June 14, 2023
As a company that specializes in the management of natural gas trades and transactions, we’re fascinated by the molecule that makes up 70-90 percent of natural gas: methane.
Larger, more complex molecules—such as polyethylene and DNA—have garnered headlines and Nobel prizes, but methane more than compensates for its simple structure and diminutive stature in the breadth of its impact on the world.
Today, we pay homage to methyl hydride, once known as “marsh gas”, and the many ways it brings value to our lives.
Molecules don’t get much more straightforward than methane—a regular tetrahedron with a single carbon atom at the center and a hydrogen atom at each corner.
Its molecular diameter is 0.68 nanometers, roughly twice the size of its mini molecule cousin, H2O, and about 100,000 times smaller than a human hair.
It is the simplest hydrocarbon and the primary component of natural gas.
Colorless and odorless, it is also lighter than air, which means it tends to rise and disperse in the atmosphere.
Conveniently, methane is also highly flammable.
Its calorific value of about 50 MJ/kg—or about 1,000 British thermal units (BTU) per standard cubic foot (scf)—is higher than other fossil fuels, allowing it to deliver more energy per unit weight and making it an efficient energy source.
Methane is produced both naturally and anthropogenically.
It is extracted from the earth during coal, oil, and natural gas production processes.
Natural sources include wetlands, termites, and the oceans, while human activities such as livestock rearing and rice cultivation contribute to its anthropogenic production.
It is also produced industrially through the process of steam reforming, where high-temperature steam (700°C–1,000°C) reacts with larger hydrocarbon molecules.
Given its gaseous state at ambient conditions, methane can either be transported via pipeline (as a gas) or by road, rail, and ship as liquefied natural gas (LNG).
Within the United States alone, there are more than 210 pipeline systems that incorporate over 300,000 miles of interstate and intrastate pipelines.
Adding gathering lines and the gas mains and service lines that distribute gas to end users, the full network is an estimated 3 million miles—delivering about 80 billion cubic feet of gas per day.
To produce LNG, natural gas is cooled to -161°C, reducing its volume by a factor of 600, which enables its efficient transportation in specialized vessels.
Today’s largest LNG ships—known as Q-Max vessels—can carry up to 9.4 million cubic feet of liquified product, the equivalent of 5.6 billion cubic feet of gas.
However, this compression process uses 280 kWh of energy per ton of LNG, consuming roughly 5 percent of the input gas and creating CO2 emissions (although newer LNG plants are replacing compressor turbines with electric motors, fed by lower-carbon sources of electricity.)
The world benefits greatly from methane, both as a source of heat and as a raw material.
In addition to its central role in power generation, it is used as fuel in industries as diverse as glass manufacturing, food processing, and metal smelting.
When compared to other fossil fuels like coal and oil, methane burns cleaner, producing less CO2 per unit of energy released and none of the nitrous oxides (NOX) and sulfurous oxides (SOX) associated with heavier hydrocarbons.
This makes natural gas an important option for both power generation and heating as the world strives to reduce CO2 emissions.
Further downstream, natural gas vehicles also emit fewer pollutants and greenhouse gases than their gasoline or diesel counterparts.
As a raw material, methane is fundamental in the chemical industry, producing a wide array of products.
Methane is a precursor to methanol, which in turn serves as a feedstock for formaldehyde, antifreeze, solvents, and biodiesel. It can also be reformed to produce synthesis gas (a mixture of hydrogen and carbon monoxide), a precursor for many valuable chemicals and fuels.
Methane-derived compounds also play a significant role in the pharmaceutical industry, and in the synthesis of vitamins and essential amino acids.
Here’s an incomplete list to help illustrate how many of the things we take for granted depend on methane from natural gas:
Despite its widespread benefits, the extraction and application of methane has significant downsides, most notably its environmental impact.
Although it is a cleaner-burning fuel, its extraction, storage, and transportation processes inevitably result in leaks, known as fugitive emissions.
Methane is a potent greenhouse gas, trapping heat in the atmosphere approximately 25 times more effectively than carbon dioxide.
Fortunately, it has a much shorter atmospheric life than CO2—around 12 years, compared to over 100 years—even though it absorbs much more energy while it’s up there.
A wide range of prevention, detection, and remediation measures are being developed and deployed to help combat this source of avoidable environmental impact.
So, as an admittedly biased judge and jury, we're prepared to give methane time off for good behavior, freeing it to continue its great work with just a warning that it had better not get caught anywhere it's not supposed to be...
Tags: Natural Gas