Special Issue on PSE Advances in Natural Gas Value Chain: Editorial

Abstract

N atural gas (NG) is the cleanest fossil fuel. It is the bridging fuel of choice and the fastest growing energy source globally, as the world transitions from fossil fuels to renewables in the coming decades. The 2018 Outlook for Energy (ExxonMobil, 2018) projects the NG demand to increase by 40% from 2016 to 2040, as NG gradually displaces coal as the preferred fuel for power generation around the world. The liquefied form of NGnamely, LNGis the most economical means for transporting NG over long distances, as necessitated by the limited sources of NG. LNG is the fastest growing gas supply source (Shell LNG Outlook, 2018) with global demand expected to increase 4% annually (versus 1% for energy and 2% for NG) from 2017 to 2035. The abundant resources of and exciting prospects for NG/LNG along with the urgent need to mitigate carbon dioxide emissions are prompting researchers around the world to address a host of issues related to the NG value chain. This special issue provides a timely focus to some efforts that employ process systems engineering (PSE) approaches.NG recovered from a hydrocarbon field is typically transported via pipelines to a plant for pretreatment and/or upgrading to pipeline specifications. If the demand is local, then distribution grids supply the gas to the end consumers such as residences, power plants, and industries. If the demand is regional, then high-pressure transmission lines send the gas (piped natural gas (PNG)) to distant distribution grids. However, if the demand centers are global and far away, then marine transport as LNG is more economical than land transmission as PNG. In this case, the plant hosts an energyintensive liquefaction facility to produce the high-energydensity LNG and an export (loading) terminal to store it in atmospheric storage tanks at approximately −160 °C. LNG tankers then carry LNG in large heavily insulated specialized cargo tanks to import (receiving) terminals around the globe. An import terminal unloads and stores the LNG cargos into atmospheric storage tanks, and regasifies LNG continuously to send out NG at elevated pressures to local distribution grids. NG from the distribution grids is normally used for power generation or heating, but it can also be a feedstock for producing chemicals and petrochemicals. In summary, the NG value chain comprises steps such as recovery,

Membrane-Assisted Removal of Hydrogen and Nitrogen from Synthetic Natural Gas for Energy-Efficient Liquefaction

“…SNG can be transported in both gaseous and liquid forms. In the gaseous form, it can be transported through a web of distribution pipelines, while in the liquid phase it can be easily transported over long distances (more than 3500 km) through cargo shipping [9,10]. To liquefy SNG, impurities such as CO 2 , CO, and low boiling point contaminations (H 2 and N 2 ) should be removed.…”

Economic Feasibility of Power Generation by Recovering Cold Energy during LNG (Liquefied Natural Gas) Regasification

“…Countries endowed with surplus NG reserves export it as piped natural gas (or PNG) via pipeline, CNG (compressed natural gas) in high-pressure cylinders, or LNG (liquefied natural gas) in cryogenic tankers. Among these alternatives, LNG is the preferred mode for long-distance transport (typically above 3500 km) since liquefaction decreases the volume of NG by a factor of about 600 . The annual growth rate of LNG trade has been nearly twice that of PNG, with LNG accounting for about 10% of global NG consumption and 31% of global NG trade .…”

“…Although seawater is a free heat source, large volumes are required, and pumping incurs significant electrical energy. Cryogenic LNG is a rich source of cold energy, which is completely wasted when seawater is used for its regasification . Instead of dumping into the sea, a sustainable approach should be to recover the available cold energy during the LNG regasification process.…”

“…Among these alternatives, LNG is the preferred mode for long-distance transport (typically above 3500 km) since liquefaction decreases the volume of NG by a factor of about 600. 2 The annual growth rate of LNG trade has been nearly twice that of PNG, with LNG accounting for about 10% of global NG consumption and 31% of global NG trade. 1 As more countries opt for LNG as the energy source, particularly where PNG is not a feasible option owing to economic or geographical limitations, LNG trade is projected to increase from about 12 Tcf in 2012 to 29 Tcf in 2040.…”

“…Cryogenic LNG is a rich source of cold energy, which is completely wasted when seawater is used for its regasification. 2 Instead of dumping into the sea, a sustainable approach should be to recover the available cold energy during the LNG regasification process. Kanbur et al 6 presented a comprehensive review of processes that can benefit from utilizing the LNG cold energy.…”