Natural Gas In A Nutshell

by Admin

in Energy In A Nutshell

Natural gas is a fast growing form of energy with a rapidly developing competitive market. Natural gas is by no means a “green energy”, but also counts as petroleum (together with oil and bitumen). Gas exploration is a hot topic as it involves highly toxic substances and often renders whole regions uninhabitable. It is very important to understand natural gas, with its regulatory dynamics, benefits, and challenges. This article gives an overview about how it is produced, distributed, and sold. All of this is very important knowledge for every Energy Risk Professional.

Natural gas consists of hydrocarbon molecules from one to four carbon atoms in length, but mainly of the hydrocarbon methane (CH4),  which is the smallest occurring hydrocarbon molecule.

The typical composition varies from field to field. The English unit of volume measurement for natural gas is the cubic foot (cf). In the metric  system, cubic metres (m3) are used for volume of gas.

As with crude oil, there is sweet and sour natural gas. Sweet natural gas does not contain any hydrogen sulfide (H2S). Sour natural gas does contain hydrogen sulfide (H2S). Hydrogen sulfide (H2S) does not count as an inert (impurity in natural gas). It is lethal and very corrosive, and it must be removed from the natural gas before it can be delivered to a pipeline.

In the ground, natural gas is often dissolved in crude oil because of high pressure in reservoir. As the pressure of the reservoir increases with depth, the amount of natural gas dissolved in crude oil increases with depth also. When crude oil is lifted to the ground, the pressure is relieved and the natural gas (solution gas) bubbles out. Nonassociated natural gas is not in contact with oil in the subsurface. A  nonassociated gas well produces almost pure methane. Associated natural gas is in contact with oil, occurring in the free gas cap above  the oil and in solution with the crude oil. Associated gas contains butane, propane, and ethane next to methane.

The heat content of natural gas is measured in British thermal units, Btu. One Btu is about the heat given off by burning one wooden match. Btu values of pipeline natural gas range from 900 to 1,200 Btus per cubic foot (cf), while the most common heat content for pipeline natural gas is 1,000 Btu/cf. The heat content varies with the composition.

There are about 179 Tm3 proven reserves of natural gas available which equals about 65 years of production at the present rate. Ultimate  reserves are estimated at about 360 Tm3. Most proven reserves are located in the Middle East and in the former USSR, but the main  markets are in Europe and the United States.

Natural gas extraction by countries in cubic meters per year.

Natural gas reserves remote from markets are called “stranded reserves”. They were viewed as a nuisance in the past, but as options for monetizing some of these stranded reserves (sometimes discovered decades ago) increase, they are being increasingly developed.

The preferred way of transporting natural gas is the pipeline.

Because it is a gas, it is about five times as costly to transport as oil. Natural gas can also be transported in liquid form as liquefied natural gas (LNG) or compressed natural gas (CNG), but both are more costly as they involve further processing. Market centers (hubs) exist near the intersection of several pipelines and provide customers (shippers and marketers) with receipt/delivery access to two or more pipeline systems. The best known, but not the largest, market center in the United Stated and Canada is the Henry Hub located in Erath, Southern Louisiana.

If it is not immediately needed, natural gas is stored in caverns (usually washed salt domes), depleted oil or gas reservoirs, aquifiers (water-bearing rock formations), or steel tanks. Demand for gas fluctuates seasonally and intraday. Operating storage is used by pipeline companies to balance short-term demand swings. It takes four days for natural gas stored on the U.S. Gulf Coast to reach the Northeast of the United States. Seasonal storage is used to accommodate for seasonal swings. Pipeline companies or local distribution companies own seasonal storage. A characteristic of the natural gas market is the alternating injection season (around March) and withdrawal season (around November), which heavily impacts price volatility.

The natural gas market is becoming more and more deregulated, and therefore more competitive. The main regulating agency is FERC (the Federal Energy Regulatory Commission). FERC is an independent agency in the United States that regulates the interstate transmission of natural gas, oil, and electricity. FERC also regulates natural gas and hydropower projects. Since 1993, FERC orders have provided for open-access storage service, the separation of  purchase and transportation services by interstate pipelines (“unbundling”), and deregulation of interstate pipeline sales sources, with only the market constraining rates. All of these actions have made natural gas more competitive compared to oil.

The main acts governing the gas market are:

  1. National Energy Conservation Policy Act. Required utilities to encourage customers to conserve energy.
  2. Power Plant and Industrial Fuel Use Act. Required power plant users to convert to coal, whenever possible.
  3. Public Utility Regulatory Policies Act (PURPA). Federal standards for termination of service, spurred development of cogeneration project  (simultaneous production of electricity and heat, more efficient).
  4. Natural Gas Policy Act. Gradually phased out curtailment measures.
  5. Energy Tax Act. Established tax credits for low-emission dwelling and transportation.

The main advantages of natural gas is its abundance and therefore its low price. Many natural gas reserves are found in the United  States, and are therefore viewed as one of the answers to the dependence on foreign oil.

The main problems with natural gas are:

  • Low energy density. High pressure is required to increase gas density and raise its energy content per unit volume so that the gas can be transported economically.
  • Storage. Large quantities of natural gas cannot be stored easily above ground as oil and coal can.

Natural gas exploration is very controversial as it is very harmful for the local flora and fauna, especially the method of hydraulic fracturing (hydrofracking) involving toxic “frakcing fluids”. Burning gas also still produces CO2, and is by no means an answer to the dependence on fossil fuel and global warming. Natural gas as a form of energy is therefore still only a half-hearted substitute for oil, and it remains to be seen how the unsolved problems of discovering and producing natural gas will impact its future as a form of energy.

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