Gas to liquid (GTL)- an Alternative to Harness Clean

Published On: February 2018

Overview

Gas-to-liquid (GTL) is a refinery process that converts natural gas or other gaseous hydrocarbons into longer-chain hydrocarbons such as gasoline or diesel fuel. The process converts methane-rich gases into liquid synthetic fuels by direct conversion or by using synthetic gas (syngas) as an intermediate through the Fisher Tropsch process.

In gas-to-liquid process, the natural gas is typically processed to remove impurities such as Sulfides, Mercaptans, and others, before being fed to the syngas generation unit. The cleaned feed gas is then fed to a syngas generation unit.

The first step in the GTL process is the conversion of natural gas (which is methane in most cases), to a mixture of hydrogen, carbon dioxide, and carbon monoxide. This mixture is called syngas. The syngas is cleaned to remove sulfur, water, and carbon dioxide, in order to prevent catalyst contamination. The F-T reaction combines hydrogen with carbon monoxide to form different liquid hydrocarbons. These liquid products are then further processed using different refining technologies into liquid fuels. The final products are diesel, kerosene, naphtha, waxes and lubricant oil.

Countries with richness of natural gas, are employing the gas to liquid production methodologies for economic growth to replace them with traditionally produced liquid fuels. Gas-to liquid-technology is a effective alternative to harness clean, abundant natural gas resources and produce high-quality petrochemical products and transportation fuels in a cost-effective and environmentally conscious manner.

Many organizations especially in Europe and Asia Pacific region have their own manufacturing units. Middle East & Africa form a major market for  gas-to-liquid. Royal Dutch Shell plc. (Netherlands), Chevron Corporation (U.S.), Sasol Limited (South Africa), PetroSA (South Africa), and Velocys Plc. (U.K.) have been recognized as global leaders with serving the quality products of gas to liquid.

In 2016, the natural gas production in the U.S. was 749.2 billion cubic metres, in volume. Currently, two GTL plants operate in the U.S. One of the plants is in Lake Charles, Louisiana, operated by Juniper GTL and is expected to produce 1,100 bpd of refined products, including waxes, drilling fluids, distillate and naphtha, from natural gas. Another plant, which is in Port of Ashtabula, Ohio, is operated by Velocys plc.

Qatar has built and commissioned significant GTL production capacity during the period from 2006 to 2012. Now, Qatar is one of the major markets for the gas-to-liquid sales. Currently, two GTL plants operate in Qatar. One of the plants, in Ras Laffan Industrial City, is operated by Oryx, a joint venture between Qatar Petroleum (51 percent) and Sasol of South Africa (49 percent). This plant is completed in December 2005. This plant has the capacity to produce 34,000 barrels of liquids (24,000 barrels of GTL diesel, 9,000 barrels of naphtha and 1,000 barrels of liquefied petroleum gas), per day. The second plant also in the same city, is operated by Qatar Petroleum and Shell. This plant produces 140 K barrels (22×103 m3/d) of petroleum liquids, per day and 120 k barrels of oil equivalent (730 TJ) into natural gas liquids and ethane.

In Mossel Bay town, South Africa, PetroSA, operates the GTL plant. It is the third largest GTL refinery, among all plants operating worldwide. It is capable of producing  an amount of crude oil that is equivalent to 45,000 barrels of GTL product, per day, which includes diesel, gasoline, kerosene and specialty products. Developed by Sasol and run by PetroSA, Mossel Bay cost USD 4 billion to build in 1992. Current production of GTL liquids is that of 40,000 barrels per day.

In Bintulu, Malaysia, Shell built the first medium-scale commercial GTL plants in 1993 using the Shell Middle Distillates Synthesis technology. The plant had a capacity of 12,500 barrels, a day, of GTL products at start, which increased to 14,700 barrels a day of GTL products in 2005. Approximately, 95 per cent of Shell GTL products from this plant are exported, worldwide.

Rising environmental considerations

Consumers are generally seen shifting to new and innovative products for better experience and more convenience. At present, the demand for energy is increasing continuously and the growing world population has necessitated the development of alternate energy sources, which has reduced the burden on conventional sources. With the rising environmental considerations of conventional sources of energy, clean sources of energy are needed for reduced carbon footprint.

Rising transportation requirements in numerous nations is further expected to foster gas to liquid technology development. The sector currently consumes over a fifth of global energy supply, and is expected to be driven by increasing affordable motor vehicles sales. Abundant natural gas reserves, which can be developed at a relatively low-cost offers ample opportunities for market participants, as well. Increasing development of smaller sized micro-channel reactors in Asia Pacific nations such as China, Japan, and India, is likely to foster the gas-to-liquid industry.