site to state matching is a common format.

    Mains angle

    1. GS Paper 3, infrastructure and energy, and India’s renewable energy mix.
    2. A question can ask how baseload renewable sources such as geothermal complement variable solar and wind in the path to energy security.

    Matching Previous Year Question

    “[2022, GS3, 15] Do you think India will meet 50 percent of its energy needs from renewable energy by 2030 ? Justify your answer. How will the shift of subsidies from fossil fuels to renewables help achieve the above objective? Explain.”

  • Geothermal Energy

    Geothermal Energy

    Why in News

    The Press Information Bureau (PIB) published a thematic Backgrounder on Geothermal Energy on 4 September 2026. The piece is a subject explainer written for exam and public awareness value.

    Core facts

    1. Definition: Geothermal energy is heat stored inside the Earth. This heat is tapped through wells at sites with high underground temperature gradients.
    2. Nature of the source: Geothermal power is a renewable and baseload source. It generates around the clock, unlike solar or wind.
    3. Nodal ministry: The Ministry of New and Renewable Energy (MNRE) is the nodal ministry for geothermal energy in India.
    4. Verification note: The release body did not resolve on the source page this run, so release-specific figures are not quoted. The static estimates below come from standard reference data.

    Static Context

    1. India’s first project: India commissioned its first geothermal wells at Puga Valley in the Changthang region of Ladakh. A 1 Megawatt (MW) pilot geothermal plant is planned as the first demonstration scale project.
    2. Implementing agency: The ONGC Energy Centre, a body of the Oil and Natural Gas Corporation (ONGC), leads the Puga project with the Ladakh Administration.
    3. Estimated potential: India’s geothermal potential is estimated at about 10,600 MW (standard reference figure).
    4. Survey base: The Geological Survey of India (GSI) has documented about 381 hot springs. India has ten geothermal provinces, including the Himalayan, Son Narmada Tapi (SONATA), West Coast, Cambay and Godavari belts.
    5. Key sites: Notable geothermal sites include Puga and Chumathang in Ladakh, Manikaran in Himachal Pradesh, Tattapani in Chhattisgarh, and Bakreshwar in West Bengal.
    6. Policy frame: A National Policy on Geothermal Energy was notified in 2025, with the MNRE as the promoting authority.

    Prelims angle

    1. Nodal ministry: MNRE. Lead agency for Puga: ONGC Energy Centre.
    2. First site: Puga Valley, Ladakh. Survey body: GSI, with about 381 hot springs mapped.
    3. Source character: Renewable and baseload, driven by internal Earth heat.
    4. Geothermal provinces: Himalayan, SONATA, West Coast, Cambay, Godavari and others.

    Mains angle

    GS Paper 3, energy and infrastructure. A question can ask how geothermal energy can add firm renewable baseload capacity to India’s energy mix, and can weigh the high exploration cost and site concentration in the Himalayas against the round the clock output advantage.

    “[2013] Consider the following :

    (1). Electromagnetic radiation

    (2). Geothermal energy

    (3). Gravitational force

    (4). Plate movements

    (5). Rotation of the earth

    (6). Revolution of the earth

    Which of the above are responsible for bringing dynamic changes on the surface of the earth?

    (a) 1, 2, 3 and 4 only

    (b) 1, 3, 5 and 6 only

    (c) 2, 4, 5 and 6 only

    (d) 1, 2, 3, 4. 5 and 6.

  • No takers for govt’s ₹37,500-crore coal gasification scheme

    Why in the News

    The coal ministry’s ₹37,500 crore financial incentive scheme for surface coal and lignite gasification has drawn no application from any private or public player. The last date for submission is 7 September 2026, fixed by a Request for Proposal issued on 7 July 2026. The Union Cabinet had approved the scheme to gasify 75 million tonnes of coal and lignite and to cut imports of liquefied natural gas, urea and methanol. The ministry attributes the absence of bids to the time a project proposal of this scale takes to prepare. An incentive of this size drawing nothing at its first deadline points at the economics of a gasification project rather than at the paperwork.

    How does coal gasification work?

    1. From solid fuel to gas: Dry fuel is converted into synthetic gas, known as syngas.
    2. What syngas is used for: Syngas serves as an alternative fuel and as the feedstock for methanol, fertilisers, hydrogen and chemicals.
    3. The stated emissions gain: Converting coal into gas rather than burning it directly is counted as a reduction in carbon emissions.

    What was the scheme designed to achieve?

    1. A volume target: The programme is built around gasifying 75 million tonnes of coal and lignite.
    2. Import substitution: The scheme is aimed at reducing dependence on imports of liquefied natural gas, urea and methanol.
    3. Insulation from external shocks: Domestic production of these inputs is intended to shield the country from global price volatility and supply chain disruption.
    4. The instrument: A financial outlay of ₹37,500 crore was approved for surface coal and lignite gasification projects.

    How has the coal ministry explained the empty first round?

    1. Proposal preparation takes time: Given the scale of funds each project involves, the preparation of pre-feasibility reports and project proposals runs long.
    2. Interest without applications: Several industries have communicated their interest in participating, and none has filed.
    3. The count is not final: The number of applications cannot be stated before the deadline passes, since submission is entirely online.
    4. The window reopens: Application rounds are envisaged every two months, giving industry repeated opportunities to enter.

    Challenges to the coal gasification incentive scheme

    1. High ash domestic coal raises the cost: Indian coal carries a high ash content, which lowers gas yield per tonne and raises the capital cost of the gasifier. Eg. Gasifier designs proven on low ash imported coal need modification before they run on Indian coal.
      The Fix: Tie the incentive to a gasifier configuration demonstrated on high ash domestic coal, rather than to project cost alone.
    2. The output price is set by policy, not by the market: Urea sold to farmers carries a maximum retail price fixed by the Centre, so a coal based producer’s revenue depends on the subsidy regime. Eg. Urea remains outside the Nutrient Based Subsidy regime and continues to be sold at a controlled price.
      The Fix: Offer a long term offtake price for coal based urea and methanol, so a project’s revenue is known before financial closure.
    3. No assured buyer for the other outputs: Lenders fund a plant only where a committed purchaser exists for its methanol or hydrogen. Eg. India has no binding methanol blending obligation comparable to the dated targets under the ethanol blending programme.
      The Fix: Notify a methanol blending obligation with dated targets, so demand exists independently of the capital subsidy.
    4. A coal based route to a fuel sold as clean: The process begins with coal, so the emissions case rests on capturing the carbon dioxide the process concentrates. Eg. Coal to methanol carries higher lifecycle emissions than natural gas based methanol.
      The Fix: Make carbon capture capability a condition of the incentive rather than an optional addition.
    5. Clearances have to be assembled before a bid: A promoter needs a coal linkage, land and water in place before a proposal is fileable, and the incentive supplies none of them. Eg. The Talcher Fertilizers coal to urea project in Odisha has run well past its original commissioning timeline.
      The Fix: Bundle a coal linkage and a land allotment with the incentive award, so a bidder is not chasing clearances and funding at the same time.

    Conclusion

    The obstacle here is not the size of the incentive but the absence of a price and a buyer for what a gasification plant would make. A capital subsidy lowers the cost of building the plant. It does not tell the promoter what the output will sell for, or who is obliged to buy it. The marker to watch is whether the next round is paired with an assured offtake price or a blending obligation, and whether a public sector energy company files before any private promoter does.

    Back2Basics: Lignite

    1. What it is: Lignite is the lowest rank of coal, high in moisture and low in fixed carbon, also called brown coal.
    2. Why it is used near the mine: Its calorific value is lower than that of bituminous coal, so transporting it long distances is uneconomic and it is burned or gasified close to the pithead.
    3. Where India’s reserves lie: The bulk of the country’s lignite sits in Tamil Nadu, with further deposits in Rajasthan, Gujarat and Jammu and Kashmir.
    4. Who mines it: NLC India Limited, a central public sector enterprise under the Ministry of Coal, is the largest lignite producer in the country.

    [2025] Consider the following substances:

    I. Ethanol

    II. Nitroglycerine

    III. Urea

    Coal gasification technology can be used in the production of how many of them?

    (a) Only one

    (b) Only two

    (c) All three

    (d) None

  • Consider the following

    Consider the following:
    1. Battery storage
    2. Biomass generators
    3. Fuel cells
    4. Rooftop solar photovoltaic units
    How many of the above are considered “Distributed Energy Resources”?

  • Catalyst that Transforms to Perform

    Why in the news?

    Scientists from the Centre for Nano and Soft Matter Sciences and collaborating institutions discovered how a catalyst changes its structure during water electrolysis for green hydrogen production. The study was published in Materials Horizons.

    Key Highlights

    • Researchers studied:
      • Molybdenum carbide (Mo₂C), an earth-abundant catalyst used in hydrogen production.
    • Molybdenum Carbide is a compound made of molybdenum and carbon that acts as an efficient catalyst in hydrogen production and other industrial chemical reactions
    • Key Features
      • Considered an earth-abundant catalyst because molybdenum is more available and cheaper than precious metals like platinum.
      • Exhibits platinum-like catalytic properties in some reactions.
      • Has high thermal stability and good electrical conductivity.
    • Role in Hydrogen Production
      • Mo₂C is widely studied for: Hydrogen Evolution Reaction (HER) in water splitting.
      • Electrochemical production of green hydrogen.
      • Improving efficiency while reducing dependence on expensive noble-metal catalysts.

    About Hydrogen Evolution Reaction (HER)

    • HER is the electrochemical reaction where hydrogen gas is produced from water during electrolysis.
    • It occurs at the cathode. (The cathode is the electrode where reduction occurs and hydrogen gas is produced.)
      • Note: Anode: The anode is the electrode where oxidation occurs. In water electrolysis, oxygen is produced at the anode through the Oxygen Evolution Reaction (OER).
    • Efficient catalysts are required to reduce energy consumption and improve hydrogen production efficiency.

    About Green Hydrogen

    • Green hydrogen is hydrogen produced using renewable energy sources through electrolysis of water.
    • It is considered a clean fuel because it emits no carbon dioxide during use.

    [2023] With reference to green hydrogen, consider the following statements:
    1. It can be used directly as a fuel for internal combustion.
    2. It can be blended with natural gas and used as fuel for heat or power generation.
    3. It can be used in the hydrogen fuel cell to run vehicles.
    How many of the above statements are correct?

    [A] Only one

    [B] Only two

    [C] All three

    [D] None

  • Which of the following pairs in respect of power generation in India is/are correctly matched

    Which of the following pairs in respect of power generation in India is/are correctly matched?
    1. Installed electricity generation capacity: 100000 MW
    2. Electricity generation: 660 billion kWh.

  • Recently, “oilzapper’’ was in the news. What is it

    Recently, “oilzapper’’ was in the news. What is it?

  • Microbial fuel cells are considered a source of sustainable energy. Why? 1. They use living organisms as catalysts to generate electricity from certain substrates.

    Microbial fuel cells are considered a source of sustainable energy. Why? 1. They use living organisms as catalysts to generate electricity from certain substrates.
    2. They use a variety of inorganic materials as substrates.
    3. They can be installed in wastewater treatment plants to cleanse water and produce electricity.

  • With reference to technology for solar power production, consider the following statements

    With reference to technology for solar power production, consider the following statements:
    1. ‘Photovoltaics’ is a technology that generates electricity by direct conversion of light into electricity, while ‘Solar Thermal’ is a technology that utilizes the Sun’s rays to generate heat which is further used in electricity generation process.
    2. Photovoltaics-generates Alternating Current (AC), while Solar Thermal generates Direct Current (DC).
    3. India has manufacturing base for Solar Thermal technology, but not for photovoltaics.
    Select the correct answer using the code given below:

  • With reference to bio-toilets used by the Indian Railways, consider the following statements

    With reference to bio-toilets used by the Indian Railways, consider the following statements :
    (1) The decomposition of human waste in the bio-toilets is initiated by a fungal inoculum.
    (2) Ammonia and water vapour are the only end products in this decomposition which are released into the atmosphere.
    Which of the statements given above is/are correct?