UCG is promoted as a relatively clean method of exploiting coal seams that are too deep or thin to be tapped economically using conventional mining.

相对于传统的采矿技术来说，煤炭地下气化技术在开采过深或过浅煤层时更为适用，这种技术不仅开采成本较低，而且开采过程较为清洁。

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Conventional oil shale mining method has higher coat because of restricting by a good many factors.

常规油页岩开采方法，由于受诸多因素限制成本较高。

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