Natural gas — pipelines, methane and heat

Wells, leaks, liquefaction, pipelines, power plants and boilers. Theory, formulas, worked examples and applications.

Invisible does not mean clean

Two ways to extract a gas you cannot see

Natural gas is extracted from two types of deposit with very different processes. Conventional deposits are pockets of gas trapped under impermeable rock layers, relatively easy to drill and exploit with traditional techniques. Unconventional deposits — shale gas or tight formations — require horizontal drilling (the well turns 90 degrees underground to run along the rock layer, not just vertically) combined with hydraulic fracturing: injecting water at high pressure, mixed with sand and chemical additives, to crack the rock and release the gas trapped in its microscopic pores. This second technique requires large volumes of water per well, generates wastewater that has to be treated or reinjected underground, and has been flagged in some studies as a possible factor in induced seismicity in certain areas.

From wellhead to burner: a long chain with potential leaks

Once extracted, gas passes through compressors and an extensive pipeline network before reaching a plant or a home. To cross oceans — when no physical pipeline exists between producer and consumer country — gas is cooled to approximately -162°C, at which point it liquefies and shrinks drastically in volume, allowing it to be shipped in specialized LNG tankers; on arrival, it is reheated and regasified before being injected into the grid. Each of these stages — compression, transport, liquefaction, regasification — consumes additional energy and is a potential leak point for methane, natural gas's main component.

Why the methane that leaks matters as much as the methane that burns

Natural gas burns more cleanly than coal at the point of combustion: a modern combined-cycle plant can generate the same electricity with less CO₂ and far fewer local pollutants than an equivalent coal plant. But that advantage assumes all extracted gas arrives intact at the burner. In practice, a fraction of the methane escapes — through valves, fittings, deliberate maintenance venting, or undetected leaks — somewhere between the well and the household meter, and unburned methane is a far more potent greenhouse gas than CO₂ while it remains in the atmosphere. This leaf's data tab develops, with IEA figures, how much methane is actually lost in the global supply chain — and why an apparently small leak rate in percentage terms can cancel out much of gas's climate advantage over coal.

At home and in industry: much more than power plants

Natural gas is not only used to generate electricity: it fuels household heating boilers, cookers, and industrial processes that need heat at specific temperatures, and also serves as a chemical feedstock for fertilizers and other products. The gas distribution network reaching a building — steel or polyethylene pipes, pressure regulators, meters — has its own maintenance, its own small-scale leak risk, and a rare but real explosion risk if gas accumulates in an enclosed space. When gas infrastructure is abandoned — a depleted well, a decommissioned pipeline stretch — it must be sealed and monitored: a poorly sealed well can keep passively emitting methane for years or decades.

The comparison that cannot be summed up in one word

Saying natural gas is "cleaner than coal" is true at the point of combustion, but it does not mean it is "low carbon" in absolute terms nor that it is climate-neutral. Before accepting that label for a specific gas supply, it is worth asking about the actually measured leak rate — not a standard industry figure —, the gas's origin (conventional or fracked), whether it had to be liquefied and shipped, the efficiency of the final consuming equipment, and the expected lifetime of all the infrastructure being built to support it. In many cases, replacing a gas end-use with direct electrification — a heat pump instead of a boiler, for example — can reduce total climate impact more than simply switching fossil fuels.

Bridge, not destination

In favor: less CO₂ from combustion and less local pollution than coal per unit of electricity; combined-cycle plants that start and stop quickly, useful for backing up solar and wind variability while there is not yet enough storage.

To watch, non-negotiably: methane leaked before combustion. A pipeline, a valve or a liquefaction plant with leaks can cancel out much of gas's climate advantage over coal, because methane warms the atmosphere far more intensely than CO₂ while it remains there. The only honest way to assess a gas supply is to require the measured leak rate, not a standard industry figure.

The risk of getting locked in: building pipelines, liquefaction plants and power stations meant to operate for 30-40 years creates infrastructure that has to be paid off — and that competes, with real economic interests, against the very decarbonization it was supposed to help. A long-term supply contract signed today can become a stranded asset if demand falls before it is amortized.

Before replacing coal with gas as a climate solution, always compare: real measured leak rate, efficiency of the end-use equipment, expected lifetime of the infrastructure, and whether an electric alternative (heat pump, renewable plus storage) solves the same service with less long-term climate risk.

The numbers, with their source

How much methane escapes before reaching the burner

According to the IEA's Global Methane Tracker 2025, global oil and gas operations emitted close to 35 million tonnes of methane in 2024. Of that figure, "downstream" operations — transport, distribution and storage, i.e. everything happening after extraction — contributed close to 13 million tonnes, around 15% of the total methane from the oil and gas sector.

The global average leak intensity in the transport and distribution phase is more than 0.4% of the gas handled; with all currently available detection and repair technology deployed, the IEA estimates it could fall below 0.2%. The difference between these two figures is not cosmetic: the agency calculates that the avoidable methane lost across the whole chain is equivalent to almost 100 billion m³ of gas — gas that leaks into the atmosphere instead of heating a home or generating electricity.

Source: IEA — Global Methane Tracker 2025, key findings and technical documentation of the model.

Why a small leak percentage matters so much for climate

Methane warms the atmosphere far more intensely than CO₂ while present: on the order of 80 times more over a 20-year window, though it breaks down faster and its 100-year effect falls to about 25-30 times that of CO₂. This means an apparently small leak rate — less than 1% of the gas handled — can cancel out much of the climate advantage of replacing coal with gas, if that leak is not actively measured and corrected.

The comparative table

What this table is missing

The "global average" leak rate hides enormous variation between operators: some fields and pipelines measure and repair systematically, others do not even monitor their own leaks. Without a specific measured figure for the supply being evaluated, any number on this page is only a starting point, not a definitive answer.

Sources

• The IEA publishes an annual Global Methane Tracker, with leak rates by country and supply-chain segment.
• NREL harmonizes natural gas's life-cycle emissions against other sources: Life Cycle Assessment Harmonization.
• The IPCC assesses gas's role in the energy transition in AR6, WG3, chapter 6.