What Is Natural Gas? Definition, Facts and Figures

What Is Natural Gas? Definition, Facts and Figures

by | Educational, Energy, Natural Gas

Natural gas is a combustible hydrocarbon gas that occurs naturally on Earth. In its pure state, it’s odorless and has no shape or color — not exactly exciting so far. 

Natural gas is mainly methane and carbon dioxide (CO₂), and as a fossil fuel, its emissions harm the Earth. But this simplified explanation cloaks the controversial use of natural gas.  

Let’s look at how natural gas has affected — and continues to shape — humanity’s relationship with climate change, our energy demands, and the natural world.  

What Is Natural Gas?  

Looking at natural gas in more detail, we know it’s a naturally occurring hydrocarbon. Natural gas is found underground and often associated with other fossil fuels. Before refinement, Naturalgas.org states that natural gas consists of: 

  • Methane (70-90%) 
  • Carbon dioxide (up to 8%) 
  • Ethane, butane, and propane (each between 0-20%) 
  • Hydrogen sulfide (0-5%) 
  • Nitrogen (0-5%) 
  • Traces of oxygen, pentane, and other rare gases 

Some of those different natural gas elements may be familiar. Many grills are powered by butane, and propane heats water and powers barbecues. 

Are Gas and Natural Gas the Same? 

A lot comes down to how we use the words. On most occasions, gas is not the same as natural gas. 

Natural gas is a fossil fuel and is sometimes, confusingly, called gas. Natural gas is found underground with petroleum, also known as crude oil. 

In North America, people often say “gas” when talking about gasoline for their cars and vehicles. This “gas” is not a gas at all, but a liquid made from petroleum (crude oil).  

So, the short answer is no, gas and natural gas are not the same, albeit this is more about how people use the word than the technical definition.  

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How Are Gas and Natural Gas Different? 

Firstly, there are many similarities between petroleum (gas/crude oil) and natural gas. 

Both are non-renewable energy sources found underground, and both emit greenhouse gases when used in power plants. They are considered fossil fuels, along with coal, and they were both formed millions of years ago from the remains of plants and fossils. Natural gas and crude oil are processed to create useful byproducts, such as gasoline for vehicles. 

Their differences are stark. Natural gas is an odorless, colorless gas comprised mainly of methane. It remains a vapor at the surface and underground, and it produces fewer pollutants than other fossil fuels when burned. 

On the other hand, gas (petroleum or crude oil) is a dense and viscous liquid found both underground and at the Earth’s surface. It’s composed mainly of hydrogen and carbon 

How Is Natural Gas Used? 

The predominant use of natural gas is to create electricity at power plants.  

The Energy Information Administration (EAI) lists the United States’ five main uses of natural gas in 2019 as: 

  • Generate electricity (36%): burned gas drives generators to create electricity. 
  • Industrial use (33%): as a heat source and for manufacturing a wide range of goods. 
  • Residential (16%): heating homes, water, and cooking. 
  • Commercial (11%): heating buildings, water, and combustion. 
  • Transportation (3%): fuel for gas-fuelled vehicles in liquefied natural gas form (LNG). 

Natural gas is considered the cleanest of fossil fuels. A new natural gas power plant emits around 30% less carbon dioxide than one burning crude oil and 50-60% less carbon dioxide than a new coal-powered plant. 

The world’s natural gas production was 2,500 billion cubic meters (88,286 billion cubic feet) in the year 2000. That figure shot up to 3,700 billion cubic meters (130,664 billion cubic feet) in 2010. Increases are leveling off, but the market continues to grow, with more than 4,000 billion cubic meters (141,258 billion cubic feet) of gas produced in 2019 to meet demand. 

What Are the 3 Biggest Uses of Natural Gas? 

Natural Gas Defined Definition Meaning - image of Gas industrialsource

As we’ve seen, the three main uses of natural gas are generating electricity, heating (homes and commercial properties), and powering industrial processes and manufacturing. 

Electricity is generated at power plants powered by burning natural gas. When heating our homes or business premises, a gas pipeline network transports natural gas to our buildings, which is then burned in the properties to heat water and power heating systems. 

In manufacturing, natural gas is an ingredient in fertilizer, plastics, pharmaceuticals, and more. Many industrial processes, such as making bricks, glass, steel, and many more commodities, require heat. Natural gas is a chemical feedstock — a raw material used to fuel machines and processes — in plastic production. Lots of chemicals are also manufactured with natural gas, from propane to ammonia. Industrial facilities also use natural gas for incineration 

What Are the 4 Natural Gases? 

The four principal gases that make up natural gas are methane, ethane, butane, and propane.  

The amount of each gas present in natural gas reserves varies for each natural gas resource.  

Where Does Gas Come From? 

Natural gas is present in the atmosphere and is stored in natural gas reserves underneath the Earth’s surface. There are three ways that natural gas forms. 

The first way produces what is called thermogenic methane. Natural gas is a fossil fuel and forms in the same way as coal. As plants and any organic material die and decompose, they drift to the bottom of lakes and swamps, undergoing chemical changes until forming peat deposits. This peat eventually gets buried, over many millions of years, underneath many layers of sediment. 

The peat is under tremendous pressure and heat, thanks to the sediment layers above. The peat undergoes several transformations until it turns into crude oil or the anthracite coal we use today. During this coal production, methane gas is produced as a by-product of the decomposing organic material. The pressure of the sediment layers above prevents the methane and natural gas from escaping and rising to the Earth’s surface. 

The deeper the deposit, the higher the temperature and pressure exerted by the sediment layers. At lower temperatures, nearer the earth’s surface, more oil is produced than natural gas. In deeper reserves, more gas forms than oil — some very deep reserves are only methane. 

Biogenic methane is created by methanogens, tiny methane-producing microorganisms that live in animal and human intestines, and places without oxygen. Those cows breaking wind, blamed for adding methane to the atmosphere? That’s their biogenic methane. Landfill sites are also new sources of biogenic methane. The oceans contribute around 2% of global methane emissions, and methane also comes from rice paddies. 

The final way natural gas forms is through abiogenic processes, whereby hydrogen-rich gases buried deep underground interact with minerals in oxygen-free environments. Under very high pressure, this can create natural gas, in a process similar to thermogenic methane. 

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How Do We Get Natural Gas? 

Some gas reserves are close to the surface and can rise through shale and loose rocks and dissipate into the general atmosphere. However, most natural gas resources are trapped between rock formations under the earth’s surface.  

Extensive natural gas deposits meet the rising global demand for gas supplies. These gas deposits — known as reservoirs — form when methane tries to rise to the surface and becomes trapped under dense, impermeable rock layers. The most common impermeable rock cap takes the shape of a dome. 

Geologists look for natural gas reservoirs using several techniques. One is to look for shale rocks because gas gets trapped within shale formations. Horizontal drilling and hydraulic fracturing, also known as fracking, can release what is called shale gas. 

A second method is to drill down into the earth’s surface. Bores, sometimes thousands of feet long, are drilled into many holes several miles apart, helping geologists map the area’s rock formations. 

After identifying a reservoir, gas companies drill down into the impermeable rock. The gas is under pressure and rises to the surface without any need for extraction. Beneath the gas is oil, and sometimes there is water beneath that, too. 

How Is Natural Gas Extracted? 

How to Extract Natural Gas - image of Gas risingsource

There are several ways to extract natural gas, and the method employed depends on the deposit type. 

A conventional gas extraction involves a company drilling a straight bore down into impermeable rocks into the natural gas reserve. Once the “cap” or “dome” of the rock is breached, the natural gas rises to the surface. A processing plant separates the gas from liquids such as crude oil and water. It then further processes the gas to achieve regulatory compliance. 

Unconventional gas is a broad name given to natural gas that is harder to extract because it is technically challenging or too expensive to access.  

There are six types of unconventional gas: 

  • Deep gas: Reservoirs found typically more than 15,000 feet below the Earth’s surface, making it expensive to reach them. 
  • Tight gas: Gas trapped under an unusually hard impermeable rock so it is tricky and expensive to extract. 
  • Shale gas: Found within shale deposits, a soft, fine-grained sedimentary rock, and a significant extraction growth area for natural gas companies. 
  • Coalbed methane: Gas trapped in coal during the coal’s formation. The scourge of coal miners, coalbed methane release can result in mine explosions. 
  • Geopressurized zones: Usually found at depths of 10,000-25,000 feet, high pressure squeezes gas into surrounding silt and sand. There are large stores of gas in geopressurized zones, but they are costly and challenging to extract. 
  • Arctic and subsea hydrates: Recently discovered methane molecules frozen into Arctic permafrosts or found under sea beds, these industries are in their infancy. Arctic permafrost releases methane when it defrosts. 

Shale gas requires hydraulic fracturing — or fracking — to extract it because the natural gas is within the shale deposits rather than in a reservoir. Water, chemicals, and sand are pumped into a well, opening cracks and fractures in rocks, allowing trapped natural gas to flow into the well. Engineers use horizontal drilling to maximize extraction. A vertical well drills downwards, then the drill bit turns horizontally to drill into the shale deposit. 

Does Natural Gas Rise or Fall? And What Does That Mean? 

Natural gas rises because it is lighter than air. Its composition of predominantly methane gas is lighter than our oxygen-rich atmosphere. Over time, methane rises above oxygenated air. 

How Much Natural Gas Is Left?  

According to the U.S. Energy Information Administration, there was an estimated 7,177 trillion cubic feet (Tcf) of gas reserves in the world as of January 1, 2019. This figure comes from gross proven reserves. 

Russia holds around 24% of those reserves, and Iran about 17%, with Qatar owning 12.5%, and the United States around 5.3%. 

Demand for natural gas in 2019 was 4,000 billion cubic meters (141,258 billion cubic feet), so there is still plenty of natural gas left on Earth. 

To put that into perspective, let’s first make a few cups of tea. It takes one British Thermal Unit (Btu) to heat one-pound (453ml) of water one degree. If we take one pound of room temperature water (68 degrees Fahrenheit) and boil it (212 degrees Fahrenheit), we need to increase its temperature by 134 degrees Fahrenheit. This uses 134 British Thermal Units (Btu) to get the pound of water ready to make around two cups of tea. 

Every cubic foot of gas is equivalent to 1,037 Btu — so one cubic foot of gas would boil about seven individual pounds (453ml) of water. Even though there are trillions and trillions of cubic feet of natural gas left — and lots of cups of tea — there are around 52 years of natural gas left, based on current annual consumption.  

Is Natural Gas Considered Clean Energy? 

Natural Gas Clean Energy | Clean Fuelsource

As the issue of climate change gathers pace, more and more people favor a “green revolution” of combining energy efficiency powered by renewable energy sources, forgoing traditional fossil fuel-based power stations. There is no getting away from the fact that natural gas is a fossil fuel. Still, the overall answer is a little more complicated. 

Natural gas is the cleanest burning of the three fossil fuels (gas, oil, and coal), releasing energy efficiently and providing us with cheap and reliable power. Emissions include water vapor and nitrogen oxides, but the nitrogen oxides get emitted at a much lower level than with gasoline and diesel used for vehicles. 

Burning natural gas produces less carbon dioxide than burning oil or coal but it’s not as clean as renewables like solar or wind power. Some human activities produce methane — landfill, sewage — and industries have started capturing this methane. It is then burned to power electricity generation. Methane from ponds and even cow manure now powers homes, businesses, and cars. 

Natural gas does seep out during its extraction. These spillages go straight into the atmosphere or pollute the local environment. Natural gas is mainly methane, and methane contributes to global warming, trapping heat thirty times more effectively than carbon dioxide. This methane disappears after around ten years. Unfortunately, it then turns into carbon dioxide, so it continues to heat the world. 

Fracking is also a controversial extraction method. Many local communities and protest groups campaign against fracking, claiming it pollutes the environment and water supplies, wastes water, and much more. 

Natural gas, therefore, cannot be considered clean energy in the way wind, solar, or geothermal energy are. 

What Does the Future Hold for Natural Gas? 

Demand for natural gas continues to rise, albeit more slowly than before, while global gas prices are, in general, falling. There’s a little more than 50 years of natural gas supplies remaining at current consumption levels. Industry and consumers are accustomed to the ease, reliability, and relatively low natural gas prices. It has spread into all corners of our lives, from heating our homes to powering our manufacturing processes. 

Capturing and using naturally-created methane to create electricity is one way to help the planet. It is much better than drilling deep into the ground to release natural gas we would be better off not using. Once natural gas runs out, we will have to look for alternative energy sources anyway. 

Using up all our natural gas resources without finding an alternative energy source would bring about a seismic lifestyle shock. The continual release of methane and other gases due to human activity adds to the climate change issues the world is facing. Add in the controversy about fracking and environmental concerns, and the demand for greener energy solutions will continue. 

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