Patent ID: 8137030

Claim:
A method comprising: (a) introducing a slurry into an underground geological formation under conditions such that the slurry produces methane; and (b) collecting the methane; wherein (c) the slurry introduced into the underground geological formation is obtained from sewage sludge that has been processed with sufficient heat at a temperature of between 150° C. to 315° C. and pressure of between 400 psi to 1200 psi in order to: (1) rupture biological cells contained in the sewage sludge, thereby freeing water trapped in the cells, reducing the viscosity of the sewage sludge such that the slurry has a viscosity between 30 cP and 2600 cP, and reducing the size of particles contained in the sewage sludge such that at least 95% of particles contained in the slurry are less than 300 micrometers in size; and (2) reduce the amount of water in the sewage sludge converted to steam during the processing.