Coal-to-Synthetic Natural Gas Efficiency and Performance

The economic viability of producing synthetic natural gas (SNG) through coal gasification is heavily dependent on the market prices of natural gas and the coal feedstock to be used, in addition to the capital cost of the gasification plant. Costs of producing SNG via gasifying coal were estimated by the 2007 interdisciplinary MIT study to be from 6.7 to 7.5 dollars per million Btus.¹

Process Efficiency
Plant process flow schemes for producing SNG from coal via gasification are described in the page on Coal-to-SNG Process Descriptions. Table 1 lists some of the published plant performance and efficiencies of the various coal-to-SNG design configurations.  The data contained in this table is taken from references 2 and 3.

* SNG exported at 250-300 psig, not including compression to pipeline pressure.
** Import power thermal energy assumes 32.8% coal-to-power conversion efficiency.

Table 1: Coal-to-SNG Process Performances

The Great Plains Synfuels Plant, which has seen gradual process improvements throughout the 25 years of operation, has an overall higher heating value (HHV) efficiency of 64.7%.  This is based on 18,500 tons of lignite per day with a 6,900 Btu per lb HHV as an input and an output of 170 million standard cubic feet (scf) per day of SNG with an HHV of 972 Btu per cubic foot. In 2000, two large compressors were installed for transporting 105 million (scf) of compressed CO₂ (60% of the total CO₂ produced at the plant) through a 205 mile pipeline to Canadian oil fields for enhanced oil recovery (EOR). Operations during 2007 demonstrated an overall plant capacity factor of 90%.

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