Coalbed methane in the Ruhr Basin, Germany: a renewable energy resource?

Origin and secondary alteration of coalbed and adjacent rock gases in the Zonguldak Basin, western Black Sea Turkey

“…Furthermore, desorption which was initiated by the uplift of the coal seams during the last 42 million years may also have led to an enrichment of 13 C, as 12 C rich compounds are more mobile then 13 C-compounds. Hence, both bacterial oxidation and desorption can be considered for the reason of unusually heavy ethane, which is also observed in some other coal basins (Thielemann et al, 2004;Dai et al, 2005;Zou et al, 2006). It is inferred that isotopically lighter ethane formed by secondary bacterial gas generation is overwhelmed by heavier ethane, formed by bacterial oxidation and desorption processes.…”

“…Xu et al (1997) observed that the carbon isotopic composition of ethane and n-butane are influenced by the microbial activity. Thielemann et al (2004) also mentioned the oxidation of the ethane and propane compounds in a coalbed gases. Under suitable conditions straight-chain hydrocarbons are influenced from microbial oxidation and this causes 13 C enrichment in the remaining gases.…”

“…Hence, the uplift gave rise to desorption due to decreasing pressures of about 200 bars . Several authors have reported an isotopic shift towards positive values of methane, ethane and propane caused by desorption of coalbed gas (Gould et al, 1987;Xu et al, 1997;Sassen et al, 2004;Thielemann et al, 2004;Mahieu et al, 2006;Strapoc et al, 2006). Magnitude of isotopic fractionation in methane by desorption is given as ~2‰ (Strapoc et al, 2006).…”

“…Magnitude of isotopic fractionation in methane by desorption is given as ~2‰ (Strapoc et al, 2006). Experimentally, the isotopic shift during desorption within 14 months for ethane and propane in coals were obtained as +1.3 to +2.8‰ and +0.5 to +3.8‰, respectively (Thielemann et al, 2004). Consequently, desorption process can also be considered as one of the reasons of the heavier ethane.…”

Biomethanization of Coal to Obtain Clean Coal Energy: A Review

“…The water leached out from coal mines contain microflora which have been reported to produce methane (Thielemann et al, 2004). Contributions on methanogenic consortia have been made by several workers (Chang et al, 2005a;2005b;Kotsyurbenko et al, 2004).…”