and desirable viscometric properties. Separator: Finally, the mixture from Reactor 4 is condensed to obtain gasoline. The non-condensed gas and gasoline are separated in a conventional condenser/separator. Most of the non-condensed gas from the product separator becomes recycled gas and is sent back to the feed stream to Reactor 1, leaving the synthetic gasoline product composed of paraffins, aromatics and naphthenes. Biological gas-to-liquids (Bio-GTL) With methane as the predominant target for GTL, much attention has focused on the three enzymes that process methane. These enzymes support the existence of methanotrophs, microorganisms that metabolize methane as their only source of carbon and energy. Aerobic methanotrophs harbor enzymes that oxygenate methane to methanol. The relevant enzymes are methane monooxygenases, which are found both in soluble and particulate (i.e. membrane-bound) varieties. They catalyze the oxygenation according to the following stoichiometry: CH4 + O2 + NADPH + H+ → CH3OH + H2O + NAD+ Anaerobic methanotrophs rely on the bioconversion of methane using the enzymes called methyl-coenzyme M reductases. These organisms effect reverse methanogenesis. Strenuous efforts have been made to elucidate the mechanisms of these methane-converting enzymes, which would enable their catalysis to be replicated in vitro. Biodiesel can be made from using the microbes Moorella thermoacetica and Yarrowia lipolytica. This process is known as biological gas-to-liquids. Commercial uses Using gas-to-liquids processes, refineries can convert some of their gaseous waste products (flare gas) into valuable fuel oils, which can be sold as is or blended only with diesel fuel. The World Bank estimates that over of natural gas are flared or vented annually, an amount worth approximately $30.6 billion, equivalent to 25% of the United States' gas consumption or 30% of the European Union's annual gas consumption, a resource that could be useful using GTL. Gas-to-liquids processes may also be used for the economic extraction of gas deposits in locations where it is not economical to build a pipeline. This process will be increasingly significant as crude oil resources are depleted. Royal Dutch Shell produces a diesel from natural gas in a factory in Bintulu, Malaysia. Another Shell GTL facility is the Pearl GTL plant in Qatar, the world's largest GTL facility. SASOL has recently built the Oryx GTL facility in Ras Laffan Industrial City, Qatar and together with Uzbekneftegaz and Petronas builds the Uzbekistan GTL plant. Chevron Corporation, in a joint venture with the Nigerian National Petroleum Corporation is commissioning the Escravos GTL