Natural Gas: What It Is, How It Works, and Why It Matters

Natural gas is a fossil fuel composed primarily of methane (CH₄), formed over millions of years from the decomposed remains of ancient plants and animals buried beneath layers of rock. It is the world's third-largest energy source, supplying roughly 23% of global primary energy, and is burned for electricity generation, heating, cooking, and industrial processes across more than 180 countries. Because it emits roughly 50% less CO₂ than coal when burned, it is widely regarded as a 'bridge fuel' in the transition away from heavier fossil fuels.

How Is Natural Gas Formed and Where Is It Found?

Natural gas forms when organic matter—marine microorganisms, algae, and plant debris—is buried under sediment and subjected to intense heat and pressure over 50 to 300 million years. This thermogenic process breaks organic compounds into hydrocarbons, leaving gas trapped in porous rock formations called reservoirs. The world's largest proven reserves sit in Russia (37.4 trillion cubic metres), Iran (32.1 tcm), and Qatar (24.7 tcm), according to BP's 2023 Statistical Review of World Energy. Beyond conventional reservoirs, vast quantities are locked in shale formations and extracted via hydraulic fracturing ('fracking'), a technique that unlocked the United States' shale boom after 2005 and turned the U.S. into the world's top natural gas producer by 2009.

How Is Natural Gas Extracted, Processed, and Transported?

Extraction begins with exploratory drilling guided by seismic surveys. Once a viable reservoir is confirmed, production wells are drilled and the gas flows to the surface under its own pressure or via pumps. Raw natural gas contains impurities—water vapour, hydrogen sulphide, carbon dioxide, and heavier hydrocarbons like ethane and propane—that are removed at processing plants before the gas enters pipelines. Transportation relies on two main methods: high-pressure pipelines (over 3 million kilometres of pipeline exist globally) and liquefied natural gas (LNG) tankers, which cool gas to −162°C, shrinking its volume by 600 times for ocean shipping. Qatar, Australia, and the United States are the world's top LNG exporters.

What Are the Environmental and Geopolitical Impacts of Natural Gas?

Natural gas burns cleaner than coal or oil, producing roughly 117 lbs of CO₂ per million BTU versus coal's 206 lbs—but its climate credentials are complicated by methane leakage. Methane is 80 times more potent than CO₂ as a greenhouse gas over a 20-year period, and the IEA estimated that the energy sector leaked 120 million tonnes of methane in 2022. Geopolitically, natural gas pipelines create powerful dependencies: Russia's Gazprom supplied about 40% of Europe's gas before the 2022 invasion of Ukraine, which triggered a global energy crisis and accelerated Europe's drive toward renewables and LNG imports. The war underscored how natural gas infrastructure can be weaponised, reshaping energy policy worldwide.