Natural gas

Topic: Energy Resources of India: Conventional and Non-conventional · NCERT: Class 10, Ch 5 "Minerals and Energy Resources"; Class 12, Ch 5 "Mineral and Energy Resources"

Meaning

Natural gas is a fossil fuel made mostly of methane. It is found in sedimentary rocks, either together with crude oil (associated gas) or on its own (free gas). It is used for power, industrial heat, fertilisers, petrochemicals and city gas.

It burns cleaner than coal or oil, so it is called a "bridge fuel" between coal and renewable energy. India wants gas to make up 15% of its primary energy mix by 2030 [7], but it still imports about half of the gas it uses [8].

Explanation

What it is and how it is found

• Natural gas is mostly methane. It is a fossil fuel, like coal and petroleum.
• Two types, based on how it is found:
• Associated gas: gas found with petroleum (crude oil) in the same rocks. When the oil is pumped up, the gas comes up with it.

• Free (non-associated) gas: gas found in a field that has no oil.

• Where it collects: in sedimentary basins (thick layers of sand and mud laid down over a very long time).

• Gas hydrates are a third, future form (see below). They are not yet produced commercially.

Uses, and why it is called a "bridge fuel"

• Power: it runs gas-based thermal power stations.
• Industrial heat: it heats furnaces in the glass, ceramics, steel and other industries.
• Feedstock for fertilisers: feedstock means the raw material an industry uses.
• Methane is the main input for making urea, a nitrogen fertiliser.

• This is why early pipelines ran to fertiliser plants.

• Petrochemicals: it is used to make plastics, polymers and chemicals.

• Transport and homes: this use is growing fast through city gas networks (CNG and PNG).
• Why it is a bridge fuel:
• It gives off less carbon dioxide than coal or oil.
• It produces almost no ash and very little sulphur.
• It helps India move from coal towards renewables.

How gas reaches users: pipelines, CGD and LNG

• Trunk pipelines are the main long-distance lines that carry gas from the fields to faraway users.
• HVJ (Hazira–Vijaipur–Jagdishpur) pipeline: built by GAIL, about 1,700 km long. It was India's first cross-country trunk gas pipeline.

• Why it was needed: the gas landed on the west coast, but the big users, such as fertiliser plants in the Ganga plains, were far inland. A pipeline was the cheapest and safest way to move it.

• Growth of the network:

• In NCERT, the network grew from 1,700 km to 18,500 km.
• Operational pipeline: 15,340 km in 2014 → 25,429 km as on June 2025 [2].
• Another 10,459 km is under execution (being built) [2].

• About 34,233 km has been authorised in total, including trunk, spur and tie-in lines [2].

• National Gas Grid ("One Nation One Grid"): one connected network of trunk pipelines. It will link every gas source (domestic fields and LNG terminals) to every market, including eastern India and the North-East [2].

• City gas distribution (CGD) is a local pipeline network inside a town or district. It supplies:
• CNG (Compressed Natural Gas): gas squeezed to high pressure and filled into vehicles.
• PNG (Piped Natural Gas): gas sent through pipes to kitchens, shops and factories, much like a water connection.
• PNGRB (Petroleum and Natural Gas Regulatory Board) gives out CGD licences, one for each Geographical Area (GA). It has authorised 307 GAs, which can cover about 100% of India's area and population [3].

• As on 30 September 2024 there were 1.36 crore PNG (domestic) connections and 7,259 CNG stations [3].

• LNG (Liquefied Natural Gas): this is how imported gas arrives.

• Gas is cooled to about –162 °C and turns into a liquid. The liquid takes up about 1/600th of the space the gas did.
• Special ships carry it to an LNG terminal.
• At the terminal it is regasified (warmed back into gas) and fed into the pipeline grid.

Gas hydrates: a future source

• Gas hydrates are ice-like solids in which methane is trapped inside a cage of frozen water molecules.
• Conditions they need: low temperature and high pressure. These are found:
• in seabed sediments on continental margins (the edges of continents, under the sea)

• below permafrost (ground that stays frozen all year).

• Why they matter: a small volume of hydrate holds a large amount of methane.

• Problems:
• It is hard to release the gas safely.
• Methane, a strong greenhouse gas, may leak.
• Taking out the hydrate may make the seabed slope unstable.

Where it occurs

• Producing basins and fields (India):
• Mumbai High and allied fields (Bassein): in the Arabian Sea, offshore Maharashtra, about 160 km off Mumbai. This is the largest offshore oil-and-gas area, and it supplied the gas for the first trunk pipeline.
• Cambay basin: onshore Gujarat (Ankleshwar, Kalol and nearby areas). It is an old onshore oil-and-gas basin.
• Krishna-Godavari (KG) basin: in the Bay of Bengal, offshore Andhra Pradesh. The deep-water KG-D6 block has produced gas since 2009.

• Assam and Tripura: some onshore gas.

• Pattern: most gas comes from sedimentary basins on the west coast offshore, in Gujarat and on the east coast.

• Pipelines:
• HVJ: Hazira (Gujarat) → Vijaipur (Madhya Pradesh) → Jagdishpur (Uttar Pradesh). It carried Mumbai High and Bassein gas to fertiliser and power plants in western and northern India.
• Pradhan Mantri Urja Ganga (GAIL):
  • Route: Jagdishpur (UP) – Haldia (West Bengal) – Bokaro (Jharkhand) – Dhamra (Odisha), later extended towards Barauni – Guwahati.
  • Length and reach: 2,650 km as first planned, serving 5 states, 40 districts and 2,600 villages [4]. About 3,300 km after extensions.
  • The 348 km Dobhi–Durgapur section was dedicated in February 2021 [5].
  • It supplies revived fertiliser plants at Gorakhpur, Barauni and Sindri, and city gas to Varanasi, Patna, Ranchi, Kolkata and Bhubaneswar.

• North-East Gas Grid (Indradhanush):

  • Indradhanush Gas Grid Ltd is a JV of IOCL, ONGC, GAIL, OIL and NRL.
  • It is 1,656 km long and costs about ₹9,265 crore.
  • Viability Gap Funding (VGF) was approved in 2020. VGF is a government grant that makes a project worth building when it would not earn enough on its own.
  • It covers all eight NE states [6] and links to the national grid at Guwahati.

• LNG terminals:

• In 2019 there were 6 terminals with 39.2 MMTPA (million metric tonnes per annum) of capacity: Dahej 17.5, Hazira 5, Dabhol 1.7, Kochi 5, Mundra 5 and Ennore 5 MMTPA [9].
• Now there are 8 terminals with about 52.7 MMTPA [10].
• Dahej (Gujarat) is the largest.

• West coast: Dahej, Hazira and Mundra (Gujarat), Dabhol (Maharashtra) and Kochi (Kerala). East coast: Ennore (Tamil Nadu).

• Gas hydrates:

• NGHP-01 (2006) confirmed hydrates in Indian offshore basins, including the KG basin.
• NGHP-02 ran from 3 March to 28 July 2015 off the east coast. It found large, highly concentrated hydrate deposits in sand-rich sediments across much of the KG basin [11][12].
• Areas B and C are the best sites for a future production test [11][12].

Don't confuse with

• Associated gas vs free gas: associated gas comes up with crude oil from the same rocks. Free (non-associated) gas comes from a field that has no oil.
• CNG vs PNG: both are supplied through CGD networks regulated by PNGRB. CNG is compressed gas for vehicles. PNG is gas piped to homes, shops and factories.
• LNG vs CNG: LNG is gas cooled to about –162 °C into a liquid (about 1/600th of its volume) so it can be shipped and imported. CNG is gas kept as a gas but squeezed under high pressure for vehicles.
• Gas hydrates vs conventional natural gas: hydrates are solid, ice-like methane on seabeds and under permafrost. They are not yet produced commercially in India. Conventional gas is drilled from sedimentary basins like Mumbai High and KG-D6.

Prelims Hooks

• HVJ pipeline = Hazira (Gujarat) – Vijaipur (MP) – Jagdishpur (UP). It was built by GAIL and was India's first trunk gas pipeline (about 1,700 km).
• KG-D6 is a deep-water block in the Bay of Bengal (KG basin, offshore Andhra Pradesh). Gas output began in 2009.
• Indradhanush Gas Grid is a JV of IOCL, ONGC, GAIL, OIL and NRL, with 1,656 km of pipeline covering all 8 NE states [6]. Trap: it is not a GAIL-only project.
• Largest LNG terminal: Dahej (Gujarat). Trap: Ennore (Tamil Nadu) is the east-coast terminal, while Dahej, Hazira, Dabhol, Kochi and Mundra are all on the west coast [9].
• Gas share target: 15% of the energy mix by 2030. It was about 6.3% in 2022 [7] and about 6.7% in 2023 [8].
• Gas hydrates are stable at low temperature and high pressure. Rich deposits were found in the KG basin by NGHP-02 (2015) [11].

Mains Points

• Spatial imbalance and the grid response (GS-III, infrastructure):
• Gas sources are on the west coast: Mumbai High, Cambay and the Gujarat LNG terminals.
• So gas use was long limited to the western and northern HVJ belt.

• The National Gas Grid, Urja Ganga and Indradhanush carry gas to the east and North-East. This revives fertiliser plants, spreads city gas and supports balanced regional development [2][4][6].

• Energy security vs import dependence (GS-III, resources):

• About half of India's gas is imported as LNG [8], which exposes India to global price shocks.
• High LNG prices keep many gas power plants running below capacity.

• Responses: raise deep-water output in the KG basin, expand regasification capacity to about 52.7 MMTPA [10], and develop gas hydrates in the long term [11].

• Gas as a transition fuel (GS-III, environment):

• Gas gives off less carbon dioxide and particulate matter than coal.
• Moving vehicles to CNG and homes to PNG improves urban air quality.
• Gas can also back up renewables, which supports the 15% gas-share target [7].
• Challenges: slow pipeline building in the hilly NE, complex pricing and regulation, and the risk of methane leaks and seabed instability when extracting hydrates.

Related concepts

• City gas distribution
• National Gas Grid
• Pradhan Mantri Urja Ganga
• Gas hydrates

Read more

• Natural gas and the national gas grid