Non-economic and Non-commercial Fundamentals

Abstract

Natural gas is a natural product, consisting mainly of methane (CH4), whereby the state depends on temperature, pressure, specific volume, and its chemical composition. Compressed natural gas (CNG) is produced from natural gas by compression to approximately 200 bar. Liquefied natural gas (LNG) is natural gas that is cooled down to approximately −161.5 °C where methane liquefies. Propane and butane are also referred to as liquefied petroleum gas (LPG) . Together with ethane, LPGs, pentanes, and higher hydrocarbons are usually referred to as natural gas liquids (NGL). The most important parameters describing the combustion properties of natural gas are (gross) calorific value and Wobbe index . All gas-fired equipment and applications are designed (and sometimes fine-tuned) for a particular natural gas quality. Gas specifications are necessary to define the minimum quality requirements that natural gas has to fulfil. Production and use of natural gas has an impact on the environment. These environmental effects might be categorized according to the part of the ecosystem influenced. Climate effects, air pollution, water pollution, and land use do occur. In general, natural gas combusts cleaner than other fossil fuels. The source material for natural gas genesis is organic matter, e.g., marine microorganisms like algae. Natural gas fields are commercially recoverable accumulations of natural gas in the Earth’s crust. Conventional natural gas fields are not found in source rocks, but in reservoir rocks. A source rock is a sedimentary rock in which petroleum and natural gas are formed. A reservoir rock is generally any porous and permeable rock containing hydrocarbons. Reservoir rocks are predominantly sedimentary (sandstones and carbonates). Other than conventional reservoirs, which allow for economic production without massive stimulation treatments, unconventional sources show usually quite low permeabilities and can therefore only be produced at economic flow rates with the assistance of large stimulation treatments and special recovery technologies. Unconventional sources are tight gas sands, shale gas, and coal-bed methane. Anthropogenic production of ‘natural’ gas delivers biogas and coal gas. Natural gas offers a wide range of applications. In the residential and commercial segment, natural gas is mainly used for cooking, heating, and cooling. In the industrial segment, natural gas might be used for heating or as chemical feedstock. Technologies to produce electricity from natural gas in centralized power plants are steam turbines, combustion turbines, and combined cycles. Furthermore, natural gas is used in the transportation sector.