Gas to Liquids Techno-Economics of Associated Natural Gas, Bio Gas, and Landfill Gas

Abstract

Methane is the second highest contributor to the greenhouse effect. Its global warming potential is 37 times that of CO2. Flaring-associated natural gas from remote oil reservoirs is currently the only economical alternative. Gas-to-liquid (GtL) technologies first convert natural gas into syngas, then it into liquids such as methanol, Fischer–Tropsch fuels or dimethyl ether. However, studies on the influence of feedstock composition are sparse, which also poses technical design challenges. Here, we examine the techno-economic analysis of a micro-refinery unit (MRU) that partially oxidizes methane-rich feedstocks and polymerizes the syngas formed via Fischer–Tropsch reaction. We consider three methane-containing waste gases: natural gas, biogas, and landfill gas. The FT fuel selling price is critical for the economy of the unit. A Monte Carlo simulation assesses the influence of the composition on the final product quantity as well as on the capital and operative expenses. The Aspen Plus simulation and Python calculate the net present value and payback time of the MRU for different price scenarios. The CO2 content in biogas and landfill gas limit the CO/H2 ratio to 1.3 and 0.9, respectively, which increases the olefins content of the final product. Compressors are the main source of capital cost while the labor cost represents 20–25% of the variable cost. An analysis of the impact of the plant dimension demonstrated that the higher number represents a favorable business model for this unit. A minimal production of 7,300,000 kg y−1 is required for MRU to have a positive net present value after 10 years when natural gas is the feedstock.

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“…Gas flaring is avoidable and preventable through the use of technology (e.g., by installing low-bleed controllers, vapor recovery units, improved compressor seals) or the application of better maintenance and best practices programs. This often requires capital investment which makes them uneconomic or marginally economic (U.S. Energy Department, 2019) [23].…”

“…Several wells may be drilled and produced for a long time before a company determines the level of investment in production facilities and pipelines that will be required to meet economic standards. Thus, for gas flaring to stop, the volumes, pressures, and rates of associated gas production needs to be sustainable at levels that can economically justify installation of new gas gathering infrastructure or expansion of existing infrastructure [23].…”

“…The need to reduce and prevents over-pressure on industrial plant equipment. The gas is flared to avoid pressure buildup in crude oil, condensate (light liquid hydrocarbons recovered from lease separators or field facilities at associated and non-associated natural gas wells) [23].…”

Direct Catalytic Oxidation of Low-Concentration Methane to Methanol in One Step on Ni-Promoted BiOCl Catalysts

“…In the process of coal mining, coalbed methane, a companion organism with methane as the main component, will be produced . However, most coalbed methane has low concentration, low energy density, and difficult utilization. − Therefore, most of them are consumed by direct discharge into the atmosphere or natural gas flare. , Considering that the greenhouse gas effect of methane is more than 20 times that of carbon dioxide, these ways will cause a serious greenhouse effect and waste of resources. Therefore, it will be a good way to use low-concentration methane to form methanol by adding an oxygen atom to the methane molecule. , This not only prepares liquid fuel and improves energy density but also solves environmental pollution.…”

“… 8 However, most coalbed methane has low concentration, low energy density, and difficult utilization. 9 − 11 Therefore, most of them are consumed by direct discharge into the atmosphere 12 or natural gas flare. 13 , 14 Considering that the greenhouse gas effect of methane is more than 20 times that of carbon dioxide, 15 these ways will cause a serious greenhouse effect and waste of resources.…”