Natural gas

• 1. Introduction

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  Natural gas is colorless and odorless, which is exactly what makes it dangerous. Because a leak gives no warning, suppliers spike it with a commercial odorizer like methanethiol, a chemical that smells of rotten eggs, so people can detect a leak by nose alone. That single design choice, adding a stench to an invisible fuel, hints at the tension running through this entire subject. Here is a fuel that burns cleaner than coal yet drives climate change. A fuel pulled from deep geological formations, formed over millions of years, now arriving in over forty million American kitchens. The gas is mostly methane, about 95 percent, with traces of higher alkanes, carbon dioxide, nitrogen, hydrogen sulfide, and helium. Methane is the second-greatest greenhouse gas behind carbon dioxide. So how did a byproduct once burned off as waste become a major global industry? Why are some cities now banning it from new homes? And why are advocates fighting over what to even call it?

• 2. A Quarrel Over A Name

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  In the early 1800s, the word "natural" was added to distinguish this fuel from coal gas, the dominant gas fuel of the day. Coal gas was manufactured by heating coal. Natural gas, by contrast, could be pulled straight from the ground in its native gaseous form, no factory required. As natural gas overtook coal gas in English-speaking countries during the 20th century, people simply called it "gas." That shorthand causes confusion, since gasoline is also clipped to "gas" in North America. The name has become a battleground. Many organizations now criticize the word "natural" for masking the fuel's role in the climate crisis. These advocates prefer "fossil gas" or "methane gas" as labels that convey the threat more honestly. A 2020 study of Americans found that across political identifications, the term "methane gas" led people to better estimate the fuel's harms and risks. The fight over a label, it turns out, shapes how the public weighs the danger.

• 3. Fire From The Ground

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  At Mount Chimaera in ancient Greece, gas seeping from the earth burned in long-lasting flames, feeding the legend of the Chimera, a fire-breathing creature. The fuel announced itself through fire long before anyone understood it. In ancient China, gas from drilling for brines was used by about 400 BC. The Chinese carried gas seeping from the ground through crude bamboo pipelines to boil salt water and extract salt in the Ziliujing District of Sichuan. Across the Atlantic, the story repeated. In the seventeenth century, French missionaries watched American Indians set fire to gas seeps around Lake Erie. European-descended settlers noted similar seeps along the eastern seaboard through the 1700s. In 1821, William Hart dug the first commercial natural gas well in the United States at Fredonia, New York, a venture that led in 1858 to the Fredonia Gas Light Company. For most of this history the gas stayed near its source, useless at a distance. That changed only with long-distance pipelines from the 1920s onward, the innovation that turned a local curiosity into a continental commodity.

• 4. From Waste To Windfall

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  In the 19th century, natural gas was mostly an unwanted by-product of pumping oil. As extracted fluids lost pressure rising to the surface, light gas chains came out of solution, much like carbon dioxide fizzing from an uncapped soft drink. In active oil fields the gas was a hazard and a disposal problem. Without expensive pipelines and storage, the large volumes simply could not reach any market. So operators released it or burned it off, a practice called flaring. Flaring is now illegal in many countries, though satellite and infrared observations show it still happens in some. The economics flipped over time. Higher demand in the last 20-30 years made gas associated with oil worth producing. Now the gas is sometimes re-injected into the formation for enhanced oil recovery, maintaining pressure underground. In Saudi Arabia, a "master gas system" invented in the late 1970s ended any need for flaring there. Whether gas gets conserved, re-injected, or flared depends largely on proximity to pipelines and on regulatory restrictions.

• 5. The Shale Revolution

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  Shale gas wells depend on fractures, because shale's matrix permeability is too low for gas to flow in economical quantities. Early wells relied on natural fractures, but almost all shale gas wells today require fractures created artificially by hydraulic fracturing. The first commercial hydraulic fracturing operation came in 1949, and since then roughly one million wells have been fractured in the United States. Fracking forces water mixed with chemicals through the wellbore casing into rock at high pressure, breaking it apart. Sand or other particles, added as a proppant, hold the fractures open so gas can flow to the surface. The technique reshaped a country. Since 2000, shale gas has become a major source of natural gas in the United States and Canada. By 2014 the United States was the world's number one natural gas producer, a shift described as a "shale gas revolution" and as "one of the landmark events in the 21st century." The water demands grew enormous. Vertical wells before 1953 used nearly 7,375 gallons per fracture, while horizontal gas wells between 2000 and 2010 used nearly 3 million gallons. The flowback that returns to the surface, 30-70 percent of the frack fluid, may carry radioactive materials, heavy metals, and salts, so most of it is recycled or injected deep underground, removed from the water cycle entirely.

• 6. Moving An Invisible Cargo

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  Due to its low density, natural gas resists easy storage and transport by vehicle. Pipelines fail across oceans, because friction heats the gas, so it must be cooled and compressed. That physical stubbornness fractures the market. The large trade cost means natural gas markets are far less globally integrated than oil, producing significant price differences across countries. Several solutions emerged to fight the geography. Compressed natural gas, or CNG, travels at high pressure, typically above 200 bar, using compressors that are less capital intensive than liquefaction plants. Liquefied natural gas opened up inter-country transport and long-term storage that simply were not widely available before its adoption. A newer idea pushes processing out to sea entirely. Floating liquefied natural gas, or FLNG, does all the work at the gas field, eliminating long pipelines to shore and onshore plant construction. It can develop offshore fields that would otherwise stay stranded, such as those offshore East Africa, and the facility can be disconnected, refurbished, and re-deployed elsewhere. Underground, gas is stored in depleted reservoirs, salt domes, or as LNG in tanks, injected when demand is low and pulled out when demand picks up. The Browse LNG project was set to begin its front-end engineering in 2019.

• 7. More Than A Flame

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  Over one-third of US households, more than 40 million homes, cook with gas, which can generate temperatures above 1100 degrees Celsius. But cooking is only the most visible use. Natural gas is a major feedstock for producing ammonia via the Haber process, the basis of synthetic nitrogen fertilizer. It has been estimated that almost half the people on Earth are currently fed as a result of synthetic nitrogen fertilizer use. The fuel feeds industry in ways most people never see. It produces hydrogen, a feedstock for chemicals and a fuel for hydrogen vehicles. Protein-rich animal and fish feed is produced by feeding natural gas to Methylococcus capsulatus bacteria on a commercial scale. Its components can be converted into olefins, with ethane becoming ethylene and propane becoming propylene. The gas also goes into fabrics, glass, steel, plastics, paint, and synthetic oil. On the road, by the end of 2014 there were over 20 million natural gas vehicles worldwide, led by Iran with 3.5 million, followed by China, Pakistan, Argentina, India, and Brazil. CNG-specific engines exploit the fuel's high octane number of 120-130. Russian manufacturer Tupolev has even pursued LNG- and hydrogen-powered aircraft since the mid-1970s, targeting variants of the Tu-204, Tu-334, and the Tu-330 cargo plane.

• 8. The Climate Reckoning

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  Methane has 84 times the global-warming potential of carbon dioxide over a 20-year period, and 28 times over 100 years. That figure is the crux of the entire climate debate around this fuel. When burned, natural gas produces 25-30 percent less carbon dioxide per joule than oil and 40-45 percent less than coal, with fewer toxic pollutants. The catch lies upstream. Natural gas leaks during extraction, storage, transport, and distribution, so its life cycle greenhouse gas emissions run about 50 percent higher than the direct emissions at the point of use. Some policy frames call gas a "bridge fuel," resting on the mistaken assumption that lower emissions at burning mean lower overall impact. The numbers tell a heavier story. In 2020, natural gas use emitted about 7.8 billion tons of carbon dioxide including flaring, against 14.4 billion from coal and 12 from oil. Governments have started drawing lines. The Netherlands is subsidizing a transition away from natural gas for all homes by 2050, and Amsterdam has allowed no new residential gas accounts since 2018. New gas appliance hookups are banned in New York State and the Australian Capital Territory, and Victoria in Australia banned new natural gas hookups starting the 1st of January 2024. The 2023 IPCC Sixth Assessment report concluded that new fossil gas infrastructure suits only very specific conditions, with carbon capture and fugitive gas prevention, or it risks emissions overshoot and becoming a stranded asset.