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Virginia Natural GasNatural gas is a versatile fuel, which adapts to a wide range of uses. Residential, commercial, and industrial energy users located throughout Virginia and the nation rely on natural gas to meet a portion of their energy needs.
Throughout the 1990s, Virginia's natural gas production grew rapidly, both in absolute terms and relative to the state's energy needs. In the southwestern Virginia counties where Virginia natural gas is produced , gas production and development activities are substantial contributors to the local economy.
The predominant chemical component of natural gas is methane, CH4 . Two major types of natural gas are produced in Virginia. Both are considered "fossil fuels," the remains of living creatures that inhabited the earth millions of years ago. "Conventional" natural gas is extracted from geologic formations that give rise to petroleum deposits and formations with similar characteristics. These formations are generally several thousand feet below the earth's surface. Petroleum is often produced in association with conventional natural gas. In Virginia, petroleum byproducts are extracted from conventional gas production wells but only in small quantities.
The other form of natural gas produced in Virginia, called "coalbed methane," occurs in association with coal deposits. Methane (CH4) is emitted by coal via an "outgassing" process. Methane can be a hazard in underground coal mines because it is easily ignited. "Coalbed methane" extraction produces marketable product by extracting gases from coal deposits that would otherwise be released into the mine or the atmosphere, if that coal were mined. To produce coalbed methane, a producing firm drills through the earth into an underground coal seam, in a manner similar to the drilling of a water well. When the coal seam is accessed, high-pressure gases are injected into the well down with the goal of fracturing the coal seam. Exposure of the fracture surfaces releases the methane gas, which is then withdrawn from the well.
Both conventional gas and coalbed methane withdrawn from wells receive additional processing prior usage in homes and businesses. From the well, the extracted gas is fed into a system of piping, known as "gathering lines," which connect the wells to facilities that process the raw gas into a marketable commodity. During processing, excess moisture and corrosive gas contaminants (such as hydrogen sulfide, H2S, and ammonia, NH3) are removed and the resulting product is checked for energy content. Natural gas sold in commercial markets has a minimum energy content of 1000 Btus per cubic foot. If the natural gas being processed is found to contain energy well in excess of that minimum, that gas may be diluted so as to attain the commercial energy-content standard. The processing facility also monitors incoming and outflowing gas to assure that product with energy contents below the commercial standard is not entered into the distribution system.
Virginia's natural gas production has increased dramatically in recent years, from less than 20 million cubic feet in 1970 to more than 85 million cubic feet in 2004. Most of this increase has occurred due to expansion of coalbed methane production in Buchanan and Dickenson counties, as conventional gas production has increased only modestly during the decade. Large portions of that coalbed methane was produced in association with operating coal mines, as extraction in advance of mining helps to maintain safe conditions in the mines by withdrawing the potentially explosive methane gases.
The majority of Virginia's natural gas is supplied from a network of interstate pipelines that connect the nation's major gas producing areas, including Louisiana, Texas, and the Gulf of Mexico, to northeastern population centers such as New York, Boston, and Washington DC. Because Virginia is located along these pipeline routes, large quantities of gas move through the state .
After processing, Virginia gas production is fed into the interstate pipeline network; some Virginia-produced gas is marketed through pipelines located in adjacent states, although the majority goes to in-state pipelines. Gas distribution utilities and industrial customers withdraw gas from that interstate pipeline network; the distribution utilities supply natural gas to homes and small businesses within their service areas .
The late 1990s have seen a rapid expansion of demand for natural gas throughout the nation, and within Virginia. As a result, several new pipelines have been proposed for construction in Virginia. Proposed pipeline routes include an extension of a pipeline currently terminating in Radford to Roanoke and Franklin County; the Greenbrier pipeline project that would extend from North Caroline to West Virginia, passing through Virginia along a path extending from Henry to Giles and Bland Counties; and the Patriot Extension pipeline that would extend from Henry to Wythe County.
Because space heating is a major use for natural gas, the bulk of gas consumption occurs during the winter months. Therefore, prices tend to be higher during the winter heating season than during other times of year. Purchasing gas during summer months for use in winter is a logical business strategy for firms that have access to large empty spaces that can be used for gas storage. Unfortunately, facilities and structures suitable for gas storage are not common. In Saltville, Smyth County, large underground caverns in the geologic salt deposits are being developed into Virginia's only major gas-storage facility.
Because of its characteristics, natural gas is a versatile fuel. Unlike coal and petroleum, natural gas can be moved easily and at low cost to purchaser locations through pipelines. Combustion devices are generally tied directly to the pipeline transportation system, eliminating need for on-site storage at the point of consumption. Burner devices are simple and inexpensive to construct and operate. The consumer is not required to physically handle the fuel. Burning the fuel itself results in only minimal production of potential air contaminants, so pollution control equipment is generally not required. In addition, natural gas produces less carbon dioxide (CO2) per unit of energy released than either of the other two principal "fossil fuels," coal and petroleum.
Because it is a versatile fuel, natural gas meets a wide range of energy uses. In Virginia, the industrial, commercial, and residential sectors are all major gas consumers , with each accounting for 20 percent or more of total gas usage. The primary residential and commercial uses are space heating, water heating, and cooking. Industrial uses include process heating and chemical feedstock.
Electric utilities also consume natural gas as a fuel for electric generation. Gas consumption by electric utilities is rising rapidly, having more than tripled during the 1990s. Use of gas for electrical generation is expected to continue rising, as new gas generation facilities are proposed for construction in several Virginia locations.
Virginia Natural Gas Flow Diagram, 2005
(Million Cubic Feet)
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